Ajax Harwood Clinic

Celiac testing: should I be tested?

Last reviewed 2026-09-23Content ved932f585d7d
Reference tool — not medical advice. Clinician judgement always required.

Celiac disease

Defined testing criteria

Also called: celiac disease, coeliac disease, gluten intolerance, celiac sprue, gluten enteropathy

Patients raise celiac disease after GI symptoms, an ND-ordered panel, a relative's diagnosis, or after noticing they feel better avoiding gluten. NDs are often the first to raise it, and are often right to: celiac disease is genuinely under-recognized in patients with non-classic presentations such as isolated iron deficiency or fatigue.

Raises suspicion

  • • Persistent diarrhea, bloating, or abdominal pain while eating a normal, gluten-containing diet
  • • Unexplained iron-deficiency anemia, or unexplained weight loss
  • • First-degree relative with celiac disease
  • • Another condition associated with higher celiac prevalence: type 1 diabetes, autoimmune thyroid disease, Down syndrome
  • • IBS-type symptoms being worked up for the first time (celiac serology is part of standard IBS work-up)

Does not raise suspicion

  • • Feeling generally better on a gluten-free diet without a confirmed diagnosis: this can reflect celiac disease, NCGS, FODMAP sensitivity, or simply eating fewer processed foods, and does not by itself confirm celiac disease
  • • Mild, occasional bloating with no other features

Red flags

  • • GI bleeding, or iron-deficiency anemia with no other explanation
  • • Weight loss that is unintentional
  • • New GI symptoms at age 50 or older, especially with a family history of colorectal cancer or IBD: needs its own work-up alongside celiac testing

Who to test

  • Anyone with suggestive symptoms, a relevant family history, or an associated autoimmune condition, currently eating gluten: Celiac serology (tTG-IgA + total IgA) (Standard)tTG-IgA plus total IgA is the correct first test; testing must happen before or without a gluten-free diet, since antibody levels fall on a gluten-free diet
  • Positive celiac serologyDuodenal biopsy (no TestSelect entry; GI-referred) confirms the diagnosis before committing to a lifelong gluten-free diet
  • Unexplained iron-deficiency anemia as the presenting feature: Ferritin (Standard), Complete blood count (CBC) (Situation-specific), Celiac serology (tTG-IgA + total IgA) (Standard)Celiac disease is a recognized, treatable cause of iron deficiency even without GI symptoms

More likely instead

Counselling script

“Celiac disease is real, testable and often missed, so it's worth checking if you have gut symptoms, low iron, a close relative with celiac, or another autoimmune condition. The blood test only works while you're still eating gluten, so if you've already cut it out we may need a supervised gluten challenge first. A positive blood test is usually confirmed with a small bowel biopsy before a lifelong gluten-free diet.”

Chart snippet (OSCAR-safe plain text)

Concern discussed, not tested

Concern re: celiac disease discussed, raised by patient or ND.
Discriminating features: GI symptoms while on gluten, unexplained iron deficiency, weight loss, family history, associated autoimmune disease; reviewed.
Assessment: features support testing; patient currently eating gluten.
Plan: celiac serology (tTG-IgA plus total IgA) ordered; biopsy referral if positive.
Ref: ACG celiac disease guideline 2023; Choosing Wisely Canada clinical biochemistry recommendations 2025.
Patient given info page: https://celiac.ajaxharwoodclinic.com/patient
Revisit if: symptoms persist despite negative testing, or new red-flag features develop.

Testing ordered

Concern re: celiac disease discussed.
Discriminating features: GI symptoms, iron deficiency, or relevant family history present; patient eating gluten confirmed.
Assessment: celiac serology indicated.
Plan: tTG-IgA and total IgA ordered; GI referral for biopsy planned if positive.
Ref: ACG celiac disease guideline 2023; OHIP Schedule of Benefits 2026.
Patient given info page: https://celiac.ajaxharwoodclinic.com/patient
Revisit if: symptoms persist, biopsy pending, or new red-flag features develop.

Revisit if

  • • Symptoms persist despite negative testing
  • • New GI bleeding, weight loss, or worsening anemia
  • • Serology positive: biopsy referral and gluten-free diet planning needed

References

  1. 1. American College of Gastroenterology. American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease (2023)tTG-IgA serology as the recommended initial screening test for celiac disease
  2. 2. Canadian Society of Clinical Chemists / Choosing Wisely Canada. Clinical Biochemistry recommendations (2025)Recommendation against tTG-IgG or deamidated gliadin peptide antibody testing as the initial screen
  3. 3. Ontario Ministry of Health. Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026) (2026)Two celiac tests are insured under OHIP for diagnosis
  4. 4. Canadian Association of Gastroenterology. Canadian Association of Gastroenterology Clinical Practice Guideline for the Management of Irritable Bowel Syndrome (IBS) (2019)Serological testing for celiac disease is part of the standard IBS work-up
Evidence notes

Tag rationale: A, not borderline. Celiac disease has well-defined serologic and histologic diagnostic criteria (ACG 2023). This record agrees with the Celiac serology (tTG-IgA + total IgA) test record it links to. Where the ND is right: celiac disease is genuinely under-recognized when the presentation is iron deficiency, fatigue, or associated autoimmune disease rather than classic GI symptoms, so an ND raising it is often a reasonable, not an overreaching, suggestion.

