Overview
Definition
A severe nephritic syndrome characterized by rapid, progressive decline in renal function over weeks to months, histologically characterized by crescent formation in most glomeruli.
Epidemiology
Rare but life-threatening emergency. Classified into three main immunopathologic types.
Etiology & Risk Factors
- Type 1: Anti-GBM disease (Goodpasture Syndrome)
- Type 2: Immune-complex mediated (Lupus, IgA, PSGN)
- Type 3: Pauci-immune (ANCA-associated vasculitis: GPA, MPA, EGPA)
Clinical Symptoms
- Rapid-onset oliguria or anuria
- Gross hematuria
- Uremic symptoms (nausea, confusion, pericarditis)
- Hemoptysis (in Goodpasture syndrome or ANCA-associated vasculitis)
Clinical Approach
Diagnosis
- Serology: Anti-GBM antibodies, ANCA, ANA, complements
- Renal biopsy showing cellular crescents in Bowman's space on LM, and linear IgG (Type 1), granular (Type 2), or negative (Type 3) immunofluorescence
Management
- Pulse intravenous corticosteroids (Methylprednisolone)
- Cyclophosphamide
- Plasmapheresis (critical in Anti-GBM disease to remove circulating antibodies)
Complications
- End-stage renal disease (often requiring immediate dialysis)
- Pulmonary hemorrhage (fatal if untreated)
- Severe uremia