Iron is one of the most abundant earth elements, yet only traces are essential for living cells of plants and animals. In humans, most of the iron is contained within the porphyrin ring of heme in proteins such as hemoglobin, myoglobin, catalase, peroxidases, and cytochromes. as well as iron-sulfur proteins such as NADH dehydrogenase and succinate dehydrogenase, in which iron is present in clusters with inorganic sulfur. In all these systems, iron has the ability to interact reversibly with oxygen and to function in election transfer reactions that makes it biologically indispensable.
The average adult male contains approximately 4 grams of body iron. About 65% to 70% is found in hemoglobin, 4% in myoglobin, and less than 1% in other iron-containing enzymes and proteins. The remaining 25% to 30% represent the storage pool of iron. By contrast, women have a much smaller iron reserve, with the adult female body containing about 3 grams of iron. Women also have a slightly lower hemoglobin concentration in blood than males. Patients with iron overload diseases may store as much as 20 g of iron.
Excess iron can result in cell injury. Menstruation, bleeding due to injury, or bloodletting help to excrete excess iron. Other than that, humans do not excrete excess iron effectively.
Iron overload can result from an increased absorption of dietary iron or from parenteral administration of iron. When the iron burden exceeds the body’s capacity for safe storage, the result is widespread damage to the liver, heart, joints, pancreas, and other endocrine organs.1 It must be noted that low serum iron alone is not an indicator of iron deficiency. Serum ferritin, transferrin levels and total iron binding capacity must confirm the diagnosis before iron is supplemented. To improve iron absorption and utilization, adequate amounts of vitamins C and B, especially folic acid, B6, and B12, must be provided. (more…)