For years, Ottawa patients who asked about a celiac blood test were told it was not covered and cost extra. That has changed: Ontario's laboratory schedule now insures the screening test, with two conditions that matter enormously, one about age and one about what you eat. This guide explains what the test looks for, who qualifies for coverage, and why going gluten-free before the blood draw is the single most common way to get a misleading result.
What the celiac blood test measures
Celiac disease is an autoimmune condition in which eating gluten, the protein in wheat, barley and rye, triggers the immune system to damage the lining of the small intestine. The screening blood test looks for tissue transglutaminase immunoglobulin A antibodies (tTG-IgA), which the immune system produces in response to that reaction. A total serum IgA is measured at the same time, because a small number of people make very little IgA and would test falsely negative on the tTG-IgA test alone; for them, the physician orders an IgG-based test instead.
A positive antibody result does not by itself confirm celiac disease. In most adults, and in many children, the diagnosis is confirmed by a gastroenterologist, often with a biopsy of the small intestine. What the blood test does well is identify who needs that referral. Our overview of celiac disease symptoms describes the wide range of ways the condition can present, from digestive complaints to anemia, skin rashes and fatigue.
What OHIP covers, and the two conditions
Ontario's Schedule of Benefits for Laboratory Services, effective April 1, 2026, lists two insured tests for the diagnosis of celiac disease: tTG-IgA (fee code L570) and celiac serum IgA (L571). They are insured only for patients who are over two years of age and on a gluten-containing diet. The serum IgA is insured only when billed together with the tTG-IgA. Coverage began as a pilot and, after advocacy by Celiac Canada, the Minister of Health made it a permanent part of the laboratory schedule; Celiac Canada notes that the ministry restricts ordering to physicians, nurse practitioners and midwives.
Additional celiac tests, such as deamidated gliadin peptide antibodies or HLA genetic typing, are not part of that listing; if your physician orders them, ask whether they are insured for you. As with every other test, a requisition from a practitioner not authorized under Ontario regulation, or a test wanted for a third party, is patient-pay. Our page on what OHIP covers explains how that works at the desk.
Why you must be eating gluten
This is the point that undoes more celiac tests than anything else. The antibodies the test detects are produced only while gluten is being eaten. Cut gluten out for a few weeks and antibody levels begin to fall; after a few months on a strict gluten-free diet they can be normal even in someone who has celiac disease. The blood test then comes back negative, the diagnosis is missed, and the person is left unsure whether to keep avoiding gluten for life.
If you already suspect a problem, the advice from gastroenterologists and from Celiac Canada is to keep eating gluten until testing is complete. If you have already gone gluten-free and want to be tested, do not simply restart on your own; talk to your physician about a supervised gluten challenge, in which a set amount of gluten, commonly described as the equivalent of a couple of slices of wheat bread a day, is eaten for a number of weeks before the blood draw. How long, and whether a challenge is advisable for you, is a decision for your physician, particularly if your previous reactions were severe.
Who is usually tested
Providers consider celiac serology for a wide range of presentations, not just classic digestive symptoms. Testing is commonly discussed for:
- Chronic diarrhea, bloating, abdominal pain or unexplained weight loss
- Iron deficiency or anemia that does not respond as expected
- First-degree relatives of someone with celiac disease
- People with type 1 diabetes or autoimmune thyroid disease, who have a higher rate of celiac disease
- Children with poor growth, delayed puberty or persistent tummy complaints; children under two need a different approach, which is why coverage starts after age two
- Persistent fatigue, mouth ulcers, an itchy blistering rash, or unexplained bone loss
Whether testing is appropriate for you is your provider's decision; the list is a guide to the conversations that often lead to a requisition.
Preparing for the test
- Keep eating gluten as normal in the weeks before the test; do not "clean up" your diet beforehand
- No fasting is needed for celiac serology on its own; if a fasting test shares the requisition, the fasting rule applies to the visit
- Bring your Ontario health card and your signed requisition, valid for six months from the date it was authorized
- For children, see our guide to blood tests for kids in Ottawa for tips on numbing cream, distraction and timing
Understanding your result
The report shows your tTG-IgA level against Bio-Test's reference range, together with your total IgA. A negative result in someone eating gluten normally makes celiac disease unlikely, though your physician may still investigate other causes of your symptoms. A positive or borderline result means a referral and further assessment, and it is important not to start a gluten-free diet at that point until your physician or gastroenterologist tells you to, because the confirmatory tests also rely on gluten being in your diet. Serology takes a little longer to report than routine chemistry; ask at collection what turnaround to expect.
Getting a celiac test in Ottawa
Celiac serology is a standard blood draw, collected on a walk-in basis at all 11 Bio-Test patient service centres across Ottawa-Carleton and Eastern Ontario, or by appointment through the patient portal. Bring your requisition and health card, keep gluten in your diet until the draw is done, and glance at our preparation guide if other tests share the form. If your physician is also checking for iron deficiency, our guide to ferritin and iron testing explains what those results mean.