Synopsis
Recognise anti-glomerular-basement-membrane disease as a pulmonary–renal emergency, secure antibody and biopsy evidence rapidly, and support immediate specialist plasma exchange and immunosuppression decisions.
- Anti-GBM disease is caused by pathogenic antibodies against the alpha-3 chain of type IV collagen in glomerular and alveolar basement membranes.
- It typically produces rapidly progressive crescentic glomerulonephritis, pulmonary alveolar haemorrhage or both; isolated renal disease is common enough that absent lung symptoms do not reassure.
- Visible haemoptysis is not required for alveolar haemorrhage; hypoxia, new bilateral opacities and a falling haemoglobin may be the only bedside cluster.
- Request serum anti-GBM antibody urgently alongside ANCA because a clinically important double-positive group has both anti-GBM severity and later vasculitis relapse risk.
- Kidney biopsy usually shows necrotising crescentic GN with strong linear IgG staining, distinguishing it from granular immune-complex and pauci-immune patterns.
- Treatment is time-critical and generally combines plasma exchange, glucocorticoids and cyclophosphamide under a specialist protocol while pulmonary and renal complications are supported.
- Plasma exchange removes circulating antibody and is usually continued until antibody becomes undetectable, with schedule and stopping criteria set by the renal centre.
- Established dialysis dependence, extensive irreversible crescents and no pulmonary haemorrhage may make aggressive treatment futile, but this is a consultant decision requiring biopsy and trajectory.
- Anti-GBM disease is usually monophasic once antibody is eradicated; prolonged maintenance immunosuppression is not routine unless the patient is also ANCA-positive.
- Kidney transplantation is deferred until anti-GBM antibodies have remained undetectable for at least six months, with timing confirmed by the transplant service.
- Smoking and hydrocarbon exposure can precipitate lung haemorrhage and should be addressed urgently without implying that exposure is required for diagnosis.
Key red flags
Creatinine rising over days to weeks, glomerular haematuria, red-cell casts, proteinuria and oliguria is the characteristic renal emergency.
New hypoxia, diffuse alveolar shadowing and falling haemoglobin can indicate pulmonary bleeding even with no visible haemoptysis.
Anuria, refractory potassium or acidosis, uraemic features and pulmonary oedema require immediate renal replacement assessment alongside disease-specific therapy.
Investigation priorities
Detect the disease-defining circulating autoantibody and establish a baseline for clearance.
Management branches
Active GN accompanies haemoptysis, hypoxia, diffuse opacities or otherwise unexplained falling haemoglobin.
- Admit, support airway and oxygenation, stop avoidable anticoagulants after senior risk review, and treat life-threatening hyperkalaemia, acidosis or pulmonary oedema.
- Send anti-GBM antibody, ANCA, cultures and baseline immune-treatment tests immediately and arrange urgent renal biopsy when safe.
- With senior nephrology, begin the centre anti-GBM protocol when suspicion is strong, coordinating plasma exchange, glucocorticoid, cyclophosphamide and critical-care support.