Purpose: Nephropathy is a common complication of sickle cell anemia and is often preceded by proteinurea. Our aim was to evaluate the effect of angiotensin-converting enzyme inhibition on microalbuminuria in sickle cell patients.

Patients and Methods: We performed a randomized, double-blind, placebo-controlled trial in 22 normotensive patients with sickle cell anemia and persistent microalbuminuria. Patients received captopril (25 mg/day) or placebo and were followed up for 6 months. Albuminuria, blood pressure, and serum creatinine and hemoglobin concentrations were measured at baseline and at 1, 3, and 6 months. The primary outcome variable was the 6-month change in albuminuria between the two groups.

Results: Baseline albuminuria was 121 (SD 66) mg per 24 hours in the captopril group and 107 (SD 86) mg per 24 hours in the placebo group. Microalbuminuria decreased from baseline in the captopril group but increased in the placebo group. The mean absolute change and the mean percentage change in microalbuminuria were significantly different between the two groups at 6 months (absolute change −45 mg per 24 hours in the captopril group versus +18 mg per 24 hours in the placebo group, P <0.01; and percentage change −37% in the captopril group versus +17% in the placebo group, P <0.01). The 95% confidence intervals (CI) for the difference in albuminuria between the two groups were 63 (CI 40 to 86) mg per 24 hours for the mean absolute change and 54% (CI 22% to 85%) for the mean percentage change. Blood pressure decreased slightly from baseline in captopril-treated patients and did not change in the placebo group. The change was significantly different between the two groups only for diastolic blood pressure at 6 months (P <0.01).

Conclusion: Captopril reduces albuminuria and slightly decreases blood pressure in patients with sickle cell anemia. More studies are required to demonstrate the sustained benefit on protein excretion.