Coeliac test at home: why must you keep eating gluten first?

Who should be tested — and who should see a doctor instead

Coeliac disease is an immune reaction to gluten that damages the small intestine. NICE recommends offering a blood test to people with persistent or unexplained stomach or bowel symptoms, prolonged tiredness, unexpected weight loss, unexplained iron, vitamin B12 or folate deficiency, type 1 diabetes or autoimmune thyroid disease, symptoms of irritable bowel syndrome, or a parent, sibling or child with coeliac disease. If tiredness is your main symptom, see also the five blood tests worth asking for when you're always tired.

See a GP or doctor rather than ordering a kit if you have blood in your stool or bleeding from your bottom, weight loss you can't explain, or a lasting change in bowel habit. The NHS says black or bloody stools need an urgent appointment or a call to NHS 111.

The gluten rule: how much, and for how long

The blood test measures antibodies your immune system makes in response to gluten. If you've stopped eating gluten, those antibodies fall, and the test can come back normal even if you have coeliac disease. That's why every guideline says to keep eating it first:

• UK: NICE advises gluten in more than one meal every day for at least six weeks. Coeliac UK puts that at a minimum of 3 grams of gluten a day and preferably 6; 3 grams is about one and a half to two slices of wheat bread or 90 grams of cooked pasta. The British Society of Gastroenterology's 2026 guideline adds that if you can't tolerate that much, you can halve it and extend the challenge by another six weeks.
• Canada: Celiac Canada describes a modified challenge of 3 grams a day for at least six weeks, or a classic challenge of 6 to 10 grams a day for six to eight weeks, under medical supervision.
• US: the Celiac Disease Foundation suggests 3 to 6 grams a day for 12 weeks, supervised, and never during pregnancy. The American College of Gastroenterology notes a challenge may not be advisable after severe reactions to gluten.

If you've already gone gluten-free, talk to your doctor before reintroducing it. A genetic test can sometimes rule coeliac disease out without a gluten challenge.

What the blood test measures, and how accurate it is

The standard first test is tissue transglutaminase IgA (tTG-IgA), measured together with total IgA. The total IgA matters because about 2% of people with coeliac disease have low IgA, which makes tTG-IgA falsely negative; they need an IgG-based test instead, according to the British Society of Gastroenterology. In people eating gluten, tTG-IgA picks up about 90% of cases, and the Celiac Disease Foundation says it is negative in about 96% of people without the condition.

After a positive result

A positive result isn't a diagnosis. The NHS and American College of Gastroenterology say adults should be referred to a gastroenterologist, who normally confirms the diagnosis with a biopsy of the small intestine. The British Society of Gastroenterology's 2026 guideline allows some adults with symptoms and very high antibody levels (at least ten times the upper limit) to be diagnosed without a biopsy, after discussion with a specialist. Either way, keep eating gluten until the specialist says otherwise.

Home kits: what they measure and what they miss

Lab-based kits that measure both tTG-IgA and total IgA are the closest to a clinic test. In the US, Everlywell sells an at-home finger-prick kit with both for $119, and Labcorp OnDemand offers a lab-drawn test for $119 that adds IgG tests automatically if your IgA is low. Quest's panel was $89.60 plus a $6 fee on sale when checked. LetsGetChecked's US celiac test was unavailable.

In the UK, the options are thinner. Rapid finger-prick tests sold in pharmacies check tTG-IgA alone, according to an NIHR review, so they can miss people with low IgA. Coeliac UK says home kits don't give a confirmed diagnosis. Because the NHS test is free, a GP is usually the better first step in the UK.

Getting tested free: US, Canada and UK

United States

When a primary-care clinician orders the test because of symptoms, it's billed to your insurance as a diagnostic test, so your usual deductible and co-pay apply. Without insurance, the cash lab prices above, $90–119, are similar to a kit.

Canada

In Ontario, the tTG-IgA and total IgA tests are covered by OHIP when a physician, nurse practitioner or midwife orders them; tests ordered by naturopaths aren't covered. In other provinces, ask your family doctor or a walk-in clinic for a requisition.

United Kingdom

Your GP can order the test free on the NHS for any of the reasons NICE lists, and will check total IgA at the same time.

Compare your options

Prices checked 18 October 2026 and can change.

What to do next

1. Check the red flags above; bleeding or weight loss need a doctor, not a kit.
2. Keep eating gluten in more than one meal a day for at least six weeks before testing.
3. Get the test free through your GP or doctor, or use a kit that measures total IgA as well as tTG-IgA.
4. If it's positive, ask for a referral to a gastroenterologist and keep eating gluten until you're seen.
5. If it's negative but symptoms continue, go back to your doctor: other causes are possible.

Common questions

Related guides

• Ferritin vs iron: why a “normal” iron result can still mean you're low
• At-home thyroid test or a GP blood test: which should you get first?
• Free care routes in the US, Canada and UK

Sources

1. NICE. Coeliac disease: recognition, assessment and management (NG20).
2. Coeliac UK. Getting diagnosed — the gluten challenge and home tests. Accessed 18 October 2026.
3. British Society of Gastroenterology. Guidelines on the diagnosis and management of coeliac disease in adults. Gut, 2026.
4. Rubio-Tapia A, et al. ACG clinical guidelines: diagnosis and management of celiac disease. American Journal of Gastroenterology, 2023.
5. Celiac Disease Foundation. Screening — blood tests and gluten challenge.
6. Celiac Canada. Gluten challenge.
7. Celiac Canada. Celiac blood test covered by OHIP in Ontario. Updated August 2026.
8. NHS. Coeliac disease — diagnosis.
9. NHS. Bowel cancer — symptoms.
10. Everlywell. Celiac disease screening test — price and markers. Accessed 18 October 2026.
11. Labcorp OnDemand. Celiac disease antibody test — price. Accessed 18 October 2026.
12. Quest Diagnostics. Celiac disease panel — price. Accessed 18 October 2026.
13. LetsGetChecked. Celiac test — availability. Accessed 18 October 2026.
14. NIHR Community Healthcare MedTech and In Vitro Diagnostics Co-operative. Horizon scanning report: point-of-care tests for coeliac disease.

General information, not medical advice — see our medical disclaimer. Written to the WhereToStart editorial policy. Next scheduled review: 18 April 2027.