Erythropoiesis and erythropoietin levels in renal transplant recipients.

Moderately increased blood levels of endogenous erythropoietin (Epo) usually induce complete restoration of renal anemia after successful kidney transplantation. With good graft function erythropoiesis is maintained by normal Epo serum levels. Persistent anemia can be related to iron deficiency, low excretory graft function, and high dosage of immunosuppressive agents leading to marrow suppression or nephrotoxicity. Acute early rejection is associated with a fall in serum Epo and abrogation of reticulocytosis. About 15% of recipients fail to exhibit the normal feedback regulation and develop a mostly transient posttransplant erythrocytosis. Both an increased sensitivity of erythrocytic progenitors to Epo and inappropriate Epo secretion by the native kidneys may account for this overshooting reaction.