Biology and Clinical Uses of Erythropoietin in Infants and Children

Erythropoietin (Epo) is a true hematopoietic hormone produced in response to lowered oxygen tension. The liver is the main source of Epo during most of fetallife, but the liver to kidney switch occurs around birth so that 90% of Epo synthesis takes place in the kidney very soon in life. E!evated serum Epo levels are observed at birth in the case of maternaI hypertension, akoholism, or diabetes mellitus, in the presence of Rh immunization or severe growth retardation, or after ~-sympathomi­ metic tocolysis, ail situations associated with fetal hypoxia. On the other hand, Epo production may be found to be inadequate for the degree of anemia in a variety of conditions, including renai failure, juvenile rheumatoid arthritis, acquired immune deficiency syndrome, surgery, cancer, chemotherapy, marrow transplantation, and prematurity. The pathophysiology of the anemia of prematurity is complex, but the most prominent feature is defective Epo synthesis in response to the anemia. In view of the risks associated with blood transfusions, recombinant human erythropoietin (rHuEpo) has been proposed to treat the anemia of prematurity. The results appear to be promising, but further information is needed about the pertinent indications, the best dosage, timing, and route of administration of rHuEpo, as weil as the appropriate method of iron supplementation. Patients with many other dinical disorders may benefit from rHuEpo therapy, but with the exception of the anemia of chronic renal failure the exact role of Epo in their management remains undefined at the presenttime.