Metformin-associated lactic acidosis after elective cervical spine fusion: a case report

A case of metformin-associated lactic acidosis after elective spinal surgery is reported. To inform spinal surgeons of this potentially fatal side effect and make them aware that metformin should be stopped 48 hours before surgery. Metformin is a commonly used oral hypoglycemic agent used in the treatment of non-insulin-dependent diabetes mellitus. A rare side effect of metformin is lactic acidosis, which has a 50% mortality rate. Risk factors for metformin-associated lactic acidosis include renal, hepatic, and cardiac failure. Two cases have been reported in postsurgical patients. No cases of this disorder have been reported after orthopedic procedures. A patient who developed metformin-associated lactic acidosis after cervical spinal fusion is presented. Recognition of the cause and aggressive medical management led to resolution of the lactic acidosis. Subsequent surgery was uneventful when metformin was discontinued more than 48 hours before surgery. Spinal surgeons should be aware of this preventable, potentially fatal side effect and stop metformin 48 hours before surgery.