Life-threatening hyperkalemia associated with captopril administration

Angiotensin converting enzyme (ACE) inhibitors have become commonly used medications for hypertension and congestive heart failure. These agents are noted for their low incidence of adverse effects; but in certain cases, these effects can be life-threatening. Severe hyperkalemia is one of the potentially dangerous effects of the ACE inhibitors. While cases of life-threatening hyperkalemia associated with the use of ACE inhibitors have been described previously, in no instance was dialysis required. Herein, we report a case of acute hyperkalemia in a patient with congestive heart failure and renal insufficiency, the resolution of which required hemodialysis. The hyperkalemia in this case occurred without an increase in the patient's azotemia. In addition, the patient did not respond to attempts to effect the intracellular shift of potassium. This suggested that there may have been a defect in internal potassium homeostasis.