ACE inhibitors and diuretics causing hypokalaemia.

Angiotensin-converting enzyme (ACE) inhibitors and diuretics are known to cause hyperkalaemia. We undertook a prospective analysis over a period of six months of patients admitted under our care. Of 217 patients, 39 (18 per cent) were admitted with congestive cardiac failure/left ventricular failure. Of these 39 patients, 21 (54 per cent) were prescribed ACE inhibitors. Seven of these 21 patients subsequently developed hypokalaemia. This was irrespective of the type or dose of the diuretic but seemed to be related to the dose of the ACE inhibitor. In three cases the hypokalaemia was corrected by the addition of a potassium-sparing diuretic; in two cases a potassium supplement was added; and in the other three an increase in the dose of the ACE inhibitor for the resistant heart failure corrected the potassium deficit. This study shows that one should be alert to both hyperkalaemia and hypokalaemia when using a combination of ACE inhibitors and diuretics.