Effect of Enalapril Treatment on Erythrocytosis after Renal Transplantation

ABSTRACT

Posttransplant erythrocytosis (PTE) is a common complication of renal transplantation. It afflicts 5-15 % of renal transplant recipients with good renal function and is associated with an increased incidence of thromboembolic events. Traditional therapies for PTE include serial phlebotomy and native nephrectomy, neither of which has proved optimal. Recently, angiotensin converting enzyme (ACE) inhibitors have been developed as an alternative for PTE treatment. The aim of the study was to evaluate the therapeutic effect of an ACE inhibitor, enalapril, on PTE by the measurement of serum erythropoietin (EPO) level. Ninety consecutive cyclosporine (CsA)-treated recipients who have received living donor kidneys were investigated during the first two years. Eleven recipients (12.2%) had developed PTE, and ten of them were prospectively treated with enalapril (5-10 mg/day) for 1 year for PTE. The average age for the nine men and one woman was 32+/-7.8 years . All retained their native kidneys. Seven recipents were hypertensive, 5 on diuretics, and 2 were smokers. Serum creatinine was 1.4+/-0.3 mg/dl. Onset of PTE occured 9.8+/-5.5 months posttransplant. Duration of PTE was 7.7+/-6.8 mos (range 1-24 mos). Three had undergone 1-2 phlebotomies during the previous year. None had experienced thromboembolic event. In 10 recipients, hematocrit (HCT) during 3 clinic visits before treatment was 55.8+/-3.4 %. After the application of enalapril, HCT in all recipients decreased. Mean HCT at 3 months was decresed to 44.1+/-3.3 % (p<0.001 vs. pre-enalapril values). One patient became anemic (HCT<40 %). One patient who had initially responsed to enalapril stopped using the drug due to dry cough and suffered a recurrence of PTE. Serum EPO levels (RIA) decresed significantly, from a mean of 15.6+/-6.7 to 8.7+/-3.8 mU/ml at 2 month (p<0.05), although the values were within the normal range for our laboratory. Regardless of pre-enalapril EPO level, the HCT normalized in all patients. Mean arterial pressure decreased (105.2+/-14 vs. 97.2+/-12 mmHg, p<0.05) at 12th month. Serum creatinine did not change (1.4+/-0.3 vs. 1.5+/-0.4 mg/dl) during the study period. No patient required phlebotomy after starting enalapril. We conclude that enalapril administration resulted in a reversible decline of HCT to normal levels in renal transplant recipients with PTE. Clinically, enalapril is a safe and effective alternative to traditional treatment of PTE.