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Classifications

Harrison's Chapter

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Definitions

1

Critical-Sample Biochemical Criteria for Hyperinsulinemic Hypoglycemia

The diagnosis is made from a critical sample — blood drawn at the moment of documented hypoglycemia (plasma glucose below about 50 mg/dL / 2.8 mmol/L), before glucose is given. The logic is not whether the insulin is high, but whether insulin action is detectable when it should be zero, which is why the suppressed-fuel markers carry more weight than the insulin assay.

DIAGNOSTIC_CRITERIA Applies to neonates, infants and children with recurrent or persistent hypoglycemia. A sample drawn within the first 72 hours of life may reflect physiological transitional hypoglycemia and should be repeated after 72 hours if hypoglycemia persists.

Inclusion criteria

Documented hypoglycemia at the time of sampling Plasma glucose below 50 mg/dL (2.8 mmol/L) when the sample is drawn.
Inappropriately detectable insulin and C-peptide Measurable plasma insulin with a concordant C-peptide at that plasma glucose.
Suppressed beta-hydroxybutyrate Plasma beta-hydroxybutyrate below approximately 1.8 mmol/L.
Suppressed free fatty acids Plasma free fatty acids below approximately 1.7 mmol/L.
Excessive glucose infusion requirement Intravenous glucose infusion above 8 mg/kg/min needed to maintain normoglycemia (normal requirement is 4-6 mg/kg/min).
Positive glycemic response to glucagon Rise in plasma glucose of more than 1.5 mmol/L (roughly 30 mg/dL) from baseline after intramuscular or intravenous glucagon given during hypoglycemia.

Exclusion criteria

Elevated free fatty acids with low ketones Redirects the diagnosis to a fatty acid oxidation disorder.
Elevated insulin with suppressed C-peptide Indicates exogenous (administered) insulin rather than endogenous hyperinsulinism.
Lactic acidosis with hepatomegaly and a ketotic response Suggests a hepatic glycogen storage disorder.
Cortisol or growth hormone deficiency Counter-regulatory hormone deficiency must be excluded on the same critical sample.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"In any patient with recurrent or persistent hypoglycaemia, HH should be suspected and critical samples at the time of hypoglycaemic episodes should be collected."

Establishes the critical-sample approach as the basis of biochemical diagnosis.

PMID:29280746 SUPPORT Human Clinical

"An intravenous glucose infusion rate requirement of >8 mg/kg/min (normally is 4-6 mg/kg/min) is virtually diagnostic of HH"

Provides the glucose-infusion-rate inclusion criterion.

Notes: The numeric beta-hydroxybutyrate (1.8 mmol/L) and free fatty acid (1.7 mmol/L) cut-points are those of the 2023 international consensus guideline (PMID:37454648); they appear in the guideline body rather than in its PubMed abstract, so they are recorded here as provenance and are not quoted as evidence snippets.

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Inheritance

3

Autosomal recessive HP:0000007

Biallelic recessive ABCC8 or KCNJ11 variants cause severe, usually diazoxide-unresponsive diffuse hyperinsulinism; recessive HADH deficiency is also inherited this way.

Autosomal recessive inheritance

Autosomal dominant HP:0000006

Monoallelic dominant ABCC8/KCNJ11 variants cause milder, often diazoxide-responsive disease; dominant activating GLUD1 and GCK variants and heterozygous HNF4A/HNF1A and SLC16A1 promoter variants are also dominant.

Autosomal dominant inheritance

Somatic mosaicism with parent-of-origin effect HP:0001442

Focal hyperinsulinism is a two-hit, parent-of-origin disorder: a paternally inherited recessive ABCC8/KCNJ11 variant is unmasked within a pancreatic clone by post-zygotic loss of heterozygosity for the maternal 11p15 allele with reduplication of the paternal allele (segmental paternal isodisomy). The germline variant alone is insufficient; the lesion is defined by the somatic second hit. Atypical/mosaic (LINE) disease similarly arises from somatic ABCC8 or GCK variants.

Somatic mosaicism

Parent-of-origin effect: Paternal origin of the germline K-ATP variant is required: the causal somatic second hit is loss of the maternal 11p15 allele with paternal isodisomy, so only a paternally inherited variant can be rendered homozygous within the lesion.

Show evidence (1 reference)

PMID:25765446 SUPPORT Human Clinical

"The epigenetic alteration at the 11p15 region plays a central role in developing focal CHI by paternally derived mutations of the KATP channel and maternal allelic loss at this region."

Establishes the two-hit, parent-of-origin mechanism (paternal K-ATP variant plus somatic maternal 11p15 loss) that defines focal disease.

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Subtypes

9

Diffuse Hyperinsulinism MONDO:0015625

Whole-pancreas involvement in which every islet is abnormal, typically from biallelic recessive (or some dominant) ABCC8/KCNJ11 variants. Diffuse disease accounts for roughly 60% of congenital hyperinsulinism, is disproportionately diazoxide-unresponsive, and — critically — is NOT surgically curable: near-total (90-98%) pancreatectomy controls but does not cure hypoglycemia and imposes a very high later burden of diabetes and exocrine insufficiency.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Diffuse disease accounts for about 60% of all CHI cases and affects all the b-cells of the pancreas."

Quantifies diffuse disease as the majority histological form and defines its whole-pancreas extent.

PMID:39741883 SUPPORT Human Clinical

"After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."

Contrasts the non-curative outcome of surgery in diffuse/atypical disease with cure in focal disease.

Focal Hyperinsulinism (paternal K-ATP variant + somatic maternal 11p15 LOH) MONDO:0019265

A discrete (typically 2-10 mm) region of adenomatous islet-cell hyperplasia in an otherwise normal pancreas. Focal disease is a two-hit lesion: a paternally inherited recessive ABCC8 or KCNJ11 variant becomes homozygous within the lesion because of post-zygotic loss of heterozygosity for the maternal 11p15 allele with paternal isodisomy, which simultaneously unmasks the K-ATP defect and — because the imprinted 11p15 domain is now paternal-only (IGF2 up, H19/CDKN1C down) — drives clonal beta-cell proliferation. This is the single most management-relevant subtype distinction in the disorder: the lesion is localizable by 18F-DOPA PET/CT and a limited lesionectomy is curative, sparing the child a near-total pancreatectomy and its diabetes risk.

Show evidence (2 references)

PMID:25765446 SUPPORT Human Clinical

"MS-MLPA and microsatellite analyses demonstrated abnormal imprinting patterns and focal loss of maternal 11p13-15 within the lesions. In contrast, parental heterozygosity was preserved in the normal tissue."

Demonstrates directly that the maternal 11p15 loss is somatic and confined to the lesion, with normal pancreas retaining heterozygosity.

PMID:39741883 SUPPORT Human Clinical

"After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."

Confirms that focal disease, unlike diffuse disease, is surgically curable.

Atypical / Mosaic Hyperinsulinism (LINE)

A third histological category, intermediate between focal and diffuse, in which abnormal beta cells occupy regional or mosaic territories (localized islet nuclear enlargement, LINE). It can arise from somatic ABCC8 or GCK variants or from inappropriate beta-cell HK1 expression. Surgical outcome is less predictable than in focal disease.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Histologically, CHI is classified into three subgroups: diffuse, focal and atypical forms"

Establishes atypical disease as a recognised third histological subgroup alongside diffuse and focal.

Hyperinsulinism-Hyperammonemia Syndrome (GLUD1) MONDO:0011717

Dominant activating GLUD1 variants that escape GTP inhibition of glutamate dehydrogenase, giving leucine/protein-sensitive hyperinsulinism together with a persistent mild hyperammonemia that is close to specific for this subtype. Usually diazoxide-responsive, and managed additionally by protein/leucine restriction.

Show evidence (2 references)

PMID:21130127 SUPPORT Human Clinical

"the hyperinsulinism/hyperammonemia syndrome caused by dominant activating mutations of GLUD1 which interfere with inhibitory regulation by GTP"

Defines the GLUD1 activating-variant basis of the HI/HA subtype.

PMID:21130127 SUPPORT Human Clinical

"The other distinctive feature of the HI/HA Syndrome is a persistent elevation of plasma ammonia concentrations."

Establishes persistent hyperammonemia as the subtype-defining biochemical feature.

Diazoxide-Responsive Hyperinsulinism

Hyperinsulinism that is controlled by diazoxide. Because diazoxide acts by binding SUR1 and holding the K-ATP channel open, responsiveness requires a structurally and functionally intact channel. Diazoxide-responsive disease therefore concentrates the non-K-ATP etiologies (GLUD1, HADH, HNF4A/HNF1A, SLC16A1, UCP2) and the perinatal-stress/transient forms.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Diazoxide functions by binding to the SUR1 subunit of KATPchannel. Thus, it requires a functionally intact KATPchannel."

Explains mechanistically why diazoxide responsiveness partitions the disorder along the K-ATP-intact versus K-ATP-defective axis.

Diazoxide-Unresponsive Hyperinsulinism MONDO:0017186

Hyperinsulinism that fails maximal diazoxide therapy. This is the pharmacologically predictable consequence of the drug's target being broken: recessive (and some dominant) ABCC8/KCNJ11 loss-of-function variants leave no functional channel for diazoxide to open. Diazoxide unresponsiveness is therefore the clinical trigger for urgent ABCC8/KCNJ11 sequencing and, when a single paternal variant is found, 18F-DOPA PET to look for a curable focal lesion.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"In diazoxide unresponsive CHI cases, urgent genetic analysis forABCC8/KCNJ11and18F-DOPA-PET/CT scan are indicated to identify those patients who could have the focal form of CHI."

Confirms diazoxide unresponsiveness as the decision point that triggers focal-lesion workup.

PMID:37056678 SUPPORT Human Clinical

"treatment remains challenging, in particular for patients with diffuse disease who do not respond to the KATP channel activator diazoxide."

Confirms that diffuse K-ATP disease is characteristically diazoxide-unresponsive.

Perinatal Stress-Induced and Transient Hyperinsulinism (including infant of a diabetic mother)

Acquired, usually transient hyperinsulinism of the newborn precipitated by maternal diabetes mellitus, perinatal asphyxia, intrauterine growth restriction, or intrapartum maternal dextrose. It presents within the first day of life and most cases resolve within days to two weeks, but a protracted form persists for weeks and requires diazoxide. It is far more common than genetic congenital hyperinsulinism and is the main reason that a first critical sample drawn during the physiological transitional period must be repeated after 72 hours before a persistent diagnosis is made.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Transient HH typically develops in newborns with certain risk factors"

Establishes the transient/stress-induced subtype as risk-factor driven in newborns.

PMID:31465295 SUPPORT Human Clinical

"Prolonged neonatal hyperinsulinism (PHI) causes hypoglycemia in the neonatal period and is associated with perinatal stress."

Documents the protracted, diazoxide-requiring form of perinatal-stress-associated hyperinsulinism.

Syndromic Hyperinsulinism (Beckwith-Wiedemann spectrum, Kabuki syndrome and others)

Hyperinsulinism occurring as one feature of a broader syndrome — most characteristically the Beckwith-Wiedemann spectrum (11p15 imprinting defect or paternal uniparental disomy, mechanistically overlapping the focal-lesion 11p15 event and occasionally combined with a paternally inherited ABCC8/KCNJ11 variant to give severe disease), Kabuki syndrome (KMT2D/KDM6A), Turner, Sotos, Costello and Simpson-Golabi-Behmel syndromes, and the congenital disorders of glycosylation. Recognising the syndromic context redirects testing (11p15 methylation, chromosomal microarray) and changes surgical planning, because endocrine overgrowth may be far more extensive than a classic focal lesion.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"or associated with various overgrowth syndromes like Beckwith-Wiedemann syndrome or metabolic conditions such as congenital disorders of glycosylation"

Establishes syndromic overgrowth (Beckwith-Wiedemann) and CDG as recognised syndromic causes of HH.

Adult-Onset Hyperinsulinemic Hypoglycemia (acquired and late-declaring genetic causes)

Endogenous hyperinsulinemic hypoglycemia presenting after infancy. Most of this group is genuinely acquired — insulinoma, post-bariatric (post-gastric-bypass) hypoglycemia, insulin autoimmune syndrome, sulfonylurea or exogenous insulin exposure — but the axis here is age of declaration, not acquisition, and it also collects late-declaring germline disease such as adult nesidioblastosis from a GCK dosage lesion. Hyperinsulinism first appearing after about age two should prompt an insulinoma evaluation rather than a congenital-hyperinsulinism workup.

Show evidence (1 reference)

PMID:39720245 SUPPORT Human Clinical

"We describe the clinical course of 25-year-old man with hypoglycemia. We diagnosed him with hyperinsulinemic hypoglycemia (HH) and treated him with laparoscopic distal pancreatectomy. Histological examination led to a diagnosis of nesidioblastosis."

Documents adult-onset hyperinsulinemic hypoglycemia due to nesidioblastosis, an acquired-presentation form of the umbrella disorder.

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Pathophysiology

12

K-ATP Channel Loss of Function

Inactivating variants in ABCC8 (SUR1) or KCNJ11 (Kir6.2), the two subunits of the beta-cell ATP-sensitive potassium channel, remove the channel that normally holds the beta-cell membrane hyperpolarized when glucose is low. Because the channel is the switch that couples fuel metabolism to secretion, its loss uncouples insulin release from the glucose signal entirely. This is the single most common molecular cause of hyperinsulinemic hypoglycemia and underlies both diffuse and focal histological disease. It is also why the first-line drug fails in this group: diazoxide works by holding a functional channel open, so a broken channel is pharmacologically unreachable.

pancreatic beta cell CL:0000169

ABCC8 hgnc:59 KCNJ11 hgnc:6257

potassium ion transmembrane transport GO:0071805 ↓ DECREASED regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

islet of Langerhans UBERON:0000006

Downstream

Dysregulated Beta-Cell Insulin Secretion With no functional K-ATP channel the beta-cell membrane stays depolarized despite low glucose, voltage-gated calcium channels remain open, cytosolic calcium stays high, and insulin granules are exocytosed continuously.

Show evidence (2 references)

PMID:37056678 SUPPORT Human Clinical

"Genetic defects that lead to loss of expression or function of KATP channels are the most common cause of HI (KATP-HI)."

Establishes K-ATP loss of function as the leading molecular cause.

PMID:29280746 SUPPORT In Vitro

"A change in the ratio of ATP to ADP causes closure of the KATPchannel and triggers depolarisation of the cell membrane, activating the voltage-gated calcium channels"

Describes the normal K-ATP-to-calcium coupling whose constitutive activation follows channel loss of function; this is islet electrophysiology restated in a review, so tagged IN_VITRO.

Glutamate Dehydrogenase Amino-Acid Amplifier Activation

The protein/leucine-sensitive arm. Dominant activating GLUD1 variants escape GTP inhibition of glutamate dehydrogenase, and recessive HADH (SCHAD) deficiency removes an inhibitory SCHAD-GDH protein-protein interaction; both leave glutamate dehydrogenase inappropriately active, so leucine-driven glutamate oxidation feeds the TCA cycle, raises the beta-cell ATP/ADP ratio and closes a structurally intact K-ATP channel. This is the only arm that also produces hyperammonemia, because the same unrestrained GDH activity in liver and kidney generates ammonia — which is why an elevated plasma ammonia in hyperinsulinemic hypoglycemia is close to specific for the GLUD1 (HI/HA) subtype and not a general feature of the disorder.

pancreatic beta cell CL:0000169

GLUD1 hgnc:4335 HADH hgnc:4799

regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

Downstream

Dysregulated Beta-Cell Insulin Secretion Leucine-driven glutamate oxidation raises ATP/ADP and closes a structurally intact K-ATP channel, converging on the same depolarization-to-exocytosis pathway as channel loss of function.

Hyperammonemia Unrestrained glutamate dehydrogenase activity in liver and kidney generates ammonia, producing the persistent mild hyperammonemia that marks the GLUD1 HI/HA subtype specifically. This edge is deliberately attached only to this node: the other amplifier and channel lesions do not cause hyperammonemia.

Show evidence (2 references)

PMID:25733449 SUPPORT Human Clinical

"Mutations in GLUD1 and HADH lead to leucine-induced HH, and these two genes encode the key enzymes glutamate dehydrogenase and short chain 3-hydroxyacyl-CoA dehydrogenase which play a key role in amino acid and fatty acid regulation of insulin secretion respectively."

Establishes GLUD1 and HADH as the leucine/amino-acid-driven amplifier arm.

PMID:21130127 SUPPORT In Vitro

"amino acids can trigger release of insulin in response to the oxidation of amino acids through glutamate via GDH into the TCA cycle under allosteric activation of GDH by leucine."

Describes the leucine-allosteric activation of glutamate dehydrogenase that drives secretion; the mechanism is established by enzyme kinetics and islet work restated in this review, so tagged IN_VITRO.

Lowered Beta-Cell Glucose Set-Point

The glucose-sensing arm. Glucokinase is the beta cell's glucose sensor, the step that sets the plasma glucose concentration at which secretion begins. Activating GCK variants (and, rarely, GCK duplication) shift that threshold downward, so the whole homeostatic system defends an inappropriately low glucose rather than failing to switch off. A non-coding HK1 variant that fails to silence hexokinase 1 in the beta cell does the same thing by a different route, installing a low-Km hexokinase that phosphorylates glucose at concentrations far below the normal threshold. Because a reset set-point is not the same as an absent brake, GCK disease can uniquely show a ketotic response on prolonged fasting.

pancreatic beta cell CL:0000169

GCK hgnc:4195 HK1 hgnc:4922

regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

Downstream

Dysregulated Beta-Cell Insulin Secretion A downward-shifted glucose threshold means the intact K-ATP channel closes, and insulin is released, at plasma glucose values that should silence secretion entirely.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"plays a critical role in acting as a gluco-sensor, providing a link between the extracellular plasma glucose concentration and the metabolism of glucose in b-cells"

Establishes glucokinase as the beta-cell glucose sensor whose activation lowers the secretion set-point.

PMID:29280746 SUPPORT Human Clinical

"It catalyses the phosphorylation of glucose to produce glucose-6-phosphate as substrate for glycolysis. Normally,HK1expression is silenced in the pancreatic b-cells."

Establishes that HK1 is normally silenced in the beta cell, so its de-silencing installs an inappropriate low-threshold sensor.

Alternative Secretagogue Import and Loss of Mitochondrial Uncoupling

Two lesions that let fuels which should be invisible to the beta cell drive secretion. SLC16A1 (MCT1) is normally silenced in beta cells precisely so that pyruvate and lactate cannot act as secretagogues; dominant promoter variants de-silence it, so monocarboxylates generated during anaerobic exercise enter the cell and trigger insulin release — giving hypoglycemia specifically after strenuous exercise. UCP2 normally leaks protons across the inner mitochondrial membrane, damping ATP generation and thereby restraining glucose-stimulated secretion; inactivating variants remove that brake, though the UCP2 association remains disputed.

pancreatic beta cell CL:0000169

SLC16A1 hgnc:10922 UCP2 hgnc:12518

regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

Downstream

Dysregulated Beta-Cell Insulin Secretion Both lesions raise ATP/ADP in the presence of an intact K-ATP channel, converging on the same depolarization-to-exocytosis pathway.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"

Supports the SLC16A1/MCT1 arm, in which exercise-derived monocarboxylates provoke hyperinsulinemic hypoglycemia.

PMID:29280746 PARTIAL In Vitro

"mediates proton leak across the inner mitochondrial membrane, thereby inhibiting ATP generation through mitochondrial oxidative metabolism and negatively regulates glucose mediated insulin secretion"

Describes the UCP2 proton-leak brake on ATP generation, a mitochondrial bioenergetic mechanism established in vitro and restated here; recorded as partial because the same review concludes the role of UCP2 in hyperinsulinism needs further investigation.

Transcription Factor Dysregulation of the Beta-Cell Secretory Program

A developmental/transcriptional rather than metabolic route. HNF4A and HNF1A are nuclear transcription factors expressed in the beta cell that regulate glucose-dependent insulin secretion. Heterozygous loss of function produces a biphasic phenotype that is diagnostically distinctive: macrosomia with diazoxide-responsive neonatal hyperinsulinism, then maturity-onset diabetes of the young decades later. The mechanism is neither an amino-acid amplifier nor a shifted glucose set-point, which is why it is modelled as its own node.

pancreatic beta cell CL:0000169

HNF4A hgnc:5024 HNF1A hgnc:11621

regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

Downstream

Dysregulated Beta-Cell Insulin Secretion Transcriptional dysregulation of the beta-cell secretory program produces glucose-inappropriate insulin release in the newborn period, typically with an intact and therefore diazoxide-responsive K-ATP channel.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"The HNFs, HNF1-a and HNF4-a, are transcription factors for nuclear hormone receptors expressed in pancreatic b-cells and regulate glucose-dependent insulin secretion"

Establishes HNF1A/HNF4A as beta-cell transcription factors regulating glucose-dependent insulin secretion.

PMID:29280746 SUPPORT Human Clinical

"Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"

Confirms the biphasic hyperinsulinism-then-MODY consequence of HNF4A/HNF1A loss of function.

Focal Lesion Formation by Paternal K-ATP Variant and Somatic 11p15 Maternal Loss

Focal hyperinsulinism is generated by two hits at the same locus. A paternally inherited recessive ABCC8 or KCNJ11 variant (both genes sit at 11p15.1) is clinically silent while the maternal allele is present. In a single pancreatic progenitor a post-zygotic mitotic recombination event replaces the maternal 11p15 region with a second copy of the paternal one (segmental paternal isodisomy), rendering the K-ATP variant homozygous in that clone while parental heterozygosity is preserved everywhere else. The same event leaves the neighbouring 11p15 imprinted domain paternal-only — doubling active IGF2 and removing the growth-suppressing maternal H19 and CDKN1C (p57) contributions — so the affected clone also proliferates, producing a discrete nodule of hyperfunctional, hypersecreting beta cells embedded in a normal pancreas. Every clinically decisive feature of focal disease follows from this architecture: it is anatomically bounded, so 18F-DOPA PET can localise it and resecting it is curative; and it is sporadic in inheritance terms, because the somatic hit is not transmitted.

pancreatic beta cell CL:0000169

ABCC8 hgnc:59 KCNJ11 hgnc:6257 CDKN1C hgnc:1786

insulin secretion GO:0030073 ↑ INCREASED

islet of Langerhans UBERON:0000006

Downstream

Dysregulated Beta-Cell Insulin Secretion Within the lesion the K-ATP channel is homozygously defective, so the clone's beta cells secrete insulin continuously; the surrounding pancreas remains normal, which is why removing the lesion cures the disease.

Show evidence (3 references)

PMID:25765446 SUPPORT Human Clinical

"The 3 patients with focal CHI harbored paternally inherited ABCC8 or KCNJ11 mutations."

Confirms the paternal origin of the germline K-ATP variant in focal disease.

PMID:25765446 SUPPORT Human Clinical

"In the 3 patients with focal CHI, homozygous ABCC8 or KCNJ11 mutations were identified within the lesions."

Demonstrates that the K-ATP variant becomes homozygous specifically within the lesion — the second hit that unmasks the channel defect focally.

PMID:35018160 SUPPORT Human Clinical

"histopathological lesions, diffuse and focal, have been associated with these different genetic alterations."

Confirms that the focal/diffuse histological dichotomy maps onto distinct underlying genetic architectures.

Perinatal Stress Lowering of the Beta-Cell Glucose Threshold

In acquired perinatal-stress hyperinsulinism there is no germline lesion. Instead, maternal diabetes, birth asphyxia/hypoxia, intrauterine growth restriction or intrapartum maternal dextrose appear to reset the beta-cell glucose threshold for suppressing insulin downward, so that secretion continues at plasma glucose values that would normally silence it. In the infant of a diabetic mother the fetal islet has additionally been chronically over-stimulated in utero by transplacental maternal glucose. The same downstream chain follows as in genetic disease, but the trigger is self-limited: most cases remit within days to two weeks as the stress resolves.

pancreatic beta cell CL:0000169

regulation of insulin secretion GO:0050796 ↕ DYSREGULATED

islet of Langerhans UBERON:0000006

Downstream

Dysregulated Beta-Cell Insulin Secretion A downward-reset secretion threshold produces the same glucose-inappropriate insulin release as a germline channel or amplifier lesion.

Show evidence (2 references)

PMID:38944478 SUPPORT Human Clinical

"Evidence indicates that all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion."

Supports the unifying claim that the acquired neonatal hypoglycemias share the same islet-secretory-dysregulation mechanism as genetic disease.

PMID:29280746 SUPPORT Human Clinical

"Some newborns with IUGR and asphyxia have a severe and protracted form of HH which requires treatment with diazoxide"

Documents perinatal asphyxia and IUGR as triggers capable of producing severe, treatment-requiring hyperinsulinism.

Dysregulated Beta-Cell Insulin Secretion

The convergent core of the disorder, reached from every etiology above: insulin is secreted at plasma glucose concentrations at which secretion should be fully suppressed. In health serum insulin becomes undetectable once plasma glucose falls below about 3 mmol/L; in hyperinsulinemic hypoglycemia it remains detectable, and it is this failure of suppression — rather than an absolute insulin concentration — that defines the disease. Everything clinically distinctive about hyperinsulinemic hypoglycemia flows from this single node, because insulin is not merely a glucose-lowering hormone but a simultaneous suppressor of every counter-regulatory fuel pathway.

pancreatic beta cell CL:0000169

insulin secretion GO:0030073 ↑ INCREASED membrane depolarization GO:0051899 ↑ INCREASED

islet of Langerhans UBERON:0000006

Downstream

Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output Circulating insulin drives glucose into muscle, liver and adipose tissue while simultaneously blocking glycogenolysis and gluconeogenesis, so plasma glucose falls and cannot be defended.

Suppression of Lipolysis and Ketogenesis The same insulin signal acts anabolically on adipose tissue, blocking free fatty acid release and hence hepatic ketone body production.

Hyperinsulinemia Insulin and C-peptide remain inappropriately detectable at the time of hypoglycemia.

Large for Gestational Age Insulin is a fetal growth factor, so intrauterine hyperinsulinemia produces macrosomia at birth.

Hypertrophic Cardiomyopathy Some infants with hyperinsulinism have hypertrophic cardiomyopathy, thought to reflect the same fetal anabolic insulin effect that causes macrosomia.

Show evidence (2 references)

PMID:37454648 SUPPORT Human Clinical

"Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children."

Defines the core mechanism and establishes its clinical primacy among causes of persistent hypoglycemia.

PMID:29280746 SUPPORT Human Clinical

"Hyperinsulinaemic hypoglycaemia (HH) is the inappropriate secretion of insulin in the presence of low plasma glucose levels and leads to severe and persistent hypoglycaemia in neonates and children."

States the defining glucose-inappropriate secretion that constitutes this node.

Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output

Insulin acts on the two arms of glucose homeostasis at once: it accelerates glucose uptake into muscle, liver and adipose tissue and it shuts down the liver's ability to release glucose by inhibiting glycogenolysis and gluconeogenesis while stimulating glycogen synthesis. The result is hypoglycemia that cannot be defended endogenously, and that clinically requires glucose infusion rates far above normal — a requirement above about 8 mg/kg/min in a neonate is itself close to diagnostic. Hepatic glycogen accumulation from this same signal contributes to the hepatomegaly seen in some patients.

hepatocyte CL:0000182

glucose homeostasis GO:0042593 ↕ DYSREGULATED gluconeogenesis GO:0006094 ↓ DECREASED glycogen catabolic process GO:0005980 ↓ DECREASED

liver UBERON:0002107

Downstream

Dual Glucose and Ketone Substrate Deprivation of the Brain Falling plasma glucose removes the brain's obligate primary fuel; this arm alone would produce neuroglycopenia, and it is compounded by the parallel loss of ketone fuel.

Hyperinsulinemic Hypoglycemia The defining biochemical state — a low plasma glucose with unsuppressed insulin action.

Neonatal Hypoglycemia In most patients the hypoglycemia first manifests during the neonatal period.

Hepatomegaly Hepatic glycogen accumulation under sustained insulin action enlarges the liver in some patients.

Hyperhidrosis Adrenergic (autonomic) symptoms — sweating, pallor, palpitations, jitteriness, hunger — are the earliest warning of falling glucose, and are characteristically blunted or absent in neonates and in patients with recurrent hypoglycemia, which is part of why the disorder is missed.

Show evidence (2 references)

PMID:25733449 SUPPORT Human Clinical

"The inappropriate insulin secretion drives glucose into the insulin-sensitive tissues, such as the muscle, liver and adipose tissue, leading to severe hyperinsulinaemic hypoglycaemia (HH)."

Establishes insulin-driven tissue glucose disposal as the immediate cause of the hypoglycemia.

PMID:29280746 SUPPORT Human Clinical

"An intravenous glucose infusion rate requirement of >8 mg/kg/min (normally is 4-6 mg/kg/min) is virtually diagnostic of HH"

Quantifies the magnitude of the glucose disposal defect at the whole-organism level.

Suppression of Lipolysis and Ketogenesis

This is the arm that makes hyperinsulinemic hypoglycemia different from every other hypoglycemia. Insulin is anabolic on adipose tissue: it stimulates lipogenesis, blocks hormone-sensitive-lipase-mediated free fatty acid release, and therefore removes the substrate for hepatic beta-oxidation and ketone body synthesis. In any other fasting hypoglycemia the falling glucose would unleash lipolysis and ketogenesis, and the resulting beta-hydroxybutyrate would partially rescue the brain. Here that rescue is disabled by the same hormone that caused the hypoglycemia. The biochemical signature — low glucose with simultaneously LOW beta-hydroxybutyrate AND LOW free fatty acids — is both the diagnostic fingerprint of the disorder and the reason its neurological toll is so high.

adipocyte CL:0000136 hepatocyte CL:0000182

lipid catabolic process GO:0016042 ↓ DECREASED ketone body biosynthetic process GO:0046951 ↓ DECREASED

adipose tissue UBERON:0001013

Downstream

Dual Glucose and Ketone Substrate Deprivation of the Brain Removing ketone bodies removes the brain's only substantial alternative fuel, converting a glucose deficit into an absolute cerebral fuel failure.

