How effective is a blood test for coeliac disease?

The test looks for antibodies linked with an immune reaction to gluten and may include a check that your body can produce the relevant antibodies. A positive result supports coeliac disease, while a negative result makes it less likely but may not exclude it if the test was done after reducing gluten, if the illness is early, or if another condition affects antibody production.

Further assessment may involve a specialist review and, in some adults, a small-bowel biopsy. Do not begin a gluten-free diet before discussing testing, because avoiding gluten can reduce the antibodies and make the result harder to interpret.

Tell the clinician about your symptoms, family history, previous diet changes and any immune conditions. Continue eating your usual gluten-containing diet unless a clinician has given different instructions. Bring a list of medicines and supplements. If the result is positive or unclear, ask what confirmation is needed before making long-term dietary changes.

Arrange medical review for ongoing diarrhoea, weight loss, persistent tiredness, recurrent mouth ulcers or signs of anaemia. Seek urgent care for severe dehydration, fainting, black or bloody stools, or intense abdominal pain with repeated vomiting. These features need assessment regardless of a previous blood-test result.

Ask which antibodies were checked, whether you need to keep eating gluten, whether your result needs repeating, and whether a gastroenterology referral or biopsy is recommended.