# Anti-GBM Disease > Anti-GBM disease for NEET-SS Nephrology: alpha-3 collagen antigen, linear IgG, plasmapheresis protocol, dual ANCA positivity and Alport transplant notes. - Canonical URL: https://prepelephant.com/topics/neet-ss/nephrology/anti-gbm-disease - Exam / course: NEET-SS · Subject: Nephrology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Anti-GBM Disease", PrepElephant, https://prepelephant.com/topics/neet-ss/nephrology/anti-gbm-disease ## Direct answer Goodpasture's antigen sits on the alpha-3 chain of type IV collagen in the glomerular and alveolar basement membranes, and antibodies against it produce the most explosive of the pulmonary–renal syndromes: a young male smoker with haemoptysis and a creatinine doubling by the week, or an older woman with renal-limited crescentic disease. Immunofluorescence is the diagnostic theatre — smooth linear IgG along every glomerular capillary wall, with no complement-heavy granularity. Treatment is the oldest protocol still standing in nephrology: daily plasmapheresis to strip the antibody, cyclophosphamide to stop its production, and high-dose steroids to hold the injury until both take effect, ideally begun before the creatinine reaches dialysis range. ## What you must remember - **Antigen:** alpha-3 chain NC1 domain of type IV collagen — the exam's one-word answer. - **Bimodal age curve:** young men, 20s to 30s, smokers, with pulmonary haemorrhage; older women, 60s, with kidney-only disease; smoking and pulmonary infection drive the lung bleed. - **Linear IgG:** smooth ribbon along the glomerular basement membrane on direct immunofluorescence, with C3 characteristically normal — the single most-tested image in this territory. - **Dual positivity:** a substantial minority — up to a third in some series — also carries ANCA (usually MPO); these double-positive patients relapse like vasculitis and need maintenance immunosuppression after the anti-GBM protocol ends. - **Protocol:** daily or alternate-day plasma exchange with albumin (fresh frozen plasma if bleeding), oral cyclophosphamide and pulsed then oral steroids, continued about two weeks beyond the disappearance of circulating antibody. - **Futility threshold:** dialysis-dependence at presentation with 100 per cent crescents and no pulmonary haemorrhage predicts non-recovery, and immunosuppression may reasonably be withheld — a decision the exam expects you to know exists. - **Transplant rule:** wait until anti-GBM antibody is undetectable for six to twelve months; recurrence in the graft is then rare. - **Alport variant:** de novo anti-GBM disease after transplantation in Alport syndrome affects roughly 3–5 per cent of transplanted males with truncating COL4A5 mutations — appears later, lacks pulmonary involvement, and usually loses the graft. ## Haemoptysis with a creatinine of five A 26-year-old man, twenty cigarettes a day since college, arrives coughing frank blood with a creatinine of 5.1 mg/dL that was 1.2 two weeks ago. Step one: stabilise and think in parallel — the pulmonary–renal differential is anti-GBM disease, ANCA vasculitis, lupus, antiphospholipid syndrome with catastrophes, cryoglobulinaemia and infective endocarditis, and the first two dominate. Step two: send anti-GBM serology and ANCA on the first draw, cross-match, and correct coagulopathy before any biopsy; a bleeding lung makes an uncorrected biopsy reckless. Step three: start empirically while waiting — in a patient this florid, plasmapheresis, cyclophosphamide and methylprednisolone begin on clinical suspicion, because the kidney loses a percentage of function each day the antibody circulates. Step four: the biopsy returns linear IgG with 85 per cent crescents — immunosuppression continues, since he still has pulmonary disease and non-oliguric renal function; had he been anuric with every glomerulus crescentic and clear lungs, the same biopsy would argue for restraint. Step five: after two weeks of daily exchange with falling titres, convert to recovery-phase management, and if the ANCA also returns positive, plan long-term vasculitis-style maintenance rather than a clean stop. ## How the examiner frames it Three framings recur. The image question shows the linear fluorescence and expects anti-GBM over granular lupus or the pauci-immune field. The double-positive stem gives you a patient who recovers, then relapses a year later — the teaching being that pure anti-GBM disease is monophasic, and relapse means the ANCA arm was missed. The transplant stem gives an Alport recipient, years after grafting, with a rapidly failing kidney and linear IgG — de novo anti-GBM disease, no lung involvement, poor salvage, distinct from classical Goodpasture's in every respect but the fluorescence pattern. One viva flourish is remembered: the eponym is strict — Goodpasture described the pulmonary–renal syndrome, the antigen carries the name, and the disease with kidney alone is still anti-GBM disease, not "Goodpasture's of the kidney". ## Frequently asked questions ### What is the target antigen in anti-GBM disease? The NC1 domain of the alpha-3 chain of type IV collagen, shared by glomerular and alveolar basement membranes. ### What is the standard treatment protocol? Daily plasmapheresis with albumin replacement, cyclophosphamide and high-dose corticosteroids, continued until circulating antibody clears — roughly two weeks beyond. ### When may immunosuppression reasonably be withheld? Dialysis-dependence at presentation with every glomerulus crescentic and no pulmonary haemorrhage — recovery of independent renal function is rare enough to justify restraint. ### How long after antibody clearance should transplantation wait? Six to twelve months of undetectable anti-GBM antibody before listing; recurrence is then uncommon. ### What distinguishes Alport post-transplant anti-GBM disease? It is de novo, appears months to years after grafting, spares the lung, resists therapy and typically loses the graft. ### What does dual ANCA positivity change? It adds a relapsing vasculitis course, mandating maintenance immunosuppression after the acute anti-GBM protocol.