Hyporesponsiveness to recombinant human erythropoietin

The introduction of recombinant human erythropoietin (rh-Epo, epoetin) as a treatment for the anaemia of renal failure has transformed the management of this condition. Nevertheless, a significant number of patients fail to r espond. There are many different possible causes of inadequate response to epoetin. Iron deficiency, whether absolute or functional, is considered to be the most important, and it is widely accepted that maintaining adequate iron levels reduces rh-Epo dosage requirement and improves efficacy in haem odialysis patients. Infection and inflammation have been shown to influence responsiveness to rh-Epo by disrupting iron metabolism and eliciting the r elease of cytokines that inhibit erythropoiesis. Another factor for conside ration is severe hyperparathyroid ism, which can lead to a reduced number o f responsive erythroid progenitor cells. Inadequate dialysis can also negat ively impact on rh-Epo therapy, and aluminium overload interferes with iron metabolism and reduces the efficacy of rh-Epo. Deficiencies in vitamin B-1 2, folic acid and potentially vitamin C can all reduce the efficacy of trea tment with rh-Epo. Optimizing patient response to rh-Epo therapy, therefore , requires consideration of many factors, some well established and others that are more controversial, and the list continues to grow with the identi fication of new factors.