Background: Angiotensin-converting enzyme (ACE) inhibitors are capable of reducing proteinuria and microalbuminuria with preservation of renal function in diabetic and non-diabetic renal disease. We designed a study investigating the effect of enalapril on the protection of renal function in autosomal dominant polycystic kidney disease (ADPKD).
Methods: We studied 61 normotensive and 28 hypertensive ADPKD patients. The normotensive group participated in a randomized double-blind placebo-controlled study, using enalapril. The hypertensive group was randomized for open label treatment with enalapril or the beta-blocker atenolol. The follow-up was 3 years, and renal function was established repetitively by measuring the clearance of inulin.
Results: In the normotensive group, renal function at baseline was 112 +/- 3 ml/min and decreased by -8 +/- 2 ml/min (P < 0.001). The loss of renal function in the patients treated with enalapril or placebo was similar (-7 +/- 3 vs -9 +/- 1 ml/min; P = 0.4). Although blood pressure significantly decreased with enalapril treatment, it had no effect on microalbuminuria. In the hypertensive group, renal function at baseline was 89 +/- 2 ml/min. The mean decline in renal function was -12 +/- 2 ml/min (P < 0.001), and was equal in patients treated with enalapril and those treated with atenolol. The patients treated with atenolol required more additional treatment to control blood pressure, but no difference on microalbuminuria was observed between the two treatments.
Conclusion: This study was unable to detect a beneficial effect of ACE inhibition on loss of renal function in ADPKD patients.