Glomerulosclerosis is the pathological process characterized by the obliteration of glomerular capillary lumens due to excessive accumulation of extracellular matrix (collagen, fibronectin, laminin) and hyalinosis, resulting in irreversible scarring and loss of filtration capacity. It is distinguished from glomerulonephritis by the predominance of matrix expansion and sclerosis over active inflammatory cellular proliferation, though the two often coexist in chronic kidney disease. The underlying mechanism involves podocyte injury and loss, dysregulated cytokine signaling (notably TGF-β, angiotensin II), and mechanical stress from hyperfiltration, triggering mesangial matrix expansion and capillary collapse. It manifests as both a physiological aging phenomenon (global, age-related glomerulosclerosis) and a pathological driver of disease (focal segmental, nodular/diabetic, or collapsing variants). The most clinically relevant subtypes encountered in coding include Focal Segmental Glomerulosclerosis (FSGS) (N04.20/N04.30)**, Diabetic Glomerulosclerosis (Kimmelstiel-Wilson nodules) (E11.21/E10.21), and Hypertensive Nephrosclerosis (I12.-/N03.-). It is commonly confused with glomerulonephritis (which implies active immune-mediated inflammation) and acute tubular necrosis (which affects tubules primarily), whereas glomerulosclerosis specifically denotes chronic, irreversible glomerular scarring.
The word entered English in the 1910s as glomerulosclerosis (noun), borrowed from German Glomerulosklerose, combining Latin glomerulus and Greek sklērosis — literally “condition of hardening of the little balls (glomeruli).” The root scler- (“hard”) connects glomerulosclerosis to the entire scler- family: atherosclerosis (athero- “gruel/porridge” + sclerosis → “hardening of plaque”), scleroderma (sclero- + derma “skin” → “hard skin”), and amyotrophic lateral sclerosis (a- “no” + myo- “muscle” + trophic “nourishment” + -sclerosis → “hardening from loss of muscle nourishment”). The combining form glomerulo- is highly productive in nephrology terminology, appearing in glomerulonephritis, glomerulopathy, glomerular, and glomerulitis.
Collapsing glomerulopathy (COLLAPSING FSGS)(aggressive etiologic subtype; glomerular capillary collapse with podocyte hyperplasia; often N04.20 or N04.3 with specific morphology)
TIP lesion glomerulosclerosis(anatomic/segmental subtype; sclerosis at tubular pole; favorable prognosis variant of FSGS)
Perihiar glomerulosclerosis(anatomic/segmental subtype; sclerosis at vascular pole; associated with adaptive hyperfiltration/reduced nephron mass)
🔗 RELATED TERMS
Glomerula HYPERFILTRATION — the hemodynamic opposite/mechanism preceding sclerosis; increased single-nephron GFR causing mechanical stretch and podocyte stress leading to sclerosis.
Glomerulonephritis — shares the glomerulo- root; immune-mediated inflammatory injury of glomeruli (proliferation, exudation) that frequently progresses to glomerulosclerosis as the chronic burned-out phase.
Chronic kidney disease (CKD) — the clinical syndrome resulting from significant glomerulosclerosis (>50% global sclerosis correlates with CKD G3-G5); staged by GFR N18.30-N18.6.
Nephrotic syndrome — complex clinical presentation overlapping heavily with FSGS and diabetic glomerulosclerosis; defined by proteinuria >3.5g/day, hypoalbuminemia, edema; coded N04.9 or specific etiology codes.
Podocyte injury/loss — the fundamental cellular mechanism; visceral epithelial cell detachment or apoptosis exposes glomerular basement membrane to parietal cells, initiating synechiae and sclerosis.
Trophic (trophic factors) — adjective describing growth factor signals (VEGF, angiopoietins) that maintain glomerular endothelial and podocyte health; loss of trophic support drives sclerosis.
Epithelial-to-mesenchymal transition (EMT) — cellular process where tubular or parietal epithelial cells transform into matrix-producing myofibroblasts, contributing to glomerular and interstitial fibrosis.
Focal segemental glomerulosclerosis (FSGS) — primary disease entity defined by this lesion; genetic forms (NPHS2, ACTN4, TRPC6) N04.20, secondary/adaptive forms N04.3.
diabetic nephropathy (KIMMELSTIEL-WILSON DISEASE) — disease entity defined by nodular glomerulosclerosis; E11.21 (Type 2), E10.21 (Type 1).
Hypertensive Nephrosclerosis — disease entity defined by vascular and glomerular sclerosis from hypertension; benign I12.9, N03.9; malignant I12.0, N03.1.
Alport syndrome — genetic basement membrane disorder (COL4A3/4/5) leading to progressive glomerulosclerosis and sensorineural hearing loss; Q87.81.
Surgical pathology, gross and microscopic examination; kidney biopsy (needle/core) — primary diagnostic code for glomerulosclerosis typing
88341
Immunohistochemistry or immunocytochemistry, per specimen; each single antibody stain (e.g., IgG, C3, PLA2R, collagen IV)
88346
Immunofluorescence, per specimen; each single antibody stain (direct immunofluorescence on frozen tissue)
88348
Electron microscopy, diagnostic (essential for FSGS variant classification, GBM thickness in diabetic nephropathy/Alport)
88307
Surgical pathology, gross and microscopic examination; kidney transplant biopsy (surveillance or dysfunction)
82043
Microalbumin, quantitative (urine) — screening/monitoring for early diabetic glomerulosclerosis
82570
Creatinine; urine (for protein/creatinine ratio 84156)
84156
Protein, total, except by refractometry; urine (protein/creatinine ratio calculation)
90945
Dialysis procedure other than hemodialysis (e.g., peritoneal dialysis) — single evaluation by physician (ESRD N18.6)
90935
Hemodialysis procedure with single evaluation by physician (ESRD N18.6)
90960
End-stage renal disease (ESRD) related services monthly, for patients 20 years of age and older (4+ visits)
90961
ESRD related services monthly, for patients 20 years of age and older (2-3 visits)
⚠️ Coding Note:glomerulosclerosis is a morphologic finding, not a standalone diagnosis code; code the underlying etiology (Diabetes E11.21, Hypertension I12.9, Primary FSGS N04.20) as the principal diagnosis. For inpatient profee, if a renal biopsy is performed, sequence the definitive pathologic diagnosis (e.g., N04.20) first, followed by CKD stage (N18.32). Undercoding Alert: “Chronic kidney disease” (N18.9) documented without a stage or etiology triggers a query; documentation of “nephrosclerosis,” “arteriolarnephrosclerosis,” or “glomerulosclerosis” on biopsy should prompt coding to the specific hypertensive (I12.9) or glomerular disease category (N04.-, E11.21). Sequencing Rule: For diabetic patients with CKD, the diabetes code (E11.22) is sequenced first per ICD-10-CM convention, not the CKD stage code. Specificity Requirement: FSGS codes (N04.20-N04.9) require 6th character specificity (nephrotic vs nephritic vs unspecified) for accurate DRG assignment and transplant listing criteria. Payers often require biopsy-proven diagnosis (CPT 88305 + 88348) for authorization of immunosuppression (e.g., rituximab, calcineurin inhibitors) in primary FSGS.
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