Iron-deficiency anemia occurs at all ages, but its pathogenesis is different in childhood and adult life. Excretion of iron is negligible. In the growing child, the needs of an expanding red cell mass require appreciable absorption of dietary iron, and the anemic child will usually be found to have a diet insufficient in iron-containing foods. In adult life, a constant amount of iron is present in the red cell mass, and an additional supply, available for hemoglobin production if needed, is stored in the tissues. Once iron stores are accrued, the adult is virtually independent of dietary iron, and iron deficiency develops only after chronic blood loss.
Pathogenesis
Iron balance during the first year is diagramed in Figure 1. An average newborn infant has a blood volume of 250 ml., of which 150 ml. represents red cells.1 In the first year, the blood volume increases to 750 ml., and