Iron deficiency is defined as a decreased total iron body content. Iron deficiency anemia occurs when iron deficiency is sufficiently severe to diminish erythropoiesis and cause the development of anemia.
Iron deficiency is the most prevalent single deficiency state on a worldwide basis.
It is important economically because it diminishes the capability of individuals who are affected to perform physical labor, and it diminishes both growth and learning in children. Persistent errors in iron balance lead to either iron deficiency anemia or hemosiderosis. Both are disorders with potential adverse consequences. Posthemorrhagic anemia is discussed in this section because it is an important cause of iron deficiency. Occasionally, patients with severe iron deficiency anemia from slow but persistent gastrointestinal bleeding have repeatedly negative testing of stool for hemoglobin.