Coeliac Disease in Primary Care: What Has Changed?
- 6 days ago
- 4 min read
Coeliac disease affects approximately 1% of the population, yet many patients remain undiagnosed for years. While traditionally associated with diarrhoea and malabsorption, modern coeliac disease frequently presents with iron deficiency anaemia, fatigue, bloating, osteoporosis, abnormal liver tests, and symptoms suggestive of irritable bowel syndrome (IBS). Diagnostic delays of 6–10 years remain common.
Why This Matters in New Zealand
In primary care, coeliac disease often hides in plain sight.
Many patients are investigated repeatedly for IBS, iron deficiency, fatigue, or bloating before coeliac disease is considered. Increasing awareness and broader testing have improved detection rates, but missed and delayed diagnoses remain common.
Routine screening should be considered in:
Type 1 diabetes
Autoimmune thyroid disease
Down syndrome
First-degree relatives of affected individuals
Testing should also be considered in patients with:
Iron deficiency anaemia
Chronic diarrhoea
Persistent bloating
Unexplained fatigue
Osteoporosis
Abnormal liver function tests
Suspected IBS
Specialist Insight
Most adults diagnosed with coeliac disease today do not present with diarrhoea.
If you only test patients with diarrhoea, you will miss many cases of coeliac disease.
What Has Changed?
The diagnosis and management of coeliac disease has evolved considerably over the last decade.
Then
Classical presentation with diarrhoea and weight loss
Biopsy required in all adults
High-dose gluten challenges
Now
Iron deficiency, fatigue and IBS-type symptoms are common presentations
Selected adults may qualify for a no-biopsy diagnostic pathway
Lower-dose gluten challenges are increasingly used in selected patients
Emerging T-cell based blood tests may simplify future diagnosis
Diagnostic Approach
First-Line Testing
Request:
tTG-IgA
Total IgA
If total IgA is low:
DGP-IgG should be used
Common Pitfall
True seronegative coeliac disease is rare.
Before concluding coeliac disease is seronegative, ask:
Was the patient eating gluten?
Is there IgA deficiency?
Has appropriate testing been performed?
Approximately 7% of patients with coeliac disease have IgA deficiency, making standard IgA-based tests unreliable.
One of the Most Common Mistakes I See
Starting a Gluten-Free Diet Before Testing
Many patients now trial a gluten-free diet before seeking medical advice.
While symptoms may improve, this does not establish a diagnosis of coeliac disease.
A confirmed diagnosis matters because it influences:
Long-term monitoring
Bone health assessment
Nutritional surveillance
Family screening
Adherence to a lifelong gluten-free diet
A New Zealand Reality
Access to public endoscopy varies considerably across New Zealand.
Obtaining appropriate serology before dietary modification is often crucial, as a gluten-free diet can complicate future diagnostic assessment and delay diagnosis.
The Modern Gluten Challenge
Traditionally, patients were asked to consume the equivalent of approximately four slices of bread daily for 4–8 weeks before testing.
Increasing evidence suggests that lower-dose challenges (approximately one slice of bread daily) may be sufficient in selected adults who are unable to tolerate traditional protocols.
What About HLA Testing?
HLA-DQ2 and HLA-DQ8 testing is primarily a rule-out test.
Negative HLA testing makes coeliac disease extremely unlikely.
A positive result does not establish the diagnosis, as a substantial proportion of the general population carry these genes.
Adult No-Biopsy Diagnosis: A Major Update
Traditionally, all adults required duodenal biopsy confirmation.
The 2025 European Society for the Study of Coeliac Disease (ESsCD) guideline introduced a selective no-biopsy pathway for carefully selected adults.
Potential criteria include:
Age under 45 years
tTG-IgA ≥10× upper limit of normal
Positive EMA on repeat testing
Ongoing gluten consumption
Compatible clinical presentation
Biopsy is still generally recommended where:
Antibody levels are lower
IgA deficiency is present
Alarm symptoms exist
Diagnostic uncertainty remains
Latest Update
This approach is increasingly being adopted internationally and is likely to influence future clinical practice in New Zealand.
Follow-Up: What Should GPs Expect?
Symptoms often improve within weeks of commencing a gluten-free diet.
However:
Serology may sometimes take over a year to normalise
Histological recovery may take several years
Antibody trends are often more important than a single result
Repeat gastroscopy is not routinely required when:
Symptoms have resolved
Serology is improving
No red flags are present
Consider specialist review if:
Symptoms persist
Serology plateaus or rises
Refractory coeliac disease is suspected
Persistent Symptoms? Think GUTS
A practical framework for evaluating ongoing symptoms in treated coeliac disease.
G — Gluten Exposure
Hidden gluten contamination remains the most common cause.
U — Unrelated Conditions
Consider:
IBS
Food intolerances
Microscopic colitis
Pancreatic exocrine insufficiency
Bile acid diarrhoea
T — Think Again
Was the original diagnosis correct?
S — Specialist Referral
True refractory coeliac disease is rare, affecting approximately 1% of patients.
Looking Ahead
Emerging T-cell and IL-2 based blood tests may eventually allow diagnosis without prolonged gluten exposure, particularly in patients already following a gluten-free diet.
Research continues into:
Gluten-degrading enzymes
Microbiome-based therapies
Immune-targeted treatments
At present, however, a strict gluten-free diet remains the cornerstone of treatment.
Five Things I Want You to Remember
Think of coeliac disease more often.
Test before starting a gluten-free diet.
Always request total IgA alongside tTG-IgA.
Selected adults may now qualify for a no-biopsy diagnostic pathway.
Persistent symptoms rarely equal refractory coeliac disease.
Most coeliac disease now hides in plain sight. Think of it, test for it, and diagnose it properly.
Useful Resources
Disclaimer
This resource is intended for healthcare professionals and reflects available evidence at the time of publication. Clinical decisions should be individualised according to patient circumstances, local referral pathways, and specialist advice where appropriate.
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