Hypoketotic Hypoglycemia The combination of low glucose with inappropriately absent ketones is the biochemical hallmark used to recognise the disorder.

Decreased Circulating Free Fatty Acids Blocked lipolysis lowers plasma free fatty acids at the time of hypoglycemia — the finding that distinguishes hyperinsulinism from fatty acid oxidation defects, where free fatty acids are high but ketones are still low.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"In HH due to the inhibitory effect of insulin on lipolysis and ketogenesis there is suppressed ketone body formation in the presence of hypoglycaemia thus leading to increased risk of hypoglycaemic brain injury."

Directly establishes the insulin-mediated ketogenesis block and links it to brain-injury risk.

PMID:38792494 SUPPORT Human Clinical

"The premise for our proposed screen is based on the known effect of hyperinsulinism in suppressing ketogenesis, thereby limiting ketone production."

Confirms the suppressed-ketogenesis mechanism, and shows it is robust enough to be proposed as the basis of a newborn screening test.

Dual Glucose and Ketone Substrate Deprivation of the Brain

The mechanistic keystone of the disorder, and the explicit reason hyperinsulinemic hypoglycemia injures the brain more than other hypoglycemias of equivalent glucose depth. The neonatal and infant brain has a disproportionately high obligate glucose requirement, and its physiological safeguard against a falling glucose is to switch to ketone bodies. In hyperinsulinemic hypoglycemia both fuels fail simultaneously and for the same reason: the excess insulin that lowers glucose also abolishes the ketone supply. Cerebral energy failure therefore begins earlier, deepens faster, and is less forgiving of diagnostic delay than in ketotic hypoglycemias, where a partial ketone rescue buffers the brain. This node is also the therapeutic rationale for the (still experimental) strategy of supplying exogenous beta-hydroxybutyrate, and the rationale for proposals to screen newborns by measuring ketones rather than glucose alone.

neuron CL:0000540

glucose homeostasis GO:0042593 ↕ DYSREGULATED

brain UBERON:0000955

Downstream

Neuroglycopenic Brain Injury Simultaneous loss of glucose and ketone substrate produces cerebral energy failure and neuronal injury.

Seizures Acute cerebral fuel failure manifests as generalized seizures, frequently the presenting event.

Lethargy Depressed consciousness is a core neuroglycopenic sign.

Feeding Difficulties Poor feeding is both an early symptom of neuroglycopenia and, later, a major chronic burden compounded by diazoxide-associated food aversion and tube feeding.

Coma Profound cerebral fuel failure can progress to coma and death.

Apnea Apnea and respiratory distress can be the presenting neonatal manifestation of neuroglycopenia.

Show evidence (3 references)

PMID:12149510 SUPPORT Human Clinical

"In persistent hyperinsulinemic hypoglycemia of infancy, ketone body concentrations are abnormally low at times of hypoglycemia, depriving the brain of its most important alternative fuel."

The core statement of the dual-deprivation mechanism.

PMID:29280746 SUPPORT Human Clinical

"This accounts for the hypoketotic state, decreasing the availability of alternative fuels for cerebral metabolism"

States that the hypoketotic state specifically reduces alternative cerebral fuel availability.

PMID:12149510 PARTIAL Human Clinical

"demonstrates effective uptake across the blood-brain barrier and could provide the basis for further evaluation of the neuroprotective effect of beta-OHB in conditions with hypoketotic hypoglycemia."

Shows in two patients that orally supplied beta-hydroxybutyrate reaches the brain, which is consistent with ketone deprivation being causal; the study explicitly frames neuroprotection as requiring further evaluation, so this is partial rather than confirmatory support.

Neuroglycopenic Brain Injury

Recurrent or prolonged dual-fuel deprivation causes permanent injury to the developing brain, with a predilection for the parieto-occipital cortex and white matter. This is the outcome that defines the clinical stakes of the disorder and it is substantially preventable: the international consensus guideline states its own purpose as reducing the prevalence of hypoglycemia-caused brain injury through earlier recognition and treatment. Neurological sequelae were reported in about half of probands in a nationwide cohort, which is a direct measure of how often recognition currently comes too late.

neuron CL:0000540

brain UBERON:0000955

Downstream

Global Developmental Delay Permanent hypoglycemic brain injury manifests as developmental delay and cognitive impairment.

Cerebral Palsy Permanent motor sequelae including cerebral palsy are among the recognised complications of untreated or late-treated hyperinsulinemic hypoglycemia.

Show evidence (3 references)

PMID:37454648 SUPPORT Human Clinical

"in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia."

Frames hypoglycemic brain injury in hyperinsulinism as a preventable outcome addressable by earlier recognition — the central clinical claim of this entry.

PMID:38963811 SUPPORT Human Clinical

"Neurologic sequelae were reported in 53% of the CHI probands."

Quantifies the burden of permanent neurological injury in a population-based cohort.

PMID:38792494 SUPPORT Human Clinical

"adverse neurodevelopmental sequelae and brain injury due to missing or delaying the CHI diagnosis"

Attributes the neurodevelopmental injury specifically to missed or delayed diagnosis.

✶

Histopathology

2

Diffuse beta-cell nuclear enlargement

In diffuse disease all islets throughout the pancreas are involved, with beta cells showing abnormally large nuclei. There is no resectable target, which is why surgery in diffuse disease is a 90-98% pancreatectomy rather than a cure.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Diffuse disease accounts for about 60% of all CHI cases and affects all the b-cells of the pancreas. Morphology of the islets of Langerhans typically show the presence of b-cells with abnormally large nuclei"

Describes the whole-pancreas involvement and nuclear enlargement that define diffuse histology.

Focal adenomatous islet-cell hyperplasia

A discrete, generally unencapsulated 2-10 mm nodule of nodular islet-cell hyperplasia including ductuloinsular complexes, with enlarged cytoplasm and irregular nuclei, surrounded by histologically normal pancreas. Loss of nuclear p57 (CDKN1C) staining within the lesion reflects the underlying maternal 11p15 loss and is used to confirm focal disease on frozen section.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Focal pancreatic lesions are generally 2-10 mm in size and appear as small regions of islet adenomatosis (nodular hyperplasia of islet-like cell clusters, including ductuloinsular complexes"

Describes the size and architecture of the focal lesion.

PMID:29280746 SUPPORT Human Clinical

"Islet cells in the lesion have large cytoplasm with dispersed abnormal nuclei of irregular shape"

Describes the cytological features of the focal lesion.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

17

Cardiovascular 1

Hypertrophic Cardiomyopathy OCCASIONAL Hypertrophic cardiomyopathy HP:0001639

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."

The source phrase "in some patients" maps to the OCCASIONAL (5-29%) band under the GeneReviews prose-to-enum convention.

Digestive 2

Feeding Difficulties Feeding difficulties HP:0011968

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"However, patients wth CHI, particularly those on diazoxide therapy usually have food aversion. Therefore a percutaneous gastrostomy is sometimes recommended to allow frequent (or continuous) feeding"

Documents food aversion and the resulting need for gastrostomy feeding.

Hepatomegaly OCCASIONAL Hepatomegaly HP:0002240

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."

The source phrase "in some patients" maps to the OCCASIONAL (5-29%) band under the GeneReviews prose-to-enum convention.

Endocrine 1

Hyperinsulinemia Hyperinsulinemia HP:0000842

Show evidence (1 reference)

PMID:40904956 SUPPORT Human Clinical

"Laboratory investigations revealed elevated insulin and C-peptide levels, absence of ketone bodies, and a positive response to the glucagon stimulation test."

Documents elevated insulin and C-peptide during hypoglycemia.

Integument 1

Hyperhidrosis Hyperhidrosis HP:0000975

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"non-specific adrenergic symptoms (poor feeding, hunger, palpitations, sweating)"

Documents sweating among the adrenergic symptoms of hypoglycemia in HH.

Metabolism 2

Hypoketotic Hypoglycemia VERY_FREQUENT Hypoketotic hypoglycemia HP:0001985

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"It is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants and is associated with a significant risk of permanent brain damage."

Identifies hypoketotic hypoglycemia as the characteristic presentation, supporting a VERY_FREQUENT band.

Hyperammonemia Hyperammonemia HP:0001987

Show evidence (1 reference)

PMID:21130127 SUPPORT Human Clinical

"The other distinctive feature of the HI/HA Syndrome is a persistent elevation of plasma ammonia concentrations."

Confirms persistent hyperammonemia as the distinctive feature of the GLUD1 subtype.

Nervous System 4

Seizures Seizure HP:0001250

Show evidence (1 reference)

PMID:40904956 SUPPORT Human Clinical

"We report the case of a male macrosomic newborn admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia (1.4 mmol/L) unresponsive to intravenous glucose therapy."

Documents generalized seizures with severe neonatal hypoglycemia.

Lethargy Lethargy HP:0001254

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain, resulting in impairment of brain function."

Lists lethargy among the neuroglycopenic symptoms.

Coma Coma HP:0001259

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain"

Lists coma among the life-threatening neuroglycopenic manifestations.

Global Developmental Delay Global developmental delay HP:0001263

No `frequency:` band is asserted. The available population figure (53% in the Norwegian cohort) is for "neurologic sequelae" as an umbrella covering epilepsy, motor deficits and cognitive impairment, not for global developmental delay specifically, so banding this phenotype from it would overstate the source.

Show evidence (1 reference)

PMID:38963811 PARTIAL Human Clinical

"Neurologic sequelae were reported in 53% of the CHI probands."

Documents a substantial burden of neurologic sequelae in a population-based cohort; the source reports a composite sequelae category rather than global developmental delay specifically, so support is partial.

Respiratory 1

Apnea Apnea HP:0002104

Show evidence (1 reference)

PMID:40904956 PARTIAL Human Clinical

"admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia"

Documents respiratory compromise at presentation; the report describes respiratory distress rather than apnea specifically, so support is partial.

Growth 1

Large for Gestational Age Large for gestational age HP:0001520

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Newborns with HH may be macrosomic due to intrauterine hyperinsulinaemia. However, the absence of macrosomia does not exclude HH."

Confirms macrosomia as a common but non-obligatory feature.

Other 4

Hyperinsulinemic Hypoglycemia VERY_FREQUENT Hyperinsulinemic hypoglycemia HP:0000825

Temporal: RECURRENT

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Hyperinsulinaemic hypoglycaemia (HH) is the inappropriate secretion of insulin in the presence of low plasma glucose levels and leads to severe and persistent hypoglycaemia in neonates and children."

The defining phenotype is present in all affected individuals by definition, supporting a VERY_FREQUENT band.

Decreased Circulating Free Fatty Acids Decreased circulating free fatty acid level HP:0040299

Show evidence (1 reference)

PMID:31465295 SUPPORT Human Clinical

"inappropriate low serum free fatty acids"

Reports inappropriately suppressed serum free fatty acids in a prolonged-hyperinsulinism cohort sampled during documented hypoglycemia.

Neonatal Hypoglycemia Neonatal hypoglycemia HP:0001998

No `frequency:` band is asserted. The available sources establish that neonatal onset is the commonest presentation but give no quantitative share, and the umbrella deliberately includes later-onset genetic and acquired forms, so banding here would overstate the evidence.

Show evidence (1 reference)

PMID:40904956 SUPPORT Human Clinical

"Congenital hyperinsulinism (CHI) is a rare but significant cause of persistent neonatal hypoglycemia (NH), associated with a high risk of neurological complications if not promptly treated."

Establishes hyperinsulinism as a cause of persistent neonatal hypoglycemia.

Cerebral Palsy Cerebral palsy HP:0100021

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"it is essential to make a prompt diagnosis and institute immediate management to prevent complications such as epilepsy, cerebral palsy and neurodevelopemental deficits"

Names cerebral palsy as a complication of delayed treatment.

🧬

Genetic Associations

10

ABCC8 (SUR1) loss-of-function variants (Causative)

Gene: ABCC8 hgnc:59 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:38963811 SUPPORT Human Clinical

"ABCC8 variants were most common (n= 40), and 5 novel variants were identified."

Confirms ABCC8 as the most frequently identified causal gene in a nationwide cohort.

PMID:38963811 SUPPORT Human Clinical

"Although most ABCC8 variants caused immediate disease onset with severe hypoglycemia and were diazoxide-unresponsive, 8 probands had a heterozygous, apparently dominant variant with milder phenotype."

Documents both the severe recessive and milder dominant ABCC8 phenotypes.

KCNJ11 (Kir6.2) loss-of-function variants (Causative)

Gene: KCNJ11 hgnc:6257 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:25733449 SUPPORT Human Clinical

"Autosomal recessive and dominant mutations in ABCC8/KCNJ11 are the commonest cause of medically unresponsive CHI."

Confirms ABCC8/KCNJ11 as the commonest cause of diazoxide-unresponsive disease.

PMID:39741883 SUPPORT Human Clinical

"Pathogenic variants in the K-ATP channel genes were the only identified genetic cause of p-CHI (ABCC8 (n=17) and KCNJ11 (n=2))"

Confirms KCNJ11 as a causal K-ATP gene in persistent disease in a national cohort.

GLUD1 activating variants (Causative)

Gene: GLUD1 hgnc:4335 relationship_type: CAUSATIVE

Show evidence (1 reference)

PMID:21130127 SUPPORT In Vitro

"the hyperinsulinism/hyperammonemia syndrome caused by dominant activating mutations of GLUD1 which interfere with inhibitory regulation by GTP"

Confirms the dominant activating GLUD1 mechanism; loss of GTP inhibition is an enzyme-kinetic property demonstrated in vitro, so tagged IN_VITRO.

GCK activating variants (Causative)

Gene: GCK hgnc:4195 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"plays a critical role in acting as a gluco-sensor, providing a link between the extracellular plasma glucose concentration and the metabolism of glucose in b-cells"

Establishes glucokinase as the beta-cell glucose sensor whose activation lowers the secretion set-point.

PMID:39720245 PARTIAL Human Clinical

"we found that the duplicated region contained the GCK gene, whose gain-of function variants could cause HH."

A single case linking GCK copy-number gain to adult nesidioblastosis; recorded as partial support because the dosage mechanism remains a case-level, not established, association.

HADH (SCHAD) loss-of-function variants (Causative)

Gene: HADH hgnc:4799 relationship_type: CAUSATIVE

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Raised plasma hydroxybutyrylcarnitine and urinary 3-hydroxyglutarate are diagnostic of a rare type of congenital HH"

Provides the diagnostic metabolite signature of HADH deficiency.

HNF4A loss-of-function variants (Causative)

Gene: HNF4A hgnc:5024 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"

Confirms the biphasic hyperinsulinism-then-MODY phenotype of HNF4A.

PMID:29280746 SUPPORT Human Clinical

"CHI due toHNF4Agene has been reported with increased levels of glycogen in erythrocytes, elevated liver transaminases and increased echogenicity on liver ultrasonography, suggesting a glycogenosis-like phenotype"

Documents the HNF4A-specific glycogenosis-like hepatic phenotype.

HNF1A loss-of-function variants (Causative)

Gene: HNF1A hgnc:11621 relationship_type: CAUSATIVE

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"

Confirms the biphasic hyperinsulinism-then-MODY phenotype of HNF1A.

PMID:29280746 SUPPORT Human Clinical

"CHI due to mutations in bothHNF1AandHNF4Aare characterized by macrosomic birth and mild transient to severe diazoxide-responsive HH"

Confirms macrosomia and diazoxide-responsive hyperinsulinism in HNF1A-related disease.

SLC16A1 (MCT1) promoter gain-of-function variants (Causative)

Gene: SLC16A1 hgnc:10922 relationship_type: CAUSATIVE

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"

Confirms the exercise/pyruvate-provoked mechanism of the SLC16A1 subtype.

UCP2 inactivating variants (Causative)

Gene: UCP2 hgnc:12518 relationship_type: DISPUTED

Show evidence (1 reference)

PMID:29280746 PARTIAL In Vitro

"mediates proton leak across the inner mitochondrial membrane, thereby inhibiting ATP generation through mitochondrial oxidative metabolism and negatively regulates glucose mediated insulin secretion"

Supports the mitochondrial bioenergetic mechanism, which is established in vitro and restated here; recorded as partial because the same review notes that the role of UCP2 in hyperinsulinism needs further investigation.

HK1 non-coding de-silencing variants (Causative)

Gene: HK1 hgnc:4922 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (2 references)

PMID:38963811 SUPPORT Human Clinical

"variants in HADH, HNF4A, KCNJ11, and HK1 were identified in 1 proband each, the latter being noncoding"

Documents an HK1 variant in a nationwide hyperinsulinism cohort and states explicitly that it is noncoding, matching the de-silencing mechanism.

PMID:29280746 PARTIAL Human Clinical

"a report identified a dominant gain-of-function mutation in theHK1gene in a family with “idiopathic hypoglycaemia of infancy”"

Supports the dominant gain-of-function nature of the HK1 lesion; the review does not itself specify that the variant is noncoding, so support is partial.

💊

Medical Actions

9

Diazoxide

Action: Pharmacotherapy NCIT:C15986

Agent: diazoxide CHEBI:4495

First-line and the only drug approved for hyperinsulinism, designated a WHO essential medicine. Diazoxide binds SUR1 and holds the K-ATP channel open, hyperpolarizing the beta cell and switching insulin secretion off — which means it can only work when a functional channel exists, and characteristically fails in recessive ABCC8/KCNJ11 disease. Dosing is 5-15 (up to 20) mg/kg/day orally, usually with chlorothiazide to counter fluid retention. Safety monitoring matters: fluid retention and cardiac failure are the dose-limiting toxicities, and hypertrichosis, neutropenia, thrombocytopenia, hyperuricemia and pulmonary hypertension are recognised adverse effects — an echocardiogram about a week after starting and periodic blood counts are advised. Response is confirmed by a safety fast, not by impression.

Mechanism Target:

ACTIVATES K-ATP Channel Loss of Function — Diazoxide activates (opens) residual functional K-ATP channels, restoring the hyperpolarizing brake on insulin secretion — hence its failure when the channel is absent.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Diazoxide functions by binding to the SUR1 subunit of KATPchannel. Thus, it requires a functionally intact KATPchannel."

Establishes that diazoxide acts on the K-ATP channel and requires it to be intact.

Show evidence (3 references)

PMID:29280746 SUPPORT Human Clinical

"Diazoxide, a KATPchannel opener, is invaluable for managing many patients with CHI"

Establishes diazoxide as the mainstay first-line therapy and a K-ATP channel opener.

PMID:29280746 SUPPORT Human Clinical

"The most severe side effect that limits and requires treatment withdrawal is fluid retention, cardiac failure and the associated electrolyte imbalance."

Documents the dose-limiting fluid-retention and cardiac-failure toxicity.

PMID:37454648 SUPPORT Human Clinical

"Diazoxide, the only drug currently approved for treating HI, was recently designated as an "essential medicine" by the World Health Organization"

Establishes diazoxide as the sole approved therapy and a WHO essential medicine.

Octreotide and Long-Acting Somatostatin Analogs

Action: Pharmacotherapy NCIT:C15986

Agent: octreotide CHEBI:7726

Second-line, off-label therapy for diazoxide-unresponsive disease. Octreotide acts through SSTR2/SSTR5 to suppress insulin gene promoter activity, inhibit calcium mobilisation and act on the beta-cell K-ATP channel, all of which reduce insulin secretion. Started at about 5 µg/kg/day subcutaneously and titrated; tachyphylaxis after about 48 hours is expected and requires dose adjustment. Patients are often transitioned to monthly lanreotide. Necrotizing enterocolitis in unstable premature infants and biliary sludge are the safety concerns that shape monitoring.

Mechanism Target:

INHIBITS Dysregulated Beta-Cell Insulin Secretion — Somatostatin-receptor agonism directly suppresses beta-cell insulin release.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Somatostatin also inhibits the KATPchannel which results in reduced insulin secretion"

Documents the direct suppression of insulin secretion by somatostatin-receptor agonism.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"The recommended initial dose of octreotide is 5 µg/kg/day given by subcutaneous injections (or as a continuous infusion) at 6-8h intervals with a maximum dose of 30-35 µg/kg/day."

Provides the dosing regimen for second-line octreotide.

PMID:38993725 SUPPORT Human Clinical

"our cases suggest a safe method of switching from octreotide to lanreotide, elucidate the efficacy of home-based CGM monitoring"

Supports the transition to long-acting lanreotide with home CGM.

Glucagon Rescue and Continuous Glucagon Infusion

Action: Pharmacotherapy NCIT:C15986

Agent: glucagon CHEBI:5391

Glucagon is the counter-regulatory hormone whose action insulin is blocking, so giving it exogenously (0.5-1 mg IM/SC) raises glucose within minutes and is the first-line rescue when intravenous access is unavailable. Continuous subcutaneous infusion is used to reduce dextrose and fluid requirements. Doses above 1 mg can cause rebound hypoglycemia through paradoxical insulin release.

Mechanism Target:

INHIBITS Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output — Glucagon reverses the insulin-imposed block on hepatic glycogenolysis and gluconeogenesis, restoring hepatic glucose output.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Glucagon, in the short-term, induces glycogenolysis, gluconeogenesis and lipolysis and causes a rapid increase in plasma glucose within a few minutes after administration."

Documents the reversal of the insulin-imposed block on hepatic glucose output.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Glucagon is a key counter-regulatory hormone and is used as a first line therapy for managing CHI patients, particularly in emergency situations where patients are unable to take oral feed and/or intravenous access is difficult to obtain"

Establishes glucagon as first-line emergency rescue therapy.

PMID:29280746 SUPPORT Human Clinical

"Glucagon, in high doses (over 1 mg), can cause rebound hypoglycemia due to a paradoxical increase in insulin secretion"

Documents the rebound-hypoglycemia hazard of high-dose glucagon.

Intravenous Dextrose and High-Rate Carbohydrate Support

Action: Pharmacotherapy NCIT:C15986

Agent: glucose (dextrose) CHEBI:17234

The immediate treatment: continuous intravenous dextrose starting at 6-8 mg/kg/min and escalated as required — patients may need more than 25 mg/kg/min — to hold plasma glucose in the normal range. Chronically this becomes frequent high-calorie carbohydrate feeds, continuous gastric dextrose, and often a gastrostomy because diazoxide-treated children develop food aversion.

Mechanism Target:

INHIBITS Dual Glucose and Ketone Substrate Deprivation of the Brain — Exogenous glucose substitutes for the fuel the brain cannot obtain, and is the only intervention that acts on the deprivation node itself rather than on its upstream cause.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Patients with HH may require >25 mg/kg/min of intravenous glucose infusion to maintain normoglycaemia."

Establishes intravenous glucose as the intervention that maintains cerebral substrate supply.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"Patients with HH may require >25 mg/kg/min of intravenous glucose infusion to maintain normoglycaemia."

Quantifies the extreme glucose requirement in severe disease.

PMID:29280746 SUPPORT Human Clinical

"Frequent feeding with high calorie carbohydrate feeds may reduce the frequency and severity of hypoglycaemic episodes."

Supports the frequent-feeding component of chronic management.

18F-DOPA PET-Guided Focal Lesionectomy

Action: focal lesionectomy (limited partial pancreatectomy) Ontology label: Partial Pancreatectomy NCIT:C51666

The one curative intervention in the disorder. When genetics indicate a single paternally inherited K-ATP variant and 18F-DOPA PET/CT localizes a discrete lesion, a limited resection with intraoperative frozen-section confirmation removes the entire disease. This is why the focal/diffuse distinction is worth the diagnostic effort: the same clinical picture leads either to cure or to a near-total pancreatectomy.

Mechanism Target:

INHIBITS Focal Lesion Formation by Paternal K-ATP Variant and Somatic 11p15 Maternal Loss — Resection physically removes the clone in which the K-ATP variant is homozygous, eliminating the source of unregulated secretion.

Show evidence (1 reference)

PMID:35018160 SUPPORT Human Clinical

"In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations."

Confirms that removing the focal lesion resolves the disease.

Show evidence (2 references)

PMID:39741883 SUPPORT Human Clinical

"After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."

Demonstrates cure in every focal case versus relapse in diffuse/atypical disease.

PMID:35018160 PARTIAL Human Clinical

"18F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion."

Supports the imaging basis for lesion-directed surgery.

Near-Total Pancreatectomy

Action: pancreatectomy Ontology label: Pancreatectomy NCIT:C15294

Reserved for medically uncontrollable diffuse disease. Removing 90-98% of the pancreas trades one disease for another: hypoglycemia frequently persists, diabetes mellitus becomes highly likely with time, and exocrine insufficiency follows resection above about half the gland. It is a control measure, not a cure, and lifelong HbA1c, fecal elastase and fat-soluble vitamin monitoring follow.

Mechanism Target:

INHIBITS Dysregulated Beta-Cell Insulin Secretion — Removing 90-98% of the pancreas removes most of the secreting beta-cell mass; because the defect is present in every islet this reduces rather than abolishes unregulated secretion, and it trades hypoglycemia for diabetes.

Show evidence (1 reference)

PMID:24840042 SUPPORT Human Clinical

"Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency."

Shows that removing beta-cell mass only partly controls secretion (hypoglycemia persists) while producing endocrine and exocrine failure.

Show evidence (1 reference)

PMID:24840042 SUPPORT Human Clinical

"Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency."

Documents persistent hypoglycemia plus diabetes and exocrine insufficiency after near-total pancreatectomy.

Nifedipine (not recommended for routine use)

Action: Pharmacotherapy NCIT:C15986

Agent: nifedipine CHEBI:7565

An L-type calcium-channel blocker used off-label on the rationale that voltage-gated calcium entry is the final step of insulin exocytosis. The rationale does not survive contact with K-ATP disease: if the channel is broken the membrane is already depolarized, and the largest dedicated study (11 ABCC8-mutated cases on long-term nifedipine) found no improvement in glycemic control in any patient. The 2023 international consensus recommends against routine use. Curated deliberately as a negative recommendation, because nifedipine is still reached for off-label.

Show evidence (2 references)

PMID:29280746 REFUTE Human Clinical

"none of patients showed any improvement in glycemic control and patients continued to have hypoglycemic episodes"

In the largest dedicated study of long-term nifedipine in K-ATP hyperinsulinism no patient improved, refuting routine efficacy.

PMID:29280746 SUPPORT Human Clinical

"This suggests that mutations in the KATPchannel genes might render the L-type calcium channel ineffective to therapy with nifedipine"

Gives the mechanistic reason nifedipine fails specifically in K-ATP disease.

Sirolimus (not recommended outside research protocols)

Action: Pharmacotherapy NCIT:C15986

Agent: sirolimus CHEBI:9168

An mTOR inhibitor trialled in severe diazoxide-unresponsive diffuse disease after early favourable reports. Subsequent evaluation was much less encouraging — effective in only 3 of 10 patients, with no reduction in beta-cell proliferation in resected tissue from non-responders — while the immunosuppressive toxicity profile (stomatitis, infection, renal dysfunction, pneumonitis, transaminase and lipid elevation) is substantial. The 2023 international consensus recommends against routine use outside approved research protocols.

Show evidence (2 references)

PMID:29280746 REFUTE Human Clinical

"mTOR inhibition has shown to be effective in only three patients (30%) with certain side effects"

Reports a low response rate with side effects, refuting sirolimus as routine therapy.

PMID:29280746 SUPPORT Human Clinical

"The most commonly reported adverse effects are stomatitis, increased risk of infection, immunosuppression, renal dysfunction, fatigue, pneumonitis and increased serum aminotransferase or lipid levels"

Documents the immunosuppressive toxicity profile that weighs against routine use.

Genotype-Specific Trigger Avoidance and Dietary Management

Action: dietary intervention Ontology label: Dietary Intervention NCIT:C15447

Because several subtypes have a specific precipitant, management is partly behavioural and genotype-directed: protein/leucine restriction in GLUD1 and HADH disease, avoidance of anaerobic/strenuous exercise in SLC16A1 disease, and — universally — avoidance of prolonged fasting, with a written emergency regimen for intercurrent illness.

Mechanism Target:

INHIBITS Glutamate Dehydrogenase Amino-Acid Amplifier Activation — Protein and leucine restriction withdraws the substrate that allosterically activates glutamate dehydrogenase, removing the trigger in GLUD1 and HADH disease.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"protein/leucine loading precipitates hypoglycaemia"

Establishes protein/leucine as the amplifier trigger whose dietary withdrawal is the genotype-specific intervention.

Show evidence (2 references)

PMID:29280746 SUPPORT Human Clinical

"protein/leucine loading precipitates hypoglycaemia"

Establishes protein/leucine as the specific precipitant in GLUD1 and HADH disease.

PMID:29280746 SUPPORT Human Clinical

"A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"

Supports exercise as the specific precipitant in the SLC16A1 subtype.

🌍

Environmental Factors

4

Maternal diabetes mellitus

Chronic transplacental glucose exposure over-stimulates the fetal islet, so the infant of a diabetic mother is born with an over-primed insulin-secretory apparatus that continues secreting once the maternal glucose supply is cut at delivery. This is a leading cause of neonatal hyperinsulinemic hypoglycemia overall and is usually transient.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"HH can be transient due to certain risk factors, such as birth asphyxia, intra-uterine growth retardation, maternal diabetes mellitus"

Names maternal diabetes among the risk factors for transient hyperinsulinemic hypoglycemia.

Perinatal asphyxia and intrauterine growth restriction

Perinatal hypoxic-ischaemic stress and IUGR appear to reset the beta-cell glucose threshold downward. Most cases resolve within days, but a protracted form requires weeks of diazoxide — and, because these infants are already at neurological risk from the asphyxia itself, the added hypoglycemia is particularly damaging.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Some newborns with IUGR and asphyxia have a severe and protracted form of HH which requires treatment with diazoxide"

Documents IUGR and asphyxia as triggers of severe, protracted hyperinsulinism.

