Iron overload states can be classified as primary or secondary. There are many disorders that can lead to iron overload (Table 29.1) . This chapter focuses on hereditary hemochromatosis (HHC), juvenile hemochromatosis (JHC), and secondary iron overload (primarily transfusion associated) in the pediatric patient and in neonatal hemochromatosis (NH). For a discussion of the rarer entities, the reader is referred to a recent review . Iron is one of the more tightly regulated nutrients in the body. Humans have no significant excretory pathway for iron. Therefore, body iron stores are normally controlled at the level of absorption, matching absorption to physiologic requirements. Under normal circumstances, only about 1mg of elemental iron is absorbed each day (Figure 29.1), in balance with gastrointestinal losses. Intestinal iron absorption is increased by low body iron stores (storage regulation), increased erythropoiesis (erythropoietic regulation), anemias associated with ineffective erythropoiesis (thalassemias, congenital dyserythropoietic anemias, and sideroblastic anemia), and acute hypoxia. Both dietary iron intake (dietary regulation) and systemic inflammation can temporarily decrease iron absorption and availability, even in the presence of iron deficiency .
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