Erythropoietin and progression of CKD.

In patients with primary as well as secondary chronic kidney disease (CKD), anemia has been identified as an independent risk factor for progression. In these patients anemia is thought to be a surrogate parameter for tissue hypoxia that perpetuates preexisting renal tissue injury, and treatment of anemia with recombinant human erythropoietin (rHuEPO) was therefore expected to retard progression. However, results of recently published large trials in patients with CKD did not fulfill these expectations. The reason for the discrepant findings may be distinct molecular pathways and/or EPO tissue receptor affinities that mediate the effect of EPO on erythropoiesis and tissue protection by EPO. A pivotal intracellular pathway is the activation of Akt (i.e., serine/threonine protein kinase B), but further potential pathways have been identified that may play an important role in tissue protection. In this study, we review data on the non-hematological effects of rHuEPO in different experimental settings of acute and chronic kidney injury, and discuss clinical renoprotective strategies with rHuEPO or analogue substances that are not related to anemia correction.