Celiac Wire

Diagnosis

Getting diagnosed with coeliac disease

The single most consequential mistake is removing gluten before you are tested. It makes a definitive diagnosis much harder to obtain.

Updated 3 min read 16 citations Evidence strength 5/5

Why you must keep eating gluten

Coeliac disease is diagnosed by detecting the immune response to gluten and the intestinal damage it causes. Remove gluten and both fade: antibodies fall toward normal over weeks to months, and the villi begin to recover. Test at that point and the result is uninterpretable.

The remedy is a gluten challenge — deliberately reintroducing gluten for several weeks before testing — which is unpleasant enough that many people decline it and end up with a lifelong restrictive diet and no diagnosis. That matters more than it sounds: without a diagnosis you may not get follow-up bone density monitoring, coeliac-specific dietetic support, or in several European countries the prescription and subsidy entitlements that come with it.

The testing sequence

Standard diagnostic pathway in adults
StepTestWhat it tells you
1Tissue transglutaminase IgA (tTG-IgA) + total IgAThe screening test. Total IgA is measured because deficiency causes false negatives.
2Endomysial antibody (EMA) if tTG is equivocalHighly specific confirmatory serology.
3Duodenal biopsy, multiple samples including the bulbVillous atrophy graded by the Marsh classification. Patchy disease is why multiple samples matter.
4HLA-DQ2/DQ8 in ambiguous casesA negative result effectively excludes coeliac disease.

The 2025 European guidelines [2] and the American College of Gastroenterology guidance agree on this general architecture, with differences at the margins — particularly around when a biopsy can be omitted.

Diagnostic pathway

Potential coeliac disease

A confusing category: positive serology, normal biopsy. A systematic review and meta-analysis in Gut examined clinical outcomes in this group, which matters because the management question — treat now or monitor — has no obvious answer. Many, though not all, progress to villous atrophy over time.

Who should be tested

  • Chronic diarrhoea, bloating, or unexplained weight loss.
  • Iron deficiency anaemia without an obvious cause — a very common presentation, and one where gastroenterology guidance specifically raises coeliac testing [7].
  • A first-degree relative with coeliac disease, where prevalence is roughly ten times the background rate.
  • Type 1 diabetes, autoimmune thyroid disease, and several other autoimmune conditions that cluster with it.
  • Unexplained raised transaminases, recurrent mouth ulcers, or early osteoporosis.
  • Dermatitis herpetiformis, which is effectively coeliac disease of the skin and is diagnostic in itself.

Note what is not on that list: bloating alone, in the absence of anything else, is far more often irritable bowel syndrome — and the ACG guideline on IBS management [4] is the more relevant document for most of those presentations. Coeliac disease and IBS overlap enough that the distinction genuinely needs testing rather than guessing.

Common questions

Can I be diagnosed without a biopsy?
In children, some pathways permit it at very high antibody titres with confirmatory testing. In adults, biopsy remains standard in most European practice.
How much gluten do I need to eat before testing?
Guidance varies but generally means normal gluten-containing meals daily for several weeks. Your gastroenterologist should specify the duration.
Are home antibody tests reliable?
They can flag a possible problem but cannot diagnose. A positive result needs laboratory confirmation and a biopsy; a negative one does not exclude the disease, particularly if you have already reduced gluten.
My tests were negative but gluten makes me ill. What now?
That is a recognised situation — see non-coeliac gluten sensitivity, where the FODMAP evidence is particularly relevant.

References

Every citation below links to the original peer-reviewed record on PubMed or via DOI. Nothing here is a substitute for medical advice.

  1. Assessment of growth status and nutritional management of prematurely born infants after hospital discharge: A position paper of the ESPGHAN Nutrition Committee Haiden N, Luque V, Domellöf M, et al. · Journal of pediatric gastroenterology and nutrition · 2025 · Clinical guideline DOIPubMed 40341618
  2. European Society for the Study of Coeliac Disease 2025 Updated Guidelines on the Diagnosis and Management of Coeliac Disease in Adults. Part 1: Diagnostic Approach Al-Toma A, Zingone F, Branchi F, et al. · United European gastroenterology journal · 2025 · Clinical guideline DOIPubMed 40999951Full text
  3. Updated joint ESPGHAN/NASPGHAN guidelines for management of Helicobacter pylori infection in children and adolescents (2023) Homan M, Jones NL, Bontems P, et al. · Journal of pediatric gastroenterology and nutrition · 2024 · Clinical guideline DOIPubMed 39148213
  4. Autoimmune diseases and adverse pregnancy outcomes: an umbrella review Singh M, Wambua S, Lee SI, et al. · Lancet (London, England) · 2023 · Systematic review DOIPubMed 37997130
  5. ACG Clinical Guideline: Management of Irritable Bowel Syndrome Lacy BE, Pimentel M, Brenner DM, et al. · The American journal of gastroenterology · 2021 · Clinical guideline DOIPubMed 33315591
  6. European Society for the Study of Coeliac Disease (ESsCD) guideline for coeliac disease and other gluten-related disorders Al-Toma A, Volta U, Auricchio R, et al. · United European gastroenterology journal · 2019 · Clinical guideline DOIPubMed 31210940Full text
  7. Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis Singh P, Arora A, Strand TA, et al. · Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association · 2018 · Meta-analysis DOIPubMed 29551598
  8. ACG clinical guidelines: diagnosis and management of celiac disease Rubio-Tapia A, Hill ID, Kelly CP, et al. · The American journal of gastroenterology · 2013 · Clinical guideline DOIPubMed 23609613Full text
  9. Down Syndrome and Autoimmune Disease Hom B, Boyd NK, Vogel BN, et al. · Clinical reviews in allergy & immunology · 2024 · Review DOIPubMed 38913142Full text
  10. AGA Clinical Practice Update on Management of Iron Deficiency Anemia: Expert Review DeLoughery TG, Jackson CS, Ko CW, et al. · Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association · 2024 · Review DOIPubMed 38864796
  11. AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review Moshiree B, Drossman D, Shaukat A · Gastroenterology · 2023 · Review DOIPubMed 37452811
  12. AGA Clinical Practice Update on Management of Refractory Celiac Disease: Expert Review Green PHR, Paski S, Ko CW, et al. · Gastroenterology · 2022 · Review DOIPubMed 36137844
  13. Dermatitis Herpetiformis: An Update on Diagnosis and Management Reunala T, Hervonen K, Salmi T · American journal of clinical dermatology · 2021 · Review DOIPubMed 33432477Full text
  14. Medical Care of Adults With Down Syndrome: A Clinical Guideline Tsou AY, Bulova P, Capone G, et al. · JAMA · 2020 · Review DOIPubMed 33079159
  15. Epidemiology of Celiac Disease Ludvigsson JF, Murray JA · Gastroenterology clinics of North America · 2019 · Review DOIPubMed 30711202
  16. Incidence, prevalence, and co-occurrence of autoimmune disorders over time and by age, sex, and socioeconomic status: a population-based cohort study of 22 million individuals in the UK Conrad N, Misra S, Verbakel JY, et al. · Lancet (London, England) · 2023 · Journal article DOIPubMed 37156255