Two Cases of Metformin-Induced Lactic Acidosis Successfully Treated by Hemodialysis

Metformin-induced lactic acidosis is a rare life-threatening complication associated with metformin treatment and has a high mortality rate. Here, two cases of metformin-induced lactic acidosis are reported. A 22-year-old woman was admitted to our hospital with a metformin overdose (25 g) and lactic acidosis. Hemodialysis was initiated to correct the acidemia, and the patient showed full recovery. Her serum creatinine level returned to normal. A 50-year-old man presented with a 5-day history of muscle weakness. His medical history included diabetes mellitus for 6 years treated with metformin at 3,000 mg/day and hypertension. An arterial blood sample showed metabolic acidosis, with a venous lactate level of 31.1 mg/dL. The patient recovered fully after treatment with bicarbonate dialysis. These cases illustrate that the presence of clinical conditions such as renal failure increase the risk of metformin-induced lactic acidosis. Prompt recognition of lactic acidosis and early treatment with bicarbonate dialysis can result in a successful clinical outcome. (Korean J Med 2011;80:473-476)