Importance of checking anti-glomerular basement membrane antibody status in patients with anti-neutrophil cytoplasmic antibody-positive vasculitis.

The case is reported of a 68-year-old man with perinuclear anti-neutrophil cytoplasmic antibody (pANCA)-associated glomerulonephritis who developed antibodies to glomerular basement membrane (anti-GBM) resulting in end stage renal failure. His pANCA titre on admission was 1:1024 IgG and he was anti-myeloperoxidase positive. A renal biopsy showed advanced sclerosing necrotising glomerulonephritis consistent with a pauci-immune ANCA-positive glomerulonephritis. He was treated with steroids and cyclophosphamide. His serum creatinine profile improved. He had a relapse of disease 16 months later, which was successfully treated. After a further 16 months, he presented with acute renal failure (creatinine 1060 micromol/l). His pANCA titre on admission was 1:64 IgG. This was treated as a further relapse of ANCA-positive vasculitis. He became oliguric and his haemoglobin concentration fell. Eight days after admission, he was found to be strongly positive for anti-GBM (138 U/ml). Despite receiving cyclophosphamide, steroids and plasma exchange, he remained dialysis-dependent.