Fatal hypermagnesemia.

Severe symptomatic hypermagnesemia is a rare clinical problem that predominantly results from excess exogenous magnesium intake in patients with renal failure. This report describes an elderly woman who was given a magnesium-containing cathartic for pre-operative bowel preparation in the context of unrecognized acute renal failure. She subsequently developed one of the highest serum magnesium concentrations ever reported. The hypermagnesemia was successfully treated with continuous arteriovenous hemodialysis, but she ultimately died from complications of hypermagnesemia, that included junctional bradycardia, myocardial infarction and respiratory failure. This case illustrates the importance of ensuring intact renal function prior to administering large quantities of oral magnesium. More specifically, large doses of magnesium salts should be avoided in patients with acute renal failure.