Rapidly progressive glomerulonephritis
Rapidly progressive glomerulonephritis is a clinical syndrome defined by at least a 50% decline in glomerular filtration rate over days to weeks with extensive glomerular crescents on biopsy, most often from ANCA-associated, anti-glomerular basement membrane, or immune-complex glomerulonephritis. Untreated disease progresses to dialysis within days to weeks, so kidney biopsy and etiology-directed immunosuppression must begin urgently.
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What this article covers
- Overview
A clinical syndrome, not a single disease: rapidly progressive glomerulonephritis (RPGN, also called crescentic glomerulonephritis) is defined by at least a 50% decline in glomerular filtration rate…
- Epidemiology
ANCA-associated (pauci-immune) glomerulonephritis is the most common cause of RPGN, accounting for more than half of cases, with particularly high prevalence in patients over 65 years presenting with AKI and active urinary sediment.
- Risk factors
Age over 65 years: the population with the highest prevalence of ANCA-associated glomerulonephritis.
- Pathophysiology
Glomerular capillary wall rupture drives crescent formation: regardless of the immune trigger, capillary wall disruption allows fibrin and fibronectin into Bowman's space, activating parietal…
- Clinical features
Oliguria with a rapidly rising serum creatinine is the hallmark, developing over days to weeks and able to progress to dialysis dependence.
- Differential diagnosis
Acute tubular necrosis: bland urine sediment or muddy brown granular casts, without dysmorphic erythrocytes or erythrocyte casts, distinguishes ATN from the active nephritic sediment of RPGN.
- Diagnosis
The diagnosis is established by the RPGN definition itself and confirmed by kidney biopsy: at least a 50% decline in GFR over days to weeks, with light microscopy showing extensive glomerular…
- Management
First, treat as a nephrologic emergency: admit for urgent nephrology consultation, expedite kidney biopsy, and begin empiric high-dose glucocorticoids while awaiting biopsy results if clinical…
- Complications
Progression to dialysis-dependent end-stage kidney disease (ESKD): untreated RPGN progresses to dialysis within days to weeks; even with treatment, ANCA-associated disease results in ESKD in up to 25% of survivors within 4 years.
- Prognosis
Presenting creatinine predicts outcome in anti-GBM disease: patients presenting with serum creatinine <5.6 mg/dL have <5% overall mortality and <20% risk of ESKD at 10 years, while those presenting…
- Prevention
No primary prevention exists for the autoimmune trigger of ANCA-associated or anti-GBM disease; the actionable prevention target is minimizing kidney damage through early recognition and treatment once RPGN is suspected.
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- Anti-glomerular basement membrane (anti-GBM) disease
Anti-glomerular basement membrane (anti-GBM) disease is a rare, rapidly progressive glomerulonephritis caused by circulating antibodies against the alpha-3 chain of type IV collagen, presenting with hematuria, acute kidney injury, and, in over half of patients, pulmonary hemorrhage (Goodpasture syndrome). Kidney biopsy showing crescentic glomerulonephritis with linear IgG staining plus a positive serum anti-GBM antibody confirms the diagnosis, and outcome depends critically on early treatment with plasma exchange, pulse glucocorticoids, and cyclophosphamide before dialysis dependence and diffuse crescents set in.
- IgA nephropathy
IgA nephropathy is the most common primary glomerular disease worldwide, caused by galactose-deficient IgA1 immune complexes depositing in the mesangium, presenting classically with synpharyngitic gross hematuria in young adults and confirmed by kidney biopsy showing dominant mesangial IgA deposits. First-line therapy is renin-angiotensin system blockade, since roughly 40% of patients progress to end-stage kidney disease within 15 years despite treatment.
- Poststreptococcal glomerulonephritis
Poststreptococcal glomerulonephritis (PSGN) is an immune-complex nephritic syndrome that follows group A streptococcal pharyngitis or skin infection by 1 to 4 weeks, presenting with cola-colored urine, edema, and hypertension in school-aged children. Diagnosis is typically clinical, supported by low complement (C3) and elevated antistreptolysin O/anti-DNase B titers, and treatment is supportive; children recover completely far more often than adults.
- Membranoproliferative glomerulonephritis
Membranoproliferative glomerulonephritis is a rare chronic glomerulonephritis divided into immune-complex forms, most often driven by hepatitis C virus infection, and complement-mediated C3 glomerulopathies from alternative-pathway dysregulation, diagnosed by kidney biopsy with immunofluorescence. Treatment targets the underlying cause plus immunosuppression for nephrotic-range proteinuria or kidney dysfunction, and more than half of patients progress to end-stage kidney disease within 15 years.
- Acute kidney injury
Acute kidney injury is a sudden rise in serum creatinine or fall in urine output from prerenal, intrinsic, or postrenal causes, defined and staged by KDIGO criteria. Management targets the underlying cause, corrects volume and electrolyte derangements, and escalates to renal replacement therapy for refractory hyperkalemia, acidosis, volume overload, or uremia.
- Approach to hematuria
Hematuria is present in urine when at least 3 erythrocytes per high-power field are seen on microscopy, and the first branch point is glomerular versus nonglomerular bleeding, based on erythrocyte morphology and casts. Gross hematuria always requires urologic evaluation and cystoscopy, asymptomatic microscopic hematuria is risk-stratified by American Urological Association criteria to select repeat testing, imaging, or cystoscopy, and glomerular hematuria is treated with disease-specific immunosuppression after biopsy.