Intrapartum maternal dextrose infusion

High-rate maternal dextrose during labour transiently drives fetal insulin secretion and can produce neonatal hyperinsulinemic hypoglycemia in the hours after delivery.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"the use of intravenous dextrose given during labour"

Names intrapartum intravenous dextrose among the transient-HH risk factors.

Prolonged fasting

The "prolonged fasting of any sort should be avoided" wording is from the Agents/Circumstances to Avoid section of the GeneReviews chapter body (PMID:20301549), which is not reproduced in the cached PubMed abstract; it is therefore recorded as provenance rather than quoted as an evidence snippet.

Fasting is the universal precipitant across every etiology of hyperinsulinemic hypoglycemia and is the one exposure that must be actively engineered out of a patient's life. GeneReviews states in its Agents/Circumstances to Avoid section that prolonged fasting of any sort should be avoided; this drives the frequent-feeding, continuous-dextrose and gastrostomy strategies used in management, and means that any incidental fast (illness, pre-operative starvation) is a hazard requiring a written emergency plan.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"Frequent feeding with high calorie carbohydrate feeds may reduce the frequency and severity of hypoglycaemic episodes."

Supports the corollary of fasting avoidance — that frequent feeding reduces hypoglycemic episodes.

🔬

Biochemical Markers

5

Plasma beta-hydroxybutyrate at the time of hypoglycemia (DECREASED)

Reference Ranges

– mmol/L (neonates and infants during documented hypoglycemia (plasma glucose <50 mg/dL))

Inappropriately suppressed (consistent with excessive insulin action) (–1.8 mmol/L) → Hypoketotic hypoglycemia Appropriate ketotic response (argues against hyperinsulinism) (1.8– mmol/L)

Inappropriately suppressed (consistent with excessive insulin action): Beta-hydroxybutyrate below 1.8 mmol/L while plasma glucose is below 50 mg/dL indicates a failure of the normal ketotic response and supports excessive insulin action.

Appropriate ketotic response (argues against hyperinsulinism): A beta-hydroxybutyrate at or above 1.8 mmol/L before glucose falls below 50-60 mg/dL is the criterion used to confirm diazoxide responsiveness on a safety fast, and in an untreated patient argues against hyperinsulinism.

Interpretive threshold rather than a population reference interval: a plasma beta-hydroxybutyrate below 1.8 mmol/L at a plasma glucose under 50 mg/dL indicates excessive insulin action. The 1.8 mmol/L cut-point is taken from the 2023 international consensus guideline (PMID:37454648), whose PubMed abstract does not reproduce the numeric criterion, so it is recorded here as provenance rather than as a quoted snippet.

Show evidence (2 references)

PMID:38944478 SUPPORT Human Clinical

"the authors propose that routine measurement of B-hydroxybutyrate should be considered an essential part of glucose monitoring in newborn infants."

Establishes beta-hydroxybutyrate as the key discriminating analyte, to the point of being proposed for routine newborn monitoring.

PMID:29280746 SUPPORT Human Clinical

"the diagnosis of HH should not be based on an isolated serum insulin/c-peptide concentration but on the clinical presentation and the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"

States explicitly that suppressed beta-hydroxybutyrate and fatty acids are more diagnostically reliable than the insulin concentration alone.

Plasma free fatty acids at the time of hypoglycemia (DECREASED)

Reference Ranges

– mmol/L (infants during documented hypoglycemia (plasma glucose <50 mg/dL))

Inappropriately suppressed (consistent with excessive insulin action) (–1.7 mmol/L) → Decreased circulating free fatty acid level Appropriate lipolytic response (argues against hyperinsulinism) (1.7– mmol/L)

Inappropriately suppressed (consistent with excessive insulin action): Free fatty acids below 1.7 mmol/L during hypoglycemia indicate suppressed lipolysis and support excessive insulin action.

Appropriate lipolytic response (argues against hyperinsulinism): Free fatty acids at or above 1.7 mmol/L during hypoglycemia represent the expected lipolytic response and argue against excessive insulin action. It is the conjunction of this appropriate free-fatty-acid rise with inappropriately low ketones that redirects the workup toward a fatty acid oxidation disorder.

In a prolonged-hyperinsulinism cohort, free fatty acids measured during documented hypoglycemia averaged 0.3 mmol/L against a stated expectation of more than 1.5 mmol/L. The 2023 international consensus guideline uses a cut-point of 1.7 mmol/L as evidence of excessive insulin action; that numeric criterion is not reproduced in the guideline's PubMed abstract and is recorded here as provenance rather than as a quoted snippet.

Show evidence (1 reference)

PMID:31465295 PARTIAL Human Clinical

"levels were measured during hypoglycemia (plasma glucose <50 mg/dL)"

Establishes only the sampling condition this interval applies to (documented hypoglycemia below 50 mg/dL), not the 1.7 mmol/L cut-point itself, which comes from the guideline body and is recorded in `notes:`.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"

Establishes suppressed fatty acids as part of the biochemical profile of insulin action.

Plasma insulin and C-peptide at the time of hypoglycemia (INCREASED)

Show evidence (2 references)

PMID:40904956 SUPPORT Human Clinical

"Laboratory investigations revealed elevated insulin and C-peptide levels, absence of ketone bodies, and a positive response to the glucagon stimulation test."

Documents the concordant insulin and C-peptide elevation of endogenous hyperinsulinism.

PMID:29280746 SUPPORT Human Clinical

"In some difficult cases, the diagnosis of HH should not be based on an isolated serum insulin/c-peptide concentration"

Cautions that an isolated insulin/C-peptide value is insufficient for diagnosis.

Plasma ammonia (INCREASED)

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"An elevated serum ammonia concentration in a patient with HH is suggestive of the hyperinsulinism and hyperammonaemia (HI/HA) syndrome"

Establishes ammonia as the subtype-discriminating analyte for HI/HA.

Glycemic response to glucagon during hypoglycemia (PRESENT)

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"In some patients, a positive glycaemic response (rise in the plasma glucose concentration of >1.5 mmol/L from baseline) following an intramuscular/intravenous injection of glucagon at the time of hypoglycaemia provides supportive evidence"

Provides the quantitative glucagon-response criterion used in the critical-sample workup.

🔀

Differential Diagnoses

7

Conditions with similar clinical presentations that must be differentiated from Hyperinsulinemic Hypoglycemia:

Fatty acid oxidation disorders MONDO:0008721

Overlapping Features The closest biochemical mimic, because both present with hypoketotic hypoglycemia. MCAD and related defects share the low-ketone finding but the lesion is in beta-oxidation, not in insulin.

Distinguishing Features

Free fatty acids are HIGH in fatty acid oxidation defects (lipolysis is intact, oxidation fails) and LOW in hyperinsulinism (lipolysis is blocked) — the single most efficient discriminator on the critical sample.
Plasma acylcarnitines are abnormal in fatty acid oxidation defects and normal in hyperinsulinism, with the single exception of HADH/SCHAD deficiency, which itself raises 3-hydroxybutyrylcarnitine.
Insulin and C-peptide are appropriately suppressed in fatty acid oxidation defects.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"

Establishes that low fatty acids alongside low ketones is the profile of insulin action, which is what separates hyperinsulinism from a fatty acid oxidation defect.

Glycogen storage disease MONDO:0002413

Overlapping Features Hepatic glycogen storage disease presents with fasting hypoglycemia and hepatomegaly, both of which also occur in hyperinsulinism.

Distinguishing Features

Glycogen storage disease type I gives a KETOTIC hypoglycemia, the inverse of the hyperinsulinism profile.
Lactic acidosis, hyperuricemia and hyperlipidemia accompany the hypoglycemia; lactate is normal in hyperinsulinism.
The glucagon stimulation test fails to raise glucose because glucose-6-phosphatase deficiency blocks release of free glucose (lactate rises instead), whereas in hyperinsulinism the response is brisk and positive.

Show evidence (1 reference)

PMID:29280746 PARTIAL Human Clinical

"a positive glycaemic response (rise in the plasma glucose concentration of >1.5 mmol/L from baseline) following an intramuscular/intravenous injection of glucagon at the time of hypoglycaemia provides supportive evidence"

Supports the glucagon-response criterion that separates hyperinsulinism (positive response) from glycogen storage disease; the cited source describes the hyperinsulinism side of that contrast only.

Insulinoma Not Yet Curated MONDO:0024677

Overlapping Features An insulin-secreting pancreatic neuroendocrine tumour produces biochemically identical endogenous hyperinsulinemic hypoglycemia.

Distinguishing Features

Age is the key discriminator — hyperinsulinemic hypoglycemia first appearing after about two years of age should prompt an insulinoma evaluation.
Insulinoma is typically a solitary, cross-sectionally visible tumour arising against previously normal glucose regulation.
Insulinoma may occur within multiple endocrine neoplasia type 1.

Show evidence (1 reference)

PMID:29280746 PARTIAL Human Clinical

"HH most commonly presents during the neonatal period, but can also present during infancy, childhood and even adulthood"

Supports the age-based framing of the differential; the source establishes the age range of congenital HH rather than the insulinoma comparison directly, so support is partial.

Exogenous insulin administration (factitious or accidental)

Overlapping Features Administered insulin — accidental, iatrogenic, or in factitious disorder or medical child abuse — reproduces the entire clinical and biochemical picture of endogenous hyperinsulinism and must be actively excluded, particularly in an atypical age group or an unwitnessed setting.

Distinguishing Features

C-peptide is the discriminator — endogenous hyperinsulinism raises insulin and C-peptide together because they are secreted in equimolar amounts from proinsulin.
Injected insulin raises insulin while SUPPRESSING C-peptide, giving an elevated insulin-to-C-peptide ratio.
Sulfonylurea ingestion raises both insulin and C-peptide and requires a drug screen to detect.

Show evidence (1 reference)

PMID:40904956 PARTIAL Human Clinical

"Laboratory investigations revealed elevated insulin and C-peptide levels"

Documents the concordant insulin-and-C-peptide elevation of endogenous disease, which is precisely the pattern that exogenous insulin breaks; recorded as partial because the source does not itself address exogenous insulin.

Adrenal insufficiency Not Yet Curated MONDO:0000004

Overlapping Features Cortisol deficiency impairs gluconeogenesis and produces fasting hypoglycemia in infants, and can co-present with the same non-specific neonatal symptoms.

Distinguishing Features

Cortisol is inappropriately low on the critical sample, whereas counter-regulatory hormones are intact in hyperinsulinism.
Adrenal insufficiency gives a ketotic hypoglycemia.
Associated hyponatremia, hyperkalemia, hyperpigmentation or ambiguous genitalia point to the adrenal.

Growth hormone deficiency and hypopituitarism Not Yet Curated MONDO:0005152

Overlapping Features Congenital hypopituitarism causes neonatal hypoglycemia through combined growth hormone and cortisol deficiency, and can itself present with a partly hypoketotic picture.

Distinguishing Features

Growth hormone and cortisol are inappropriately low on the critical sample.
Midline defects, micropenis, prolonged jaundice or septo-optic dysplasia point to the pituitary.
Insulin and C-peptide are appropriately suppressed, unlike in hyperinsulinism.

Idiopathic ketotic hypoglycemia

Overlapping Features A common cause of hypoglycemia in toddlers and young children, presenting with fasting hypoglycemia during intercurrent illness.

Distinguishing Features

Ketotic by definition — beta-hydroxybutyrate is appropriately elevated at the time of hypoglycemia, the exact inverse of the hyperinsulinism profile.
Insulin is appropriately suppressed.
The intravenous glucose infusion requirement is normal rather than above 8 mg/kg/min.

Show evidence (1 reference)

PMID:29280746 SUPPORT Human Clinical

"It is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants"

Establishes hyperinsulinism as a HYPOketotic hypoglycemia, the defining contrast with ketotic hypoglycemia.

🔬

Clinical Trials

4

NCT06208215 PHASE_III ACTIVE_NOT_RECRUITING

Phase 3 randomized, double-blind, placebo-controlled study of RZ358 (ersodetug), an allosteric anti-insulin-receptor antibody that acts distal to the beta cell by blunting insulin action at the receptor rather than trying to suppress a broken secretory apparatus — a mechanistically distinct approach that should work irrespective of the underlying genotype.

Target Phenotypes: Hyperinsulinemic hypoglycemia HP:0000825

Show evidence (1 reference)

clinicaltrials:NCT06208215 SUPPORT

"The Phase 3 pivotal study is designed to evaluate the efficacy and safety of RZ358 for the treatment of congenital hyperinsulinism (HI) as add-on to standard-of-care (SOC) therapy compared to SOC alone over 24 weeks"

Confirms the phase 3 evaluation of RZ358 as add-on therapy for hyperinsulinism.

NCT04538989 PHASE_II COMPLETED

Open-label multiple-dose phase 2 study of RZ358 (ersodetug), the predecessor to the phase 3 programme; results were first posted in May 2025.

Target Phenotypes: Hyperinsulinemic hypoglycemia HP:0000825

Show evidence (1 reference)

clinicaltrials:NCT04538989 SUPPORT

"The objective of this trial is to evaluate the safety, tolerability and glucose-raising effects of RZ358 in patients with Congenital Hyperinsulinism (HI)."

Documents the phase 2 evaluation of RZ358 that preceded the phase 3 study.

NCT04732416 PHASE_II ACTIVE_NOT_RECRUITING

Phase 2 multiple-ascending-dose proof-of-concept study of HM15136 (efpegerglucagon), a long-acting glucagon analogue given once weekly as add-on therapy — the same counter-regulatory strategy as dasiglucagon but on a weekly rather than continuous-infusion schedule.

Target Phenotypes: Hypoglycemia HP:0001943

Show evidence (1 reference)

clinicaltrials:NCT04732416 SUPPORT

"This study is designed to evaluate the safety, tolerability, pharmacokinetics (PK), and efficacy of HM15136 when used as add-on therapy in subjects with CHI with persistent hypoglycemia while on standard of care treatment (SoC)."

Documents weekly efpegerglucagon as an investigational add-on therapy for persistent hypoglycemia in hyperinsulinism.

NCT03777176 PHASE_III COMPLETED

Two-period open-label phase 3 trial of dasiglucagon, a soluble glucagon analogue delivered by continuous subcutaneous infusion, exploiting the counter-regulatory arm that insulin is suppressing.

Target Phenotypes: Hypoglycemia HP:0001943

Show evidence (1 reference)

clinicaltrials:NCT03777176 SUPPORT

"The objective of the trial is to evaluate the efficacy and safety of dasiglucagon administered as a subcutaneous (SC) infusion in reducing hypoglycemia in children with CHI."

Confirms the phase 3 evaluation of continuous subcutaneous dasiglucagon in hyperinsulinism.

