Inorganic, nonheme iron is absorbed by duodenal enterocytes. In the plasma, iron circulates bound to transferrin (Tf). The principal consumer of iron is the erythroid bone marrow, and most of that iron comes from internal recycling by tissue macrophages, predominantly splenic macrophages. Liver is the major storage site of iron. Iron entering the liver is stored in ferritin and can be mobilized when required by the body. Some iron is incorporated in other tissues. Hepcidin regulates systemic iron homeostasis by inhibiting iron release from duodenal enterocytes, macrophages, and hepatocytes.