Optimal hematocrit in patients on dialysis therapy

Although recombinant erythropoietin (rHuEPO) has been available for use in dialysis patients since 1989, there is little information available on the optimal hematocrit to target in this patient population. The optimal hematocrit is the value that supplies the amount of oxygen to specific tissues and organs that maximizes the efficiency and effectiveness of organ function. Very few prospective studies have been published on this issue, and the retrospective review of clinical practice data is inadequate because of the small number of patients maintained with a hematocrit greater than 36%. Several recent abstracts shed light on this issue, however, and additional publications are likely soon. The available data indicate that brain and cognitive function are better at a normal hematocrit compared with the currently achieved values (31% to 32%). In addition, quality of life and exercise capacity improve as hematocrit is normalized. The AMGEN Normal Hematocrit Cardiac Trial (NHCT), studying the effects of normalizing the hematocrit in dialysis patients with heart disease, does not clearly show the benefit or harm of a normal hematocrit in this patient setting, although within both study groups (hematocrit of 30% v 42%), survival was better in patients with higher hematocrits. The challenge for clinicians is to determine the optimal hematocrit for a specific patient that maximizes organ function but does not cause adverse effects. Over the next few years, several studies should be published based on current abstracts, and if the results remain as reported, the evidence will be accumulating that normal hematocrits are beneficial in end-stage renal disease (ESRD) patients.