Patient information · Anaemia
I have anaemia – what tests do I need?
Quick answer
Anaemia is first investigated with blood tests (full blood count, ferritin and iron studies, B12, folate and a coeliac screen).
If unexplained iron-deficiency anaemia is confirmed, examining the gut with a gastroscopy and colonoscopy is usually recommended to find the cause.
Being told you have anaemia – a low level of haemoglobin or iron in the blood – can be worrying, especially when no cause is obvious. The most common type is iron-deficiency anaemia, and in adults this sometimes points to a problem in the gut that needs investigating. The good news is that the cause can usually be found with a clear, step-by-step set of tests.
Why anaemia is taken seriously
Iron-deficiency anaemia happens either because you are not absorbing enough iron, or because you are losing blood – often slowly and invisibly from the digestive tract. In men and in women past the menopause especially, unexplained iron-deficiency anaemia is an important signal to examine the stomach and bowel, because it can be the first sign of a condition that is much easier to treat when caught early. This is recognised in national (NICE) guidance.
The tests you are likely to need
Step 1 – blood tests
- Full blood count to confirm anaemia and show the size of the red cells.
- Ferritin and iron studies to confirm iron deficiency.
- B12 and folate, as deficiency in these also causes anaemia.
- Coeliac screen, since coeliac disease can cause poor iron absorption.
- Kidney, liver and thyroid tests, and inflammatory markers, to look for other causes.
Step 2 – checking the gut
If iron deficiency is confirmed without an obvious explanation, the next step is usually to examine the digestive tract:
- Gastroscopy (OGD) to look at the oesophagus, stomach and upper small bowel, with biopsies if needed.
- Colonoscopy to examine the whole large bowel.
- A FIT test may be used to help guide urgency, and occasionally further imaging or capsule studies are needed if both examinations are clear.
What happens after the tests
Most people with iron-deficiency anaemia turn out to have a treatable, non-serious cause – but the purpose of the tests is to be sure. Once a cause is identified it can be treated directly, and the iron levels are usually corrected with supplements or, occasionally, an iron infusion. Arranging the blood tests and endoscopy together privately means you can get from “I have anaemia” to a clear answer in a short space of time.
Frequently asked questions
Does anaemia always mean something is wrong with my bowel?
No. There are many causes of anaemia. But unexplained iron-deficiency anaemia in adults is an important reason to examine the stomach and bowel, because it can occasionally be the first sign of a condition that is best treated early.
Will I need both a gastroscopy and a colonoscopy?
Often yes, when iron-deficiency anaemia has no obvious cause, because the bleeding could come from either the upper or lower digestive tract. The two procedures can sometimes be arranged for the same day.
Can I just take iron tablets instead of having tests?
Iron supplements treat the low iron but not the underlying cause. If you have unexplained iron-deficiency anaemia, it is important to find out why, rather than only correcting the numbers.
How quickly can the tests be arranged privately?
Blood tests and endoscopy can usually be arranged within days privately, so you are not left waiting for answers.