Iron Deficiency - Diagnosis

How is iron deficiency diagnosed?

A blood test is taken to look for the levels of iron (ferritin) in your blood and to make sure that you aren't also anaemic. If you are short of iron, your ferritin level will usually be low. A full blood count (FBC) will also be taken. This looks at the number, size and colour of your red blood cells. If you have iron deficiency, your red blood cells will be smaller and paler than normal. If there are also not as many red blood cells as normal then you also have iron-deficiency anaemia.

Will I need any other tests?

Sometimes it isn't possible to be absolutely certain that you are iron-deficient from the results of these two blood tests. In that case other tests may be needed, such as:

  • A blood film, in which blood is looked at down a microscope.
  • Measurement of vitamin B12 and folate.
  • Other tests of the body's iron stores - serum iron, transferrin (carries iron around the body), iron-binding capacity (IBC), for example.
  • Bone marrow biopsy.

Occasionally a trial of iron treatment will be recommended and the tests then repeated after a few weeks.

Whether or not you need other tests will also depend on whether the reason for you being short of iron is obvious. For example, if you are a woman in your twenties with heavy periods, it is unlikely you will need any other tests to confirm the reason for you having iron deficiency (although you would, of course, benefit from treatment to help your periods). If, however, you are in your sixties and also have indigestion as well as iron deficiency, your doctor will want to make sure that you don't have a condition such as a stomach ulcer or oesophagitis. Therefore, you may need further tests to look for such conditions.

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Dr Jacqueline Payne
Peer Reviewer:
Dr Hannah Gronow
Document ID:
29400 (v1)
Last Checked:
26 May 2017
Next Review:
26 June 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.