antiGBM

Anti-GBM disease, or anti-glomerular basement membrane disease, is a rare autoimmune disorder characterized by circulating antibodies that target the glomerular basement membrane. Most antibodies bind to the NC1 domain of the alpha-3 chain of type IV collagen, leading to injury of the kidneys and, in many patients, the lungs. The disease causes rapid inflammation and crescentic glomerulonephritis and, when the lungs are involved, pulmonary hemorrhage.

Clinical features: It typically presents as rapidly progressive glomerulonephritis with hematuria, proteinuria, and rising creatinine, often within days to weeks. Pulmonary involvement causes dyspnea and hemoptysis. Some patients have kidney injury without lung symptoms; others have both organs affected.

Diagnosis: Detection of circulating anti-GBM antibodies supports diagnosis. Renal biopsy classically shows crescentic glomerulonephritis with linear IgG staining along the glomerular basement membrane on immunofluorescence. ANCA is positive in a minority of cases.

Management: It is a medical emergency. Treatment combines plasmapheresis to remove circulating antibodies with immunosuppression, typically high-dose corticosteroids and cyclophosphamide to halt antibody production. Plasmapheresis is continued until anti-GBM antibodies disappear or pulmonary/renal disease stabilizes. Relapses are uncommon.

Prognosis and epidemiology: Renal outcome is highly dependent on function at presentation; dialysis-dependent patients have poorer prognosis. Overall survival has improved with early plasmapheresis and immunosuppression. Anti-GBM disease is rare, with incidence around 0.5–1 per million per year, occurring mainly in young to middle-aged adults with a slight male predominance in some series.