{ }

Source YAML

click to show

name: Hyperinsulinemic Hypoglycemia
creation_date: "2026-08-01T05:30:00Z"
description: >-
  Hyperinsulinemic hypoglycemia (HH) is the etiology-spanning umbrella disorder
  of inappropriate insulin secretion in the presence of a low plasma glucose. It
  is the most common and most severe cause of persistent hypoglycemia in infants
  and children, and — because insulin simultaneously drives glucose into
  insulin-sensitive tissues, blocks hepatic glucose production, and suppresses
  lipolysis and ketogenesis — the brain is deprived of BOTH glucose and its
  principal alternative ketone fuel. That dual substrate deprivation is why
  neuroglycopenic injury in HH is more profound than in other hypoglycemias and
  why HH is a major preventable cause of permanent brain injury: recognition
  speed, not therapeutic novelty, is the dominant determinant of outcome.
  Mechanistically the disorder converges on unregulated beta-cell insulin
  release, most often from loss-of-function ABCC8/KCNJ11 (SUR1/Kir6.2) K-ATP
  channel defects that leave the beta-cell membrane depolarized, with distinct
  routes via activating GLUD1 (hyperinsulinism-hyperammonemia), activating GCK
  (a lowered glucose set-point), HADH, HNF4A/HNF1A, SLC16A1 (exercise-induced),
  UCP2 and HK1. Beyond the congenital genetic forms the umbrella also spans
  perinatal-stress-induced and maternal-diabetes-associated transient HH,
  syndromic HH (Beckwith-Wiedemann spectrum, Kabuki syndrome), and acquired
  adult disease (insulinoma, post-bariatric hypoglycemia). The clinically
  decisive axis is histological: focal disease — a paternally inherited
  ABCC8/KCNJ11 variant unmasked by somatic loss of the maternal 11p15 allele
  within a discrete lesion — is localizable by 18F-DOPA PET and surgically
  curable, whereas diffuse disease is not.
category: Genetic
disease_term:
  preferred_term: hyperinsulinemic hypoglycemia
  term:
    id: MONDO:0005803
    label: hyperinsulinemic hypoglycemia
parents:
- Endocrine Disease
- Inborn Error of Metabolism
synonyms:
- hyperinsulinism
- hyperinsulinaemic hypoglycaemia
- persistent hyperinsulinemic hypoglycemia of infancy
- congenital hyperinsulinism
notes: >-
  SCOPE / RELATIONSHIP TO Congenital_Isolated_Hyperinsulinism. This entry is the
  deliberately broader umbrella for MONDO:0005803 (a MONDO `disease_grouping`
  term whose xrefs include HP:0000825, OMIMPS:256450 and Orphanet:443095). The
  existing dismech entry `Congenital Isolated Hyperinsulinism` (MONDO:0019010,
  Orphanet:657) is a distinct, narrower MONDO entity restricted to the
  nonsyndromic congenital genetic forms and carries the per-gene subtype detail
  (HHF1/HHF2, HI/HA, SCHAD-HI, HNF4A/HNF1A-HI). To avoid duplicating that graph,
  this umbrella entry deliberately (a) models the etiology-agnostic final common
  pathway — unregulated insulin secretion, the dual glucose-plus-ketone
  substrate deprivation, and neuroglycopenic injury; (b) covers the etiologies
  the congenital-isolated entry excludes by definition (perinatal-stress-induced
  and maternal-diabetes-associated transient HH, syndromic HH, acquired adult
  HH); and (c) adds the umbrella-level clinical artifacts absent there — the
  critical-sample biochemical criteria, structured differential diagnoses, and
  histopathology of the focal/diffuse/atypical split. The `genetic:` block here
  is deliberately the full etiologic gene spectrum of the umbrella (adding GCK,
  SLC16A1, UCP2 and HK1, which the narrower entry does not carry) at one
  paragraph per gene; the per-subtype HHF-numbered molecular detail, variant-level
  curation and subtype-specific evidence stay in
  `Congenital_Isolated_Hyperinsulinism`. Both MONDO:0005803 and MONDO:0019010 are
  MONDO `disease_grouping` terms, so whether this pair is better expressed as a
  `kb/groupings/` Grouping plus a shared `kb/modules/` module for the
  final-common-pathway chain is a genuine lump-versus-split question flagged for
  human adjudication rather than settled here.
references:
- reference: PMID:20301549
  title: "Nonsyndromic Genetic Hyperinsulinism Overview."
  tags:
  - GeneReviews
- reference: PMID:37454648
  title: "International Guidelines for the Diagnosis and Management of Hyperinsulinism."
- reference: PMID:25957977
  title: "Recommendations from the Pediatric Endocrine Society for Evaluation and Management of Persistent Hypoglycemia in Neonates, Infants, and Children."
classifications:
  harrisons_chapter:
  - classification_value: ENDOCRINOLOGY_METABOLISM
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
inheritance:
- name: Autosomal recessive
  description: >-
    Biallelic recessive ABCC8 or KCNJ11 variants cause severe, usually
    diazoxide-unresponsive diffuse hyperinsulinism; recessive HADH deficiency is
    also inherited this way.
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
- name: Autosomal dominant
  description: >-
    Monoallelic dominant ABCC8/KCNJ11 variants cause milder, often
    diazoxide-responsive disease; dominant activating GLUD1 and GCK variants and
    heterozygous HNF4A/HNF1A and SLC16A1 promoter variants are also dominant.
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
- name: Somatic mosaicism with parent-of-origin effect
  description: >-
    Focal hyperinsulinism is a two-hit, parent-of-origin disorder: a paternally
    inherited recessive ABCC8/KCNJ11 variant is unmasked within a pancreatic
    clone by post-zygotic loss of heterozygosity for the maternal 11p15 allele
    with reduplication of the paternal allele (segmental paternal isodisomy).
    The germline variant alone is insufficient; the lesion is defined by the
    somatic second hit. Atypical/mosaic (LINE) disease similarly arises from somatic
    ABCC8 or GCK variants.
  parent_of_origin_effect: >-
    Paternal origin of the germline K-ATP variant is required: the causal somatic
    second hit is loss of the maternal 11p15 allele with paternal isodisomy, so
    only a paternally inherited variant can be rendered homozygous within the
    lesion.
  inheritance_term:
    preferred_term: Somatic mosaicism
    term:
      id: HP:0001442
      label: Typified by somatic mosaicism
  evidence:
  - reference: PMID:25765446
    reference_title: "Three novel pathogenic mutations in KATP channel genes and somatic imprinting alterations of the 11p15 region in pancreatic tissue in patients with congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The epigenetic alteration at the 11p15 region plays a central role in developing focal CHI by paternally derived mutations of the KATP channel and maternal allelic loss at this region."
    explanation: >-
      Establishes the two-hit, parent-of-origin mechanism (paternal K-ATP
      variant plus somatic maternal 11p15 loss) that defines focal disease.
has_subtypes:
- name: Diffuse HI
  display_name: Diffuse Hyperinsulinism
  subtype_term:
    preferred_term: diazoxide-resistant diffuse hyperinsulinism
    term:
      id: MONDO:0015625
      label: diazoxide-resistant diffuse hyperinsulinism
  description: >-
    Whole-pancreas involvement in which every islet is abnormal, typically from
    biallelic recessive (or some dominant) ABCC8/KCNJ11 variants. Diffuse
    disease accounts for roughly 60% of congenital hyperinsulinism, is
    disproportionately diazoxide-unresponsive, and — critically — is NOT
    surgically curable: near-total (90-98%) pancreatectomy controls but does not
    cure hypoglycemia and imposes a very high later burden of diabetes and
    exocrine insufficiency.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diffuse disease accounts for about 60% of all CHI cases and affects all the b-cells of the pancreas."
    explanation: Quantifies diffuse disease as the majority histological form and defines its whole-pancreas extent.
  - reference: PMID:39741883
    reference_title: "Congenital hyperinsulinism in the Ukraine: a 10-year national study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."
    explanation: Contrasts the non-curative outcome of surgery in diffuse/atypical disease with cure in focal disease.
- name: Focal HI
  display_name: Focal Hyperinsulinism (paternal K-ATP variant + somatic maternal 11p15 LOH)
  subtype_term:
    preferred_term: diazoxide-resistant focal hyperinsulinism
    term:
      id: MONDO:0019265
      label: diazoxide-resistant focal hyperinsulinism
  description: >-
    A discrete (typically 2-10 mm) region of adenomatous islet-cell hyperplasia
    in an otherwise normal pancreas. Focal disease is a two-hit lesion: a
    paternally inherited recessive ABCC8 or KCNJ11 variant becomes homozygous
    within the lesion because of post-zygotic loss of heterozygosity for the
    maternal 11p15 allele with paternal isodisomy, which simultaneously unmasks
    the K-ATP defect and — because the imprinted 11p15 domain is now
    paternal-only (IGF2 up, H19/CDKN1C down) — drives clonal beta-cell
    proliferation. This is the single most management-relevant subtype
    distinction in the disorder: the lesion is localizable by 18F-DOPA PET/CT and
    a limited lesionectomy is curative, sparing the child a near-total
    pancreatectomy and its diabetes risk.
  evidence:
  - reference: PMID:25765446
    reference_title: "Three novel pathogenic mutations in KATP channel genes and somatic imprinting alterations of the 11p15 region in pancreatic tissue in patients with congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MS-MLPA and microsatellite analyses demonstrated abnormal imprinting patterns and focal loss of maternal 11p13-15 within the lesions. In contrast, parental heterozygosity was preserved in the normal tissue."
    explanation: >-
      Demonstrates directly that the maternal 11p15 loss is somatic and confined
      to the lesion, with normal pancreas retaining heterozygosity.
  - reference: PMID:39741883
    reference_title: "Congenital hyperinsulinism in the Ukraine: a 10-year national study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."
    explanation: Confirms that focal disease, unlike diffuse disease, is surgically curable.
- name: Atypical HI
  display_name: Atypical / Mosaic Hyperinsulinism (LINE)
  description: >-
    A third histological category, intermediate between focal and diffuse, in
    which abnormal beta cells occupy regional or mosaic territories (localized
    islet nuclear enlargement, LINE). It can arise from somatic ABCC8 or GCK
    variants or from inappropriate beta-cell HK1 expression. Surgical outcome is
    less predictable than in focal disease.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Histologically, CHI is classified into three subgroups: diffuse, focal and atypical forms"
    explanation: Establishes atypical disease as a recognised third histological subgroup alongside diffuse and focal.
- name: HI/HA Syndrome
  display_name: Hyperinsulinism-Hyperammonemia Syndrome (GLUD1)
  subtype_term:
    preferred_term: hyperinsulinism-hyperammonemia syndrome
    term:
      id: MONDO:0011717
      label: hyperinsulinism-hyperammonemia syndrome
  description: >-
    Dominant activating GLUD1 variants that escape GTP inhibition of glutamate
    dehydrogenase, giving leucine/protein-sensitive hyperinsulinism together with
    a persistent mild hyperammonemia that is close to specific for this subtype.
    Usually diazoxide-responsive, and managed additionally by protein/leucine
    restriction.
  evidence:
  - reference: PMID:21130127
    reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the hyperinsulinism/hyperammonemia syndrome caused by dominant activating mutations of GLUD1 which interfere with inhibitory regulation by GTP"
    explanation: Defines the GLUD1 activating-variant basis of the HI/HA subtype.
  - reference: PMID:21130127
    reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The other distinctive feature of the HI/HA Syndrome is a persistent elevation of plasma ammonia concentrations."
    explanation: Establishes persistent hyperammonemia as the subtype-defining biochemical feature.
- name: Diazoxide-Responsive HI
  display_name: Diazoxide-Responsive Hyperinsulinism
  description: >-
    Hyperinsulinism that is controlled by diazoxide. Because diazoxide acts by
    binding SUR1 and holding the K-ATP channel open, responsiveness requires a
    structurally and functionally intact channel. Diazoxide-responsive disease
    therefore concentrates the non-K-ATP etiologies (GLUD1, HADH, HNF4A/HNF1A,
    SLC16A1, UCP2) and the perinatal-stress/transient forms.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diazoxide functions by binding to the SUR1 subunit of KATPchannel. Thus, it requires a functionally intact KATPchannel."
    explanation: >-
      Explains mechanistically why diazoxide responsiveness partitions the
      disorder along the K-ATP-intact versus K-ATP-defective axis.
- name: Diazoxide-Unresponsive HI
  display_name: Diazoxide-Unresponsive Hyperinsulinism
  subtype_term:
    preferred_term: diazoxide-resistant hyperinsulinism
    term:
      id: MONDO:0017186
      label: diazoxide-resistant hyperinsulinism
  description: >-
    Hyperinsulinism that fails maximal diazoxide therapy. This is the
    pharmacologically predictable consequence of the drug's target being broken:
    recessive (and some dominant) ABCC8/KCNJ11 loss-of-function variants leave no
    functional channel for diazoxide to open. Diazoxide unresponsiveness is
    therefore the clinical trigger for urgent ABCC8/KCNJ11 sequencing and, when a
    single paternal variant is found, 18F-DOPA PET to look for a curable focal
    lesion.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In diazoxide unresponsive CHI cases, urgent genetic analysis forABCC8/KCNJ11and18F-DOPA-PET/CT scan are indicated to identify those patients who could have the focal form of CHI."
    explanation: Confirms diazoxide unresponsiveness as the decision point that triggers focal-lesion workup.
  - reference: PMID:37056678
    reference_title: "K(ATP) channel mutations in congenital hyperinsulinism: Progress and challenges towards mechanism-based therapies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "treatment remains challenging, in particular for patients with diffuse disease who do not respond to the KATP channel activator diazoxide."
    explanation: Confirms that diffuse K-ATP disease is characteristically diazoxide-unresponsive.
- name: Perinatal Stress-Induced HI
  display_name: Perinatal Stress-Induced and Transient Hyperinsulinism (including infant of a diabetic mother)
  description: >-
    Acquired, usually transient hyperinsulinism of the newborn precipitated by
    maternal diabetes mellitus, perinatal asphyxia, intrauterine growth
    restriction, or intrapartum maternal dextrose. It presents within the first
    day of life and most cases resolve within days to two weeks, but a protracted
    form persists for weeks and requires diazoxide. It is far more common than
    genetic congenital hyperinsulinism and is the main reason that a first
    critical sample drawn during the physiological transitional period must be
    repeated after 72 hours before a persistent diagnosis is made.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Transient HH typically develops in newborns with certain risk factors"
    explanation: Establishes the transient/stress-induced subtype as risk-factor driven in newborns.
  - reference: PMID:31465295
    reference_title: "Characterization of the duration of treatment with diazoxide in infants with prolonged hyperinsulinism (PHI)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prolonged neonatal hyperinsulinism (PHI) causes hypoglycemia in the neonatal period and is associated with perinatal stress."
    explanation: Documents the protracted, diazoxide-requiring form of perinatal-stress-associated hyperinsulinism.
- name: Syndromic HI
  display_name: Syndromic Hyperinsulinism (Beckwith-Wiedemann spectrum, Kabuki syndrome and others)
  description: >-
    Hyperinsulinism occurring as one feature of a broader syndrome — most
    characteristically the Beckwith-Wiedemann spectrum (11p15 imprinting defect
    or paternal uniparental disomy, mechanistically overlapping the focal-lesion
    11p15 event and occasionally combined with a paternally inherited
    ABCC8/KCNJ11 variant to give severe disease), Kabuki syndrome (KMT2D/KDM6A),
    Turner, Sotos, Costello and Simpson-Golabi-Behmel syndromes, and the
    congenital disorders of glycosylation. Recognising the syndromic context
    redirects testing (11p15 methylation, chromosomal microarray) and changes
    surgical planning, because endocrine overgrowth may be far more extensive
    than a classic focal lesion.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "or associated with various overgrowth syndromes like Beckwith-Wiedemann syndrome or metabolic conditions such as congenital disorders of glycosylation"
    explanation: Establishes syndromic overgrowth (Beckwith-Wiedemann) and CDG as recognised syndromic causes of HH.
- name: Adult-Onset HI
  display_name: Adult-Onset Hyperinsulinemic Hypoglycemia (acquired and late-declaring genetic causes)
  description: >-
    Endogenous hyperinsulinemic hypoglycemia presenting after infancy. Most of
    this group is genuinely acquired — insulinoma, post-bariatric
    (post-gastric-bypass) hypoglycemia, insulin autoimmune syndrome, sulfonylurea
    or exogenous insulin exposure — but the axis here is age of declaration, not
    acquisition, and it also collects late-declaring germline disease such as
    adult nesidioblastosis from a GCK dosage lesion. Hyperinsulinism first appearing after about age two should
    prompt an insulinoma evaluation rather than a congenital-hyperinsulinism
    workup.
  evidence:
  - reference: PMID:39720245
    reference_title: "Case report: Duplication of the GCK gene is a novel cause of nesidioblastosis: evidence from a case with Silver-Russell syndrome-like phenotype related to chromosome 7."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We describe the clinical course of 25-year-old man with hypoglycemia. We diagnosed him with hyperinsulinemic hypoglycemia (HH) and treated him with laparoscopic distal pancreatectomy. Histological examination led to a diagnosis of nesidioblastosis."
    explanation: Documents adult-onset hyperinsulinemic hypoglycemia due to nesidioblastosis, an acquired-presentation form of the umbrella disorder.
prevalence:
- population: Norway live births
  measure_type: BIRTH_PREVALENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 5.154639
  notes: >-
    Minimum birth prevalence of the persistent (congenital) form, from a
    nationwide Norwegian cohort (1 in 19,400 live births). Reported incidence of
    persistent hyperinsulinism elsewhere ranges from roughly 1:25,000 to 1:50,000
    in outbred Western populations, rising sharply in populations with high
    consanguinity. The acquired perinatal-stress form is far more common than
    this figure and is not captured by it.
  evidence:
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The minimum birth prevalence of CHI in Norway is 1:19,400 live births."
    explanation: Provides a nationwide population-based birth-prevalence estimate for the persistent congenital form.
progression:
- phase: Neonatal presentation
  age_range: first hours to days of life
  notes: >-
    Severe K-ATP hyperinsulinism typically presents within hours to days of
    birth, often with macrosomia, and with hypoglycemia refractory to routine
    intravenous dextrose. Perinatal-stress-induced hyperinsulinism presents
    within the first 24 hours.
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report the case of a male macrosomic newborn admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia (1.4 mmol/L) unresponsive to intravenous glucose therapy."
    explanation: Illustrates the classic neonatal presentation within the first days of life.
- phase: Resolution versus persistence
  age_range: 10 days to 2 years
  notes: >-
    Perinatal-stress-induced disease usually resolves within 10-14 days, though a
    protracted form can require weeks of diazoxide. Genetic disease persists;
    some ABCC8, KCNJ11, HNF1A and HNF4A forms attenuate with age, allowing
    medication reduction, while diffuse K-ATP disease generally does not.
  evidence:
  - reference: PMID:31465295
    reference_title: "Characterization of the duration of treatment with diazoxide in infants with prolonged hyperinsulinism (PHI)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "duration of treatment was 44.9 ± 27.9 days"
    explanation: Quantifies the weeks-long diazoxide course of the protracted perinatal-stress form before resolution.
- phase: Late-onset presentation
  age_range: after 2 years
  notes: >-
    Hyperinsulinemic hypoglycemia first appearing after about age two shifts the
    differential toward insulinoma and other acquired causes rather than
    congenital hyperinsulinism; mild genetic forms (GCK, SLC16A1, HNF) may
    nevertheless first declare themselves in later childhood or adulthood.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HH most commonly presents during the neonatal period, but can also present during infancy, childhood and even adulthood"
    explanation: Confirms the full age range of presentation, including adult onset.
pathophysiology:
- name: K-ATP Channel Loss of Function
  biological_scale: MOLECULAR
  role: trigger
  description: >
    Inactivating variants in ABCC8 (SUR1) or KCNJ11 (Kir6.2), the two subunits of
    the beta-cell ATP-sensitive potassium channel, remove the channel that
    normally holds the beta-cell membrane hyperpolarized when glucose is low.
    Because the channel is the switch that couples fuel metabolism to secretion,
    its loss uncouples insulin release from the glucose signal entirely. This is
    the single most common molecular cause of hyperinsulinemic hypoglycemia and
    underlies both diffuse and focal histological disease. It is also why the
    first-line drug fails in this group: diazoxide works by holding a functional
    channel open, so a broken channel is pharmacologically unreachable.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: potassium ion transmembrane transport
    term:
      id: GO:0071805
      label: potassium ion transmembrane transport
    modifier: DECREASED
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  locations:
  - preferred_term: islet of Langerhans
    term:
      id: UBERON:0000006
      label: islet of Langerhans
  genes:
  - preferred_term: ABCC8
    term:
      id: hgnc:59
      label: ABCC8
  - preferred_term: KCNJ11
    term:
      id: hgnc:6257
      label: KCNJ11
  evidence:
  - reference: PMID:37056678
    reference_title: "K(ATP) channel mutations in congenital hyperinsulinism: Progress and challenges towards mechanism-based therapies."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic defects that lead to loss of expression or function of KATP channels are the most common cause of HI (KATP-HI)."
    explanation: Establishes K-ATP loss of function as the leading molecular cause.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "A change in the ratio of ATP to ADP causes closure of the KATPchannel and triggers depolarisation of the cell membrane, activating the voltage-gated calcium channels"
    explanation: >-
      Describes the normal K-ATP-to-calcium coupling whose constitutive
      activation follows channel loss of function; this is islet
      electrophysiology restated in a review, so tagged IN_VITRO.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: DIRECT
    description: >-
      With no functional K-ATP channel the beta-cell membrane stays depolarized
      despite low glucose, voltage-gated calcium channels remain open, cytosolic
      calcium stays high, and insulin granules are exocytosed continuously.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Calcium enters into b-cells through these voltage-gated calcium channels and an increase in intracellular calcium triggers secretory granule exocytosis and insulin release"
      explanation: >-
        Establishes the depolarization-calcium-exocytosis step that becomes
        constitutive when the channel cannot open; canonical islet
        stimulus-secretion coupling restated in a review, so tagged IN_VITRO.
- name: Glutamate Dehydrogenase Amino-Acid Amplifier Activation
  biological_scale: MOLECULAR
  role: trigger
  description: >
    The protein/leucine-sensitive arm. Dominant activating GLUD1 variants escape
    GTP inhibition of glutamate dehydrogenase, and recessive HADH (SCHAD)
    deficiency removes an inhibitory SCHAD-GDH protein-protein interaction; both
    leave glutamate dehydrogenase inappropriately active, so leucine-driven
    glutamate oxidation feeds the TCA cycle, raises the beta-cell ATP/ADP ratio
    and closes a structurally intact K-ATP channel. This is the only arm that
    also produces hyperammonemia, because the same unrestrained GDH activity in
    liver and kidney generates ammonia — which is why an elevated plasma ammonia
    in hyperinsulinemic hypoglycemia is close to specific for the GLUD1 (HI/HA)
    subtype and not a general feature of the disorder.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  genes:
  - preferred_term: GLUD1
    term:
      id: hgnc:4335
      label: GLUD1
  - preferred_term: HADH
    term:
      id: hgnc:4799
      label: HADH
  evidence:
  - reference: PMID:25733449
    reference_title: "Molecular mechanisms of congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mutations in GLUD1 and HADH lead to leucine-induced HH, and these two genes encode the key enzymes glutamate dehydrogenase and short chain 3-hydroxyacyl-CoA dehydrogenase which play a key role in amino acid and fatty acid regulation of insulin secretion respectively."
    explanation: Establishes GLUD1 and HADH as the leucine/amino-acid-driven amplifier arm.
  - reference: PMID:21130127
    reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "amino acids can trigger release of insulin in response to the oxidation of amino acids through glutamate via GDH into the TCA cycle under allosteric activation of GDH by leucine."
    explanation: >-
      Describes the leucine-allosteric activation of glutamate dehydrogenase that
      drives secretion; the mechanism is established by enzyme kinetics and islet
      work restated in this review, so tagged IN_VITRO.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Unrestrained glutamate oxidation raises the beta-cell ATP/ADP ratio.
    - Rising ATP/ADP closes an intact K-ATP channel and depolarizes the membrane.
    description: >-
      Leucine-driven glutamate oxidation raises ATP/ADP and closes a structurally
      intact K-ATP channel, converging on the same depolarization-to-exocytosis
      pathway as channel loss of function.
    evidence:
    - reference: PMID:21130127
      reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "insulin secretion is stimulated by oxidation of glucose via an increase in ATP/ADP ratio which leads to closure of ATP-sensitive KATP channels, membrane depolarization, activation of voltage-gated calcium channels, an increase in cytosolic calcium, and a mobilization of insulin-containing vesicles to release insulin into the circulation."
      explanation: >-
        Establishes the shared ATP/ADP-to-secretion coupling on which the
        amplifier arm converges; this is canonical islet stimulus-secretion
        coupling restated in a review, so tagged IN_VITRO.
  - target: Hyperammonemia
    causal_link_type: DIRECT
    description: >-
      Unrestrained glutamate dehydrogenase activity in liver and kidney generates
      ammonia, producing the persistent mild hyperammonemia that marks the GLUD1
      HI/HA subtype specifically. This edge is deliberately attached only to this
      node: the other amplifier and channel lesions do not cause hyperammonemia.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "An elevated serum ammonia concentration in a patient with HH is suggestive of the hyperinsulinism and hyperammonaemia (HI/HA) syndrome"
      explanation: Links the GLUD1 arm, and only that arm, to hyperammonemia.
- name: Lowered Beta-Cell Glucose Set-Point
  biological_scale: MOLECULAR
  role: trigger
  description: >
    The glucose-sensing arm. Glucokinase is the beta cell's glucose sensor, the
    step that sets the plasma glucose concentration at which secretion begins.
    Activating GCK variants (and, rarely, GCK duplication) shift that threshold
    downward, so the whole homeostatic system defends an inappropriately low
    glucose rather than failing to switch off. A non-coding HK1 variant that
    fails to silence hexokinase 1 in the beta cell does the same thing by a
    different route, installing a low-Km hexokinase that phosphorylates glucose
    at concentrations far below the normal threshold. Because a reset set-point
    is not the same as an absent brake, GCK disease can uniquely show a ketotic
    response on prolonged fasting.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  genes:
  - preferred_term: GCK
    term:
      id: hgnc:4195
      label: GCK
  - preferred_term: HK1
    term:
      id: hgnc:4922
      label: HK1
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "plays a critical role in acting as a gluco-sensor, providing a link between the extracellular plasma glucose concentration and the metabolism of glucose in b-cells"
    explanation: Establishes glucokinase as the beta-cell glucose sensor whose activation lowers the secretion set-point.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It catalyses the phosphorylation of glucose to produce glucose-6-phosphate as substrate for glycolysis. Normally,HK1expression is silenced in the pancreatic b-cells."
    explanation: Establishes that HK1 is normally silenced in the beta cell, so its de-silencing installs an inappropriate low-threshold sensor.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: DIRECT
    description: >-
      A downward-shifted glucose threshold means the intact K-ATP channel closes,
      and insulin is released, at plasma glucose values that should silence
      secretion entirely.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "When the plasma glucose concentration is increased, the activity ofGCKis also increased, hence increasing insulin secretion from the b-cells"
      explanation: Establishes the direct GCK-activity-to-insulin-secretion coupling that an activating variant shifts downward.
- name: Alternative Secretagogue Import and Loss of Mitochondrial Uncoupling
  biological_scale: MOLECULAR
  role: trigger
  description: >
    Two lesions that let fuels which should be invisible to the beta cell drive
    secretion. SLC16A1 (MCT1) is normally silenced in beta cells precisely so
    that pyruvate and lactate cannot act as secretagogues; dominant promoter
    variants de-silence it, so monocarboxylates generated during anaerobic
    exercise enter the cell and trigger insulin release — giving hypoglycemia
    specifically after strenuous exercise. UCP2 normally leaks protons across the
    inner mitochondrial membrane, damping ATP generation and thereby restraining
    glucose-stimulated secretion; inactivating variants remove that brake, though
    the UCP2 association remains disputed.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  genes:
  - preferred_term: SLC16A1
    term:
      id: hgnc:10922
      label: SLC16A1
  - preferred_term: UCP2
    term:
      id: hgnc:12518
      label: UCP2
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"
    explanation: Supports the SLC16A1/MCT1 arm, in which exercise-derived monocarboxylates provoke hyperinsulinemic hypoglycemia.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: PARTIAL
    evidence_source: IN_VITRO
    snippet: "mediates proton leak across the inner mitochondrial membrane, thereby inhibiting ATP generation through mitochondrial oxidative metabolism and negatively regulates glucose mediated insulin secretion"
    explanation: >-
      Describes the UCP2 proton-leak brake on ATP generation, a mitochondrial
      bioenergetic mechanism established in vitro and restated here; recorded as
      partial because the same review concludes the role of UCP2 in
      hyperinsulinism needs further investigation.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Imported pyruvate/lactate or an unopposed proton gradient raises the beta-cell ATP/ADP ratio.
    - Rising ATP/ADP closes an intact K-ATP channel and depolarizes the membrane.
    description: >-
      Both lesions raise ATP/ADP in the presence of an intact K-ATP channel,
      converging on the same depolarization-to-exocytosis pathway.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "A change in the ratio of ATP to ADP causes closure of the KATPchannel and triggers depolarisation of the cell membrane, activating the voltage-gated calcium channels"
      explanation: Establishes the ATP/ADP-to-depolarization step these lesions exploit.
- name: Transcription Factor Dysregulation of the Beta-Cell Secretory Program
  biological_scale: MOLECULAR
  role: trigger
  description: >
    A developmental/transcriptional rather than metabolic route. HNF4A and HNF1A
    are nuclear transcription factors expressed in the beta cell that regulate
    glucose-dependent insulin secretion. Heterozygous loss of function produces a
    biphasic phenotype that is diagnostically distinctive: macrosomia with
    diazoxide-responsive neonatal hyperinsulinism, then maturity-onset diabetes of
    the young decades later. The mechanism is neither an amino-acid amplifier nor
    a shifted glucose set-point, which is why it is modelled as its own node.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  genes:
  - preferred_term: HNF4A
    term:
      id: hgnc:5024
      label: HNF4A
  - preferred_term: HNF1A
    term:
      id: hgnc:11621
      label: HNF1A
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The HNFs, HNF1-a and HNF4-a, are transcription factors for nuclear hormone receptors expressed in pancreatic b-cells and regulate glucose-dependent insulin secretion"
    explanation: Establishes HNF1A/HNF4A as beta-cell transcription factors regulating glucose-dependent insulin secretion.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"
    explanation: Confirms the biphasic hyperinsulinism-then-MODY consequence of HNF4A/HNF1A loss of function.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Loss of HNF-dependent transcriptional control of the beta-cell secretory program.
    description: >-
      Transcriptional dysregulation of the beta-cell secretory program produces
      glucose-inappropriate insulin release in the newborn period, typically with
      an intact and therefore diazoxide-responsive K-ATP channel.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "CHI due to mutations in bothHNF1AandHNF4Aare characterized by macrosomic birth and mild transient to severe diazoxide-responsive HH"
      explanation: Confirms that HNF-related disease presents as diazoxide-responsive hyperinsulinemic hypoglycemia.
- name: Focal Lesion Formation by Paternal K-ATP Variant and Somatic 11p15 Maternal Loss
  biological_scale: CELLULAR
  role: trigger
  description: >
    Focal hyperinsulinism is generated by two hits at the same locus. A
    paternally inherited recessive ABCC8 or KCNJ11 variant (both genes sit at
    11p15.1) is clinically silent while the maternal allele is present. In a
    single pancreatic progenitor a post-zygotic mitotic recombination event
    replaces the maternal 11p15 region with a second copy of the paternal one
    (segmental paternal isodisomy), rendering the K-ATP variant homozygous in
    that clone while parental heterozygosity is preserved everywhere else. The
    same event leaves the neighbouring 11p15 imprinted domain paternal-only —
    doubling active IGF2 and removing the growth-suppressing maternal H19 and
    CDKN1C (p57) contributions — so the
    affected clone also proliferates, producing a discrete nodule of
    hyperfunctional, hypersecreting beta cells embedded in a normal pancreas.
    Every clinically decisive feature of focal disease follows from this
    architecture: it is anatomically bounded, so 18F-DOPA PET can localise it and
    resecting it is curative; and it is sporadic in inheritance terms, because
    the somatic hit is not transmitted.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: insulin secretion
    term:
      id: GO:0030073
      label: insulin secretion
    modifier: INCREASED
  locations:
  - preferred_term: islet of Langerhans
    term:
      id: UBERON:0000006
      label: islet of Langerhans
  genes:
  - preferred_term: ABCC8
    term:
      id: hgnc:59
      label: ABCC8
  - preferred_term: KCNJ11
    term:
      id: hgnc:6257
      label: KCNJ11
  - preferred_term: CDKN1C
    term:
      id: hgnc:1786
      label: CDKN1C
  evidence:
  - reference: PMID:25765446
    reference_title: "Three novel pathogenic mutations in KATP channel genes and somatic imprinting alterations of the 11p15 region in pancreatic tissue in patients with congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The 3 patients with focal CHI harbored paternally inherited ABCC8 or KCNJ11 mutations."
    explanation: Confirms the paternal origin of the germline K-ATP variant in focal disease.
  - reference: PMID:25765446
    reference_title: "Three novel pathogenic mutations in KATP channel genes and somatic imprinting alterations of the 11p15 region in pancreatic tissue in patients with congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In the 3 patients with focal CHI, homozygous ABCC8 or KCNJ11 mutations were identified within the lesions."
    explanation: >-
      Demonstrates that the K-ATP variant becomes homozygous specifically within
      the lesion — the second hit that unmasks the channel defect focally.
  - reference: PMID:35018160
    reference_title: "Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "histopathological lesions, diffuse and focal, have been associated with these different genetic alterations."
    explanation: Confirms that the focal/diffuse histological dichotomy maps onto distinct underlying genetic architectures.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: DIRECT
    description: >-
      Within the lesion the K-ATP channel is homozygously defective, so the
      clone's beta cells secrete insulin continuously; the surrounding pancreas
      remains normal, which is why removing the lesion cures the disease.
    evidence:
    - reference: PMID:35018160
      reference_title: "Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations."
      explanation: Confirms that the hypersecretion is confined to the lesion and is abolished by its removal.
- name: Perinatal Stress Lowering of the Beta-Cell Glucose Threshold
  biological_scale: CELLULAR
  role: trigger
  description: >
    In acquired perinatal-stress hyperinsulinism there is no germline lesion.
    Instead, maternal diabetes, birth asphyxia/hypoxia, intrauterine growth
    restriction or intrapartum maternal dextrose appear to reset the beta-cell
    glucose threshold for suppressing insulin downward, so that secretion
    continues at plasma glucose values that would normally silence it. In the
    infant of a diabetic mother the fetal islet has additionally been
    chronically over-stimulated in utero by transplacental maternal glucose. The
    same downstream chain follows as in genetic disease, but the trigger is
    self-limited: most cases remit within days to two weeks as the stress
    resolves.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: regulation of insulin secretion
    term:
      id: GO:0050796
      label: regulation of insulin secretion
    modifier: DYSREGULATED
  locations:
  - preferred_term: islet of Langerhans
    term:
      id: UBERON:0000006
      label: islet of Langerhans
  evidence:
  - reference: PMID:38944478
    reference_title: "Etiology of the Neonatal Hypoglycemias."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Evidence indicates that all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion."
    explanation: >-
      Supports the unifying claim that the acquired neonatal hypoglycemias share
      the same islet-secretory-dysregulation mechanism as genetic disease.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Some newborns with IUGR and asphyxia have a severe and protracted form of HH which requires treatment with diazoxide"
    explanation: Documents perinatal asphyxia and IUGR as triggers capable of producing severe, treatment-requiring hyperinsulinism.
  downstream:
  - target: Dysregulated Beta-Cell Insulin Secretion
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Perinatal hypoxic or metabolic stress lowers the beta-cell glucose threshold for suppressing insulin.
    description: >-
      A downward-reset secretion threshold produces the same glucose-inappropriate
      insulin release as a germline channel or amplifier lesion.
    evidence:
    - reference: PMID:38944478
      reference_title: "Etiology of the Neonatal Hypoglycemias."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "all of the major forms of neonatal hypoglycemia are the result of hyperinsulinism due to dysregulation of pancreatic islet insulin secretion"
      explanation: >-
        States directly that the acquired neonatal hypoglycemias converge on the
        same dysregulated islet insulin secretion as genetic disease.
- name: Dysregulated Beta-Cell Insulin Secretion
  biological_scale: CELLULAR
  role: central_effector
  description: >
    The convergent core of the disorder, reached from every etiology above:
    insulin is secreted at plasma glucose concentrations at which secretion
    should be fully suppressed. In health serum insulin becomes undetectable once
    plasma glucose falls below about 3 mmol/L; in hyperinsulinemic hypoglycemia
    it remains detectable, and it is this failure of suppression — rather than an
    absolute insulin concentration — that defines the disease. Everything
    clinically distinctive about hyperinsulinemic hypoglycemia flows from this
    single node, because insulin is not merely a glucose-lowering hormone but a
    simultaneous suppressor of every counter-regulatory fuel pathway.
  cell_types:
  - preferred_term: pancreatic beta cell
    term:
      id: CL:0000169
      label: type B pancreatic cell
  biological_processes:
  - preferred_term: insulin secretion
    term:
      id: GO:0030073
      label: insulin secretion
    modifier: INCREASED
  - preferred_term: membrane depolarization
    term:
      id: GO:0051899
      label: membrane depolarization
    modifier: INCREASED
  chemical_entities:
  - preferred_term: insulin
    term:
      id: CHEBI:145810
      label: insulin
    modifier: INCREASED
  locations:
  - preferred_term: islet of Langerhans
    term:
      id: UBERON:0000006
      label: islet of Langerhans
  evidence:
  - reference: PMID:37454648
    reference_title: "International Guidelines for the Diagnosis and Management of Hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children."
    explanation: Defines the core mechanism and establishes its clinical primacy among causes of persistent hypoglycemia.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hyperinsulinaemic hypoglycaemia (HH) is the inappropriate secretion of insulin in the presence of low plasma glucose levels and leads to severe and persistent hypoglycaemia in neonates and children."
    explanation: States the defining glucose-inappropriate secretion that constitutes this node.
  downstream:
  - target: Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output
    causal_link_type: DIRECT
    description: >-
      Circulating insulin drives glucose into muscle, liver and adipose tissue
      while simultaneously blocking glycogenolysis and gluconeogenesis, so plasma
      glucose falls and cannot be defended.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Insulin decreases blood glucose level by increasing its peripheral consumption, stimulates glycogen synthesis and inhibits glycogenolysis and gluconeogenesis."
      explanation: Establishes the dual glucose-lowering action of insulin on uptake and hepatic output.
  - target: Suppression of Lipolysis and Ketogenesis
    causal_link_type: DIRECT
    description: >-
      The same insulin signal acts anabolically on adipose tissue, blocking free
      fatty acid release and hence hepatic ketone body production.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "It stimulates lipogenesis, inhibits free fatty acid release, and their beta-oxidation and thus inhibits ketone body formation."
      explanation: Establishes the insulin-driven block on lipolysis and ketogenesis.
  - target: Hyperinsulinemia
    causal_link_type: DIRECT
    description: Insulin and C-peptide remain inappropriately detectable at the time of hypoglycemia.
    evidence:
    - reference: PMID:40904956
      reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Laboratory investigations revealed elevated insulin and C-peptide levels, absence of ketone bodies, and a positive response to the glucagon stimulation test."
      explanation: Documents the inappropriately detectable insulin and C-peptide during hypoglycemia.
  - target: Large for Gestational Age
    causal_link_type: DIRECT
    description: >-
      Insulin is a fetal growth factor, so intrauterine hyperinsulinemia produces
      macrosomia at birth.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Newborns with HH may be macrosomic due to intrauterine hyperinsulinaemia."
      explanation: Attributes macrosomia to the growth-factor action of fetal hyperinsulinemia.
  - target: Hypertrophic Cardiomyopathy
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Fetal hyperinsulinemia acts as an anabolic growth signal on the myocardium.
    description: >-
      Some infants with hyperinsulinism have hypertrophic cardiomyopathy, thought
      to reflect the same fetal anabolic insulin effect that causes macrosomia.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: "Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."
      explanation: >-
        Documents the association; the source explicitly notes the mechanism is
