Acute interstitial nephritis after amoxycillin with hematuria, red blood cell casts and hematuria-induced acute tubular injury.

A 62-year-old Caucasian man is described who developed acute kidney injury (AKI) and gross hematuria after a course with amoxycillin. At admission, urinalysis showed mild proteinuria, marked microscopic hematuria and cylindruria, which also included red blood cell casts. At renal biopsy an acute interstitial nephritis (AIN) was found, which was associated with many intratubular red blood cells and red blood cell casts, consequent acute tubular injury and red blood cell phagocytosis by tubular cells. After a course with corticosteroids, renal function partly recovered. This case demonstrates that red blood cell cylindruria, red blood cell intratubular casts and red blood cell-induced tubular injury can also be observed in patients with acute interstitial nephritis and not only in patients with glomerulonephritis as described so far.