How does iron deficiency anemia develop?
Iron balance is tightly regulated under normal physiologic conditions (Figure 1). Iron absorption is also normally tightly regulated. Under normal circumstances, the small amount of iron lost from the stool (usually in sloughed intestinal cells or by tiny amounts of bleeding) is approximately 1 mg per day. Iron deficiency results when the absorptive capacity of the small intestine (which increases to a maximum of 2-4 fold above normal) is exceeded by iron loss over a prolonged period of time. It is clear that it takes considerable time (several months at the very least) to exhaust the normal body stores of iron. However, this happens frequently when specific lesions in the gastrointestinal tract bleed as little as several mL of blood per day. Definition of iron deficiency anemia The diagnosis of iron deficiency and iron deficiency anemia should be considered any time that a low serum hemoglobin level or hematocrit is encountered. A reduced mean corpuscular volume (MCV) supports the dia
