The Anemia of Prematurity

Abstract

We performed sequential studies in 45 premature infants (birth weights<1500 g) from 7 to 120 days of age to determine factors governing the erythropoietin response to a declining hemoglobin concentration. The hemoglobin level and the plasma erythropoietin showed a significant inverse correlation (r = -0.50, P<0.001), as did, even more strikingly, the plasma erythropoietin response and the infants' oxygen-unloading capacity (r = -0.55, P<0.001). In infants with "right-shifted" oxygen-hemoglobin dissociation curves (hemoglobin F60 per cent) before comparable erythropoietin responses occurred. It appears that premature infants respond appropriately to alterations in oxygen unloading capacity and that the position of the oxygen-hemoglobin dissociation curve and not the hemoglobin concentration alone has a major role in modulated erythropoiesis. (N Engl J Med 296:647–650, 1977)