Human iron metabolism: Encyclopedia II - Human iron metabolism - Body iron stores

Human iron metabolism - Body iron stores

Most well-nourished people in developing countries have 3-4 grams of iron in their bodies. Of this, perhaps 2.5 g is bound up in the hemoglobin needed to carry oxygen through the blood. Another 400 mg is devoted to cellular proteins that use iron for important cellular processes like storing oxygen (myoglobin), or performing energy-producing redox reactions (cytochromes). And around 3-4 mg circulates through the plasma, bound to transferrin. ^[3] Because so much iron is required for hemoglobin, iron deficiency anemia is the first and primary clinical manifestation of iron deficiency.

Also, some iron is stored. Physiologically, most stored iron is bound by ferritin molecules; the largest amount of ferritin-bound iron is found in cells of the liver hepatocytes), the bone marrow and the spleen. Macrophages of the reticuloendothelial system store iron as part of the process of breaking down and processing hemoglobin from engulfed red blood cells.

Apparently pathologically, iron is also stored in hemosiderin. This molecule appears to be mainly the result of cell damage and is often found engulfed by macrophages that are scavenging regions of damage. It can also be found among people with iron overload due to frequent blood cell destruction and transfusions. The liver's stores of ferritin are the primary physiologic source of reserve iron in the body.

Men tend to have more stored iron than women, particularly women who must use their stores to compensate for iron lost through menstruation, pregnancy or lactation.

Adapted from the Wikipedia article "Body iron stores", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki