This is a mechanism module, not a specific disease. Disorder entries reference individual nodes via conforms_to (e.g., "nephrolithiasis_crystal_nucleation#Crystal Retention and Epithelial Adhesion"). The module defines the expected pathophysiology structure; conforming nodes in disorder files should include the corresponding cell types, biological processes, and causal edges, specialized to their disease context. Key disease-specific substitutions: cystinuria substitutes defective cystine reabsorption (SLC3A1/SLC7A9) at the supersaturation trigger; primary hyperoxaluria substitutes hepatic glyoxylate-metabolism enzyme deficiency driving hyperoxaluria; uric acid stone disease substitutes persistently acidic urine as the dominant abnormality. Mineral and solute chemistry is described in prose only; modules bind GO and CL terms only and do not use chemical (CHEBI) or disease (MONDO) term bindings.
Urinary Supersaturation
trigger
An abnormal combination of metabolic factors raises the relative supersaturation of urine with respect to a stone-forming mineral above its formation product. The dominant drivers are increased renal excretion of lithogenic solutes (calcium, oxalate, urate, cystine), low urine volume, and pH derangements (alkaline urine favouring calcium phosphate, acidic urine favouring uric acid). Supersaturation is the thermodynamic driving force for crystallization and is the necessary upstream state for stone formation; the specific solute and handling defect differ by disorder but the supersaturated state is shared.
Downstream
-
Crystal Nucleation and Growth
Crystal Nucleation and Growth
amplifier
Once supersaturation exceeds the formation product, solute molecules cluster and nucleate into crystals, predominantly by heterogeneous nucleation on pre-existing particulates, organic matrix or another mineral. Nucleation is followed by crystal growth and aggregation within the tubular lumen (free-particle mechanism) or on the calcium phosphate Randall's plaque exposed at the papillary surface (fixed-particle mechanism). This is the amplifying step that converts a metabolic supersaturated state into a solid crystalline mass capable of being retained. No well-defined GO biomineralization term currently exists, so this node relies on evidence rather than a biological-process binding.
Downstream
-
Crystal Retention and Epithelial Adhesion
Crystal Retention and Epithelial Adhesion
central effector
For a stone to form, crystals must be retained in the kidney rather than flushed out in the urine, which is the rate-limiting and pivotal step distinguishing common harmless crystalluria from rare stone disease. Retention is achieved when aggregated crystals become too large to pass the tubular lumen or, critically, adhere to the apical surface of renal tubular epithelial cells via crystal-binding membrane proteins. Crystal-epithelial adhesion anchors the crystal nidus and seeds further growth into a stone.
Downstream
-
Crystal-Induced Tubular Injury and Inflammation
Crystal-Induced Tubular Injury and Inflammation
effector
Retained and growing crystals injure the renal tubular epithelium and are sensed as danger signals (DAMPs) that activate the NLRP3/caspase-1 inflammasome in resident and recruited mononuclear phagocytes, driving release of interleukin-1 beta and an interstitial inflammatory response. Epithelial injury exposes basement membrane and produces dysfunctional crystallization modulators, which in turn promote further crystal nucleation and adhesion, establishing a feed-forward loop that enlarges the stone and can progress to chronic kidney injury.
Downstream
-
Symptomatic Kidney Stones
Symptomatic Kidney Stones
consequence
Continued growth and aggregation of retained, matrix-coated crystals on plugs or plaques produces a clinically significant calculus. The stone can obstruct the urinary tract and classically presents with reno-ureteral (renal) colic, often with haematuria, and has a high recurrence rate. This is the clinical phenotype of nephrolithiasis, the consequence of the conserved supersaturation-nucleation-retention-injury chain.