A blood test that looks for the antibodies most closely linked with coeliac disease, an autoimmune condition in which eating gluten damages the lining of the small intestine. The panel measures total IgA alongside IgA tissue transglutaminase antibodies, the first-line test recommended in UK guidance, and adds IgA and IgG gliadin antibodies.
Results are only meaningful if you are eating gluten regularly at the time of the test. A positive result is a reason to see your GP, who can refer you to a gastroenterology specialist to confirm or exclude the diagnosis. This test cannot diagnose coeliac disease on its own, and it does not test for wheat allergy or non-coeliac gluten sensitivity.
What is measured
- Total IgA: checks that you make enough IgA for the IgA antibody tests to be reliable
- Tissue transglutaminase IgA (tTG IgA): the main screening antibody for coeliac disease
- Gliadin IgA: antibodies to gliadin, a component of gluten
- Gliadin IgG: an IgG-class antibody that can add information, particularly when IgA is low
Useful for
- People with ongoing digestive symptoms, tiredness or unexplained weight loss who want to discuss coeliac testing with their GP armed with a result
- People with a parent, brother, sister or child who has coeliac disease
- People with type 1 diabetes or autoimmune thyroid disease, where UK guidance recommends testing
Sample: venous blood (serum). Biomarkers: 4. Laboratory turnaround: 16 working days. Interpretation is not included in the price and is available separately.
Gluten & Coeliac Screen
- Total IgA (measured): the overall amount of immunoglobulin A in your blood. NICE defines IgA deficiency as total IgA below 0.07 g/L. If IgA is this low, IgA-based antibody results can be falsely negative.
- Tissue transglutaminase IgA (measured): the antibody NICE recommends as the first-choice test. It is the most important result on this panel.
- Gliadin IgA (measured): antibodies of the IgA class directed against gliadin. Interpreted together with tTG IgA.
- Gliadin IgG (measured): antibodies of the IgG class against gliadin. IgG-class results are mainly useful where total IgA is low.
None of the four results is calculated. The panel does not include endomysial antibodies, IgG tTG or genetic (HLA-DQ2/DQ8) testing. If your results need a second-line test, your GP or specialist can arrange it.
What happens in coeliac disease
Gluten is a group of proteins found in wheat, barley and rye. In people with coeliac disease, fragments of gluten (mainly gliadin) trigger an immune reaction in the small intestine. An enzyme called tissue transglutaminase modifies gliadin so that it is recognised more strongly by the immune system, and the body begins to produce antibodies against both the modified gliadin and the enzyme itself. Over time, the inflammation flattens the villi, the finger-like projections that absorb nutrients.
Because the antibodies are produced in response to gluten, their levels fall when gluten is removed from the diet. This is why every test in this panel depends on gluten being eaten at the time of sampling. NICE advises that any test is accurate only if a gluten-containing diet is being eaten during the diagnostic process.
Why these antibodies are measured
NICE guideline NG20 recommends that laboratories test for total IgA and IgA tissue transglutaminase (tTG) as the first choice in young people and adults. Where IgA tTG is only weakly positive, IgA endomysial antibodies (EMA) are used as a second step. Where a person is IgA deficient, IgG-based tests (IgG EMA, IgG deamidated gliadin peptide or IgG tTG) are considered instead.
The earliest blood tests for coeliac disease measured antibodies to native (unmodified) gliadin. Laboratory guidance now states that native gliadin antibodies are not recommended for detecting coeliac disease. Newer assays measure antibodies to deamidated gliadin peptides (DGP), which behave more like the modified gliadin seen in the gut. The British Society of Gastroenterology lists IgG DGP as an alternative when IgA is low. Your laboratory report will name the type of gliadin assay used, and a clinician will weigh the gliadin results alongside tTG IgA rather than in isolation.
How diagnosis is confirmed
Blood tests identify people who need further assessment. In adults, the diagnosis has traditionally been confirmed by a gastroenterologist using an endoscopy and small-bowel biopsy. Coeliac UK notes that newer approaches allow some adults with very high antibody levels to be diagnosed with a further blood test instead of a biopsy, but this decision belongs to the specialist team.
