Importance of checking anti-glomerular basement membrane antibody status in patients with antineutrophil 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 pauciimmune 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 mu mol/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.