Glomerular Basement Membrane IgG Antibody

Glomerular basement membrane (GBM) antibody IgG is an autoantibody that targets the α3 non‑collagenous domain of type IV collagen in the kidney’s glomerular basement membrane. It is directly pathogenic, causing anti‑GBM disease (Goodpasture’s) with rapidly progressive crescentic glomerulonephritis and sometimes pulmonary hemorrhage. Blood testing confirms diagnosis and informs treatment such as plasmapheresis and immunosuppression.

Goodpasture syndrome classically presents with a triad of pulmonary hemorrhage (often hemoptysis), rapidly progressive glomerulonephritis with hematuria and acute renal failure, and circulating anti–glomerular basement membrane (anti‑GBM) antibodies with linear IgG deposition along the basement membrane on renal biopsy. Prompt recognition and treatment are critical due to risk of respiratory failure and rapid renal loss.

An abnormal glomerular basement membrane is a structural change in the kidney's filtration barrier—thickening, thinning, irregularity or splitting—caused by disease or immune deposits. These changes disrupt filtration, causing proteinuria, hematuria and reduced kidney function. Common causes include diabetic kidney disease, autoimmune or genetic disorders, and can lead to progressive renal damage without treatment.

Anti–glomerular basement membrane (anti-GBM) disease, also called Goodpasture syndrome, is defined by linear deposition of IgG along the glomerular basement membrane. It causes rapidly progressive (crescentic) glomerulonephritis and often affects lungs, producing hemoptysis. Diagnosis is by anti‑GBM antibodies and linear IgG on immunofluorescence. Histology shows crescent formation in affected glomeruli.

A positive IgG means your immune system has produced antibodies from past infection or vaccination, suggesting some level of prior exposure and likely partial protection. It doesn’t guarantee complete or long-lasting immunity, and reinfection is possible. Test results should be interpreted with clinical history and timing; if you have symptoms or need confirmation, seek medical advice and consider diagnostic PCR or follow-up antibody testing.

Treatment of glomerular basement membrane (anti‑GBM) disease involves urgent immunosuppression and antibody removal. Prompt plasmapheresis clears circulating antibodies while high‑dose corticosteroids and cyclophosphamide suppress further antibody production. Supportive care includes dialysis for renal failure and respiratory support for pulmonary hemorrhage. Early nephrology/pulmonology input is essential; rituximab may be considered in refractory cases.