        unclear and only might be related to fetal hyperinsulinaemia, so this
        edge is recorded as partial support.
- name: Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output
  biological_scale: ORGANISM
  role: effector
  description: >
    Insulin acts on the two arms of glucose homeostasis at once: it accelerates
    glucose uptake into muscle, liver and adipose tissue and it shuts down the
    liver's ability to release glucose by inhibiting glycogenolysis and
    gluconeogenesis while stimulating glycogen synthesis. The result is
    hypoglycemia that cannot be defended endogenously, and that clinically
    requires glucose infusion rates far above normal — a requirement above about
    8 mg/kg/min in a neonate is itself close to diagnostic. Hepatic glycogen
    accumulation from this same signal contributes to the hepatomegaly seen in
    some patients.
  cell_types:
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  biological_processes:
  - preferred_term: glucose homeostasis
    term:
      id: GO:0042593
      label: glucose homeostasis
    modifier: DYSREGULATED
  - preferred_term: gluconeogenesis
    term:
      id: GO:0006094
      label: gluconeogenesis
    modifier: DECREASED
  - preferred_term: glycogen catabolic process
    term:
      id: GO:0005980
      label: glycogen catabolic process
    modifier: DECREASED
  chemical_entities:
  - preferred_term: glucose
    term:
      id: CHEBI:17234
      label: glucose
    modifier: DECREASED
  locations:
  - preferred_term: liver
    term:
      id: UBERON:0002107
      label: liver
  evidence:
  - reference: PMID:25733449
    reference_title: "Molecular mechanisms of congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The inappropriate insulin secretion drives glucose into the insulin-sensitive tissues, such as the muscle, liver and adipose tissue, leading to severe hyperinsulinaemic hypoglycaemia (HH)."
    explanation: Establishes insulin-driven tissue glucose disposal as the immediate cause of the hypoglycemia.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An intravenous glucose infusion rate requirement of >8 mg/kg/min (normally is 4-6 mg/kg/min) is virtually diagnostic of HH"
    explanation: Quantifies the magnitude of the glucose disposal defect at the whole-organism level.
  downstream:
  - target: Dual Glucose and Ketone Substrate Deprivation of the Brain
    causal_link_type: DIRECT
    description: >-
      Falling plasma glucose removes the brain's obligate primary fuel; this arm
      alone would produce neuroglycopenia, and it is compounded by the parallel
      loss of ketone fuel.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "As the brain of neonates and infants has a higher rate of glucose comsumption compared to adult subjects, it is more vulnerable to hypoglycaemic brain injury."
      explanation: Establishes the developing brain's high obligate glucose requirement and consequent vulnerability.
  - target: Hyperinsulinemic Hypoglycemia
    causal_link_type: DIRECT
    description: The defining biochemical state — a low plasma glucose with unsuppressed insulin action.
    evidence:
    - reference: PMID:25733449
      reference_title: "Molecular mechanisms of congenital hyperinsulinism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The inappropriate insulin secretion drives glucose into the insulin-sensitive tissues, such as the muscle, liver and adipose tissue, leading to severe hyperinsulinaemic hypoglycaemia (HH)."
      explanation: Directly links the insulin-driven disposal to the defining hypoglycemia.
  - target: Neonatal Hypoglycemia
    causal_link_type: DIRECT
    description: In most patients the hypoglycemia first manifests during the neonatal period.
    evidence:
    - reference: PMID:40904956
      reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Congenital hyperinsulinism (CHI) is a rare but significant cause of persistent neonatal hypoglycemia (NH), associated with a high risk of neurological complications if not promptly treated."
      explanation: Establishes persistent neonatal hypoglycemia as the characteristic presenting manifestation.
  - target: Hepatomegaly
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Insulin stimulates hepatic glycogen synthesis and blocks glycogenolysis, so glycogen accumulates.
    description: Hepatic glycogen accumulation under sustained insulin action enlarges the liver in some patients.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."
      explanation: Attributes the hepatomegaly explicitly to increased hepatic glycogen storage.
  - target: Hyperhidrosis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Falling plasma glucose triggers a counter-regulatory adrenergic response.
    description: >-
      Adrenergic (autonomic) symptoms — sweating, pallor, palpitations,
      jitteriness, hunger — are the earliest warning of falling glucose, and are
      characteristically blunted or absent in neonates and in patients with
      recurrent hypoglycemia, which is part of why the disorder is missed.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with HH can present with a wide range of symptoms ranging from non-specific adrenergic symptoms (poor feeding, hunger, palpitations, sweating) to life-threatening, neuroglycopenic symptoms"
      explanation: Documents adrenergic sweating and palpitations as the autonomic manifestation of hypoglycemia in HH.
- name: Suppression of Lipolysis and Ketogenesis
  biological_scale: ORGANISM
  role: effector
  description: >
    This is the arm that makes hyperinsulinemic hypoglycemia different from every
    other hypoglycemia. Insulin is anabolic on adipose tissue: it stimulates
    lipogenesis, blocks hormone-sensitive-lipase-mediated free fatty acid release,
    and therefore removes the substrate for hepatic beta-oxidation and ketone body
    synthesis. In any other fasting hypoglycemia the falling glucose would
    unleash lipolysis and ketogenesis, and the resulting beta-hydroxybutyrate
    would partially rescue the brain. Here that rescue is disabled by the same
    hormone that caused the hypoglycemia. The biochemical signature — low glucose
    with simultaneously LOW beta-hydroxybutyrate AND LOW free fatty acids — is
    both the diagnostic fingerprint of the disorder and the reason its
    neurological toll is so high.
  cell_types:
  - preferred_term: adipocyte
    term:
      id: CL:0000136
      label: adipocyte
  - preferred_term: hepatocyte
    term:
      id: CL:0000182
      label: hepatocyte
  biological_processes:
  - preferred_term: lipid catabolic process
    term:
      id: GO:0016042
      label: lipid catabolic process
    modifier: DECREASED
  - preferred_term: ketone body biosynthetic process
    term:
      id: GO:0046951
      label: ketone body biosynthetic process
    modifier: DECREASED
  chemical_entities:
  - preferred_term: 3-hydroxybutyrate
    term:
      id: CHEBI:37054
      label: 3-hydroxybutyrate
    modifier: DECREASED
  - preferred_term: free fatty acid
    term:
      id: CHEBI:35366
      label: fatty acid
    modifier: DECREASED
  locations:
  - preferred_term: adipose tissue
    term:
      id: UBERON:0001013
      label: adipose tissue
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In HH due to the inhibitory effect of insulin on lipolysis and ketogenesis there is suppressed ketone body formation in the presence of hypoglycaemia thus leading to increased risk of hypoglycaemic brain injury."
    explanation: Directly establishes the insulin-mediated ketogenesis block and links it to brain-injury risk.
  - reference: PMID:38792494
    reference_title: "Proposed Screening for Congenital Hyperinsulinism in Newborns: Perspective from a Neonatal-Perinatal Medicine Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The premise for our proposed screen is based on the known effect of hyperinsulinism in suppressing ketogenesis, thereby limiting ketone production."
    explanation: >-
      Confirms the suppressed-ketogenesis mechanism, and shows it is robust enough
      to be proposed as the basis of a newborn screening test.
  downstream:
  - target: Dual Glucose and Ketone Substrate Deprivation of the Brain
    causal_link_type: DIRECT
    description: >-
      Removing ketone bodies removes the brain's only substantial alternative
      fuel, converting a glucose deficit into an absolute cerebral fuel failure.
    evidence:
    - reference: PMID:12149510
      reference_title: "Oral beta-hydroxybutyrate supplementation in two patients with hyperinsulinemic hypoglycemia: monitoring of beta-hydroxybutyrate levels in blood and cerebrospinal fluid, and in the brain by in vivo magnetic resonance spectroscopy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In persistent hyperinsulinemic hypoglycemia of infancy, ketone body concentrations are abnormally low at times of hypoglycemia, depriving the brain of its most important alternative fuel."
      explanation: States explicitly that the suppressed ketones deprive the brain of its most important alternative fuel.
  - target: Hypoketotic Hypoglycemia
    causal_link_type: DIRECT
    description: >-
      The combination of low glucose with inappropriately absent ketones is the
      biochemical hallmark used to recognise the disorder.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "It is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants and is associated with a significant risk of permanent brain damage."
      explanation: Identifies hypoketotic hypoglycemia as the defining biochemical phenotype of the disorder.
  - target: Decreased Circulating Free Fatty Acids
    causal_link_type: DIRECT
    description: >-
      Blocked lipolysis lowers plasma free fatty acids at the time of hypoglycemia
      — the finding that distinguishes hyperinsulinism from fatty acid oxidation
      defects, where free fatty acids are high but ketones are still low.
    evidence:
    - reference: PMID:31465295
      reference_title: "Characterization of the duration of treatment with diazoxide in infants with prolonged hyperinsulinism (PHI)."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "inappropriate low serum free fatty acids"
      explanation: >-
        Reports inappropriately suppressed serum free fatty acids in a
        prolonged-hyperinsulinism cohort sampled during documented hypoglycemia.
- name: Dual Glucose and Ketone Substrate Deprivation of the Brain
  biological_scale: ORGANISM
  role: central_effector
  description: >
    The mechanistic keystone of the disorder, and the explicit reason
    hyperinsulinemic hypoglycemia injures the brain more than other hypoglycemias
    of equivalent glucose depth. The neonatal and infant brain has a
    disproportionately high obligate glucose requirement, and its physiological
    safeguard against a falling glucose is to switch to ketone bodies. In
    hyperinsulinemic hypoglycemia both fuels fail simultaneously and for the same
    reason: the excess insulin that lowers glucose also abolishes the ketone
    supply. Cerebral energy failure therefore begins earlier, deepens faster, and
    is less forgiving of diagnostic delay than in ketotic hypoglycemias, where a
    partial ketone rescue buffers the brain. This node is also the therapeutic
    rationale for the (still experimental) strategy of supplying exogenous
    beta-hydroxybutyrate, and the rationale for proposals to screen newborns by
    measuring ketones rather than glucose alone.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: glucose homeostasis
    term:
      id: GO:0042593
      label: glucose homeostasis
    modifier: DYSREGULATED
  chemical_entities:
  - preferred_term: glucose
    term:
      id: CHEBI:17234
      label: glucose
    modifier: DECREASED
  - preferred_term: 3-hydroxybutyrate
    term:
      id: CHEBI:37054
      label: 3-hydroxybutyrate
    modifier: DECREASED
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:12149510
    reference_title: "Oral beta-hydroxybutyrate supplementation in two patients with hyperinsulinemic hypoglycemia: monitoring of beta-hydroxybutyrate levels in blood and cerebrospinal fluid, and in the brain by in vivo magnetic resonance spectroscopy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In persistent hyperinsulinemic hypoglycemia of infancy, ketone body concentrations are abnormally low at times of hypoglycemia, depriving the brain of its most important alternative fuel."
    explanation: The core statement of the dual-deprivation mechanism.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This accounts for the hypoketotic state, decreasing the availability of alternative fuels for cerebral metabolism"
    explanation: States that the hypoketotic state specifically reduces alternative cerebral fuel availability.
  - reference: PMID:12149510
    reference_title: "Oral beta-hydroxybutyrate supplementation in two patients with hyperinsulinemic hypoglycemia: monitoring of beta-hydroxybutyrate levels in blood and cerebrospinal fluid, and in the brain by in vivo magnetic resonance spectroscopy."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "demonstrates effective uptake across the blood-brain barrier and could provide the basis for further evaluation of the neuroprotective effect of beta-OHB in conditions with hypoketotic hypoglycemia."
    explanation: >-
      Shows in two patients that orally supplied beta-hydroxybutyrate reaches the
      brain, which is consistent with ketone deprivation being causal; the study
      explicitly frames neuroprotection as requiring further evaluation, so this
      is partial rather than confirmatory support.
  downstream:
  - target: Neuroglycopenic Brain Injury
    causal_link_type: DIRECT
    description: >-
      Simultaneous loss of glucose and ketone substrate produces cerebral energy
      failure and neuronal injury.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In HH due to the inhibitory effect of insulin on lipolysis and ketogenesis there is suppressed ketone body formation in the presence of hypoglycaemia thus leading to increased risk of hypoglycaemic brain injury."
      explanation: Directly links the hypoketotic state to increased hypoglycemic brain-injury risk.
  - target: Seizures
    causal_link_type: DIRECT
    description: Acute cerebral fuel failure manifests as generalized seizures, frequently the presenting event.
    evidence:
    - reference: PMID:40904956
      reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We report the case of a male macrosomic newborn admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia (1.4 mmol/L) unresponsive to intravenous glucose therapy."
      explanation: Documents seizures as an acute neuroglycopenic manifestation.
  - target: Lethargy
    causal_link_type: DIRECT
    description: Depressed consciousness is a core neuroglycopenic sign.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain, resulting in impairment of brain function."
      explanation: Lists lethargy among the neuroglycopenic manifestations of inadequate cerebral glucose supply.
  - target: Feeding Difficulties
    causal_link_type: DIRECT
    description: >-
      Poor feeding is both an early symptom of neuroglycopenia and, later, a major
      chronic burden compounded by diazoxide-associated food aversion and tube
      feeding.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with HH can present with a wide range of symptoms ranging from non-specific adrenergic symptoms (poor feeding, hunger, palpitations, sweating)"
      explanation: Documents poor feeding as a presenting symptom of hypoglycemia in HH.
  - target: Coma
    causal_link_type: DIRECT
    description: Profound cerebral fuel failure can progress to coma and death.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain"
      explanation: Lists coma and death among the neuroglycopenic outcomes.
  - target: Apnea
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Neuroglycopenia depresses brainstem respiratory control in the neonate.
    description: Apnea and respiratory distress can be the presenting neonatal manifestation of neuroglycopenia.
    evidence:
    - reference: PMID:40904956
      reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: "admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia"
      explanation: >-
        Documents respiratory compromise co-presenting with severe neonatal
        hypoglycemia; the source reports respiratory distress rather than apnea
        specifically, so this edge is recorded as partial support.
- name: Neuroglycopenic Brain Injury
  biological_scale: TISSUE
  role: consequence
  description: >
    Recurrent or prolonged dual-fuel deprivation causes permanent injury to the
    developing brain, with a predilection for the parieto-occipital cortex and
    white matter. This is the outcome that defines the clinical stakes of the
    disorder and it is substantially preventable: the international consensus
    guideline states its own purpose as reducing the prevalence of
    hypoglycemia-caused brain injury through earlier recognition and treatment.
    Neurological sequelae were reported in about half of probands in a nationwide
    cohort, which is a direct measure of how often recognition currently comes
    too late.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:37454648
    reference_title: "International Guidelines for the Diagnosis and Management of Hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia."
    explanation: >-
      Frames hypoglycemic brain injury in hyperinsulinism as a preventable
      outcome addressable by earlier recognition — the central clinical claim of
      this entry.
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurologic sequelae were reported in 53% of the CHI probands."
    explanation: Quantifies the burden of permanent neurological injury in a population-based cohort.
  - reference: PMID:38792494
    reference_title: "Proposed Screening for Congenital Hyperinsulinism in Newborns: Perspective from a Neonatal-Perinatal Medicine Group."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "adverse neurodevelopmental sequelae and brain injury due to missing or delaying the CHI diagnosis"
    explanation: Attributes the neurodevelopmental injury specifically to missed or delayed diagnosis.
  downstream:
  - target: Global Developmental Delay
    causal_link_type: DIRECT
    description: Permanent hypoglycemic brain injury manifests as developmental delay and cognitive impairment.
    evidence:
    - reference: PMID:35183224
      reference_title: "Congenital hyperinsulinism in infancy and childhood: challenges, unmet needs and the perspective of patients and families."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children, and carries a considerable risk of neurological damage and developmental delays if diagnosis and treatment are delayed."
      explanation: Links delayed recognition to neurological damage and developmental delay.
  - target: Cerebral Palsy
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Hypoglycemic injury to developing motor pathways and white matter.
    description: >-
      Permanent motor sequelae including cerebral palsy are among the recognised
      complications of untreated or late-treated hyperinsulinemic hypoglycemia.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "it is essential to make a prompt diagnosis and institute immediate management to prevent complications such as epilepsy, cerebral palsy and neurodevelopemental deficits"
      explanation: Names cerebral palsy explicitly among the preventable complications.
phenotypes:
- category: Laboratory
  name: Hyperinsulinemic Hypoglycemia
  description: >-
    The defining state: a low plasma glucose with biochemical evidence of
    unsuppressed insulin action — detectable insulin and C-peptide together with
    suppressed beta-hydroxybutyrate and free fatty acids.
  diagnostic: true
  phenotype_term:
    preferred_term: Hyperinsulinemic hypoglycemia
    term:
      id: HP:0000825
      label: Hyperinsulinemic hypoglycemia
    temporality: RECURRENT
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hyperinsulinaemic hypoglycaemia (HH) is the inappropriate secretion of insulin in the presence of low plasma glucose levels and leads to severe and persistent hypoglycaemia in neonates and children."
    explanation: >-
      The defining phenotype is present in all affected individuals by
      definition, supporting a VERY_FREQUENT band.
- category: Laboratory
  name: Hypoketotic Hypoglycemia
  description: >-
    Hypoglycemia with inappropriately absent ketone bodies. This is the
    discriminating laboratory phenotype of the disorder and the mechanistic
    reason for its neurological severity.
  diagnostic: true
  phenotype_term:
    preferred_term: Hypoketotic hypoglycemia
    term:
      id: HP:0001985
      label: Hypoketotic hypoglycemia
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants and is associated with a significant risk of permanent brain damage."
    explanation: >-
      Identifies hypoketotic hypoglycemia as the characteristic presentation,
      supporting a VERY_FREQUENT band.
- category: Laboratory
  name: Hyperinsulinemia
  description: >-
    Inappropriately detectable or frankly elevated plasma insulin and C-peptide
    measured at the time of documented hypoglycemia. A normal-looking absolute
    insulin value is still abnormal if glucose is low.
  phenotype_term:
    preferred_term: Hyperinsulinemia
    term:
      id: HP:0000842
      label: Hyperinsulinemia
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Laboratory investigations revealed elevated insulin and C-peptide levels, absence of ketone bodies, and a positive response to the glucagon stimulation test."
    explanation: Documents elevated insulin and C-peptide during hypoglycemia.
- category: Laboratory
  name: Decreased Circulating Free Fatty Acids
  description: >-
    Suppressed plasma free fatty acids during hypoglycemia. Together with
    suppressed ketones this distinguishes hyperinsulinism from fatty acid
    oxidation defects, in which free fatty acids are high while ketones are still
    low.
  diagnostic: true
  phenotype_term:
    preferred_term: Decreased circulating free fatty acid level
    term:
      id: HP:0040299
      label: Decreased circulating free fatty acid level
  evidence:
  - reference: PMID:31465295
    reference_title: "Characterization of the duration of treatment with diazoxide in infants with prolonged hyperinsulinism (PHI)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "inappropriate low serum free fatty acids"
    explanation: >-
      Reports inappropriately suppressed serum free fatty acids in a
      prolonged-hyperinsulinism cohort sampled during documented hypoglycemia.
- category: Clinical
  name: Neonatal Hypoglycemia
  description: >-
    Persistent hypoglycemia beginning in the neonatal period, characteristically
    refractory to routine intravenous dextrose and requiring glucose infusion
    rates well above the normal 4-6 mg/kg/min.
  phenotype_term:
    preferred_term: Neonatal hypoglycemia
    term:
      id: HP:0001998
      label: Neonatal hypoglycemia
  notes: >-
    No `frequency:` band is asserted. The available sources establish that
    neonatal onset is the commonest presentation but give no quantitative share,
    and the umbrella deliberately includes later-onset genetic and acquired
    forms, so banding here would overstate the evidence.
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Congenital hyperinsulinism (CHI) is a rare but significant cause of persistent neonatal hypoglycemia (NH), associated with a high risk of neurological complications if not promptly treated."
    explanation: Establishes hyperinsulinism as a cause of persistent neonatal hypoglycemia.
- category: Clinical
  name: Seizures
  description: >-
    Generalized seizures from acute neuroglycopenia, frequently the presenting
    event and a driver of the epilepsy seen in long-term follow-up.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We report the case of a male macrosomic newborn admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia (1.4 mmol/L) unresponsive to intravenous glucose therapy."
    explanation: Documents generalized seizures with severe neonatal hypoglycemia.
- category: Clinical
  name: Lethargy
  description: Depressed level of consciousness as a neuroglycopenic manifestation.
  phenotype_term:
    preferred_term: Lethargy
    term:
      id: HP:0001254
      label: Lethargy
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain, resulting in impairment of brain function."
    explanation: Lists lethargy among the neuroglycopenic symptoms.
- category: Clinical
  name: Feeding Difficulties
  description: >-
    Poor feeding, food aversion, impaired suck/swallow and frequent tube
    dependence. Feeding dysfunction is one of the heaviest chronic burdens in
    this disorder, driven by the disease, by diazoxide, and by the
    high-carbohydrate/continuous-feeding regimens used to prevent hypoglycemia.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "However, patients wth CHI, particularly those on diazoxide therapy usually have food aversion. Therefore a percutaneous gastrostomy is sometimes recommended to allow frequent (or continuous) feeding"
    explanation: Documents food aversion and the resulting need for gastrostomy feeding.
- category: Clinical
  name: Apnea
  description: Apnea and respiratory compromise as a neonatal neuroglycopenic presentation.
  phenotype_term:
    preferred_term: Apnea
    term:
      id: HP:0002104
      label: Apnea
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "admitted on the second day of life for respiratory distress, generalized seizures, and severe hypoglycemia"
    explanation: >-
      Documents respiratory compromise at presentation; the report describes
      respiratory distress rather than apnea specifically, so support is partial.
- category: Clinical
  name: Coma
  description: Coma from profound cerebral fuel failure; death can occur.
  phenotype_term:
    preferred_term: Coma
    term:
      id: HP:0001259
      label: Coma
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "life-threatening, neuroglycopenic symptoms (seizures, unconsciousness, lethargy, coma and even death) arising from an inadequate supply of glucose to the brain"
    explanation: Lists coma among the life-threatening neuroglycopenic manifestations.
- category: Clinical
  name: Hyperhidrosis
  description: >-
    Sweating with pallor, palpitations and jitteriness — the adrenergic
    counter-regulatory warning signs of falling glucose, characteristically
    blunted in neonates and in patients with recurrent hypoglycemia.
  phenotype_term:
    preferred_term: Hyperhidrosis
    term:
      id: HP:0000975
      label: Hyperhidrosis
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "non-specific adrenergic symptoms (poor feeding, hunger, palpitations, sweating)"
    explanation: Documents sweating among the adrenergic symptoms of hypoglycemia in HH.
- category: Clinical
  name: Large for Gestational Age
  description: >-
    Macrosomia from the growth-factor action of intrauterine hyperinsulinemia.
    Its absence does not exclude the diagnosis.
  phenotype_term:
    preferred_term: Large for gestational age
    term:
      id: HP:0001520
      label: Large for gestational age
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Newborns with HH may be macrosomic due to intrauterine hyperinsulinaemia. However, the absence of macrosomia does not exclude HH."
    explanation: Confirms macrosomia as a common but non-obligatory feature.
- category: Clinical
  name: Hepatomegaly
  description: Liver enlargement from insulin-driven hepatic glycogen accumulation.
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."
    explanation: >-
      The source phrase "in some patients" maps to the OCCASIONAL (5-29%) band
      under the GeneReviews prose-to-enum convention.
- category: Clinical
  name: Hypertrophic Cardiomyopathy
  description: >-
    Myocardial hypertrophy in a minority of patients, attributed to the same
    fetal anabolic insulin effect that produces macrosomia.
  phenotype_term:
    preferred_term: Hypertrophic cardiomyopathy
    term:
      id: HP:0001639
      label: Hypertrophic cardiomyopathy
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Hypertrophic cardiomyopathy and hepatomegaly (increased storage of glucose as glycogen) are observed in some patients with HH."
    explanation: >-
      The source phrase "in some patients" maps to the OCCASIONAL (5-29%) band
      under the GeneReviews prose-to-enum convention.
- category: Laboratory
  name: Hyperammonemia
  description: >-
    Persistent mild elevation of plasma ammonia, the biochemical marker of the
    GLUD1 hyperinsulinism-hyperammonemia subtype.
  subtype: HI/HA Syndrome
  phenotype_term:
    preferred_term: Hyperammonemia
    term:
      id: HP:0001987
      label: Hyperammonemia
  evidence:
  - reference: PMID:21130127
    reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The other distinctive feature of the HI/HA Syndrome is a persistent elevation of plasma ammonia concentrations."
    explanation: Confirms persistent hyperammonemia as the distinctive feature of the GLUD1 subtype.
- category: Neurologic
  name: Global Developmental Delay
  description: >-
    Developmental delay and cognitive impairment from permanent hypoglycemic
    brain injury; reported in roughly half of probands in a nationwide cohort.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  notes: >-
    No `frequency:` band is asserted. The available population figure (53% in the
    Norwegian cohort) is for "neurologic sequelae" as an umbrella covering
    epilepsy, motor deficits and cognitive impairment, not for global
    developmental delay specifically, so banding this phenotype from it would
    overstate the source.
  evidence:
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Neurologic sequelae were reported in 53% of the CHI probands."
    explanation: >-
      Documents a substantial burden of neurologic sequelae in a population-based
      cohort; the source reports a composite sequelae category rather than global
      developmental delay specifically, so support is partial.
- category: Neurologic
  name: Cerebral Palsy
  description: Permanent motor disability from hypoglycemic injury to the developing brain.
  phenotype_term:
    preferred_term: Cerebral palsy
    term:
      id: HP:0100021
      label: Cerebral palsy
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "it is essential to make a prompt diagnosis and institute immediate management to prevent complications such as epilepsy, cerebral palsy and neurodevelopemental deficits"
    explanation: Names cerebral palsy as a complication of delayed treatment.
biochemical:
- name: Plasma beta-hydroxybutyrate at the time of hypoglycemia
  presence: DECREASED
  notes: >-
    The single most informative analyte in the critical sample. In any normal
    fasting response a plasma glucose below about 50 mg/dL should be accompanied
    by a brisk ketotic response; in hyperinsulinemic hypoglycemia
    beta-hydroxybutyrate is inappropriately suppressed. Because insulin's
    anti-ketogenic action is a more sensitive readout than the measured insulin
    concentration, a suppressed beta-hydroxybutyrate is a more reliable indicator
    of excessive insulin action than the insulin level itself.
  reference_ranges:
  - unit: mmol/L
    population: neonates and infants during documented hypoglycemia (plasma glucose <50 mg/dL)
    notes: >-
      Interpretive threshold rather than a population reference interval: a
      plasma beta-hydroxybutyrate below 1.8 mmol/L at a plasma glucose under
      50 mg/dL indicates excessive insulin action. The 1.8 mmol/L cut-point is
      taken from the 2023 international consensus guideline (PMID:37454648),
      whose PubMed abstract does not reproduce the numeric criterion, so it is
      recorded here as provenance rather than as a quoted snippet.
    interpretation_bands:
    - name: Inappropriately suppressed (consistent with excessive insulin action)
      upper_bound: 1.8
      unit: mmol/L
      abnormal_flag: LOW
      phenotype_term:
        preferred_term: Hypoketotic hypoglycemia
        term:
          id: HP:0001985
          label: Hypoketotic hypoglycemia
      interpretation: >-
        Beta-hydroxybutyrate below 1.8 mmol/L while plasma glucose is below
        50 mg/dL indicates a failure of the normal ketotic response and supports
        excessive insulin action.
    - name: Appropriate ketotic response (argues against hyperinsulinism)
      lower_bound: 1.8
      unit: mmol/L
      abnormal_flag: NORMAL
      interpretation: >-
        A beta-hydroxybutyrate at or above 1.8 mmol/L before glucose falls below
        50-60 mg/dL is the criterion used to confirm diazoxide responsiveness on
        a safety fast, and in an untreated patient argues against hyperinsulinism.
  evidence:
  - reference: PMID:38944478
    reference_title: "Etiology of the Neonatal Hypoglycemias."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the authors propose that routine measurement of B-hydroxybutyrate should be considered an essential part of glucose monitoring in newborn infants."
    explanation: >-
      Establishes beta-hydroxybutyrate as the key discriminating analyte, to the
      point of being proposed for routine newborn monitoring.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the diagnosis of HH should not be based on an isolated serum insulin/c-peptide concentration but on the clinical presentation and the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"
    explanation: >-
      States explicitly that suppressed beta-hydroxybutyrate and fatty acids are
      more diagnostically reliable than the insulin concentration alone.
- name: Plasma free fatty acids at the time of hypoglycemia
  presence: DECREASED
  notes: >-
    Suppressed free fatty acids during hypoglycemia reflect insulin's block on
    lipolysis. The result carries specific discriminating information: in a fatty
    acid oxidation defect the ketones are also low, but free fatty acids are HIGH
    because lipolysis is intact and it is the oxidation step that fails. Low
    ketones with low free fatty acids points to hyperinsulinism; low ketones with
    high free fatty acids points to a fatty acid oxidation disorder.
  reference_ranges:
  - unit: mmol/L
    population: infants during documented hypoglycemia (plasma glucose <50 mg/dL)
    notes: >-
      In a prolonged-hyperinsulinism cohort, free fatty acids measured during
      documented hypoglycemia averaged 0.3 mmol/L against a stated expectation of
      more than 1.5 mmol/L. The 2023 international consensus guideline uses a
      cut-point of 1.7 mmol/L as evidence of excessive insulin action; that
      numeric criterion is not reproduced in the guideline's PubMed abstract and
      is recorded here as provenance rather than as a quoted snippet.
    interpretation_bands:
    - name: Inappropriately suppressed (consistent with excessive insulin action)
      upper_bound: 1.7
      unit: mmol/L
      abnormal_flag: LOW
      phenotype_term:
        preferred_term: Decreased circulating free fatty acid level
        term:
          id: HP:0040299
          label: Decreased circulating free fatty acid level
      interpretation: >-
        Free fatty acids below 1.7 mmol/L during hypoglycemia indicate suppressed
        lipolysis and support excessive insulin action.
    - name: Appropriate lipolytic response (argues against hyperinsulinism)
      lower_bound: 1.7
      unit: mmol/L
      abnormal_flag: NORMAL
      interpretation: >-
        Free fatty acids at or above 1.7 mmol/L during hypoglycemia represent the
        expected lipolytic response and argue against excessive insulin action.
        It is the conjunction of this appropriate free-fatty-acid rise with
        inappropriately low ketones that redirects the workup toward a fatty acid
        oxidation disorder.
    evidence:
    - reference: PMID:31465295
      reference_title: "Characterization of the duration of treatment with diazoxide in infants with prolonged hyperinsulinism (PHI)."
      supports: PARTIAL
      evidence_source: HUMAN_CLINICAL
      snippet: "levels were measured during hypoglycemia (plasma glucose <50 mg/dL)"
      explanation: >-
        Establishes only the sampling condition this interval applies to
        (documented hypoglycemia below 50 mg/dL), not the 1.7 mmol/L cut-point
        itself, which comes from the guideline body and is recorded in `notes:`.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"
    explanation: Establishes suppressed fatty acids as part of the biochemical profile of insulin action.
- name: Plasma insulin and C-peptide at the time of hypoglycemia
  presence: INCREASED
  notes: >-
    Detectable insulin with a concordantly detectable C-peptide during documented
    hypoglycemia indicates endogenous insulin secretion. The C-peptide is what
    separates endogenous hyperinsulinism from exogenous insulin administration:
    injected insulin raises insulin while suppressing C-peptide, giving a high
    insulin-to-C-peptide ratio. A single insulin value is not sufficient to make
    or exclude the diagnosis.
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Laboratory investigations revealed elevated insulin and C-peptide levels, absence of ketone bodies, and a positive response to the glucagon stimulation test."
    explanation: Documents the concordant insulin and C-peptide elevation of endogenous hyperinsulinism.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In some difficult cases, the diagnosis of HH should not be based on an isolated serum insulin/c-peptide concentration"
    explanation: Cautions that an isolated insulin/C-peptide value is insufficient for diagnosis.
- name: Plasma ammonia
  presence: INCREASED
  subtype: HI/HA Syndrome
  notes: >-
    Persistently, mildly elevated plasma ammonia in a patient with
    hyperinsulinemic hypoglycemia is close to specific for the GLUD1
    hyperinsulinism-hyperammonemia subtype.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An elevated serum ammonia concentration in a patient with HH is suggestive of the hyperinsulinism and hyperammonaemia (HI/HA) syndrome"
    explanation: Establishes ammonia as the subtype-discriminating analyte for HI/HA.
- name: Glycemic response to glucagon during hypoglycemia
  presence: PRESENT
  notes: >-
    A brisk rise in plasma glucose after intramuscular or intravenous glucagon
    given at the time of hypoglycemia demonstrates that hepatic glycogen stores
    are intact and are being held back by insulin — a paradoxical finding at a
    glucose level that should already have exhausted them, and therefore strong
    functional evidence of excessive insulin action.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In some patients, a positive glycaemic response (rise in the plasma glucose concentration of >1.5 mmol/L from baseline) following an intramuscular/intravenous injection of glucagon at the time of hypoglycaemia provides supportive evidence"
    explanation: Provides the quantitative glucagon-response criterion used in the critical-sample workup.
definitions:
- name: Critical-Sample Biochemical Criteria for Hyperinsulinemic Hypoglycemia
  definition_type: DIAGNOSTIC_CRITERIA
  derivation_basis: ESTABLISHED_CRITERIA
  description: >-
    The diagnosis is made from a critical sample — blood drawn at the moment of
    documented hypoglycemia (plasma glucose below about 50 mg/dL / 2.8 mmol/L),
    before glucose is given. The logic is not whether the insulin is high, but
    whether insulin action is detectable when it should be zero, which is why the
    suppressed-fuel markers carry more weight than the insulin assay.
  scope: >-
    Applies to neonates, infants and children with recurrent or persistent
    hypoglycemia. A sample drawn within the first 72 hours of life may reflect
    physiological transitional hypoglycemia and should be repeated after 72 hours
    if hypoglycemia persists.
  inclusion_criteria:
  - preferred_term: Documented hypoglycemia at the time of sampling
    description: Plasma glucose below 50 mg/dL (2.8 mmol/L) when the sample is drawn.
  - preferred_term: Inappropriately detectable insulin and C-peptide
    description: Measurable plasma insulin with a concordant C-peptide at that plasma glucose.
  - preferred_term: Suppressed beta-hydroxybutyrate
    term:
      id: HP:0001985
      label: Hypoketotic hypoglycemia
    description: Plasma beta-hydroxybutyrate below approximately 1.8 mmol/L.
  - preferred_term: Suppressed free fatty acids
    term:
      id: HP:0040299
      label: Decreased circulating free fatty acid level
    description: Plasma free fatty acids below approximately 1.7 mmol/L.
  - preferred_term: Excessive glucose infusion requirement
    description: >-
      Intravenous glucose infusion above 8 mg/kg/min needed to maintain
      normoglycemia (normal requirement is 4-6 mg/kg/min).
  - preferred_term: Positive glycemic response to glucagon
    description: >-
      Rise in plasma glucose of more than 1.5 mmol/L (roughly 30 mg/dL) from
      baseline after intramuscular or intravenous glucagon given during
      hypoglycemia.
  exclusion_criteria:
  - preferred_term: Elevated free fatty acids with low ketones
    description: Redirects the diagnosis to a fatty acid oxidation disorder.
  - preferred_term: Elevated insulin with suppressed C-peptide
    term:
      id: HP:0034384
      label: Elevated circulating insulin:C-peptide ratio
    description: Indicates exogenous (administered) insulin rather than endogenous hyperinsulinism.
  - preferred_term: Lactic acidosis with hepatomegaly and a ketotic response
    description: Suggests a hepatic glycogen storage disorder.
  - preferred_term: Cortisol or growth hormone deficiency
    description: >-
      Counter-regulatory hormone deficiency must be excluded on the same critical
      sample.
  notes: >-
    The numeric beta-hydroxybutyrate (1.8 mmol/L) and free fatty acid
    (1.7 mmol/L) cut-points are those of the 2023 international consensus
    guideline (PMID:37454648); they appear in the guideline body rather than in
    its PubMed abstract, so they are recorded here as provenance and are not
    quoted as evidence snippets.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In any patient with recurrent or persistent hypoglycaemia, HH should be suspected and critical samples at the time of hypoglycaemic episodes should be collected."
    explanation: Establishes the critical-sample approach as the basis of biochemical diagnosis.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An intravenous glucose infusion rate requirement of >8 mg/kg/min (normally is 4-6 mg/kg/min) is virtually diagnostic of HH"
    explanation: Provides the glucose-infusion-rate inclusion criterion.
histopathology:
- name: Diffuse beta-cell nuclear enlargement
  description: >-
    In diffuse disease all islets throughout the pancreas are involved, with beta
    cells showing abnormally large nuclei. There is no resectable target, which is
    why surgery in diffuse disease is a 90-98% pancreatectomy rather than a cure.
  subtype: Diffuse HI
  diagnostic: true
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diffuse disease accounts for about 60% of all CHI cases and affects all the b-cells of the pancreas. Morphology of the islets of Langerhans typically show the presence of b-cells with abnormally large nuclei"
    explanation: Describes the whole-pancreas involvement and nuclear enlargement that define diffuse histology.
- name: Focal adenomatous islet-cell hyperplasia
  description: >-
    A discrete, generally unencapsulated 2-10 mm nodule of nodular islet-cell
    hyperplasia including ductuloinsular complexes, with enlarged cytoplasm and
    irregular nuclei, surrounded by histologically normal pancreas. Loss of
    nuclear p57 (CDKN1C) staining within the lesion reflects the underlying
    maternal 11p15 loss and is used to confirm focal disease on frozen section.
  subtype: Focal HI
  diagnostic: true
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Focal pancreatic lesions are generally 2-10 mm in size and appear as small regions of islet adenomatosis (nodular hyperplasia of islet-like cell clusters, including ductuloinsular complexes"
    explanation: Describes the size and architecture of the focal lesion.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Islet cells in the lesion have large cytoplasm with dispersed abnormal nuclei of irregular shape"
    explanation: Describes the cytological features of the focal lesion.
genetic:
- name: ABCC8 (SUR1) loss-of-function variants
  gene_term:
    preferred_term: ABCC8
    term:
      id: hgnc:59
      label: ABCC8
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    ABCC8 encodes SUR1, the regulatory subunit of the beta-cell K-ATP channel and
    the binding site for diazoxide. It is the most frequently identified gene in
    hyperinsulinism cohorts. Biallelic recessive variants give severe,
    diazoxide-unresponsive diffuse disease; monoallelic dominant variants give
    milder, often diazoxide-responsive disease; and a single paternally inherited
    recessive variant predicts a focal lesion.
  evidence:
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "ABCC8 variants were most common (n= 40), and 5 novel variants were identified."
    explanation: Confirms ABCC8 as the most frequently identified causal gene in a nationwide cohort.
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although most ABCC8 variants caused immediate disease onset with severe hypoglycemia and were diazoxide-unresponsive, 8 probands had a heterozygous, apparently dominant variant with milder phenotype."
    explanation: Documents both the severe recessive and milder dominant ABCC8 phenotypes.
- name: KCNJ11 (Kir6.2) loss-of-function variants
  gene_term:
    preferred_term: KCNJ11
    term:
      id: hgnc:6257
      label: KCNJ11
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    KCNJ11 encodes Kir6.2, the pore-forming subunit of the beta-cell K-ATP
    channel. It is the second most common cause of medically unresponsive
