Azathioprine induced acute interstitial nephritis as the cause of rapidly progressive renal failure in a patient with Wegener's granulomatosis.

Wegener's granulomatosis (WG) is a primary systemic vasculitis involving predominantly the upper and lower respiratory tracts and the kidneys. Few diseases can cause deterioration of renal function and progression to renal failure as rapidly as WG. We describe a woman with WG who developed rapid progression to renal failure within 10 days of starting azathioprine prescribed as maintenance therapy for vasculitis. Her renal biopsy showed acute tubulointerstitial nephritis and no active glomerulonephritis. This case illustrates the importance of the history and urine sediment in differentiating drug hypersensitivity from rapidly progressive glomerulonephritis in patients with WG.