RESUMEN
Erythropoietin is the major hormonal regulator of erythropoiesis. It is controlled by many factors inducing hypoxia in tissue. The serum erythropoietin levels of neonates have shown gradual dccrease until 1 month of age, which they are reactivated in the period of physiologic anemia. This change is exaggerated if the meonates are born prematurely, and the levels of erythropoietin respond to lower hemoglobin are lower than those of term neonates and adults. The purpose of this study was to assess the values of erythropoietin levels to compare hemoglobin on the preterm and term neonates until 1 month of age. The results were as follows: 1) At birth mean erythropoietin values of preterm and term neonates were 16.5+/-1.4mU/ml, 16.5+/-1.7mU/ml respectively, there was no significant difference. Also erythropoietin values in preterm and term neonates were 23.6+/-13.3mU/ml, 10.9+/-1.5mU/ml respectively. Resticulocyte counts in preterm and term neonates were 10.7+/-3.3%, 5.7+/-2.9% respectively, so they were significantly higher in preterm than in term neonates. 2) The changes of mean hemoglobin, reticulocyte counts and erythropoietin according to postnatal ages were that those of reticulocyte counts and erythropoietin were significantly increased about 1 month of age. 3) At the 1 month of age, mean erythropoietin values in preterm neonates were lower than those of term neonates and adults, despite of the lowest hemoblobin. This results showed that erythropoietin values in preterm neonates during the physilolgic anemia were lower values than those of term neonates and adults in spite of the lowest hemoglobin.