Non-celiac gluten/wheat sensitivity (NCGS)

Clinical diagnosis — no single test

Also called: non-celiac gluten sensitivity, gluten sensitivity, wheat sensitivity, gluten intolerance (non-celiac), NCGS

Patients who feel better avoiding gluten, but who have tested negative for celiac disease and wheat allergy, are often told by an ND or by their own research that they have 'gluten sensitivity.' The symptom improvement on a gluten-free diet is frequently real; the question is whether gluten specifically, rather than something else in wheat or the diet change itself, is the cause.

Raises suspicion

  • • GI symptoms (bloating, diarrhea, abdominal pain) or extra-intestinal symptoms (fatigue, brain fog, headache) that reproducibly worsen with gluten-containing food and improve off it, in a patient who has been properly tested for celiac disease and wheat allergy while still eating gluten
  • • Symptom improvement on a gluten-free diet that is confirmed, not just recalled, ideally with a structured reintroduction

Does not raise suspicion

  • • Feeling better gluten-free without having been tested for celiac disease first: testing must happen before or the result is unreliable
  • • Self-diagnosis based on online symptom checklists alone

Red flags

  • • Same red flags as celiac disease (GI bleeding, unexplained weight loss, iron-deficiency anemia, new symptoms at age 50 or older): these should redirect to the celiac and red-flag GI work-up, not a diet trial

Who to test

  • Anyone considering an NCGS diagnosis: Celiac serology (tTG-IgA + total IgA) (Standard)Celiac disease and wheat allergy must be excluded first, while the patient is still eating gluten, before NCGS is considered
  • Celiac disease and wheat allergy excluded, symptoms persist and are attributed to glutenDouble-blind placebo-controlled gluten challenge (Salerno criteria; no TestSelect entry; best done with dietitian support) is the closest thing to a confirmatory test, though in practice a supervised open elimination-reintroduction is more feasible

More likely instead

  • • IBS
  • • FODMAP sensitivity (fructans in wheat, rather than gluten itself, may explain the response)
  • • Celiac disease (if serology or exposure history was inadequate before testing)
  • • Food allergy (IgE-mediated) (wheat allergy, if reactions are rapid and involve hives, swelling, or breathing symptoms)

Counselling script

“If celiac disease and wheat allergy have been properly ruled out while you were still eating gluten, and your symptoms clearly track with gluten, non-celiac gluten sensitivity is a reasonable working diagnosis. Without that testing done first, we can't be confident it's specifically gluten and not something else in wheat, like the FODMAPs. A structured trial, ideally with a dietitian, is the most reliable way to confirm the pattern.”

Chart snippet (OSCAR-safe plain text)

Concern discussed, not tested

Concern re: non-celiac gluten sensitivity discussed.
Discriminating features: symptom pattern tracking with gluten intake; celiac and wheat allergy status reviewed.
Assessment: no validated diagnostic test for NCGS exists; diagnosis is one of exclusion.
Plan: celiac serology reviewed or ordered before any gluten-free trial; structured elimination-reintroduction discussed.
Ref: Salerno Experts' Criteria for NCGS 2015; ACG celiac disease guideline 2023.
Patient given info page: https://celiac.ajaxharwoodclinic.com/patient
Revisit if: red-flag features develop, or symptoms do not track clearly with gluten on structured reintroduction.

Testing ordered

Concern re: non-celiac gluten sensitivity discussed.
Discriminating features: gluten-associated symptoms present; celiac disease and wheat allergy not yet excluded.
Assessment: celiac serology indicated before considering NCGS, while patient is still eating gluten.
Plan: tTG-IgA and total IgA ordered.
Ref: Salerno Experts' Criteria for NCGS 2015; ACG celiac disease guideline 2023.
Patient given info page: https://celiac.ajaxharwoodclinic.com/patient
Revisit if: serology returns positive, or symptoms persist despite a confirmed gluten-free trial.

Revisit if

  • • Celiac serology returns positive: reassess as celiac disease
  • • Symptoms do not clearly improve on a confirmed gluten-free trial
  • • New red-flag GI features develop

References

  1. 1. International panel of experts (Catassi et al.). Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts' Criteria (2015)— older guidelineExpert consensus diagnostic protocol for NCGS using a double-blind placebo-controlled gluten challenge after excluding celiac disease and wheat allergy
  2. 2. Canadian Association of Gastroenterology. Canadian Association of Gastroenterology Clinical Practice Guideline for the Management of Irritable Bowel Syndrome (IBS) (2019)Context: routine food-related testing beyond celiac serology is not recommended in IBS-type symptoms, supporting a structured rather than broad-panel approach
Evidence notes

Tag rationale: B, not borderline. NCGS is a real, patient-reported pattern, but per the Salerno consensus ([1], flagged older_than_10y at 2015; still the standard-cited diagnostic framework and not superseded by a newer consensus located in this session) there is no biomarker and no single confirmatory test; diagnosis rests on excluding celiac disease and wheat allergy, then a supervised gluten challenge. In practice the formal double-blind challenge is rarely done outside research; an honest gap is that no Canadian guideline for NCGS specifically was located in this session, so the primary source is the international Salerno consensus. Subdomain is 'celiac' per batch instruction, alongside the celiac record, since patients typically arrive asking about gluten broadly and the two conditions are worked up together.

General clinical reference for Ajax Harwood Clinic. Not medical advice, and not a substitute for individualized clinical assessment.