    hyperinsulinism and, like ABCC8, sits at 11p15.1 — which is why a paternally
    inherited KCNJ11 variant can be unmasked focally by loss of the maternal
    11p15 allele.
  evidence:
  - reference: PMID:25733449
    reference_title: "Molecular mechanisms of congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal recessive and dominant mutations in ABCC8/KCNJ11 are the commonest cause of medically unresponsive CHI."
    explanation: Confirms ABCC8/KCNJ11 as the commonest cause of diazoxide-unresponsive disease.
  - reference: PMID:39741883
    reference_title: "Congenital hyperinsulinism in the Ukraine: a 10-year national study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pathogenic variants in the K-ATP channel genes were the only identified genetic cause of p-CHI (ABCC8 (n=17) and KCNJ11 (n=2))"
    explanation: Confirms KCNJ11 as a causal K-ATP gene in persistent disease in a national cohort.
- name: GLUD1 activating variants
  gene_term:
    preferred_term: GLUD1
    term:
      id: hgnc:4335
      label: GLUD1
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    Dominant activating GLUD1 variants impair GTP inhibition of glutamate
    dehydrogenase, producing leucine/protein-sensitive hyperinsulinism plus the
    persistent mild hyperammonemia of the HI/HA syndrome. Usually
    diazoxide-responsive; dietary protein management is genotype-specific.
  evidence:
  - reference: PMID:21130127
    reference_title: "Two genetic forms of hyperinsulinemic hypoglycemia caused by dysregulation of glutamate dehydrogenase."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "the hyperinsulinism/hyperammonemia syndrome caused by dominant activating mutations of GLUD1 which interfere with inhibitory regulation by GTP"
    explanation: >-
      Confirms the dominant activating GLUD1 mechanism; loss of GTP inhibition is
      an enzyme-kinetic property demonstrated in vitro, so tagged IN_VITRO.
- name: GCK activating variants
  gene_term:
    preferred_term: GCK
    term:
      id: hgnc:4195
      label: GCK
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    Glucokinase is the beta cell's glucose sensor. Activating variants — and,
    rarely, gene duplication — lower the glucose threshold for insulin secretion,
    resetting the whole system to defend an inappropriately low glucose. Unlike
    most hyperinsulinism, GCK disease can show a ketotic response on prolonged
    fasting, and it is often diazoxide-unresponsive.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "plays a critical role in acting as a gluco-sensor, providing a link between the extracellular plasma glucose concentration and the metabolism of glucose in b-cells"
    explanation: Establishes glucokinase as the beta-cell glucose sensor whose activation lowers the secretion set-point.
  - reference: PMID:39720245
    reference_title: "Case report: Duplication of the GCK gene is a novel cause of nesidioblastosis: evidence from a case with Silver-Russell syndrome-like phenotype related to chromosome 7."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "we found that the duplicated region contained the GCK gene, whose gain-of function variants could cause HH."
    explanation: >-
      A single case linking GCK copy-number gain to adult nesidioblastosis;
      recorded as partial support because the dosage mechanism remains a
      case-level, not established, association.
- name: HADH (SCHAD) loss-of-function variants
  gene_term:
    preferred_term: HADH
    term:
      id: hgnc:4799
      label: HADH
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    Recessive short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency causes
    protein/leucine-sensitive hyperinsulinism through loss of an inhibitory
    SCHAD-glutamate-dehydrogenase interaction. Distinctively it leaves a
    metabolite trail — raised plasma hydroxybutyrylcarnitine and urinary
    3-hydroxyglutarate — so it can be picked up on acylcarnitine and organic-acid
    screening.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Raised plasma hydroxybutyrylcarnitine and urinary 3-hydroxyglutarate are diagnostic of a rare type of congenital HH"
    explanation: Provides the diagnostic metabolite signature of HADH deficiency.
- name: HNF4A loss-of-function variants
  gene_term:
    preferred_term: HNF4A
    term:
      id: hgnc:5024
      label: HNF4A
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    Heterozygous HNF4A loss of function produces a biphasic phenotype —
    macrosomia with diazoxide-responsive neonatal hyperinsulinism, then
    maturity-onset diabetes of the young decades later. A MODY family history is
    a specific clue, and these patients need lifelong diabetes surveillance.
    HNF4A disease has additionally been reported with a glycogenosis-like hepatic
    picture (raised erythrocyte glycogen, elevated transaminases).
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"
    explanation: Confirms the biphasic hyperinsulinism-then-MODY phenotype of HNF4A.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CHI due toHNF4Agene has been reported with increased levels of glycogen in erythrocytes, elevated liver transaminases and increased echogenicity on liver ultrasonography, suggesting a glycogenosis-like phenotype"
    explanation: Documents the HNF4A-specific glycogenosis-like hepatic phenotype.
- name: HNF1A loss-of-function variants
  gene_term:
    preferred_term: HNF1A
    term:
      id: hgnc:11621
      label: HNF1A
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    Heterozygous HNF1A loss of function causes the same biphasic
    hyperinsulinism-then-MODY course as HNF4A, with macrosomic birth and mild
    transient to severe diazoxide-responsive hyperinsulinism in the newborn
    period. HNF1A and HNF4A variants may together be a common cause of
    diazoxide-responsive disease.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Heterozygous loss-of-function mutations inHNF4AandHNF1Alead to HH in the newborn period and maturity onset-diabetes (type 1 and 3) later in life"
    explanation: Confirms the biphasic hyperinsulinism-then-MODY phenotype of HNF1A.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CHI due to mutations in bothHNF1AandHNF4Aare characterized by macrosomic birth and mild transient to severe diazoxide-responsive HH"
    explanation: Confirms macrosomia and diazoxide-responsive hyperinsulinism in HNF1A-related disease.
- name: SLC16A1 (MCT1) promoter gain-of-function variants
  gene_term:
    preferred_term: SLC16A1
    term:
      id: hgnc:10922
      label: SLC16A1
  association: Causative
  relationship_type: CAUSATIVE
  features: >-
    SLC16A1 is normally silenced in beta cells precisely so that pyruvate and
    lactate cannot act as secretagogues. Dominant promoter variants de-silence
    MCT1, so exercise-generated monocarboxylates enter the beta cell and trigger
    insulin release — producing hypoglycemia specifically after anaerobic or
    strenuous exercise. Diagnosis uses an exercise or pyruvate load; management is
    largely trigger avoidance.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"
    explanation: Confirms the exercise/pyruvate-provoked mechanism of the SLC16A1 subtype.
- name: UCP2 inactivating variants
  gene_term:
    preferred_term: UCP2
    term:
      id: hgnc:12518
      label: UCP2
  association: Causative
  relationship_type: DISPUTED
  features: >-
    UCP2 normally leaks protons across the inner mitochondrial membrane, damping
    ATP generation and thereby restraining glucose-stimulated insulin secretion.
    Inactivating heterozygous variants remove that brake. The gene's role remains
    debated because some reported variants are common polymorphisms, and the
    source review concludes that the role of UCP2 in hyperinsulinism needs
    further investigation.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: PARTIAL
    evidence_source: IN_VITRO
    snippet: "mediates proton leak across the inner mitochondrial membrane, thereby inhibiting ATP generation through mitochondrial oxidative metabolism and negatively regulates glucose mediated insulin secretion"
    explanation: >-
      Supports the mitochondrial bioenergetic mechanism, which is established in
      vitro and restated here; recorded as partial because the same review notes
      that the role of UCP2 in hyperinsulinism needs further investigation.
- name: HK1 non-coding de-silencing variants
  gene_term:
    preferred_term: HK1
    term:
      id: hgnc:4922
      label: HK1
  association: Causative
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  features: >-
    HK1 is normally silenced in the beta cell; a dominant non-coding variant that
    fails to silence it installs a low-Km hexokinase that phosphorylates glucose —
    and therefore drives secretion — at plasma glucose concentrations far below
    the normal threshold. Practically important because a deep non-coding variant
    is invisible to standard exome and panel testing.
  evidence:
  - reference: PMID:38963811
    reference_title: "Clinical and Genetic Characteristics of Congenital Hyperinsulinism in Norway: A Nationwide Cohort Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "variants in HADH, HNF4A, KCNJ11, and HK1 were identified in 1 proband each, the latter being noncoding"
    explanation: >-
      Documents an HK1 variant in a nationwide hyperinsulinism cohort and states
      explicitly that it is noncoding, matching the de-silencing mechanism.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "a report identified a dominant gain-of-function mutation in theHK1gene in a family with “idiopathic hypoglycaemia of infancy”"
    explanation: >-
      Supports the dominant gain-of-function nature of the HK1 lesion; the review
      does not itself specify that the variant is noncoding, so support is partial.
environmental:
- name: Maternal diabetes mellitus
  description: >-
    Chronic transplacental glucose exposure over-stimulates the fetal islet, so
    the infant of a diabetic mother is born with an over-primed insulin-secretory
    apparatus that continues secreting once the maternal glucose supply is cut at
    delivery. This is a leading cause of neonatal hyperinsulinemic hypoglycemia
    overall and is usually transient.
  presence: PRESENT
  effect: RISK_FACTOR
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HH can be transient due to certain risk factors, such as birth asphyxia, intra-uterine growth retardation, maternal diabetes mellitus"
    explanation: Names maternal diabetes among the risk factors for transient hyperinsulinemic hypoglycemia.
- name: Perinatal asphyxia and intrauterine growth restriction
  description: >-
    Perinatal hypoxic-ischaemic stress and IUGR appear to reset the beta-cell
    glucose threshold downward. Most cases resolve within days, but a protracted
    form requires weeks of diazoxide — and, because these infants are already at
    neurological risk from the asphyxia itself, the added hypoglycemia is
    particularly damaging.
  presence: PRESENT
  effect: RISK_FACTOR
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Some newborns with IUGR and asphyxia have a severe and protracted form of HH which requires treatment with diazoxide"
    explanation: Documents IUGR and asphyxia as triggers of severe, protracted hyperinsulinism.
- name: Intrapartum maternal dextrose infusion
  description: >-
    High-rate maternal dextrose during labour transiently drives fetal insulin
    secretion and can produce neonatal hyperinsulinemic hypoglycemia in the hours
    after delivery.
  presence: PRESENT
  effect: RISK_FACTOR
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the use of intravenous dextrose given during labour"
    explanation: Names intrapartum intravenous dextrose among the transient-HH risk factors.
- name: Prolonged fasting
  description: >-
    Fasting is the universal precipitant across every etiology of hyperinsulinemic
    hypoglycemia and is the one exposure that must be actively engineered out of a
    patient's life. GeneReviews states in its Agents/Circumstances to Avoid
    section that prolonged fasting of any sort should be avoided; this drives the
    frequent-feeding, continuous-dextrose and gastrostomy strategies used in
    management, and means that any incidental fast (illness, pre-operative
    starvation) is a hazard requiring a written emergency plan.
  presence: PRESENT
  effect: RISK_FACTOR
  notes: >-
    The "prolonged fasting of any sort should be avoided" wording is from the
    Agents/Circumstances to Avoid section of the GeneReviews chapter body
    (PMID:20301549), which is not reproduced in the cached PubMed abstract; it is
    therefore recorded as provenance rather than quoted as an evidence snippet.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Frequent feeding with high calorie carbohydrate feeds may reduce the frequency and severity of hypoglycaemic episodes."
    explanation: >-
      Supports the corollary of fasting avoidance — that frequent feeding reduces
      hypoglycemic episodes.
treatments:
- name: Diazoxide
  description: >-
    First-line and the only drug approved for hyperinsulinism, designated a WHO
    essential medicine. Diazoxide binds SUR1 and holds the K-ATP channel open,
    hyperpolarizing the beta cell and switching insulin secretion off — which
    means it can only work when a functional channel exists, and characteristically
    fails in recessive ABCC8/KCNJ11 disease. Dosing is 5-15 (up to 20) mg/kg/day
    orally, usually with chlorothiazide to counter fluid retention. Safety
    monitoring matters: fluid retention and cardiac failure are the dose-limiting
    toxicities, and hypertrichosis, neutropenia, thrombocytopenia, hyperuricemia
    and pulmonary hypertension are recognised adverse effects — an echocardiogram
    about a week after starting and periodic blood counts are advised. Response is
    confirmed by a safety fast, not by impression.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: diazoxide
      term:
        id: CHEBI:4495
        label: diazoxide
  target_mechanisms:
  - target: K-ATP Channel Loss of Function
    treatment_effect: ACTIVATES
    description: >-
      Diazoxide activates (opens) residual functional K-ATP channels, restoring
      the hyperpolarizing brake on insulin secretion — hence its failure when the
      channel is absent.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Diazoxide functions by binding to the SUR1 subunit of KATPchannel. Thus, it requires a functionally intact KATPchannel."
      explanation: Establishes that diazoxide acts on the K-ATP channel and requires it to be intact.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diazoxide, a KATPchannel opener, is invaluable for managing many patients with CHI"
    explanation: Establishes diazoxide as the mainstay first-line therapy and a K-ATP channel opener.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most severe side effect that limits and requires treatment withdrawal is fluid retention, cardiac failure and the associated electrolyte imbalance."
    explanation: Documents the dose-limiting fluid-retention and cardiac-failure toxicity.
  - reference: PMID:37454648
    reference_title: "International Guidelines for the Diagnosis and Management of Hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diazoxide, the only drug currently approved for treating HI, was recently designated as an \"essential medicine\" by the World Health Organization"
    explanation: Establishes diazoxide as the sole approved therapy and a WHO essential medicine.
- name: Octreotide and Long-Acting Somatostatin Analogs
  description: >-
    Second-line, off-label therapy for diazoxide-unresponsive disease. Octreotide
    acts through SSTR2/SSTR5 to suppress insulin gene promoter activity, inhibit
    calcium mobilisation and act on the beta-cell K-ATP channel, all of which
    reduce insulin secretion. Started at about 5 µg/kg/day
    subcutaneously and titrated; tachyphylaxis after about 48 hours is expected and
    requires dose adjustment. Patients are often transitioned to monthly lanreotide.
    Necrotizing enterocolitis in unstable premature infants and biliary sludge are
    the safety concerns that shape monitoring.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: octreotide
      term:
        id: CHEBI:7726
        label: octreotide
  target_mechanisms:
  - target: Dysregulated Beta-Cell Insulin Secretion
    treatment_effect: INHIBITS
    description: Somatostatin-receptor agonism directly suppresses beta-cell insulin release.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Somatostatin also inhibits the KATPchannel which results in reduced insulin secretion"
      explanation: Documents the direct suppression of insulin secretion by somatostatin-receptor agonism.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The recommended initial dose of octreotide is 5 µg/kg/day given by subcutaneous injections (or as a continuous infusion) at 6-8h intervals with a maximum dose of 30-35 µg/kg/day."
    explanation: Provides the dosing regimen for second-line octreotide.
  - reference: PMID:38993725
    reference_title: "Clinical management of diazoxide-unresponsive congenital hyperinsulinism: A single-center experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "our cases suggest a safe method of switching from octreotide to lanreotide, elucidate the efficacy of home-based CGM monitoring"
    explanation: Supports the transition to long-acting lanreotide with home CGM.
- name: Glucagon Rescue and Continuous Glucagon Infusion
  description: >-
    Glucagon is the counter-regulatory hormone whose action insulin is blocking,
    so giving it exogenously (0.5-1 mg IM/SC) raises glucose within minutes and is
    the first-line rescue when intravenous access is unavailable. Continuous
    subcutaneous infusion is used to reduce dextrose and fluid requirements. Doses
    above 1 mg can cause rebound hypoglycemia through paradoxical insulin release.
  therapeutic_modality: PEPTIDE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: glucagon
      term:
        id: CHEBI:5391
        label: glucagon
  target_mechanisms:
  - target: Insulin-Driven Glucose Disposal and Suppressed Hepatic Glucose Output
    treatment_effect: INHIBITS
    description: >-
      Glucagon reverses the insulin-imposed block on hepatic glycogenolysis and
      gluconeogenesis, restoring hepatic glucose output.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Glucagon, in the short-term, induces glycogenolysis, gluconeogenesis and lipolysis and causes a rapid increase in plasma glucose within a few minutes after administration."
      explanation: Documents the reversal of the insulin-imposed block on hepatic glucose output.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Glucagon is a key counter-regulatory hormone and is used as a first line therapy for managing CHI patients, particularly in emergency situations where patients are unable to take oral feed and/or intravenous access is difficult to obtain"
    explanation: Establishes glucagon as first-line emergency rescue therapy.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Glucagon, in high doses (over 1 mg), can cause rebound hypoglycemia due to a paradoxical increase in insulin secretion"
    explanation: Documents the rebound-hypoglycemia hazard of high-dose glucagon.
- name: Intravenous Dextrose and High-Rate Carbohydrate Support
  description: >-
    The immediate treatment: continuous intravenous dextrose starting at 6-8
    mg/kg/min and escalated as required — patients may need more than 25 mg/kg/min
    — to hold plasma glucose in the normal range. Chronically this becomes frequent
    high-calorie carbohydrate feeds, continuous gastric dextrose, and often a
    gastrostomy because diazoxide-treated children develop food aversion.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: glucose (dextrose)
      term:
        id: CHEBI:17234
        label: glucose
  target_mechanisms:
  - target: Dual Glucose and Ketone Substrate Deprivation of the Brain
    treatment_effect: INHIBITS
    description: >-
      Exogenous glucose substitutes for the fuel the brain cannot obtain, and is
      the only intervention that acts on the deprivation node itself rather than
      on its upstream cause.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with HH may require >25 mg/kg/min of intravenous glucose infusion to maintain normoglycaemia."
      explanation: Establishes intravenous glucose as the intervention that maintains cerebral substrate supply.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with HH may require >25 mg/kg/min of intravenous glucose infusion to maintain normoglycaemia."
    explanation: Quantifies the extreme glucose requirement in severe disease.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Frequent feeding with high calorie carbohydrate feeds may reduce the frequency and severity of hypoglycaemic episodes."
    explanation: Supports the frequent-feeding component of chronic management.
- name: 18F-DOPA PET-Guided Focal Lesionectomy
  description: >-
    The one curative intervention in the disorder. When genetics indicate a single
    paternally inherited K-ATP variant and 18F-DOPA PET/CT localizes a discrete
    lesion, a limited resection with intraoperative frozen-section confirmation
    removes the entire disease. This is why the focal/diffuse distinction is worth
    the diagnostic effort: the same clinical picture leads either to cure or to a
    near-total pancreatectomy.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: focal lesionectomy (limited partial pancreatectomy)
    term:
      id: NCIT:C51666
      label: Partial Pancreatectomy
  target_mechanisms:
  - target: Focal Lesion Formation by Paternal K-ATP Variant and Somatic 11p15 Maternal Loss
    treatment_effect: INHIBITS
    description: >-
      Resection physically removes the clone in which the K-ATP variant is
      homozygous, eliminating the source of unregulated secretion.
    evidence:
    - reference: PMID:35018160
      reference_title: "Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations."
      explanation: Confirms that removing the focal lesion resolves the disease.
  evidence:
  - reference: PMID:39741883
    reference_title: "Congenital hyperinsulinism in the Ukraine: a 10-year national study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "After surgery, complete recovery was observed in all 14 with focal disease, while relapse occurred in three patients with diffuse or atypical histology."
    explanation: Demonstrates cure in every focal case versus relapse in diffuse/atypical disease.
  - reference: PMID:35018160
    reference_title: "Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "18F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion."
    explanation: Supports the imaging basis for lesion-directed surgery.
- name: Near-Total Pancreatectomy
  description: >-
    Reserved for medically uncontrollable diffuse disease. Removing 90-98% of the
    pancreas trades one disease for another: hypoglycemia frequently persists,
    diabetes mellitus becomes highly likely with time, and exocrine insufficiency
    follows resection above about half the gland. It is a control measure, not a
    cure, and lifelong HbA1c, fecal elastase and fat-soluble vitamin monitoring
    follow.
  therapeutic_modality: SURGERY
  treatment_term:
    preferred_term: pancreatectomy
    term:
      id: NCIT:C15294
      label: Pancreatectomy
  target_mechanisms:
  - target: Dysregulated Beta-Cell Insulin Secretion
    treatment_effect: INHIBITS
    description: >-
      Removing 90-98% of the pancreas removes most of the secreting beta-cell
      mass; because the defect is present in every islet this reduces rather than
      abolishes unregulated secretion, and it trades hypoglycemia for diabetes.
    evidence:
    - reference: PMID:24840042
      reference_title: "Pancreatic endocrine and exocrine function in children following near-total pancreatectomy for diffuse congenital hyperinsulinism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency."
      explanation: >-
        Shows that removing beta-cell mass only partly controls secretion
        (hypoglycemia persists) while producing endocrine and exocrine failure.
  evidence:
  - reference: PMID:24840042
    reference_title: "Pancreatic endocrine and exocrine function in children following near-total pancreatectomy for diffuse congenital hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Post-pancreatectomy, in addition to persistent hypoglycaemia, there is a very high risk of diabetes mellitus and pancreatic exocrine insufficiency."
    explanation: Documents persistent hypoglycemia plus diabetes and exocrine insufficiency after near-total pancreatectomy.
- name: Nifedipine (not recommended for routine use)
  description: >-
    An L-type calcium-channel blocker used off-label on the rationale that
    voltage-gated calcium entry is the final step of insulin exocytosis. The
    rationale does not survive contact with K-ATP disease: if the channel is
    broken the membrane is already depolarized, and the largest dedicated study
    (11 ABCC8-mutated cases on long-term nifedipine) found no improvement in
    glycemic control in any patient. The 2023 international consensus recommends
    against routine use. Curated deliberately as a negative recommendation,
    because nifedipine is still reached for off-label.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: nifedipine
      term:
        id: CHEBI:7565
        label: nifedipine
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "none of patients showed any improvement in glycemic control and patients continued to have hypoglycemic episodes"
    explanation: >-
      In the largest dedicated study of long-term nifedipine in K-ATP
      hyperinsulinism no patient improved, refuting routine efficacy.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This suggests that mutations in the KATPchannel genes might render the L-type calcium channel ineffective to therapy with nifedipine"
    explanation: Gives the mechanistic reason nifedipine fails specifically in K-ATP disease.
- name: Sirolimus (not recommended outside research protocols)
  description: >-
    An mTOR inhibitor trialled in severe diazoxide-unresponsive diffuse disease
    after early favourable reports. Subsequent evaluation was much less
    encouraging — effective in only 3 of 10 patients, with no reduction in
    beta-cell proliferation in resected tissue from non-responders — while the
    immunosuppressive toxicity profile (stomatitis, infection, renal dysfunction,
    pneumonitis, transaminase and lipid elevation) is substantial. The 2023
    international consensus recommends against routine use outside approved
    research protocols.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: sirolimus
      term:
        id: CHEBI:9168
        label: sirolimus
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: "mTOR inhibition has shown to be effective in only three patients (30%) with certain side effects"
    explanation: Reports a low response rate with side effects, refuting sirolimus as routine therapy.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The most commonly reported adverse effects are stomatitis, increased risk of infection, immunosuppression, renal dysfunction, fatigue, pneumonitis and increased serum aminotransferase or lipid levels"
    explanation: Documents the immunosuppressive toxicity profile that weighs against routine use.
- name: Genotype-Specific Trigger Avoidance and Dietary Management
  description: >-
    Because several subtypes have a specific precipitant, management is partly
    behavioural and genotype-directed: protein/leucine restriction in GLUD1 and
    HADH disease, avoidance of anaerobic/strenuous exercise in SLC16A1 disease,
    and — universally — avoidance of prolonged fasting, with a written emergency
    regimen for intercurrent illness.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: NCIT:C15447
      label: Dietary Intervention
  target_mechanisms:
  - target: Glutamate Dehydrogenase Amino-Acid Amplifier Activation
    treatment_effect: INHIBITS
    description: >-
      Protein and leucine restriction withdraws the substrate that allosterically
      activates glutamate dehydrogenase, removing the trigger in GLUD1 and HADH
      disease.
    evidence:
    - reference: PMID:29280746
      reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "protein/leucine loading precipitates hypoglycaemia"
      explanation: >-
        Establishes protein/leucine as the amplifier trigger whose dietary
        withdrawal is the genotype-specific intervention.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "protein/leucine loading precipitates hypoglycaemia"
    explanation: Establishes protein/leucine as the specific precipitant in GLUD1 and HADH disease.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A pyruvate load or excercise test may precipitate HH and may be used for diagnostic purposes"
    explanation: Supports exercise as the specific precipitant in the SLC16A1 subtype.
diagnosis:
- name: Critical Sample During Documented Hypoglycemia
  description: >-
    Blood drawn at the moment of documented hypoglycemia, before glucose is given,
    for glucose, insulin, C-peptide, beta-hydroxybutyrate, free fatty acids,
    cortisol, growth hormone, lactate, ammonia, acylcarnitines and urine organic
    acids — followed by a glucagon stimulation test. Missing the critical sample is
    a common reason a diagnosis is delayed, because once dextrose is running the
    biochemical signature is gone.
  notes: >-
    No `diagnosis_term` is bound: the "critical sample" is a timed multi-analyte
    panel drawn during spontaneous hypoglycemia, and neither NCIT nor MAXO
    provides a term for that composite procedure. The individual analytes are
    modelled in `biochemical:` and the decision rule in `definitions:`. This is a
    candidate for an ontology new-term request rather than a false match.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In any patient with recurrent or persistent hypoglycaemia, HH should be suspected and critical samples at the time of hypoglycaemic episodes should be collected."
    explanation: Establishes the critical-sample protocol as the diagnostic foundation.
- name: 18F-DOPA PET/CT Localization
  description: >-
    Beta cells take up L-DOPA and decarboxylate it to dopamine, and uptake scales
    with insulin synthesis, so an 18F-DOPA tracer concentrates in hyperfunctional
    tissue. This is the only imaging able to distinguish focal from diffuse disease
    and to localize a focal lesion preoperatively; conventional ultrasound, CT and
    MRI do not reliably detect these lesions.
  diagnosis_term:
    preferred_term: positron emission tomography procedure
    term:
      id: NCIT:C17007
      label: Positron Emission Tomography
  evidence:
  - reference: PMID:35018160
    reference_title: "Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "18F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion."
    explanation: >-
      Supports the role of 18F-DOPA PET/CT in separating focal from diffuse
      disease; recorded as partial because the source is a short case report
      restating a review claim rather than a measured accuracy series, and 100%
      is not the pooled real-world localization accuracy.
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The uptake of the positron emitting tracer18F-DOPA-PET is increased in b-cells with a high rate of insulin synthesis and secretion compared to unaffected areas"
    explanation: Explains the tracer mechanism that makes focal lesions visible.
- name: Rapid ABCC8/KCNJ11 Sequencing with Parental Testing
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  description: >-
    In diazoxide-unresponsive disease, urgent K-ATP gene sequencing with parental
    samples is the decisive test — not to name the disease, but to determine
    parent of origin. A single paternally inherited recessive variant predicts a
    focal, curable lesion and sends the child to PET rather than to a near-total
    pancreatectomy.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In diazoxide unresponsive CHI cases, urgent genetic analysis forABCC8/KCNJ11and18F-DOPA-PET/CT scan are indicated to identify those patients who could have the focal form of CHI."
    explanation: Establishes urgent K-ATP sequencing plus PET as the focal-lesion identification pathway.
  - reference: PMID:37454648
    reference_title: "International Guidelines for the Diagnosis and Management of Hyperinsulinism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Rapid turnaround of genetic test results combined with advanced radiologic imaging can permit identification and localization of surgically-curable focal lesions in a large proportion of children with congenital forms of HI"
    explanation: Confirms that rapid genetics plus imaging identifies surgically curable focal lesions.
differential_diagnoses:
- name: Fatty acid oxidation disorders
  disease_term:
    preferred_term: medium chain acyl-CoA dehydrogenase deficiency
    term:
      id: MONDO:0008721
      label: medium chain acyl-CoA dehydrogenase deficiency
  description: >-
    The closest biochemical mimic, because both present with hypoketotic
    hypoglycemia. MCAD and related defects share the low-ketone finding but the
    lesion is in beta-oxidation, not in insulin.
  distinguishing_features:
  - Free fatty acids are HIGH in fatty acid oxidation defects (lipolysis is intact, oxidation fails) and LOW in hyperinsulinism (lipolysis is blocked) — the single most efficient discriminator on the critical sample.
  - Plasma acylcarnitines are abnormal in fatty acid oxidation defects and normal in hyperinsulinism, with the single exception of HADH/SCHAD deficiency, which itself raises 3-hydroxybutyrylcarnitine.
  - Insulin and C-peptide are appropriately suppressed in fatty acid oxidation defects.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the biochemical profiles of insulin action (low b-hydroxybutyrate and fatty acid concentrations)"
    explanation: >-
      Establishes that low fatty acids alongside low ketones is the profile of
      insulin action, which is what separates hyperinsulinism from a fatty acid
      oxidation defect.
- name: Glycogen storage disease
  disease_term:
    preferred_term: glycogen storage disease I
    term:
      id: MONDO:0002413
      label: glycogen storage disease I
  description: >-
    Hepatic glycogen storage disease presents with fasting hypoglycemia and
    hepatomegaly, both of which also occur in hyperinsulinism.
  distinguishing_features:
  - Glycogen storage disease type I gives a KETOTIC hypoglycemia, the inverse of the hyperinsulinism profile.
  - Lactic acidosis, hyperuricemia and hyperlipidemia accompany the hypoglycemia; lactate is normal in hyperinsulinism.
  - The glucagon stimulation test fails to raise glucose because glucose-6-phosphatase deficiency blocks release of free glucose (lactate rises instead), whereas in hyperinsulinism the response is brisk and positive.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "a positive glycaemic response (rise in the plasma glucose concentration of >1.5 mmol/L from baseline) following an intramuscular/intravenous injection of glucagon at the time of hypoglycaemia provides supportive evidence"
    explanation: >-
      Supports the glucagon-response criterion that separates hyperinsulinism
      (positive response) from glycogen storage disease; the cited source
      describes the hyperinsulinism side of that contrast only.
- name: Insulinoma
  disease_term:
    preferred_term: pancreatic insulinoma
    term:
      id: MONDO:0024677
      label: pancreatic insulinoma
  description: >-
    An insulin-secreting pancreatic neuroendocrine tumour produces biochemically
    identical endogenous hyperinsulinemic hypoglycemia.
  distinguishing_features:
  - Age is the key discriminator — hyperinsulinemic hypoglycemia first appearing after about two years of age should prompt an insulinoma evaluation.
  - Insulinoma is typically a solitary, cross-sectionally visible tumour arising against previously normal glucose regulation.
  - Insulinoma may occur within multiple endocrine neoplasia type 1.
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "HH most commonly presents during the neonatal period, but can also present during infancy, childhood and even adulthood"
    explanation: >-
      Supports the age-based framing of the differential; the source establishes
      the age range of congenital HH rather than the insulinoma comparison
      directly, so support is partial.
- name: Exogenous insulin administration (factitious or accidental)
  description: >-
    Administered insulin — accidental, iatrogenic, or in factitious disorder or
    medical child abuse — reproduces the entire clinical and biochemical picture
    of endogenous hyperinsulinism and must be actively excluded, particularly in
    an atypical age group or an unwitnessed setting.
  distinguishing_features:
  - C-peptide is the discriminator — endogenous hyperinsulinism raises insulin and C-peptide together because they are secreted in equimolar amounts from proinsulin.
  - Injected insulin raises insulin while SUPPRESSING C-peptide, giving an elevated insulin-to-C-peptide ratio.
  - Sulfonylurea ingestion raises both insulin and C-peptide and requires a drug screen to detect.
  notes: >-
    MONDO does not provide a distinct disease term for exogenous or factitious
    insulin-induced hypoglycemia. Binding this differential to MONDO:0005803
    would make the disease its own differential, so no `disease_term` is
    asserted; the discriminating HP:0034384 phenotype is bound instead.
  phenotypes:
  - name: Elevated insulin-to-C-peptide ratio
    phenotype_term:
      preferred_term: Elevated circulating insulin:C-peptide ratio
      term:
        id: HP:0034384
        label: Elevated circulating insulin:C-peptide ratio
  evidence:
  - reference: PMID:40904956
    reference_title: "Neonatal Congenital Hyperinsulinism: A Case-Based Contribution to the Understanding of a Rare Disorder."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Laboratory investigations revealed elevated insulin and C-peptide levels"
    explanation: >-
      Documents the concordant insulin-and-C-peptide elevation of endogenous
      disease, which is precisely the pattern that exogenous insulin breaks;
      recorded as partial because the source does not itself address exogenous
      insulin.
- name: Adrenal insufficiency
  disease_term:
    preferred_term: adrenocortical insufficiency
    term:
      id: MONDO:0000004
      label: adrenocortical insufficiency
  description: >-
    Cortisol deficiency impairs gluconeogenesis and produces fasting hypoglycemia
    in infants, and can co-present with the same non-specific neonatal symptoms.
  distinguishing_features:
  - Cortisol is inappropriately low on the critical sample, whereas counter-regulatory hormones are intact in hyperinsulinism.
  - Adrenal insufficiency gives a ketotic hypoglycemia.
  - Associated hyponatremia, hyperkalemia, hyperpigmentation or ambiguous genitalia point to the adrenal.
  notes: >-
    Adrenal insufficiency is listed in the differential-diagnosis section of the
    GeneReviews chapter body (PMID:20301549, NBK1375) and cortisol is measured on
    the same critical sample for exactly this reason. That chapter section is not
    reproduced in the cached PubMed abstract, so the attribution is recorded here
    as provenance rather than as a quoted evidence snippet.
- name: Growth hormone deficiency and hypopituitarism
  disease_term:
    preferred_term: hypopituitarism
    term:
      id: MONDO:0005152
      label: hypopituitarism
  description: >-
    Congenital hypopituitarism causes neonatal hypoglycemia through combined
    growth hormone and cortisol deficiency, and can itself present with a partly
    hypoketotic picture.
  distinguishing_features:
  - Growth hormone and cortisol are inappropriately low on the critical sample.
  - Midline defects, micropenis, prolonged jaundice or septo-optic dysplasia point to the pituitary.
  - Insulin and C-peptide are appropriately suppressed, unlike in hyperinsulinism.
  notes: >-
    Counter-regulatory hormone deficiency is listed in the differential-diagnosis
    section of the GeneReviews chapter body (PMID:20301549, NBK1375), and growth
    hormone and cortisol are drawn on the same critical sample for exactly this
    reason. That chapter section is not reproduced in the cached PubMed abstract,
    so the attribution is recorded here as provenance rather than as a quoted
    evidence snippet.
- name: Idiopathic ketotic hypoglycemia
  description: >-
    A common cause of hypoglycemia in toddlers and young children, presenting with
    fasting hypoglycemia during intercurrent illness.
  distinguishing_features:
  - Ketotic by definition — beta-hydroxybutyrate is appropriately elevated at the time of hypoglycemia, the exact inverse of the hyperinsulinism profile.
  - Insulin is appropriately suppressed.
  - The intravenous glucose infusion requirement is normal rather than above 8 mg/kg/min.
  notes: >-
    MONDO does not provide a term for idiopathic ketotic hypoglycemia at the time
    of curation, so this differential is recorded without a bound disease_term;
    the contrasting phenotype is bound instead.
  phenotypes:
  - name: Ketotic hypoglycemia
    phenotype_term:
      preferred_term: Ketotic hypoglycemia
      term:
        id: HP:0012734
        label: Ketotic hypoglycemia
  evidence:
  - reference: PMID:29280746
    reference_title: "Congenital Hyperinsulinism: Diagnosis and Treatment Update."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "It is the most common cause of persistent hypoketotic hypoglycaemia in neonates and infants"
    explanation: >-
      Establishes hyperinsulinism as a HYPOketotic hypoglycemia, the defining
      contrast with ketotic hypoglycemia.
clinical_trials:
- name: NCT06208215
  phase: PHASE_III
  status: ACTIVE_NOT_RECRUITING
  description: >-
    Phase 3 randomized, double-blind, placebo-controlled study of RZ358
    (ersodetug), an allosteric anti-insulin-receptor antibody that acts distal to
    the beta cell by blunting insulin action at the receptor rather than trying to
    suppress a broken secretory apparatus — a mechanistically distinct approach
    that should work irrespective of the underlying genotype.
  target_phenotypes:
  - preferred_term: Hyperinsulinemic hypoglycemia
    term:
      id: HP:0000825
      label: Hyperinsulinemic hypoglycemia
  evidence:
  - reference: clinicaltrials:NCT06208215
    reference_title: "A Phase 3, Randomized, Double-Blind, Placebo-Controlled, Parallel-Arm Study to Evaluate the Efficacy and Safety of RZ358 in Patients With Congenital Hyperinsulinism"
    supports: SUPPORT
    snippet: "The Phase 3 pivotal study is designed to evaluate the efficacy and safety of RZ358 for the treatment of congenital hyperinsulinism (HI) as add-on to standard-of-care (SOC) therapy compared to SOC alone over 24 weeks"
    explanation: Confirms the phase 3 evaluation of RZ358 as add-on therapy for hyperinsulinism.
- name: NCT04538989
  phase: PHASE_II
  status: COMPLETED
  description: >-
    Open-label multiple-dose phase 2 study of RZ358 (ersodetug), the predecessor
    to the phase 3 programme; results were first posted in May 2025.
  target_phenotypes:
  - preferred_term: Hyperinsulinemic hypoglycemia
    term:
      id: HP:0000825
      label: Hyperinsulinemic hypoglycemia
  evidence:
  - reference: clinicaltrials:NCT04538989
    reference_title: "An Open-Label Multiple-Dose Study of RZ358 in Patients With Congenital Hyperinsulinism"
    supports: SUPPORT
    snippet: "The objective of this trial is to evaluate the safety, tolerability and glucose-raising effects of RZ358 in patients with Congenital Hyperinsulinism (HI)."
    explanation: Documents the phase 2 evaluation of RZ358 that preceded the phase 3 study.
- name: NCT04732416
  phase: PHASE_II
  status: ACTIVE_NOT_RECRUITING
  description: >-
    Phase 2 multiple-ascending-dose proof-of-concept study of HM15136
    (efpegerglucagon), a long-acting glucagon analogue given once weekly as
    add-on therapy — the same counter-regulatory strategy as dasiglucagon but on
    a weekly rather than continuous-infusion schedule.
  target_phenotypes:
  - preferred_term: Hypoglycemia
    term:
      id: HP:0001943
      label: Hypoglycemia
  evidence:
  - reference: clinicaltrials:NCT04732416
    reference_title: "A Phase 2, Multiple Ascending Dose, Open-label, Proof-of-concept Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Efficacy of HM15136 (Efpegerglucagon) Treatment for 8 Weeks in Subjects Aged ≥2 Years With Congenital Hyperinsulinism (CHI)"
    supports: SUPPORT
    snippet: "This study is designed to evaluate the safety, tolerability, pharmacokinetics (PK), and efficacy of HM15136 when used as add-on therapy in subjects with CHI with persistent hypoglycemia while on standard of care treatment (SoC)."
    explanation: Documents weekly efpegerglucagon as an investigational add-on therapy for persistent hypoglycemia in hyperinsulinism.
- name: NCT03777176
  phase: PHASE_III
  status: COMPLETED
  description: >-
    Two-period open-label phase 3 trial of dasiglucagon, a soluble glucagon
    analogue delivered by continuous subcutaneous infusion, exploiting the
    counter-regulatory arm that insulin is suppressing.
  target_phenotypes:
  - preferred_term: Hypoglycemia
    term:
      id: HP:0001943
      label: Hypoglycemia
  evidence:
  - reference: clinicaltrials:NCT03777176
    reference_title: "A Two-Period, Open-label Trial Evaluating the Efficacy and Safety of Dasiglucagon for the Treatment of Children With Congenital Hyperinsulinism"
    supports: SUPPORT
    snippet: "The objective of the trial is to evaluate the efficacy and safety of dasiglucagon administered as a subcutaneous (SC) infusion in reducing hypoglycemia in children with CHI."
    explanation: Confirms the phase 3 evaluation of continuous subcutaneous dasiglucagon in hyperinsulinism.
datasets: []

