Iron deficiency anaemia can be effectively diagnosed by a full blood examination and serum ferritin. Serum iron levels should not be used to diagnose iron deficiency.
Anaemia is defined as a haemoglobin (Hb) concentration below the reference range for the laboratory performing the test. The World Health Organization (WHO) defines anaemia as a Hb level below 130 g/L in men, 120 g/L in non-pregnant women and 110 g/L in pregnant women and preschool children.
A serum ferritin level below 30 μg/L for an adult is diagnostic of iron deficiency.
Ferritin is an acute phase reactant and is elevated in inflammation, infection, liver disease and malignancy. This can potentially lead to misleading results in patients who are iron deficient with co-existing systemic illness.
Serum ferritin levels of 30-100 ug/L in an anaemic adult may represent iron deficiency if there is coexisting inflammatory disease. A C-Reactive protein (CRP) may be useful in these cases. See initial tests for further information.
Additional tests may be considered when the clinical features and haematology profile are suggestive of iron deficiency, but ferritin is normal. Consider consulting with a pathologist or haematologist before ordering these additional tests. Guidance may be required for results interpretation of additional tests of iron status where co-existing illness is present.
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