Metformin-induced lactic acidosis associated with acute renal failure.

A 69-year-old diabetic woman with diffuse atherosclerosis presented with acute renal failure due to contrast nephropathy and severe metformin-induced lactic acidosis. There was a discrepancy between the patient's elevated serum creatinine level, indicative of severe renal insufficiency, and her very low blood urea nitrogen content. It is postulated that the patient's extremely severe acidosis interfered with her hepatic urea generation, contributing to this unusual biochemical abnormality.