High dose enalapril impairs the response to erythropoietin treatment in haemodialysis patients

Background. The resistance to recombinant human erythropoietin (rHuEpo) therapy in haemodialysis (HD) patients has multifactorial aetiologies: erythropoietin insufficiency, dialysis insufficiency, iron deficiency, and secondary hyperparathyroidism. Angiotensin-converting enzyme (ACE) inhibitors induce anaemia in patients with essential hypertension, congestive heart failure, chronic renal insufficiency, and renal transplants. Data exist suggesting that ACE inhibitors impair erythropoiesis in HD patients. Therefore the aim of this study was to investigate the impact of enalapril on rHuEpo requirement. Methods. In the present prospective non-randomized study of 12 months, we compared the effects of enalapril and nifedipine on rHuEpo requirement in 40 hypertensive patients receiving rHuEpo for more than 6 months on maintenance haemodialysis. Twenty normotensive rHuEpo-dependent patients served as a control group. All patients with severe hyperparathyroidism or iron deficiency were excluded. Results. The mean (+/- SD) haemoglobin concentration was >10 g/dl in all groups. The mean weekly rHuEpo dose increased in the enalapril group (P<0.0001 vs before) and remained constant in the nifedipine and control groups (P=NS vs before). Statistically, there was no differences with regard to iPTH levels, dialysis parameters, iron status, and underlying renal diseases among all groups. Conclusion. High-dose enalapril increases rHuEpo requirement and should be reserved for dialysis patients with hypertension uncontrollable with other antihypertensive medications or dialysis patients with cardiac failure.