Your GP will take a blood sample and test it for antibodies usually present in the bloodstream of people with coeliac disease.
You should include gluten in your diet when the blood test is carried out because avoiding it could lead to an inaccurate result.
If coeliac disease antibodies are found in your blood, your GP will refer you for a biopsy of your gut.
However, it's sometimes possible to have coeliac disease and not have these antibodies in your blood.
If you continue to have coeliac disease-like symptoms despite having a negative blood test, your GP may still recommend you have a biopsy.
A biopsy is carried out in hospital, usually by a gastroenterologist (a specialist in treating conditions of the stomach and intestines). A biopsy can help confirm a diagnosis of coeliac disease.
If you need to have a biopsy, an endoscope (a thin, flexible tube with a light and camera at one end) will be inserted into your mouth and gently passed down to your small intestine.
Before the procedure, you'll be given a local anaesthetic to numb your throat and perhaps a sedative to help you relax.
The gastroenterologist will pass a tiny biopsy tool through the endoscope to take samples of the lining of your small intestine. The sample will then be examined under a microscope for signs of coeliac disease.
Tests after diagnosis
If you're diagnosed with coeliac disease, you may also have other tests to assess how the condition has affected you so far.
You may have further blood tests to check the levels of iron and other vitamins and minerals in your blood. This will help determine whether coeliac disease has led to you developing anaemia (a lack of iron in your blood) as the result of poor digestion.
If you appear to have dermatitis herpetiformis (an itchy rash caused by gluten intolerance), you may have a skin biopsy to confirm it. This will be carried out under local anaesthetic, and involves a small skin sample being taken from the affected area so it can be examined under a microscope.
A DEXA scan may also be recommended in some cases of coeliac disease. This is a type of X-ray that measures bone density. It may be necessary if your GP thinks your condition may have started to thin your bones.
In coeliac disease, a lack of nutrients caused by poor digestion can make bones weak and brittle (osteoporosis). A DEXA scan is not a test for arthritis, and only measures bone density to see whether you're at risk of bone fractures as you get older.
Many people feel overwhelmed when they're first diagnosed with coeliac disease. Switching to a gluten-free diet can be confusing, particularly if you've been eating foods that contain gluten for many years.
In the first few months after being diagnosed, many people accidentally eat foods that contain gluten, which may trigger a return of their symptoms.
You can learn more about coeliac disease and receive practical advice about switching to a gluten-free diet by contacting your local coeliac disease support group.
Support groups provide help and support for people with coeliac disease, including those recently diagnosed and those who've been living with the condition for years.
The Coeliac UK website provides further information as well as advice and details of support groups in your area.
The 2015 guidance published by the National Institute for Health and Care Excellence (NICE) provides details about when testing for coeliac disease should be carried out.
Adults or children should be tested if they have the following signs or symptoms:
- persistent unexplained gastrointestinal symptoms, such as feeling sick and being sick
- faltering growth
- prolonged fatigue (feeling tired all the time)
- unexpected weight loss
- severe or persistent mouth ulcers
- unexplained iron deficiency anaemia, vitamin B12 or folate deficiency anaemia
- type 1 diabetes, at diagnosis
- autoimmune thyroid disease (an underactive thyroid or overactive thyroid), at diagnosis
- irritable bowel syndrome (IBS) (in adults)
Testing is also recommended if you have a first-degree relative (parent, sibling or child) with coeliac disease.
Read the NICE guidance about the recognition, assessment and management of coeliac disease.