Rapid life-threatening hyperkalemia after addition of amiloride HCl hydrochlorothiazide to angiotensin-converting enzyme inhibitor therapy

study objective: To highlight the dangers of a precipitous rise in serum potassium levels in patients at risk for renal insufficiency, already receiving an angiotensin-converting enzyme (ACE) inhibitor, who are given a potassium-sparing diuretic. Methods: We conducted a retrospective chart review of five patients who were taking the above combination of medications who were seen in our ED with hyperkalemia. Results: All five patients had diabetes and were older than 50 years of age. Except for one patient, they had some degree of renal impairment and all were receiving an ACE inhibitor. Each had amiloride HCl/hydrochlorothiazide added to their therapeutic regimen 8 to 18 days before presenting to our ED with hyperkalemia. Potassium levels were between 9.4 and 11 mEq/L in 4 of the patients; 2 did not respond to resuscitation measures. Conclusion: The concomitant use of ACE inhibitor and potassium-sparing diuretic therapy should be avoided. If impossible, weekly monitoring of both renal function and serum potassium should be performed. In the ED patients who are receiving such a combination should receive immediate ECG monitoring.