Ferric cation
Iron is a transition metal with a symbol Fe and atomic number 26. By mass, it is the most common element on Earth. Iron is an essential element involved in various metabolic processes, including oxygen transport, deoxyribonucleic acid (DNA) synthesis, and energy production in electron transport. Resulting from inadequate supply of iron to cells due to depletion of stores, iron deficiency is the most common nutritional deficiency worldwide, particularly affecting children, women of childbearing age, and pregnant women. Iron deficiency may be characterized without the development of anemia, and may result in functional impairments affecting cognitive development and immunity mechanisms, as well as infant or maternal mortality if it occurs during pregnancy. The main therapeutic preparation of iron is [DB13257], and iron-sucrose may also be given intravenously.  Iron exists in two oxidation states: the ferrous cation (Fe2+) and ferric cation (Fe3+). Non-haem iron in food is mainly in the ferric state, which is the insoluble form of iron, and must be reduced to the ferrous cation for absorption. Ferric citrate (tetraferric tricitrate decahydrate) is a phosphate binder indicated for the control of serum phosphorus levels in patients with chronic kidney disease on dialysis.