Prolonged hemodialysis for severe metformin intoxication

Lactic acidosis is a rare and often lethal complication of metformin therapy. We describe a patient who ingested at least 52 g, and possibly more, of metformin and presented with severe lactic acidosis and acute renal failure. He was treated with prolonged hemodialysis: a 3.5 h treatment that did not result in significant clinical improvement, followed by an additional 31 h treatment. With this treatment regimen, his lactate levels gradually decreased and his clinical status improved. A metformin level drawn approximately 25 h after the initiation of the second hemodialysis treatment was still elevated at about five times the upper therapeutic limit. It is suggested that prolonged dialysis is indicated in patients with severe metformin overdose, particularly those with renal failure. In patients whose cardiovascular status permits, prolonged hemodialysis should be strongly considered.