Factors affecting the therapeutic response of enalapril in treatment of post transplant erythrocytosis

Summary: Enalapril was used for post transplant erythrocytosis (PTE) in 19 stable male hypertensive renal allograft recipients. Post transplant erythrocytosis was defined as haematocrit (Hct) >0.45 for 3 consecutive months. Dosage of enalapril was adjusted according to the blood pressure of individual patients and varied from 2.5 mg to 20 mg per day in divided doses. Patients'serum creatinine level, blood pressure and haematocrit were monitored. Therapeutic response was expressed as percentage drop in Hct (Δ%Hct). Factors affecting Δ%Hct was then determined. After 32 weeks of treatment, haematocrit fell from 0.495 ± 0.021 to 0.396 ± 0.053, which represented a 19.9% drop (paired Student's t-test, P > 0.001). With multiple regression analysis, reciprocal of plasma creatinine (RCr) prior to enalapril therapy (B = 3.40 ± 0.72, P > 0.0005), dose of enalapril adjusted with bodyweight (B = - 0.058 ± 0.020, P > 0.02, and pre-treatment haematocrit level (B = - 1.90 ± 0.71, P > 0.02) were found to be independent factors affecting Δ%Hct. We concluded that the dosage of enalapril, renal allograft function and severity of erythrocytosis were the major factors affecting the therapeutic response of PTE by enalapril treatment.