Anaemia, iron deficiency - Diagnosing iron deficiency anaemia

See your GP if you experience symptoms of iron deficiency anaemia, such as tiredness, shortness of breath and heart palpitations.

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 help 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'll 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, it means there isn't much iron stored in your body and you may have iron deficiency anaemia.

Read more about blood tests and a red blood cell count.

Vitamin B12 and folate deficiency

If your GP thinks your anaemia may be the result of 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.

Vitamin B12 and folate deficiency anaemia is more common in people who are over the age of 75.

Finding the cause

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

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

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

Physical examination

A physical examination will usually only be needed if the cause of your iron anaemia deficiency hasn't been identified by examining your medical history and asking you about your symptoms.

In such cases, your GP may:

  • examine your stomach (abdomen) to check for any physical signs of gastrointestinal bleeding
  • look for signs of heart failure, such as swollen ankles ‐ 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

A rectal examination is usually only needed if you're bleeding from your bottom. It's a common procedure that can help your GP find out if there's something in your gastrointestinal tract that's causing bleeding.

Your GP will insert a lubricated gloved finger into your bottom to feel for any abnormalities.

A rectal examination isn't something to be embarrassed about, as it's a procedure your GP will be used to doing. It shouldn't cause significant pain, but it may cause some slight discomfort ‐ this will only last for a minute.

Pelvic examination

Women may have a pelvic examination if their GP thinks 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 lubricated gloved fingers into your vagina to feel whether your womb (uterus) is tender or enlarged.

A pelvic examination won't be carried out without your consent (permission), 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. They'll 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's a possibility your symptoms could be caused by stomach cancer or bowel cancer, although this is unlikely.

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


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