Reversible renal failure after combined treatment with enalapril and frusemide in a patient with congestive heart failure.

A patient with congestive heart failure and moderate renal insufficiency developed severe reversible non-oliguric renal failure while on frusemide and enalapril. Renal failure developed when enalapril was given in the presence of pronounced sodium depletion. When positive sodium balance was restored the plasma creatinine concentration began to fall while angiotensin converting enzyme inhibition remained effective and blood pressure was stable. These observations suggest that the degree of sodium depletion plays an important role in the tendency for angiotensin converting enzyme inhibitors to induce renal failure in patients with congestive heart failure and moderate renal insufficiency. Restoration of a positive sodium balance promotes the recovery of renal function after the combined administration of angiotensin converting enzyme inhibitors and diuretics.