title: Metformin-Associated Lactic Acidosis Presenting as Acute ST-Elevation Myocardial Infarction.
abstract: BACKGROUND
  Metformin-associated lactic acidosis (MALA) is a rare but life-threatening adverse drug reaction of metformin, the most frequently prescribed medication for patients with type 2 diabetes mellitus. The diagnosis of MALA is difficult to make because of diverse clinical presentations that can masquerade as other critical illnesses.
  
  
  METHODS
  A 52-year-old woman presented with altered mental status, hypoglycemia, and shock. A prehospital electrocardiogram showed findings consistent with posterolateral ST-elevation myocardial infarction, and the cardiac catheterization laboratory was activated before patient arrival. On arrival to the emergency department, she was found to have severe metabolic derangements and hypothermia, and the catheterization laboratory was canceled. Aggressive supportive measures and emergent hemodialysis were instituted. A metformin concentration was sent from the ED and returned at 51 μg/mL (therapeutic range 1-2 μg/mL), making MALA the most likely diagnosis. She recovered after prolonged critical illness and was discharged in good condition. No alternate diagnoses were found despite extensive work-up. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Metformin is the most prescribed antidiabetic drug in the world. Although MALA is a rare complication, it is important for emergency physicians to keep MALA on the differential for diabetic patients presenting with severe metabolic acidosis.
authors.affiliation: Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota.
authors.forename: Scott
authors.initials: S
authors.lastname: White
authors.affiliation: Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Driver
authors.affiliation: Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota; Hennepin Regional Poison Center, Minneapolis, Minnesota.
authors.forename: Jon B
authors.initials: JB
authors.lastname: Cole
mesh_terms: D000140:Acidosis, Lactic / Q000139:chemically induced* / Q000175:diagnosis*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000009:adverse effects*; D008687:Metformin / Q000009:adverse effects*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin
keywords: ECG; acute coronary syndrome; critical care; diabetes mellitus; lactic acidosis; metformin