Clinical Review

ABC of Clinical haematology: Iron deficiency anaemia

BMJ 1997; 314 doi: http://dx.doi.org/10.1136/bmj.314.7077.360 (Published 01 February 1997) Cite this as: BMJ 1997;314:360
  1. Rebecca FrewinAndrew HensonDrew Provan

    Introduction

    Iron deficiency is the commonest cause of anaemia worldwide and is frequently seen in general practice. The anaemia of iron deficiency is caused by defective synthesis of haemoglobin, resulting in red cells that are smaller than normal (microcytic) and contain reduced amounts of haemoglobin (hypochromic).

    Diagnosing iron deficiency is usually straightforward–the major challenge is determining the cause of the anaemia

    Iron metabolism

    Iron has a pivotal role in many metabolic processes, and the average adult contains 3-5 g of iron, of which two thirds is in the oxygen-carrying molecule haemoglobin.

    View this table:

    Daily dietary iron requirements per 24 hours

    A normal Western diet provides about 15 mg of iron daily, of which 5-10% is absorbed, principally in the duodenum and upper jejunum, where the acidic conditions help the absorption of iron in the ferrous form. Absorption is helped by the presence of other reducing substances, such as hydrochloric acid and ascorbic acid. The body has the capacity to increase its iron absorption in the face of increased demand–for example, in pregnancy, lactation, growth spurts, and iron deficiency.

    Once absorbed from the bowel, iron is transported across the mucosal cell to the blood, where it is carried by the protein transferrin to developing red cells in the bone marrow. Iron stores comprise ferritin, a labile and readily accessible source of iron, and haemosiderin, an insoluble form found predominantly in macrophages.

    About 1 mg of iron a day is shed from the body in urine, faeces, sweat, and cells shed from the skin and gastrointestinal tract. Menstrual losses of an additional 20 mg a month and the increased requirements of pregnancy (500-1000 mg) contribute to the higher incidence of iron deficiency in women of reproductive age.

    Nail changes in iron deficiency anaemia (koilonychia).

    Clinical features of iron deficiency

    The symptoms accompanying iron deficiency depend on how rapidly the anaemia develops. In …

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