Your report will show each antibody result with the laboratory's own reference range or cut-off. Antibody assays from different manufacturers use different units and thresholds, so results from one laboratory cannot be compared directly with another.
A positive tTG IgA result
NICE recommends that adults with positive serology are referred to a gastrointestinal specialist. A clearly positive tTG IgA, or a weakly positive tTG IgA confirmed by a positive endomysial antibody test, counts as a positive result. If your tTG IgA is raised, please take your report to your GP. Do not start a gluten-free diet until the specialist assessment is complete, because removing gluten can make confirmatory tests unreliable.
A positive gliadin antibody with a normal tTG IgA
This pattern is harder to interpret, as gliadin antibodies can be found in people without coeliac disease. A clinician will weigh the assay type, your symptoms and your other results.
Negative results
A negative panel makes coeliac disease less likely, but it does not rule it out. Results can be falsely negative if you have been eating little or no gluten, if total IgA is low, or if you take medicines that suppress the immune system. NICE advises referral to a specialist if coeliac disease is still suspected despite negative serology.
Low total IgA
If total IgA is below the laboratory's threshold, the IgA-based results cannot be relied on, and the IgG gliadin result becomes more relevant. Low IgA is worth mentioning to your GP in its own right.
Coeliac disease can cause a wide range of symptoms, from diarrhoea, bloating and abdominal pain to tiredness, anaemia and weight loss, and some people have few symptoms at all. NICE recommends offering testing to people with persistent unexplained abdominal or gastrointestinal symptoms, prolonged fatigue or unexpected weight loss; to adults with irritable bowel syndrome; to people with type 1 diabetes or autoimmune thyroid disease at diagnosis; and to first-degree relatives of people with coeliac disease. It suggests considering testing in people with metabolic bone disorders, unexplained neurological symptoms, or unexplained subfertility or recurrent miscarriage.
If any of these apply to you, testing is also available through your GP on the NHS. A confirmed diagnosis requires specialist assessment, and the GP is the usual route to it.
Gluten sensitivity and wheat allergy
This panel is designed around coeliac disease. It does not diagnose non-coeliac gluten sensitivity, for which there is no validated biomarker; expert criteria rely on a structured dietary assessment under clinical supervision. It also does not test for wheat allergy, which involves a different type of antibody (IgE).
This test may suit
- Adults with symptoms in the groups NICE recommends for testing, who are currently eating gluten
- First-degree relatives of someone with coeliac disease
This test is less suitable if
- You already follow a gluten-free or low-gluten diet. Results are likely to be falsely reassuring. Please speak to your GP rather than reintroducing gluten on your own.
- You have already been diagnosed with coeliac disease. Antibody monitoring is usually arranged by your GP or specialist team.
- You are seeking a test for a child. Children should be assessed through the GP or a paediatric team.
- You have symptoms that need prompt medical review, such as blood in your stool, persistent vomiting, difficulty swallowing or significant unintended weight loss. Please contact your GP or NHS 111 rather than waiting for a private test.
Coeliac disease can be diagnosed at any age, including later life. Untreated, it can affect the absorption of iron, folate, calcium and other nutrients, which is why NICE lists metabolic bone disorders such as osteoporosis among the reasons to consider testing. These are established clinical associations; they do not mean that everyone with low bone density or anaemia has coeliac disease.
UK guidance does not recommend routine coeliac screening for adults with no symptoms and no family history.
- Keep eating gluten. NICE advises people undergoing testing to eat some gluten in more than one meal every day for at least six weeks before testing. If you have cut down or stopped eating gluten, talk to your GP before booking; reintroducing gluten should be planned with clinical guidance, particularly if it previously made you unwell.
- No fasting needed. You can eat and drink normally.
- Medicines: continue any prescribed medicines. Tell us if you take steroids or other medicines that suppress the immune system, as they can lower antibody levels.
- Timing: any time of day.
Choose how your sample is taken when you book. We confirm the collection option, any collection fee and the expected turnaround time before you book.
