Review Question - QID 109549

This patient is presenting with altered mental status as well as a high anion gap acidosis in the setting of impaired renal function, suggesting a diagnosis of lactic acidosis. The patient's predisposing medications should be discontinued, namely ibuprofen, naproxen, and metformin.

Metformin is a first-line agent for glycemic control in pre-diabetic and diabetic patients. A rare but feared complication of metformin is lactic acidosis. Lactic acidosis presents in patients with poor renal function in the setting of the use of nephrotoxic agents or NSAIDs. The best initial step in management of lactic acidosis is to discontinue the offending agents (NSAIDs and metformin).

Incorrect Answers:
Answer 1: Insulin would be appropriate management for this patient's glycemic control. However, in the setting of this patient's type II diabetes and blood glucose that is not severely elevated, it is less likely that this patient is in diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic coma (HHC). For this reason, the most likely diagnosis is lactic acidosis, and the best initial step in management is to discontinue offending agents.

Answer 2: Potassium administration would be important in this patient if insulin were to be administered. Insulin would drive potassium intracellularly and cause hypokalemia.

Answer 3: Bicarbonate administration could be administered to counteract the lactic acidosis, but would not be as important as treating the underlying cause of the lactic acidosis.

Answer 4: Insulin and potassium administration is the appropriate management of DKA and HHC as it returns the patient to normoglycemia, corrects the anion gap, and repletes potassium which is likely depleted. However, a more likely diagnosis in the setting of this patient's renal failure, medications, and blood glucose is lactic acidosis.

Bullet Summary:
Metformin and NSAIDs combined in a diabetic patient with poor renal function can predispose them to experience lactic acidosis.