Iron balance following recombinant human erythropoietin therapy for anemia associated with chronic renal failure.

Erythrokinetic changes before and after rHuEPO therapy in 15 anemic patients with chronic renal failure undergoing maintenance hemodialysis were analyzed by means of ferrokinetics and measurement of red cell mass and survival. To estimate the change in iron status no exogenous iron was administered during the observation period unless a lack of response due to iron deficiency was confirmed. During 13-29 weeks of therapy there was an increase in red cell mass from 12.5 +/- 1.7 mg/kg to 20.1 +/- 3.6 ml/kg, compatible with the increase in hematocrit from 21.5% to 31.8%. In ferrokinetics the plasma iron disappearance time (t1/2) shortened from 163 +/- 44 min to 92 +/- 24 min. The plasma iron turnover rate rose from 0.39 +/- 0.10 mg/dl per day to 0.56 +/- 0.11 mg/dl per day. Serum ferritin levels were decreased from 160 +/- 115 ng/ml to 26 +/- 22 ng/ml, although there was only one patient showing poor response to rHuEPO because of iron deficiency. The increase in red cell volume correlated with the decrease in serum ferritin levels (p less than 0.02). There was no significant difference in these ferrokinetic parameters between transfused and non-transfused patients not only before, but also after, rHuEPO therapy. It is suggested that an elevation of about 8 ml/kg of red cell mass (approx. 10% as hematocrit) exhausts iron stores in the majority of patients.