Iron deficiency anemia is the most common cause of microcytic anemia. Iron absorption occurs in the duodenum and proximal jejunem and is related to total dietary iron intake, as well as to its bioavailability. A small amount of iron is lost daily via sweat, skin desquamation and GI tract shedding, and a small amount is absorbed from the diet. Citrates and vitamin C, in contrast, promote iron absorption by forming soluble complexes. A normal ferritin level does not rule out iron deficiency, as it is an acute phase reactant and often rises in the presence of chronic inflammation, liver dysfunction, malignancy or infection.
Microcytosis occurs after several months of decreased total body iron stores.
The definitive test for iron deficiency is the demonstration of absence of iron on a Prussian blue stain of bone marrow aspirate, but this is usually unnecessary to make the diagnosis. Table 3 Work-up of iron deficiency anemia 1. Humoral factors such as tumor necrosis factor, interleukin-1 and prostaglandins, which are released in infections and inflammatory disorders, contribute to the development of anemia by suppressing erythropoesis. Patients with AOCD have an inappropriately low erythropoeitin level. Management is best directed towards the identification and treatment of the underlying disease, but transfusions may be given if the anemia is severe.