Iron deficiency in patients with dialysis-associated anemia during erythropoietin replacement therapy: strategies for assessment and management

Abstract

Iron deficiency frequently complicates both acute and chronic phases of recombinant human erythropoietin (r-HuEPO; EPOGEN [epoetin alfa], AMGEN Inc, Thousand Oaks, CA) therapy for dialysis-associated anemia. During acute correction of anemia, iron needed for new hemoglobin production may outstrip available body iron stores. During maintenance r-HuEPO therapy, blood lost both through the dialysis process and the uremic predisposition to gastrointestinal bleeding promotes ongoing negative iron balance. Failure to recognize and treat iron deficiency may lead to impaired efficacy of r-HuEPO in the anemic patient by converting the anemia associated with chronic renal failure to the anemia associated with iron deficiency. The risk of iron deficiency is assessed by weighing available iron stores, as reflected by the level of serum ferritin, against anticipated iron needs for new hemoglobin synthesis, as measured by the difference between the current and target hemoglobin. Using this approach, body iron reserves can be determined, iron deficits predicted, and appropriate iron replacement therapy planned. Once patients are identified as being at risk for iron deficiency, they are treated prophylactically with oral iron supplements. Parenteral iron therapy is reserved for those at greatest risk for iron deficiency during acute r-HuEPO treatment and those intolerant or unresponsive to oral iron supplements during chronic r-HuEPO treatment. Although no dose-response relationship has been observed in the restoration of iron balance with oral iron supplements, those taking supplements show distinctly higher projected iron stores and daily iron balance than those not given supplements.