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Coeliac Tests and Getting Diagnosed

A medical diagnosis of coeliac disease is key to managing and improving your health. If you suspect you have coeliac disease, it is important to first talk to your doctor. It can take some time before symptoms are identified as being caused by coeliac disease as not all people have typical symptoms. Indeed, some people have minimal or no symptoms. Because the presentation of coeliac disease is so variable, many people remain unaware that they have the disease. When talking with your doctor, it’s important to mention all symptoms you’ve noticed. Remember also to mention if a relative has coeliac disease or dermatitis herpertiformis, or if you or a family member has been treated for anaemia. People with a first-degree relative with coeliac disease (parent, child or sibling) have a 1 in 10 risk of also developing the disease. This will give your doctor the best information and help in planning the best tests to work out if you do have coeliac disease. Making a definitive and correct diagnosis is essential to ensure that you receive the correct treatment and management and enable access to benefits such as the Pharmac part-subsidy.

Coeliac Disease Tests Used in Diganosis

Blood tests

Blood tests, or coeliac serology, measure specific antibody levels in the blood. These are typically elevated in people with untreated coeliac disease. They can be used to screen for coeliac disease, but a diagnosis should not be made on the basis of a single blood test alone. In children who have typical symptoms and who fit certain criteria, it is possible to make a diagnosis of coeliac disease without doing a small bowel biopsy if two separate blood samples show highly positive coeliac markers. However, this way of diagnosing coeliac disease without a small bowel biopsy is only able to be considered after discussion with a paediatric gastroenterologist. Other blood tests (such as blood count and iron studies) may also be helpful in working out when someone needs further tests for possible coeliac disease. These tests look at nutrients that might be low in someone with coeliac disease due to the damage in the gut interrupting normal absorption

Duodenal (Small Bowel) Biopsy This testing involves a gastroscopy (scope procedure) in which several tiny samples (biopsies) of the small bowel are taken under direct vision through the scope. An endoscopy takes less 10 minutes and is usually conducted as a day procedure under sedation. Children would typically have this procedure conducted during a light general anaesthetic. Once processed, the biopsies are then examined with a microscope for the presence of changes consistent with coeliac disease, including damage to the surface of the bowel (for example, villous atrophy).

Gene tests

Coeliac disease is associated with specific genetic markers known as HLA DQ2 and HLA DQ8, which can be tested for on a blood test. Almost everyone with coeliac disease will have one or other of these markers. However, at least half (if not more) of people in New Zealand will have a positive gene test – most of these people will never develop coeliac disease. Gene testing can be a very helpful test to do when the diagnosis is uncertain, because a negative test more-or-less rules out coeliac disease. However, a positive HLA test is not enough to confirm that a person has coeliac disease due to the widespread presence of the gene in the community.

Staying on a normal gluten-containing diet

Remain on a Gluten-containing diet

It is vital to continue eating gluten (not excluding gluten-containing foods) until the diagnosis of coeliac disease is confirmed (which for most people will be after the scope test). Reducing or excluding gluten prior to doing antibody blood tests, or especially prior to endoscopy and small bowel biopsy, will likely affect the results and delay or obscure the correct diagnosis. While the results of the gene testing will not be affected by being on a gluten-free diet, this testing is not often helpful in making a diagnosis (as detailed above). When someone has already been on a gluten-free diet for some time without a definitive diagnosis a gluten challenge would then be required to establish the diagnosis. A gluten challenge involves the consumption of gluten-containing foods (at a minimum of 4 slices of wheat-based bread or equivalent) daily for 4-8 weeks prior to testing (2 slices daily for children for a month). Following this period of time, blood tests and/or a small bowel biopsy would then be undertaken. A gluten challenge should only be conducted after a discussion with your doctor and planned in a coordinated and consistent fashion to ensure optimal outcomes.

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Already Diagnosed - What Next?

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Coeliac New Zealand is here to support health professionals with information and resources as they guide patients through their coeliac disease diagnosis and assist them in managing their gluten free diet. Health professionals are able to join as a paid members and can connect with our Medical Advisory Panel by emailing admin@coeliac.org.nz

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Coeliac New Zealand is available throughout your journey. As part of our community, you’ll get support, advice, and assistance. We work with health professionals, manufacturers, and researchers to raise awareness of coeliac disease in NZ.

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Latest News

14/11/2025

Travelling with coeliac disease - Part 3

Firenze is well known as the home of Coccoli, a golden, pillowy ball of fried dough, traditionally served warm with prosciutto and creamy cheese like stracchino or burrata. I haven't tried making it myself now that I'm back in New Zealand, as I have a feeling it won’t necessarily translate well, so I'm glad I […]