Iron release from the stores: a mechanism in maintenance of concentration of hemoglobin in low-birth-weight infants.

After the resuming of the postnatal red cell production at two months of age infants are dependant on storage iron due to the great need for iron at a time when the iron content of the diet is low. This is even further accentuated in low-birth-weight infants. In this study the release of storage iron in the hemoglobin pool. During the two month period from two to four months of age at least 20 mg of iron per month was transferred from the storage sites for hemoglobin production. This amount represents 5 mg per kg of body weight and exceeds the rate iron was mobilized from storage sites in an adult male under experimental conditions. Rapid weight gain was associated with early depletion of iron stores. However, residual iron stores in infants with the slowest growth rate could not maintain the level of hemoglobin achieved in iron-supplemented low-birth-weight infants. These findings suggest that in rapidly growing low-birth-weight infants the need of iron for erythropoiesis is so great that iron deficient erythropoiesis may develop in the presence of iron stores if the diet is not supplemented with iron.