Iron Deficiency

Abstract

Iron deficiency is a leading cause of anaemia, affecting more than half a billion people worldwide. Depletion of iron stores precedes impaired production of iron‐containing proteins, most importantly haemoglobin. The two important stages of iron deficiency are (1) depletion of iron stores without anaemia and (2) depletion of iron stores with anaemia. The gastrointestinal tract mediates iron uptake into the body but is also the major source of iron loss and iron deficiency. Although anaemia is the most commonly recognised consequence of iron deficiency, injury to other organs has serious consequences that include fatigue, weakness and developmental delay in infants. Maternal iron deficiency during pregnancy can result in poor neonatal low iron stores and heightened risk of neurocognitive impairment. Oral iron supplements are the most convenient form of replacement but attention should be directed to the preparation as tolerance varies greatly depending on the specific iron salt.

Key Concepts

  • Iron is the second most common metal in the surface of the earth, but absorption is a challenge due to the low solubility of iron salts.
  • Gastric acidity and weak iron chelators, such as ascorbic acid, greatly facilitate iron absorption that occurs primarily in the duodenum and upper jejunum.
  • Gastrointestinal blood loss is the most common cause of iron deficiency.
  • Females of reproductive age suffer a high rate of iron deficiency due to menstrual blood loss.
  • Iron deficiency often produces anaemia in which extremely low haemoglobin levels are tolerated because of the slow rate of fall from the normal range.
  • Growth and developmental delay are particularly serious consequences of iron deficiency during infancy, often occurring in the wake of substantial maternal iron deficiency during gestation.
  • Oral iron is the most convenient form of replacement but often is poorly tolerated when sulphate is the anion in the salt.
  • A dramatic decline has occurred in serious complications of intravenous iron replacement, including anaphylaxis, with the advent of newer formulations.

Keywords: iron; anaemia; haemoglobin; bleeding; fatigue

Figure 1. Photomicrograph of microcytic, hypochromic red cells in a patient with iron deficiency.
Figure 2. Effect of iron deficiency on circulating iron and haematocrit. The number of red cells falls because there is insufficient iron to maintain haematopoiesis. The quantity of transferrin in the circulation rises while the amount of iron falls. The transferrin saturation (the ratio of plasma iron to transferrin) consequently falls as well.
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Further Reading

Bini EJ, Micale PL and Weinshel EH (1998) Evaluation of the gastrointestinal tract in premenopausal women with iron deficiency anemia. American Journal of Medicine 105: 281–286.

Bridges KR and Pearson HA (2007) Iron Deficiency. In: Anemia and Other Red Cell Disorders, pp. 97–131. New York: McGraw‐Hill.

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Stoltzfus RJ, Dreyfuss ML, Chwaya HM and Albonico M (1997) Hookworm control as a strategy to prevent iron deficiency. Nutrition Reviews 55: 223–232.

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How to Cite close
Bridges, Kenneth R(Feb 2015) Iron Deficiency. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002277.pub2]