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

STUDY DESIGN: A case of metformin-associated lactic acidosis after elective spinal surgery is reported. OBJECTIVE: To inform spinal surgeons of this potentially fatal side effect and make them aware that metformin should be stopped 48 hours before surgery. SUMMARY OF BACKGROUND DATA: 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. METHODS: A patient who developed metformin-associated lactic acidosis after cervical spinal fusion is presented. RESULTS: 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. CONCLUSION: Spinal surgeons should be aware of this preventable, potentially fatal side effect and stop metformin 48 hours before surgery.