Rapidly Progressive Glomerulonephritis

RPGN is a kidney-injury pattern that demands two questions at once: Is filtration failing quickly, and is the glomerular injury immune-mediated? A rising creatinine alone cannot answer the second. Hematuria with dysmorphic red blood cells or red blood cell casts and proteinuria points toward an active glomerular sediment; oliguria, edema, hypertension, or new pulmonary findings determine immediate danger. The etiologic categories matter because the treatment clock differs. Anti-GBM disease can injure both glomerular and alveolar basement membranes. ANCA-associated vasculitis can damage the kidneys and lungs with little or no immune deposition. Immune-complex disease requires a different search for lupus, infection, or another systemic cause. Obtain serologies and arrange kidney biopsy when feasible, but do not let a pending biopsy delay specialist-directed treatment in a rapidly deteriorating patient whose presentation strongly supports ANCA-associated vasculitis or anti-GBM disease.