Sulfamethoxazole-Trimethoprim and Hyperkalemia in an Infant

Hyperkalemia is a potentially life-threatening electrolyte abnormality in both children and adults. In the setting of elevated serum potassium concentrations, cardiac conduction disturbances and cardiac arrest may occur. In the pediatric intensive care unit (PICU) setting, the differential diagnosis of hyperkalemia may be extensive including increased potassium intake or administration, increased endogenous production, decreased renal excretion, and intracellular to extracellular shifts related to changes in acid-base status. We present a 4-month-old infant who developed hyperkalemia during the recovery phase of her PICU course for respiratory failure. A thorough investigation demonstrated that the hyperkalemia was most likely the result of the commonly used antibiotic, trimethoprim-sulfamethoxazole (Bactrim(®)). Potential etiologies of hyperkalemia in the PICU patient are discussed and previous reports of hyperkalemia associated with trimethoprim-sulfamethoxazole presented.