ANTI-GBM DISEASE

Anti-GBM disease occurs when autoantibodies directly target the glomerular basement membrane, causing inflammation that almost always leads to RPGN. Because anti-GBM disease (either isolated or as part of Goodpasture syndrome) is rare, however, it accounts for only 15% of total RPGN cases. A characteristic finding of anti-GBM disease is smooth, linear immunofluorescent staining of the capillary wall for antibodies and complement components. Treatment consists of plasmapheresis to remove the pathogenic antibodies, along with steroids and either cyclophosphamide or azathioprine. With treatment, mortality is about 10%. Without treatment, anti-GBM disease invariably produces end-stage renal disease (ESRD). Patients who deteriorate to the point of requiring dialysis may need to continue immunomodulatory treatment to prevent pulmonary hemorrhage, but treatment usually does not result in any recovery of renal function.

EVALUATION AND TREATMENT

When a patient has a rapid decline in renal function, complement levels and serologies should be obtained (ANA, anti-DNA antibodies, ANCA, anti-GBM antibodies, cryoglobulins, hepatitis B and C), and a renal biopsy should be performed without delay. Diseases with presentations similar to RPGN but with no evidence of crescents on biopsy include thrombotic microangiopathy and atheroembolic disease. If RPGN is strongly suspected, presumptive treatment with steroids is typically initiated at the time of presentation, with further treatment dictated by the results of the renal biopsy.