Most of the iron in the body is found in the blood but some is present in every cell that is bound to iron containing enzymes. Functional iron (most abundant iron in the body) is bound within structures of hemoglobin.

Hemoglobin is a protein in the blood that carries oxygen to all parts of the body. Non- functional iron of the body is held in iron storing compounds present in the liver, spleen and bone marrow. Some of these iron stores are held in large internal cavity within protein called ferritin.

Ferritin is a soluble iron storing compound whereas hemosiderin is an insoluble iron- protein complex that are specially designed for the reversible storage of iron. Very small amounts of ferritin are present in the plasma and they determine the amount of iron present in the iron stores. So non- functional iron gets transported by attaching itself to transferrin or ferritin. Transferrin carries iron from the intestine to the bone marrow and other cells in the body during growth and development.