Iron deficiency. Misunderstood, misdiagnosed and mistreated.

Iron deficiency is a common medical problem that may present in a variety of ways to the general practitioner or the specialist. An understanding of iron physiology is relevant to diagnosis and treatment of iron deficiency. Human iron metabolism is a system based on conservation. For this reason, the most common cause of iron deficiency is loss of the normal conservation of iron and this usually means blood loss. The important implication is that the search for the cause of iron deficiency will usually focus on the gastrointestinal tract in males and non-pregnant, non-menstruating females. Iron deficiency is commonly misdiagnosed. The usual error is misinterpretation of the laboratory features of the anaemia of chronic disease. The serum iron is low, but the iron binding capacity is normal and ferritin is normal or high. There are problems and exceptions involved in interpretation of iron indices. Treatment of iron deficiency requires an understanding of iron absorption and the ability of the marrow to respond. In most circumstances, iron deficiency will respond to adequate doses of oral iron; however, there are a few situations when oral iron is unsuitable and parenteral iron is required. An inadequate response to iron may indicate inadequate supply of iron to the bone marrow (e.g. malabsorption, non-compliance) or failure of the marrow to respond (e.g. concomitant folate deficiency). Pregnancy is a special situation in which conservation of iron is overcome by fetal iron requirements and in which application of the knowledge of iron physiology should be applied to prevent and treat iron deficiency.