IgA-MEDIATED ANTI-GLOMERULAR BASEMENT MEMBRANE DISEASE

A SIRIWARDANA1, F PETTIT1

1Department of Renal Medicine, St George Hospital, Kogarah, NSW

Background: Anti-glomerular basement membrane (anti-GBM) disease is an aggressive glomerulonephritis mediated by IgG autoantibodies against the glomerular basement membrane. IgA-mediated anti-GBM is rare and has been described in the literature in fewer than 15 cases. Optimal therapy for these patients is unknown and renal prognosis is poor. Case report: A 74 year old male was hospitalised with a 1-week diarrhoeal illness and acute kidney injury with creatinine 299μmol/L, microscopic haematuria and heavy proteinuria. Past medical history included irritable bowel syndrome, skin cancers and a current smoking habit. Imaging studies and vasculitic screen (including anti-GBM antibodies) were unremarkable. Creatinine partially improved with intravenous fluids. Over following weeks creatinine rose to 335μmol/L and renal biopsy showed a focal proliferative necrotising glomerulonephritis with 70% crescents (50% cellular) and linear GBM staining for IgA. He received pulse and oral steroids, oral cyclophosphamide, and plasma exchange. Despite 5 weeks of therapy, creatinine rose to 450μmol/L with persistent microscopic haematuria and nephrotic-range proteinuria. Repeat renal biopsy showed persistent active crescenteric glomerulonephritis with strong IgA linear GBM staining and moderate acute tubular injury. Serum IgG anti-GBM antibodies remained negative. High dose steroids and oral cyclophosphamide were continued. Creatinine rose to 652μmol/L. His course was complicated by a febrile illness and likely drug-induced neutropenia. Prednisone was weaned, cyclophosphamide ceased and dialysis is imminent. Conclusion: IgA-mediated anti-GBM disease is a rare clinical and histopathological entity. This case adds to the limited literature and is in keeping with the suggestion that IgA-mediated anti-GBM disease confers poor renal prognosis.

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