Iron is an essential element of various metabolic processes in humans, including DNA synthesis, electron transport, and oxygen transport. Unlike other minerals, iron levels in the human body are controlled only by absorption. The mechanism of iron excretion is an unregulated process arrived at through loss in sweat, menstruation, shedding of hair and skin cells, and rapid turnover and excretion of enterocytes. In the human body, iron exists mainly in erythrocytes as the heme compound hemoglobin (approximately 2 g of iron in men and 1.5 g in women), to a lesser extent in storage compounds (ferritin and hemosiderin) and in muscle cells as myoglobin. Iron is also found bound to proteins (hemoprotein) and non-heme enzymes involved in oxidation-reduction reactions and the transfer of electrons (cytochromes and catalase).
Additionally, approximately 2.2% of total body iron is found in the so-called labile pool, a poorly defined and reactive pool of iron that forms reactive oxygen species via the Fenton Reaction, which forms complexes with a drug class known as chelators. Iron chelators treat iron overload, a condition often caused by transfusion therapies used to treat thalassemias and other anemias.
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