- Juvenology Clinic, Maidstone (82 King Street, Maidstone ME14 1BH): Available.
- Partner collection location, including London: Available on request. We confirm availability for your postcode before you book.
- Postal home finger-prick kit: Ask before ordering. We offer a home kit only where the laboratory confirms this test is suitable for a finger-prick sample.
Sample: Venous blood sample (serum)
Collection notes: You must be eating gluten regularly for the results to be meaningful (NICE advises gluten in more than one meal a day for at least six weeks before testing). If you have reduced or stopped gluten, speak to your GP before booking. No fasting needed; any time of day. Finger-prick suitability is confirmed by the laboratory before a home kit is offered.
The price of this test covers laboratory analysis and the laboratory's results report. The report lists each result beside the laboratory's reference range.
Beyond the blood test: optional support, priced separately
- Personalised written interpretation report: £50
- General consultation: £50
- Results consultation (results discussion and follow-up advice): £100
- Personalised programme: from £150, after we assess whether a programme suits you
Consultations are with Marina, an NMC-registered nurse with an Executive MSc in Longevity from the Geneva College of Longevity Science. She explains what your results show and how they relate to lifestyle. No prescription service is offered with these tests.
If a result suggests you need medical follow-up, we will recommend that you see your GP and, with your consent, can provide a letter to take with you. A blood test cannot rule out every condition. If you have symptoms, speak to your GP or NHS 111, and call 999 in an emergency.
Do I need to be eating gluten for this test?
Yes. Antibody levels fall once gluten is removed, so results taken on a low-gluten diet can be falsely reassuring. If you have already reduced gluten, please discuss this with your GP before you book.
Should I go gluten-free if my result is positive?
Not yet. NICE advises not starting a gluten-free diet until a specialist has confirmed the diagnosis, because doing so can make confirmatory tests inaccurate.
Why is total IgA included?
A small number of people make very little IgA. In them, the IgA antibody tests can read as negative even when coeliac disease is present. Measuring total IgA shows whether the IgA results can be trusted.
Will this tell me if I am gluten intolerant?
Not in the sense most people mean. It looks for the antibodies of coeliac disease. Non-coeliac gluten sensitivity has no validated blood marker, and wheat allergy needs a different type of test.
How long do results take?
The laboratory's stated turnaround for this panel is 16 working days.
Is interpretation included?
The price covers laboratory analysis and the laboratory's report, which shows each result against its reference range. If you would like help understanding your results, you can add a personalised written interpretation report (£50) or book a results consultation (£100). Where a result needs medical follow-up, we will advise you to see your GP and, with your consent, can write to them.
- Coeliac disease: recognition, assessment and management (NG20). National Institute for Health and Care Excellence, 2015. https://www.nice.org.uk/guidance/ng20/chapter/1-Guidance
- Ludvigsson JF, et al. Diagnosis and management of adult coeliac disease: guidelines from the British Society of Gastroenterology. Gut, 2014;63(8):1210–1228. https://doi.org/10.1136/gutjnl-2013-306578
- Husby S, et al. European Society Paediatric Gastroenterology, Hepatology and Nutrition guidelines for diagnosing coeliac disease 2020. Journal of Pediatric Gastroenterology and Nutrition, 2020;70(1):141–157. https://doi.org/10.1097/MPG.0000000000002497
- Anti-gliadin antibody assay. Association for Diagnostics & Laboratory Medicine (ADLM), Optimal Testing Guide to Lab Test Utilization, 2023. https://myadlm.org/advocacy-and-outreach/Optimal-Testing-Guide-to-Lab-Test-Utilization/A-F/Anti-Gliadin-Antibody-Assay
- Getting diagnosed. Coeliac UK. https://coeliac.org.uk/coeliac-disease/getting-diagnosed
- Catassi C, et al. Diagnosis of non-celiac gluten sensitivity (NCGS): the Salerno Experts' Criteria. Nutrients, 2015;7(6):4966–4977. https://doi.org/10.3390/nu7064966
