Impact of erythropoietic activity on red cell parameters in chronic renal failure patients.

We measured red cell parameters during recombinant human erythropoietin (rHuEPO) therapy associated with appropriate iron supplementation in chronic hemodialysis patients. Increased erythropoietic activity led to a bias in red cell parameter determination. The percentage of hypochromic red blood cells, usually used as the most effective predictor of response to iron supplementation, increased following the appearance of a younger red cell population since the same Hb content in these younger, larger cells gives a lower Hb concentration