ERYTHROPOIETIN IN PREMATURE-INFANTS

The regulation of erythropoiesis during the first 3 mo. of life was studied in 30 premature infants who had Hb concentrations which were lower than in term infants of the same postdelivery age. Erythropoietin and erythropoiesis inhibitors were measured by an exhypoxic polycythemic mouse bioassay. The percentage of Hb F was determined as well. An increased erythropoietin level was detected only in 6 infants older than 6 wk, whose blood Hb concentration was < 100 g/l, while in serum from other babies erythropoietin was undetectable by the method used. Erythropoiesis inhibitors were present in 80% of the samples tested. In premature infants erythropoiesis apparently is regulated through erythropoietin, inhibitors of erythropoiesis take part in this regulation as well, but the Hb level at which erythropoietin is increased is lower in preterm infants than in term babies.