ERYTHROPOEITIN

Erythropoietin (Epo), the first growth factor to be discovered, is an endocrine hormone produced by specialized renal cells. The rate of Epo production is determined primarily by the oxygen demands of these ren al cells relative to their oxygen supply. However, Epo production is m odulated by various hormones, nutritional factors, cytokines, and the integrity of the erythron. Epo interacts with specific receptors found almost exclusively on erythroid progenitors. This interaction results in an expansion of the number of the erythroid progenitor and trigger s late committed progenitors to undergo terminal maturation when provi ded with essential nutrients. Recombinant human Epo (rHuEpo) is commer cially available for human use. It is safe, easily administered, and a lmost universally effective in treating the anemia of patients with re nal failure. It has also been successful in treating the anemia of som e patients with neoplasms, myelodysplastic syndromes, HIV infection, r heumatoid arthritis, and aplastic anemia. Much remains to be learned a bout the regulation of Epo production, the physiologic actions of Epo, and how best to use this growth factor in the treatment of anemia.