📚

References & Deep Research

References

3

PMID:20301549

Nonsyndromic Genetic Hyperinsulinism Overview.

No top-level findings curated for this source.

PMID:37454648

International Guidelines for the Diagnosis and Management of Hyperinsulinism.

No top-level findings curated for this source.

PMID:25957977

Recommendations from the Pediatric Endocrine Society for Evaluation and Management of Persistent Hypoglycemia in Neonates, Infants, and Children.

No top-level findings curated for this source.

Deep Research

1

Falcon ▸

Hyperinsulinemic Hypoglycemia: Disease-Characteristics Research Report

Edison Scientific Literature 26 citations 2026-08-01T05:11:53.485420

Hyperinsulinemic Hypoglycemia: Disease-Characteristics Research Report

Scope. “Hyperinsulinemic hypoglycemia” (HH) is a biochemical-clinical state rather than one molecular disease. This report focuses on congenital hyperinsulinism (CHI)—the principal genetic category requested—while separating acquired perinatal-stress HI, syndromic HI, insulinoma, autoimmune HI, and drug-associated causes. Evidence is chiefly aggregated disease-level literature and registries, not individual EHR data. The leading authority is the international consensus published July 2023, DOI/URL: https://doi.org/10.1159/000531766. A major recent primary source is the Ukrainian national registry published 17 December 2024, DOI/URL: https://doi.org/10.3389/fendo.2024.1497579. PMIDs were not consistently exposed in the retrieved records; DOI links are therefore supplied rather than unverified PMID values.

1. Disease information

HH is inappropriate insulin action or failure to suppress insulin during hypoglycemia. Excess insulin simultaneously increases glucose utilization and prevents hepatic glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis; the resulting hypoketotic hypoglycemia deprives the brain of both glucose and alternative ketone fuel. CHI is the most common and most severe cause of persistent hypoglycemia in infancy and childhood. It is clinically, genetically, and histologically heterogeneous, encompassing focal, diffuse, and atypical/mosaic pancreatic disease. The 2024 Ukrainian study defines it directly as a condition “caused by inappropriate insulin secretion during hypoglycemia.” (globa2024congenitalhyperinsulinismin pages 1-2, leon2024internationalguidelinesfor pages 3-5)

Names: congenital hyperinsulinism; congenital hyperinsulinism of infancy; persistent hyperinsulinemic hypoglycemia of infancy; hyperinsulinemic hypoglycemia; familial hyperinsulinism; hyperinsulinism/hyperammonemia syndrome for the GLUD1 subtype. “Nesidioblastosis” is a historical/pathologic term and should not be used as a universal synonym.

Suggested identifiers: MONDO disease mapping should use the specific congenital hyperinsulinism/familial hyperinsulinism concept rather than generic hypoglycemia; OMIM uses separate phenotype entries by molecular subtype rather than one universal CHI entry. MeSH concepts include Hyperinsulinism and Hypoglycemia. ICD-10-CM commonly maps congenital hyperinsulinism to E16.1, Other hypoglycemia or E16.2, Hypoglycemia, unspecified, depending on local coding; ICD-11 should be mapped to the specific hyperinsulinism/hypoglycemia concept in the implementation used. Exact MONDO/Orphanet numeric identifiers should be database-validated before ingestion because HH and familial hyperinsulinism are represented at different granularity.

2. Etiology, risk, protective factors, and gene–environment interaction

Genetic causes

The most frequent causes are loss-of-function variants in ABCC8 and KCNJ11, encoding SUR1 and Kir6.2 of the pancreatic β-cell ATP-sensitive potassium channel. Other established or reported genes include GLUD1, GCK, HADH, HK1, SLC16A1, HNF4A, HNF1A, FOXA2, UCP2, PGM1, PMM2, ADK, CACNA1D, and additional rare/syndromic loci. The 2024 Ukrainian registry states that variants in more than 30 genes can cause CHI, although gene lists and strength of evidence vary across panels. (globa2024congenitalhyperinsulinismin pages 1-2, leon2024internationalguidelinesfor pages 5-6, maines2023anarrativereview pages 1-2)

Gene / etiology	Molecular defect and inheritance	Distinguishing phenotype / biomarker	Focal / diffuse / syndromic status	Management implication
ABCC8 / KCNJ11	Loss-of-function variants in beta-cell KATP channel genes; diffuse HI from recessive bi-allelic or dominant mono-allelic variants; focal HI from a paternally inherited recessive variant plus paternal isodisomy of 11p15 confined to the lesion (leon2024internationalguidelinesfor pages 5-6, globa2024congenitalhyperinsulinismin pages 1-2)	Severe neonatal hypoketotic hypoglycemia; diazoxide-unresponsive cases strongly enriched for KATP defects; paternally inherited single variant predicts focal lesion with high PPV/sensitivity; persistent CHI commonly due to these genes (leon2024internationalguidelinesfor pages 5-6, globa2024congenitalhyperinsulinismin pages 1-2, globa2024congenitalhyperinsulinismin pages 3-5)	Diffuse or focal; atypical/mosaic forms also reported with somatic variants (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 11-13)	Rapid ABCC8/KCNJ11 testing guides care; if diazoxide-unresponsive and focal likely, perform 18F-DOPA PET and limited resection; focal lesions are usually surgically curable, whereas diffuse disease may require 90–98% pancreatectomy and long-term diabetes surveillance (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 6-8, leon2024internationalguidelinesfor pages 11-13)
GLUD1	Activating/regulatory variants affecting glutamate dehydrogenase; inheritance not specified in retrieved evidence (leon2024internationalguidelinesfor pages 5-6)	Moderately elevated plasma ammonia; protein/leucine-induced hypoglycemia; neurodevelopmental and seizure burden may be high (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 13-15)	Non-syndromic genetic HI (leon2024internationalguidelinesfor pages 5-6)	Gene-specific dietary management may include protein restriction; usually considered outside KATP/focal surgical pathway (mittal2024molecularmechanismsunderlying pages 7-9, leon2024internationalguidelinesfor pages 5-6)
HADH (SCHAD)	Enzyme defect; inheritance not specified in retrieved evidence (leon2024internationalguidelinesfor pages 5-6)	May show elevated plasma C4-OH acylcarnitine and urine 3-OH-glutarate; protein-induced hypoglycemia reported (leon2024internationalguidelinesfor pages 5-6)	Non-syndromic genetic HI (leon2024internationalguidelinesfor pages 5-6)	Dietary modification may help; review cited high-carbohydrate/low-fat diet as gene-specific support, but evidence level in retrieved material is limited (mittal2024molecularmechanismsunderlying pages 7-9)
GCK	Activating variants; somatic GCK variants also linked to LINE/mosaic pathology; one 2024 case report suggests GCK duplication as a novel cause of nesidioblastosis (mechanism/new association still uncertain) (leon2024internationalguidelinesfor pages 5-6, shoji2024casereportduplication pages 8-8)	May develop ketotic hypoglycemia with prolonged fasting, unlike typical hypoketotic HI (leon2024internationalguidelinesfor pages 5-6)	Can be diffuse/non-focal; localized islet nuclear enlargement (LINE)/mosaic with somatic variants; adult nesidioblastosis reported in a case with chromosome 7 duplication containing GCK (leon2024internationalguidelinesfor pages 5-6, shoji2024casereportduplication pages 8-8)	Often diazoxide-unresponsive per guideline discussion; if localized somatic disease suspected, pathology/imaging interpretation is important; mechanistic significance of copy-number gain remains provisional (leon2024internationalguidelinesfor pages 8-10, leon2024internationalguidelinesfor pages 5-6, shoji2024casereportduplication pages 8-8)
HK1	Heterozygous non-coding variants preventing beta-cell silencing of HK1; inappropriate pancreatic HK1 expression also reported in atypical tissue (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 11-13)	Isolated HI; mechanism is aberrant beta-cell expression of hexokinase 1 rather than classic KATP dysfunction (leon2024internationalguidelinesfor pages 5-6)	Usually isolated; may contribute to atypical / mosaic pancreatic disease (leon2024internationalguidelinesfor pages 11-13, leon2024internationalguidelinesfor pages 5-6)	Include non-coding regions in testing because exome/panels can miss deep intronic/non-coding causes; no gene-specific approved therapy identified in retrieved evidence (leon2024internationalguidelinesfor pages 5-6)
SLC16A1	Activating promoter-region variants affecting monocarboxylate transporter 1 (MCT1) (leon2024internationalguidelinesfor pages 5-6)	Anaerobic exercise-induced hypoglycemia (leon2024internationalguidelinesfor pages 5-6)	Non-syndromic genetic HI (leon2024internationalguidelinesfor pages 5-6)	History of exercise-triggered episodes helps diagnosis; management implication is trigger recognition/avoidance plus standard HI therapy as needed (leon2024internationalguidelinesfor pages 5-6)
HNF1A / HNF4A	MODY-related transcription factor variants; transient neonatal hyperinsulinism may occur with family history suggestive of MODY (leon2024internationalguidelinesfor pages 3-5)	Family history of MODY; some cases improve over time (leon2024internationalguidelinesfor pages 3-5, leon2024internationalguidelinesfor pages 13-15)	Non-syndromic genetic HI; not focal KATP-type disease in retrieved evidence (leon2024internationalguidelinesfor pages 3-5)	Consider targeted testing when MODY pedigree is present; severity may decrease over time, allowing medication reduction; requires later diabetes surveillance (leon2024internationalguidelinesfor pages 13-15, leon2024internationalguidelinesfor pages 3-5)
KMT2D / KDM6A (Kabuki syndrome)	Chromatin-regulating genes; KMT2D usually de novo AD, KDM6A X-linked dominant in Kabuki syndrome; mechanism for HH is not fully clarified and likely epigenetic/beta-cell developmental (maines2023anarrativereview pages 1-2, globa2024congenitalhyperinsulinismin pages 1-2)	Syndromic features of Kabuki syndrome; HH prevalence reported as 0.3–4% in KS and association is stronger for KDM6A-KS than KMT2D-KS (maines2023anarrativereview pages 1-2)	Syndromic HI (maines2023anarrativereview pages 1-2, globa2024congenitalhyperinsulinismin pages 1-2)	Evaluate for multisystem syndrome and provide genetic counseling; mechanism remains uncertain, so management is mostly standard HI treatment plus syndrome-specific care (leon2024internationalguidelinesfor pages 3-5, maines2023anarrativereview pages 1-2)
11p15 / Beckwith-Wiedemann spectrum (BWS/BWSp)	Imprinting defect / paternal UPD11p; in focal lesions there is loss of maternal heterozygosity at 11p15 with loss of nuclear p57 staining; severe HI in BWSp can occur with 11pUPD plus a paternally inherited ABCC8/KCNJ11 variant (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 11-13, globa2024congenitalhyperinsulinismin pages 3-5)	Syndromic overgrowth context; pathology may show expanded endocrine tissue over large pancreatic areas; requires methylation testing when clinically suspected (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 11-13)	Syndromic, may mimic/extensively involve pancreas; focal-type molecular mechanism overlaps with 11p15 loss in lesion tissue (leon2024internationalguidelinesfor pages 11-13, leon2024internationalguidelinesfor pages 5-6)	Perform 11p methylation testing if BWSp suspected; surgery can be more complex than classic focal HI because endocrine overgrowth may be extensive (leon2024internationalguidelinesfor pages 5-6, leon2024internationalguidelinesfor pages 11-13)
Acquired perinatal-stress HI (PSHI)	Acquired, not established genetic etiology in current evidence; linked to maternal diabetes, perinatal stress, birth asphyxia, IUGR, maternal drug exposure, or high maternal glucose infusion during delivery (leon2024internationalguidelinesfor pages 3-5)	Presents in first 24 h of life; affects about 1 in 1,200–1,700 newborns; often resolves within 10–14 days; severe persistent form beyond 2 weeks occurs in about 1 in 12,000–13,600 newborns (leon2024internationalguidelinesfor pages 3-5)	Acquired, not focal genetic CHI (leon2024internationalguidelinesfor pages 3-5)	Genetic testing is not usually recommended initially; treat supportively, including diazoxide if prolonged/severe; retest after 72 h if still hypoglycemic during transitional period (leon2024internationalguidelinesfor pages 3-5)

Table: This table summarizes the main genetic and acquired etiologies of hyperinsulinemic hypoglycemia/congenital hyperinsulinism, highlighting distinguishing biomarkers, histologic patterns, inheritance, and immediate management implications. It is designed as a concise knowledge-base artifact for genotype-phenotype-treatment mapping.

