Iron deficiency and iron deficiency anaemia are common. The serum ferritin level is the most useful indicator of iron deficiency but interpretation can be complex. Identifying the cause of iron deficiency is crucial. Oral iron supplements are effective first-line treatment. Intravenous iron infusions, if required, are safe, effective and practical.
- Measurement of the serum ferritin level is the most useful diagnostic assay for detecting iron deficiency, but interpretation may be difficult in patients with comorbidities.
- Identifying the cause of iron deficiency is crucial; referral to a gastroenterologist is often required.
- Faecal occult blood testing is not recommended in the evaluation of iron deficiency; a negative result does not impact on the diagnostic evaluation.
- Oral iron is an effective first-line treatment, and simple strategies can facilitate patient tolerance.
- For patients who cannot tolerate oral therapy or require more rapid correction of iron deficiency, intravenous iron infusions are safe, effective and practical, given the short infusion times of available formulations.
- Intramuscular iron is no longer recommended for patients of any age.
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Iron deficiency and iron deficiency anaemia are common conditions that are often encountered in general practice. Iron deficiency refers to the state of reduced iron stores, whereas in iron deficiency anaemia the deficiency is severe enough to cause anaemia.1 Iron deficiency is the most common cause of anaemia worldwide, affecting more than two billion people.1,2 In a study of Australian blood donors, 12% of female and 1.3% of male new donors had iron deficiency, and 3.8% of all potential new donors had anaemia.3 Our recognition of the importance of iron in health and disease has increased significantly in recent years, and new concepts have emerged. Common terms pertaining to iron deficiency are defined in Box 1.1,4
Even in the absence of anaemia, iron deficiency can affect cognition in people of all ages, and impair quality of life and worsen comorbid disease in adults.5-8 Iron deficiency anaemia in pregnancy has been associated with a risk of low birthweight, prematurity and maternal morbidity.9-11 Iron deficiency affects between 37 and 61% of patients with chronic heart failure, and its treatment can improve exercise capacity and quality of life.12 Iron deficiency is common among people with chronic kidney disease, and correction is required to address anaemia and improve disease-specific quality of life scores.12
Iron deficiency and iron deficiency anaemia are therefore highly prevalent in the community and in hospital patients and are associated with considerable morbidity. This review outlines important considerations for identifying at-risk individuals and diagnosing and treating iron deficiency and iron deficiency anaemia. An algorithm for the identification and management of adults with iron deficiency is shown in the Flowchart.
How to diagnose iron deficiency
Diagnosing iron deficiency can be straightforward, but many patients have active comorbid disease that influences laboratory test results and their interpretation. Understanding the impact of patient factors on the clinical and laboratory manifestations is important, as physiological states of increased iron requirement, chronic inflammation and disorders that impair absorption will influence both the diagnosis and management of iron deficiency.