Total body level in the body of a healthy male and female adult is about 3.5 g and 2.45 g, respectively. Some 66%-70% of this amount is found in hemoglobin, 4% in myoglobin, and 30% in the storage form (e.g., hemosiderin and ferritin). A small portion of iron is found in the composition of some body compounds (e.g., flavoprotein, catalase).

Iron is taken by food where it is found in a divalent (ferro-) or trivalent (ferri-) form. In the intestinal lumen, it is reduced to a divalent form, as it can cross the cellular membrane in this form. In the intestinal epithelial cells, iron is transformed back to the ferri-form (Fe+++), and is transferred to plasma where it binds to the protein named transferrin (siderophylline). The transferrin bound iron (7-28 μmol/L) is normally transferred to the organs, where it is accepted by the protein named apoferritin, and iron is then stored in the form of ferritin and hemosiderin. A major part of iron stores are found in the liver, and some in the bone marrow and spleen.