Electrocardiographic changes after shoulder arthroplasty.

Hyperkalemia is a commonly encountered electrolyte abnormality in the hospitalized patient population, and can be fatal if not recognized and treated in a timely matter. Although most cases of hyperkalemia in the acute care setting occur in the context of renal failure, certain drugs can cause an increase in serum potassium. One such drug is trimethoprim-suflamethoxazole, a broad spectrum antibiotic utilized for a variety of infections. Reported herein, is the case of an elderly patient who developed marked changes noted on the cardiac monitor following shoulder surgery who was found to have severe hyperkalemia secondary to recent administration of trimethoprim-sulfamethoxazole for a urinary tract infection.