Inheritance: biallelic recessive or monoallelic dominant ABCC8/KCNJ11 variants cause diffuse HI. Focal HI is a two-hit, parent-of-origin disorder: a paternally inherited recessive ABCC8/KCNJ11 variant is unmasked by somatic paternal isodisomy/loss of the maternal 11p15 region in a pancreatic clone. A single paternal KATP variant predicts focal disease with sensitivity around 97% and positive predictive value up to 94%. Somatic ABCC8 or GCK variants and inappropriate HK1 expression occur in LINE/mosaic disease. (leon2024internationalguidelinesfor pages 5-6)

Syndromic/chromosomal causes: Beckwith–Wiedemann spectrum/11p15 imprinting defects, Kabuki syndrome (KMT2D/KDM6A), Sotos syndrome, Turner syndrome, Costello syndrome, Simpson–Golabi–Behmel syndrome, trisomy 13, congenital disorders of glycosylation, and rare chromosomal deletions/duplications are reported. A December 2024 human case linked mosaic chromosome 7 duplication containing GCK to adult nesidioblastosis; this remains a novel case-level association rather than an established recurrent cause. (leon2024internationalguidelinesfor pages 19-20, leon2024internationalguidelinesfor pages 17-19, shoji2024casereportduplication pages 8-8, maines2023anarrativereview pages 1-2)

Acquired and environmental/perinatal causes

Maternal diabetes, birth asphyxia/hypoxia, intrauterine growth restriction, perinatal stress, maternal drugs, and high intrapartum maternal glucose infusion can produce perinatal-stress HI. The proposed interaction is hypoxia-mediated lowering of the β-cell glucose threshold for insulin suppression. PSHI usually presents in the first 24 hours and resolves in 10–14 days; a severe form persists beyond two weeks. These exposures are triggers for acquired HI, not established causes of germline CHI. (leon2024internationalguidelinesfor pages 3-5)

No reproducible lifestyle, toxin, smoking, alcohol, pollution, occupational, or infectious cause is established for genetic CHI. Rare autoimmune insulin syndromes or postinfectious associations belong in the broader HH differential, not the congenital genetic entry. No validated protective allele is known. Practical “protective factors” are therefore prevention of fasting, rapid glucose rescue, avoidance of genotype-specific triggers—protein/leucine in GLUD1/HADH disease and anaerobic exercise in SLC16A1 disease—and early specialist treatment. (leon2024internationalguidelinesfor pages 29-29, leon2024internationalguidelinesfor pages 5-6)

3. Phenotypes

Biochemical hypoglycemia—usually neonatal or infantile, episodic/recurrent, and potentially severe; suggested HPO: Hypoglycemia (HP:0001943), Hyperinsulinemia (HP:0000842). Insulin action suppresses β-hydroxybutyrate and free fatty acids. Severity ranges from spontaneous remission to glucose requirements of 20–30 mg/kg/min. (leon2024internationalguidelinesfor pages 25-29, leon2024internationalguidelinesfor pages 6-8)
Neuroglycopenic/autonomic manifestations—jitteriness, lethargy, poor feeding, apnea/cyanosis, altered consciousness, seizures, and coma; suggested HPO: neonatal hypoglycemia, seizures, lethargy, feeding difficulties, apnea, coma. Onset is commonly neonatal, but milder genetic disease can appear later. Frequency is cohort-dependent.
Neurologic sequelae—epilepsy, infantile spasms, microcephaly, cerebral palsy, motor/speech delay, cognitive impairment, and attention, memory, visual, and sensorimotor deficits; suggested HPO: Seizure (HP:0001250), Global developmental delay (HP:0001263), Microcephaly (HP:0000252), Abnormality of movement, speech delay, intellectual disability. Transient HI still carries reported neurodevelopmental-deficit rates of 26–44%. In the 2024 Ukrainian persistent-CHI cohort, 11/22 (50%) had epilepsy and/or psychomotor retardation. GLUD1-HI has particularly high seizure/neurodevelopmental burden. (globa2024congenitalhyperinsulinismin pages 3-5, leon2024internationalguidelinesfor pages 13-15)
Feeding dysfunction—vomiting, impaired suck/swallow, food aversion, tube dependence, and reflux; suggested HPO: feeding difficulties, dysphagia, vomiting. Feeding problems were reported in 68.6%, often reflecting disease plus medications, high-carbohydrate feeds, IV glucose, and tube feeding. (leon2024internationalguidelinesfor pages 13-15)
Gene-specific phenotypes: moderate hyperammonemia and protein-induced hypoglycemia in GLUD1-HI; C4-OH acylcarnitine/urinary 3-hydroxyglutarate abnormalities in HADH-HI; exercise-induced episodes in SLC16A1-HI; occasionally ketotic fasting hypoglycemia in GCK-HI. (leon2024internationalguidelinesfor pages 5-6)

Quality of life is impaired by unpredictable episodes, sleep/feeding schedules, intensive glucose monitoring, medication toxicity, pump/tube failure, developmental disability, and caregiver anxiety. The guideline notes that caregiver worry affects physical and mental health and recommends psychological and patient-organization support. Disease-specific EQ-5D/SF-36 population norms were not identified. (leon2024internationalguidelinesfor pages 13-15)

4. Genetic and molecular information

Variant classes include missense, nonsense, frameshift, splice, exon-level copy-number, deep-intronic/regulatory, imprinting, and somatic variants. Germline variants predominate in inherited diffuse disease; focal lesions combine a germline paternal allele with a pancreatic somatic 11p15 event. LINE/mosaic disease can arise from somatic ABCC8/GCK variants. Variant classification must follow ACMG/AMP criteria with ClinVar/ClinGen review and segregation/functional evidence; a gene finding should not automatically be called pathogenic. Population allele frequency should be checked variant-by-variant in gnomAD, because no single useful “CHI allele frequency” exists.

The Ukrainian cohort provides current real-world data: a molecular diagnosis was obtained in 27/40 (67.5%); yield was 19/22 (86.4%) in persistent versus 8/18 (44.4%) in early-remission disease. Causes were ABCC8 (n=20), KCNJ11 (n=2), INSR (n=2), KMT2D (n=1), and 11p15 imprinting defects (n=2); one ABCC8 VUS was not counted as causal. (globa2024congenitalhyperinsulinismin pages 1-2, globa2024congenitalhyperinsulinismin pages 3-5)

No robust, generally accepted modifier-gene set, protective variant, anticipation phenomenon, or recurrent germline mosaicism rate is established. Consanguinity increases the probability of recessive diffuse CHI; founder variants explain high rates in some endogamous populations, but carrier frequencies are population- and variant-specific.

Epigenetics: 11p15 imprinting is causal in focal HI and BWS. In Kabuki syndrome, KMT2D and KDM6A alter H3K4/H3K27 chromatin regulation and may disturb β-cell differentiation and insulin-secretory gene expression, but the review explicitly concludes that the pathway “remains to be fully clarified.” Kabuki-associated HH occurs in approximately 0.3–4%, more strongly with KDM6A-Kabuki than KMT2D-Kabuki. (leon2024internationalguidelinesfor pages 11-13, maines2023anarrativereview pages 1-2)

5. Environmental information

Genetic CHI is not attributable to diet, obesity, smoking, alcohol, radiation, pollution, or infection. Feeding composition and physical activity can modify episode occurrence after disease exists: protein/leucine can trigger GLUD1, HADH, and sometimes KATP-HI; anaerobic exercise can trigger SLC16A1-HI; fasting is a general precipitant. Perinatal hypoxia, IUGR, maternal diabetes, and delivery-related glucose exposure cause acquired PSHI. Vaccines and antimicrobial measures are not etiologic or preventive interventions for CHI. (leon2024internationalguidelinesfor pages 3-5, leon2024internationalguidelinesfor pages 5-6)

6. Mechanism and pathophysiology

Canonical causal chain: glucose enters the β cell → metabolism raises ATP/ADP → KATP channels close → membrane depolarization → voltage-gated Ca²⁺ entry → insulin-granule exocytosis. ABCC8/KCNJ11 loss of function keeps the membrane depolarized despite low glucose, causing unsuppressed insulin. Diazoxide works upstream by opening functional KATP channels; it therefore often fails when the channel is severely defective. (leon2024internationalguidelinesfor pages 25-29, leon2024internationalguidelinesfor pages 8-10)

Downstream chain: excess insulin → increased peripheral glucose uptake plus suppressed hepatic glucose production, lipolysis, and ketogenesis → low glucose, free fatty acids, and β-hydroxybutyrate → cerebral fuel failure → seizures and hypoglycemic brain injury. Relevant GO suggestions include regulation of insulin secretion (GO:0050796), insulin secretion (GO:0030073), membrane depolarization during action potential, calcium-ion transmembrane transport, glucose homeostasis (GO:0042593), fatty-acid oxidation, and ketone-body biosynthesis.

Other upstream mechanisms include altered nutrient sensing (activating GCK), deregulated amino-acid oxidation (GLUD1), fatty-acid oxidation/SCHAD–GDH coupling (HADH), inappropriate low-Km hexokinase expression (HK1), pyruvate transport into β cells (SLC16A1), transcription-factor defects, and chromatin/imprinting abnormalities. Immune activation is not a core mechanism in genetic CHI. Tissue injury is secondary: repeated neuroglycopenia injures the developing brain, while near-total pancreatectomy can cause endocrine and exocrine insufficiency.

Cell types: pancreatic β cell—CL:0000169—is primary; α/δ cells and acinar/ductal structures are relevant to histology and surgery. Neurons, astrocytes, and oligodendroglial lineages are downstream targets of fuel deprivation. Subcellular terms: plasma membrane, KATP channel complex, voltage-gated calcium-channel complex, insulin secretory granule, cytosol, mitochondrion, and nucleus/chromatin.

Current single-cell, spatial-transcriptomic, proteomic, metabolomic, lipidomic, and multi-omic signatures are not sufficiently standardized for clinical annotation. No omics assay is currently a routine diagnostic replacement for biochemical and DNA testing.

7. Anatomical structures affected

The primary organ is the pancreas—suggested UBERON pancreas (UBERON:0001264)—specifically islets of Langerhans and β cells. Focal lesions are usually unencapsulated, approximately 0.5–1 cm, with increased endocrine-cell mass; diffuse disease displays β-cell nuclear enlargement throughout the pancreas; atypical disease has regional/mosaic abnormalities. There is no lateralization. (leon2024internationalguidelinesfor pages 10-11)

The main secondary organ is the brain, particularly the developing cerebral cortex, hippocampal/visual pathways, and white matter affected by recurrent hypoglycemia. Liver, skeletal muscle, and adipose tissue are metabolic effectors of insulin. After large pancreatic resection, both endocrine pancreas and exocrine acinar tissue are affected.

8. Temporal development

Severe KATP-CHI commonly begins in the first days of life, acutely or with recurrent episodes; genetic forms can occasionally present later. PSHI presents within 24 hours and usually resolves by days 10–14. “Early-remission” CHI in the Ukrainian study was defined by remission by age two years and no hypoglycemia for 24 months. Persistent CHI can remain lifelong, although ABCC8, KCNJ11, HNF1A, and HNF4A disease may attenuate with age. Later-onset HI after age two years requires insulinoma evaluation. (globa2024congenitalhyperinsulinismin pages 1-2, leon2024internationalguidelinesfor pages 13-15, leon2024internationalguidelinesfor pages 3-5)

The critical intervention window is immediate: the neonatal brain has high glucose requirements and limited alternative fuel because insulin suppresses ketogenesis. Prompt recognition, normal-range glucose restoration, and avoidance of recurrent episodes are more important than waiting for molecular confirmation.

9. Inheritance and population

Non-syndromic genetic HI is estimated at 1 per 25,000–45,000 births; a UK minimum estimate cited by recent literature is 1 per 28,389. PSHI is much more common, approximately 1 per 1,200–1,700 newborns, while prolonged severe PSHI occurs in about 1 per 12,000–13,600. (leon2024internationalguidelinesfor pages 3-5, globa2024congenitalhyperinsulinismin pages 10-11)

No consistent sex bias is established. In the Ukrainian registry, sex distributions differed numerically but not significantly: persistent CHI 36.4% male/63.6% female and early-remission CHI 55.6% male/44.4% female. Median diagnosis was 3.5 versus 17 days, respectively. (globa2024congenitalhyperinsulinismin pages 3-5)

Autosomal recessive, autosomal dominant, X-linked dominant syndromic, imprinting/parent-of-origin, and somatic mosaic mechanisms all occur. Penetrance and expressivity are gene- and variant-dependent; dominant KATP disease can be variably expressed. Genetic anticipation is not characteristic. Founder effects and consanguinity can markedly increase incidence in particular populations, but global carrier-frequency estimates are inappropriate.

10. Diagnostics

Biochemical diagnosis

Obtain a critical sample during plasma glucose <50 mg/dL (2.8 mmol/L). Evidence of excessive insulin action includes β-hydroxybutyrate <1.8 mmol/L, free fatty acids <1.7 mmol/L, glucose infusion requirement >8 mg/kg/min in neonates, and a glucagon-associated glucose rise ≥30 mg/dL. Inappropriately detectable insulin >1.25 μU/mL and C-peptide >0.5 ng/mL support diagnosis, but suppressed ketones/FFA and glucagon response are more sensitive than insulin concentration alone. Measure glucose, insulin, C-peptide, BOHB, FFA, cortisol, growth hormone, lactate, ammonia, acylcarnitines, and urine organic acids as clinically indicated. (leon2024internationalguidelinesfor pages 25-29, leon2024internationalguidelinesfor pages 3-5)

Infants tested before 72 hours during transitional hypoglycemia should be retested after 72 hours if hypoglycemia persists. Provocative glucose/leucine/protein tests are not needed to establish HI but can subtype selected disease. (leon2024internationalguidelinesfor pages 3-5)

Genetic and imaging algorithm

Exclude likely acquired PSHI and assess syndromic features.
In diazoxide-unresponsive disease, perform rapid ABCC8/KCNJ11 sequencing with parental testing.
If negative or disease persists beyond three months, use a comprehensive HI panel or WES/WGS with copy-number and non-coding coverage.
Add 11p15 methylation testing when BWS is suspected. WES can miss deep-intronic/regulatory variants; Sanger can miss CNVs. WGS is useful when panel/exome testing is negative but is not universally first-line. CMA is appropriate for syndromic/CNV suspicion; routine karyotype, FISH, mitochondrial DNA, and repeat-expansion testing are not indicated without phenotype-specific reasons. (leon2024internationalguidelinesfor pages 5-6)
For diazoxide-unresponsive cases without genetic proof of diffuse disease, perform 18F-DOPA PET/CT or PET/MRI. Across 286 histologically assessed cases, sensitivity was 75–100%, specificity 88–100%, and localization accuracy over 90% when a lesion was detected. Conventional ultrasound/CT/MRI does not reliably detect congenital focal lesions. (leon2024internationalguidelinesfor pages 6-8)

Differentials include transitional/PSHI, cortisol or growth-hormone deficiency, fatty-acid oxidation disorders, glycogen-storage disease, congenital glycosylation disorders, exogenous insulin or sulfonylurea exposure, insulinoma—especially after age two—insulin autoimmune syndrome, and non-insulin-mediated hypoglycemia. (leon2024internationalguidelinesfor pages 3-5)

No universal population newborn screen exists. Bedside glucose surveillance is indicated in high-risk newborns. Cascade testing, prenatal diagnosis, or preimplantation genetic testing is feasible once a familial pathogenic variant is known.

11. Outcome and prognosis

Survival is generally good with effective treatment; meaningful 5- or 10-year disease-specific survival statistics are not established because morbidity, not mortality, dominates. Untreated severe episodes can cause coma, death, epilepsy, cerebral palsy, and permanent cognitive/visual/motor disability.

Outcome depends on diagnostic delay, depth/duration and recurrence of hypoglycemia, genotype, diazoxide responsiveness, focal versus diffuse histology, and treatment access. More than 65.2% of patients required regimen adjustment in the first three months after discharge. Formal developmental surveillance and early intervention are strongly recommended. (leon2024internationalguidelinesfor pages 13-15)

Focal resection is curative in over 95% in expert series and generally avoids later diabetes if only the lesion is removed. After 95–98% pancreatectomy for diffuse disease, hypoglycemia recurs in 50–60%; approximately 25% have diabetes immediately after surgery and cumulative diabetes can reach 91% by age 14. Resection over 50% also risks exocrine pancreatic insufficiency. (leon2024internationalguidelinesfor pages 11-13)

The 2024 Ukrainian cohort provides contemporary implementation data: 14/19 operated patients had focal disease, and all 14 were cured; relapse occurred in three patients with diffuse or atypical disease. (globa2024congenitalhyperinsulinismin pages 1-2, globa2024congenitalhyperinsulinismin pages 3-5)

12. Treatment

Acute and chronic algorithm

IV dextrose: 200 mg/kg—2 mL/kg of D10—then generally ≥8 mg/kg/min, escalating rapidly when necessary, to maintain plasma glucose 70–100 mg/dL. NCIt suggestions: dextrose, glucose infusion. (leon2024internationalguidelinesfor pages 6-8)
Glucagon rescue: 0.5–1 mg or 20–30 μg/kg IM/SC when IV access is delayed. Continuous IV glucagon 2.5–20 μg/kg/h reduces dextrose/fluid requirements; vomiting 13%, rash 2%, respiratory distress 19%, and rare necrolytic migratory erythema are reported. (leon2024internationalguidelinesfor pages 6-8)
Diazoxide: first-line established therapy, 5–15 mg/kg/day orally in children. Add chlorothiazide 10 mg/kg/day or hydrochlorothiazide 1–2 mg/kg/day to limit fluid retention. Confirm response by a safety fast showing BOHB >1.8 mmol/L before glucose falls below 50–60 mg/dL. Stop if maximal therapy fails after five days. Adverse effects include hypertrichosis 84.1%, facial coarsening 24%, pulmonary hypertension 2.4%, neutropenia 15.6%, thrombocytopenia 4.7%, hyperuricemia 5.0%, and serious events requiring discontinuation 9.7%. Obtain an echocardiogram about one week after initiation and periodic CBC/uric acid. NCIt: diazoxide. (leon2024internationalguidelinesfor pages 8-10)
Somatostatin analogues: second-line off-label treatment. Octreotide starts at 5–10 μg/kg/day, maximum around 20 μg/kg/day; tachyphylaxis and necrotizing enterocolitis, especially in unstable premature infants, are major concerns. Lanreotide commonly starts at 30–60 mg monthly. Monitor growth, gallbladder ultrasound, liver enzymes, thyroid function, and growth factors. NCIt: octreotide; lanreotide. (leon2024internationalguidelinesfor pages 8-10, leon2024internationalguidelinesfor pages 10-11)
Nutrition/support: frequent feeds, carbohydrate-enriched formula, and continuous gastric dextrose up to 20% via NG/gastrostomy when needed. Uncooked cornstarch 1–2 g/kg may help after nine months, but controlled evidence is lacking. Feeding, speech, occupational, physical, and neurodevelopmental therapy are integral. (leon2024internationalguidelinesfor pages 10-11)
Avoid routine nifedipine, sirolimus, and glucocorticoids. The international panel found inadequate efficacy for nifedipine and serious infection, diabetes, hepatitis, and pancreatic-insufficiency concerns for sirolimus; use only in approved research protocols, apart from rare genotype-specific considerations such as CACNA1D. (leon2024internationalguidelinesfor pages 10-11)

Surgery

Resect localized focal disease in an expert center with intraoperative pathology. For medically uncontrollable diffuse disease, 90–98% pancreatectomy balances hypoglycemia control against diabetes risk. Monitor postoperative glucose, HbA1c every 6–12 months, fecal elastase, fat-soluble vitamins, and need for insulin or pancreatic enzymes. (leon2024internationalguidelinesfor pages 11-13, leon2024internationalguidelinesfor pages 10-11)

Real-world implementation and experimental therapy

A 2024 four-patient KATP-CHI series used IV glucagon, pump-delivered octreotide, later monthly long-acting somatostatin analogues, CGM, specialized feeds, and developmental follow-up. All octreotide-treated patients developed biliary debris, resolving with ursodeoxycholic acid; catheter obstruction and bloodstream infection complicated IV glucagon. This is useful implementation evidence but too small for response-rate inference. (takasawa2024clinicalmanagementof pages 10-13)

RZ358/ersodetug, an allosteric insulin-receptor antibody, completed a 23-participant phase 2 study, NCT04538989; results were first posted 28 May 2025. A 56-participant phase 3 trial, NCT06208215, is active/not recruiting and uses CGM hypoglycemia endpoints. It remains investigational. (NCT04538989 chunk 1, NCT06208215 chunk 2)
Dasiglucagon, a soluble glucagon analogue delivered by continuous SC infusion, completed a 32-participant phase 3 trial, NCT03777176; a 42-participant long-term extension, NCT03941236, is active/not recruiting through an estimated 2026 completion. It remains investigational for CHI. (NCT03941236 chunk 1, NCT03777176 chunk 1, NCT03777176 chunk 2)
Efpegerglucagon/HM15136, weekly SC therapy, is in a 16-participant phase 2 study, NCT04732416, active/not recruiting with estimated completion in 2027. (NCT04732416 chunk 1)
Continuous SC glucagon was tested in five infants in NCT02937558; the very small trial precludes broad conclusions. (NCT02937558 chunk 1)

No approved gene, RNA, or cell therapy is available. Genotype-guided focal-lesion surgery is currently the strongest precision-medicine implementation.

13. Prevention

Primary prevention of a de novo or inherited CHI phenotype is generally unavailable. Genetic counseling enables reproductive risk assessment, carrier/cascade testing, prenatal diagnosis, and PGT-M when a familial variant is known. Optimization of maternal diabetes and prevention of perinatal hypoxia/IUGR may reduce acquired PSHI risk but does not prevent genetic CHI.

Secondary prevention is rapid identification of at-risk neonates, critical-sample testing, early genetic diagnosis, and immediate maintenance of glucose above 70 mg/dL. Tertiary prevention includes home glucose monitoring, individualized fasting plans, rescue glucagon, CGM as an adjunct rather than sole diagnostic device, developmental and feeding surveillance, and diabetes/exocrine screening after surgery. No immunization or infectious prophylaxis is specific to CHI. (leon2024internationalguidelinesfor pages 11-13, leon2024internationalguidelinesfor pages 13-15, leon2024internationalguidelinesfor pages 6-8)

14. Other species and natural disease

The core β-cell KATP, glucokinase, glutamate-dehydrogenase, and insulin-signaling pathways are evolutionarily conserved. Naturally occurring hyperinsulinemic hypoglycemia/insulinoma is recognized in companion animals, especially dogs and ferrets, but it is usually tumor-associated rather than a validated orthologous congenital syndrome. No zoonotic transmission exists. Species-specific OMIA/VBO claims and breed associations were not sufficiently supported by the retrieved evidence and should not be populated without dedicated veterinary-database verification.

15. Model organisms

Available models include Abcc8/Kcnj11 knockout or channel-defective mice, activating-Gck mice, Glud1 hyperactivity models, isolated rodent/human islets, β-cell lines, and patient-derived pancreatic tissue. Genetic glucokinase activation causes hypoglycemia in mice, supporting GCK dosage/activity as causal, but mouse insulin-secretory thresholds and compensatory physiology do not fully reproduce neonatal human disease. (shoji2024casereportduplication pages 8-8)

Model applications include KATP electrophysiology, stimulus–secretion coupling, diazoxide response, amino-acid sensitivity, focal-lesion genetics, and candidate-drug testing. Important limitations are inability of simple germline models to recreate the human pancreatic somatic 11p15 focal lesion, species differences in islet architecture, and limited modeling of human neonatal brain injury. In-vitro calcium-channel and mTOR observations supplied rationale for nifedipine and sirolimus, but lack of reliable clinical effectiveness illustrates the translational limitation. (leon2024internationalguidelinesfor pages 10-11)

Robust CHI-specific single-cell atlases, spatial transcriptomics, mature patient-iPSC β-cell models, and CRISPR screens remain research opportunities rather than validated knowledge-base facts.

Overall assessment

Current expert consensus treats CHI as a time-critical, genotype-informed disorder of pancreatic β-cell insulin secretion. The strongest recent advance is not a newly approved drug but integration of rapid genetics, 18F-DOPA PET, expert pathology, and lesion-directed surgery. The 2024 Ukrainian national study demonstrates that international access to this pathway can produce molecular diagnoses in 67.5% overall and cure all identified focal cases. However, diffuse disease, feeding burden, medication toxicity, unequal access, and neurodevelopmental injury remain major unmet needs. (globa2024congenitalhyperinsulinismin pages 1-2, globa2024congenitalhyperinsulinismin pages 3-5, leon2024internationalguidelinesfor pages 13-15)

Selected exact source statements

2024 Ukrainian registry: “Pathogenic variants were identified in 19/22 (86.3%) individuals with persistent CHI … and 8/18 (44.4%) with early remission CHI.” (globa2024congenitalhyperinsulinismin pages 1-2)
Same study: “After surgery, complete recovery was observed in all 14 with focal disease.” (globa2024congenitalhyperinsulinismin pages 1-2)
2023 international guideline: “We Recommend Diazoxide as the First-Line Treatment for Patients with an Established Diagnosis of Hyperinsulinism.” (leon2024internationalguidelinesfor pages 8-10)
2023 Kabuki review: “The impact of pathogenic variants in KDM6A and KMT2D genes on β-cell insulin release remains to be fully clarified.” (maines2023anarrativereview pages 1-2)

References

(globa2024congenitalhyperinsulinismin pages 1-2): Evgenia Globa, Henrik Thybo Christesen, Michael Bau Mortensen, Jayne A. L. Houghton, Anne Lerberg Nielsen, Sönke Detlefsen, and Sarah E. Flanagan. Congenital hyperinsulinism in the ukraine: a 10-year national study. Frontiers in Endocrinology, Dec 2024. URL: https://doi.org/10.3389/fendo.2024.1497579, doi:10.3389/fendo.2024.1497579. This article has 6 citations.
(leon2024internationalguidelinesfor pages 3-5): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 5-6): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(maines2023anarrativereview pages 1-2): Evelina Maines, Arianna Maiorana, Letizia Leonardi, Giovanni Piccoli, Massimo Soffiati, and Roberto Franceschi. A narrative review on pathogenetic mechanisms of hyperinsulinemic hypoglycemia in kabuki syndrome. Endocrine Regulations, 57:128-137, Jan 2023. URL: https://doi.org/10.2478/enr-2023-0016, doi:10.2478/enr-2023-0016. This article has 3 citations.
(globa2024congenitalhyperinsulinismin pages 3-5): Evgenia Globa, Henrik Thybo Christesen, Michael Bau Mortensen, Jayne A. L. Houghton, Anne Lerberg Nielsen, Sönke Detlefsen, and Sarah E. Flanagan. Congenital hyperinsulinism in the ukraine: a 10-year national study. Frontiers in Endocrinology, Dec 2024. URL: https://doi.org/10.3389/fendo.2024.1497579, doi:10.3389/fendo.2024.1497579. This article has 6 citations.
(leon2024internationalguidelinesfor pages 11-13): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 6-8): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 13-15): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(mittal2024molecularmechanismsunderlying pages 7-9): Medha Mittal, Amit Kumar Gupta, and Seema Kapoor. Molecular mechanisms underlying congenital hyperinsulinemia of infancy and its relevance to management – a review. Journal of Pediatric Endocrinology and Diabetes, 4:9-20, Aug 2024. URL: https://doi.org/10.25259/jped_25_2024, doi:10.25259/jped_25_2024. This article has 1 citations.
(shoji2024casereportduplication pages 8-8): Takashi Shoji, Ichiro Yamauchi, Hidenori Kawasaki, Kogoro Iwanaga, Takuro Hakata, Daisuke Tanaka, Junji Fujikura, Toshihiko Masui, Hisato Suzuki, Mamiko Yamada, Kenjiro Kosaki, Yosuke Kasai, Etsuro Hatano, Akira Inaba, Takahito Wada, Shinji Kosugi, Yohei Ueda, Toshihito Fujii, Daisuke Taura, and Nobuya Inagaki. Case report: duplication of the gck gene is a novel cause of nesidioblastosis: evidence from a case with silver-russell syndrome-like phenotype related to chromosome 7. Frontiers in Endocrinology, Dec 2024. URL: https://doi.org/10.3389/fendo.2024.1431547, doi:10.3389/fendo.2024.1431547. This article has 0 citations.
(leon2024internationalguidelinesfor pages 8-10): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 19-20): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 17-19): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 29-29): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 25-29): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(leon2024internationalguidelinesfor pages 10-11): Diva D. De Leon, Jean Baptiste Arnoux, Indraneel Banerjee, Ignacio Bergada, Tricia Bhatti, Louise S. Conwell, Junfen Fu, Sarah E. Flanagan, David Gillis, Thomas Meissner, Klaus Mohnike, Tai L.S. Pasquini, Pratik Shah, Charles A. Stanley, Adrian Vella, Tohru Yorifuji, and Paul S. Thornton. International guidelines for the diagnosis and management of hyperinsulinism. Jul 2023. URL: https://doi.org/10.1159/000531766, doi:10.1159/000531766. This article has 102 citations and is from a peer-reviewed journal.
(globa2024congenitalhyperinsulinismin pages 10-11): Evgenia Globa, Henrik Thybo Christesen, Michael Bau Mortensen, Jayne A. L. Houghton, Anne Lerberg Nielsen, Sönke Detlefsen, and Sarah E. Flanagan. Congenital hyperinsulinism in the ukraine: a 10-year national study. Frontiers in Endocrinology, Dec 2024. URL: https://doi.org/10.3389/fendo.2024.1497579, doi:10.3389/fendo.2024.1497579. This article has 6 citations.
(takasawa2024clinicalmanagementof pages 10-13): Kei Takasawa, Ryosei Iemura, Ryuta Orimoto, Haruki Yamano, Shizuka Kirino, Eriko Adachi, Yoko Saito, Kurara Yamamoto, Nozomi Matsuda, Shigeru Takishima, Kumi Shuno, Hanako Tajima, Manabu Sugie, Yuki Mizuno, Akito Sutani, Kentaro Okamoto, Michiya Masue, Tomohiro Morio, and Kenichi Kashimada. Clinical management of diazoxide-unresponsive congenital hyperinsulinism: a single-center experience. Clinical Pediatric Endocrinology, 33:187-194, Jun 2024. URL: https://doi.org/10.1297/cpe.2024-0004, doi:10.1297/cpe.2024-0004. This article has 4 citations and is from a peer-reviewed journal.
(NCT04538989 chunk 1): An Open-Label Multiple Dose Study of RZ358 in Patients With Congenital Hyperinsulinism. Rezolute. 2020. ClinicalTrials.gov Identifier: NCT04538989
(NCT06208215 chunk 2): RZ358 Treatment for Congenital Hyperinsulinism. Rezolute. 2024. ClinicalTrials.gov Identifier: NCT06208215
(NCT03941236 chunk 1): Extension Trial Evaluating the Long-term Safety and Efficacy of Dasiglucagon in Children With Congenital Hyperinsulinism. Zealand Pharma. 2019. ClinicalTrials.gov Identifier: NCT03941236
(NCT03777176 chunk 1): A Two-Period Open-label Trial Evaluating Efficacy and Safety of Dasiglucagon in Children With Congenital Hyperinsulinism. Zealand Pharma. 2019. ClinicalTrials.gov Identifier: NCT03777176
(NCT03777176 chunk 2): A Two-Period Open-label Trial Evaluating Efficacy and Safety of Dasiglucagon in Children With Congenital Hyperinsulinism. Zealand Pharma. 2019. ClinicalTrials.gov Identifier: NCT03777176
(NCT04732416 chunk 1): HM15136 (Efpegerglucagon) Treatment for 8 Weeks in Subjects Aged ≥2 Years With Congenital Hyperinsulinism (CHI). Hanmi Pharmaceutical Company Limited. 2022. ClinicalTrials.gov Identifier: NCT04732416
(NCT02937558 chunk 1): CSI-Glucagon for Prevention of Hypoglycemia in Children With Congenital Hyperinsulinism. Xeris Pharmaceuticals. 2016. ClinicalTrials.gov Identifier: NCT02937558

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Hyperinsulinemic Hypoglycemia: Disease-Characteristics Research Report

1. Disease information

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3. Phenotypes

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