| Iron is important in the transfer of molecular oxygen and is a component of heme in hemoglobin and myoglobin. Cytochromes a,b, and c also contain iron.
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Iron is present in the body in in the ferrous (2+) form in the heme molecule and is transported and stored in the ferric (3+) form. Altogether, there are 3-4 g of iron in the body. Seventy five percent of body iron is in hemoglobin and myoglobin, and 25% is stored in the tissues such as bone marrow, liver, and reticuloendothelial system. It is absorbed in the upper small
intestine, and about 10% is absorbed from diet. Meat and ascorbic acid increase its absorption, and vegetable fibre inhibits it. It is transported in blood bound to transferrin and is stored as ferritin and hemosiderin. Transferrin is normally about 30% saturated with iron. Iron is lost through the skin and through the gastrointestinal tract. Human beings cannot excrete excess iron and free iron is toxic.
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| Requirement for iron increases during growth and pregnancy. Iron deficiency results in defective erythropoiesis and in normocytic or microcytic (small erythrocytes) hypochromic anemia. This is most likely to develop in infants and adolescents, in pregnant and menstruating women, and also in the elderly. Iron deficiency most often develops as a result of abnormal blood loss, and therefore persons who present with iron deficiency anemia are always investigated for causes of bleeding, particularly from the gastrointestinal tract.
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| Dietary sources of iron include organ meats, poultry and fish and oysters, and also egg yolks, dried beans, dried figs and dates, and some green vegetables. The assessment of iron status includes the measurements of transferrin and ferritin in plasma, the assessment of hematological variables, and the bone marrow smear.
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