Iron deficiency anaemia - Diagnosis 

Diagnosing iron deficiency anaemia 

If you experience symptoms of iron deficiency anaemia, see your GP. A simple blood test can usually confirm the diagnosis.

Your GP may also carry out a physical examination and ask you a number of questions, to determine the cause of your anaemia.

Blood test

To diagnose iron deficiency anaemia, a blood sample is taken from a vein in your arm and a full blood count is made. This means all the different types of blood cells in the sample will be measured.

If you have anaemia:

  • your levels of haemoglobin (a substance that transports oxygen) will be lower than normal
  • you will have fewer red blood cells (which contain haemoglobin) than normal
  • your red blood cells may be smaller and paler than usual

Your GP may also test for a substance called ferritin – a protein that stores iron. If your ferritin levels are low, there is not much iron stored in your body and you may have iron deficiency anaemia.

Read more about blood tests.

Vitamin B12 and folate deficiency

If your GP thinks your anaemia may be due to a vitamin B12 and folate deficiency, the levels of these substances may be tested. Folate works with vitamin B12 to help your body produce red blood cells.

This type of anaemia is more common in people who are over 75 years old.

Read more about vitamin B12 and folate deficiency anaemia.

Finding the cause

To determine the underlying cause of your anaemia, your GP may ask questions about your lifestyle and medical history. For example, you may be asked about:

  • your diet  to see what you typically eat and whether this includes any iron-rich foods
  • any medicines that you take  to see if you have been regularly taking a type of medicine that can cause gastrointestinal bleeding (bleeding from the stomach and intestines), such as ibuprofen or aspirin
  • your menstrual pattern  if you're a woman, your GP may ask if you have been experiencing particularly heavy periods
  • your family history  you will be asked if your immediate family has anaemia or a history of gastrointestinal bleeding or blood disorders
  • blood donation  your GP may ask if you regularly donate blood
  • other medical conditions  your GP may ask if you have recently had another illness or experienced other symptoms, such as weight loss

Iron deficiency anaemia is common during pregnancy. If you are pregnant, your GP will usually only look for an alternative cause if a blood test has shown a particularly low haemoglobin level, or if your symptoms or medical history suggest your anaemia may be due to something else.

Physical examination

A physical examination will usually only be needed if the cause has not been found through your medical history and symptoms.

In these cases, your GP may:

  • examine your abdomen (stomach) to check for any physical signs of gastrointestinal bleeding
  • look for signs of heart failure (when your heart is not pumping blood around your body very efficiently), such as swollen ankles, as heart failure can have some similar symptoms to iron deficiency anaemia

Two other possible types of physical examination you may have are explained below.

Rectal examination

rectal examination is usually only needed if you are bleeding from your bottom. This is a common procedure that can help your GP find out if there is something in your gastrointestinal tract that is causing bleeding. Your GP will insert a gloved, lubricated finger into your bottom so they can feel any abnormalities.

A rectal examination is not something to be embarrassed about, as it is a procedure your GP will be used to doing. It should not cause great pain or discomfort, and you will only feel a slight feeling, as if your bowels are moving.

Pelvic examination

Women may have a pelvic examination if their GP suspects heavy menstrual bleeding (menorrhagia) may be the cause of their anaemia.

During a pelvic examination, your GP will examine your vulva and labia (external sex organs) for signs of bleeding or infection. They may also examine you internally. This will involve your GP inserting gloved, lubricated fingers into your vagina to feel whether your uterus (womb) is tender or enlarged.

A pelvic examination will not be done without your consent, and you can choose to have someone with you.

Referral to a specialist

In some cases, your GP may refer you to a gastroenterologist (a specialist in treating digestive conditions), who can carry out a more thorough examination.

For example, you may be referred to a gastroenterologist if your GP can't identify a cause and you have a particularly low haemoglobin level, or if your GP thinks there is a possibility your symptoms could be caused by stomach or colon cancer (although these are unlikely to be the cause).

If you are a woman with heavy periods, you may be referred to a gynaecologist if you don't respond to treatment with iron supplements.

Page last reviewed: 24/03/2014

Next review due: 24/03/2016


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The 5 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Gareth5000 said on 14 September 2014

Dilberts mom (comment on 09/08/2013)
One cause of low iron is hypothyroidism which is very poorly understood and diagnosed. It also causes a wide variety of symptoms including those that you mention.
The diagnosis of hypothyroidism in the UK and worldwide is hopeless. You may wish to look into this.
I have been discharged twice from the endocrinology department at a very large teaching hospital in London, being told that there is nothing wrong with me from an endocrine point of view.
I went on to have a parathyroidectomy surgery in January this year having diagnosed myself with Primary Hyperparathyroidism and, having got my own private tests done, find that I am also hypothyroid and have some sort of adrenal problem.
Well done NHS!

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smarterthanyou said on 03 May 2014

I think it very important that anyone using this site is aware that it isn't totally informative. I have pernicious anaemia and tested strongly positive for parietal cell antibodies. These antibodies destroy the parietal cells in the stomach that produce hydrochloric acid, without which iron from food is poorly absorbed. I became extremely iron anaemic but a whole team of gastroenterologists, not to mention my GP were not aware that pernicious anaemia is also a cause for iron deficiency anaemia. The parietal cells also produce the intrinsic factor vital for breaking down the B12 molecule. I was extremely ill but when I got my diagnosis my serum B12 was "normal" as the test used by the NHS is wholly inaccurate. Guidelines for treatment with B12 injections are also inadequate. I saved my own life and my own health and I now take ferrous fumerate daily and do my own B12 injections weekly. Anyone reading this website should be aware of the importance of the parietal cell in the stomach and how ignorant the NHS is on this subject.

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Dilberts mom said on 09 August 2013

I have iron deficient anemia that continues to come back when I stop taking the iron. My Ferritin level is 4 this time, last time it as 2. I have had all the tests done last year which showed absolutely nothing. I don't want to repeat the tests again this year. I am reading about Kidney issues and heart problems associated with this. I have all the symptoms of iron deficient anemia and would like to know what the chances are that I have the other problems. I have swollen ankles, shortness of breath, brittle nails, rapid heartbeat when I walk up the stairs, sore tongue, extreme fatigue, basically nearly everything listed I have. Can anyone answer what other causes there could be for this? I am so exhausted all the time I can hardly stay awake driving home. I don't like the side affects from the iron pills but have no alternative. I am being retested in 3 months to see if my levels are up, if so than I have to stop the pills again for another 4-5 months, be retested if low then repeat all those tests again. This is frustrating. Any insight to this is greatly appreciated.

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iron defeciency anaemia said on 31 May 2013

the information given on iron deficiency anemia is good

similarly i am suffering from iron deficiency anemia since last 8 years due to pregnancy to improve my blood i have taken so many measures like (yoga and diet) but i could not recover from my problem instead i became obese pesent i am getting tired for simple things also so kindly provide me suggestion for this problem

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skimbo22 said on 27 August 2012

does not answer my problem.will have to seek answers elsewhere.

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Blood tests

Blood tests are carried out for a variety of reasons and can provide a wide range of information