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Diagnosing coeliac disease – the key facts

Coeliac disease is common and treatment improves outcomes 

  • Coeliac disease is an autoimmune disorder occurring in genetically susceptible individuals that results in an abnormal immune response to dietary gluten. 
  • Over 1 in 70 Australians are affected, but the broad clinical presentation means that coeliac disease is often overlooked – 4 out of 5 Australians remain undiagnosed. 
  • Symptoms often go unrecognised or patients may be truly asymptomatic. Targeted screening of at-risk patients is the most effective way to detect coeliac disease. 
  • Untreated coeliac disease is associated with a range of complications, including nutrient deficiencies; premature osteoporosis; abnormal liver function; higher rates of other autoimmune diseases, such as thyroid disease; infertility and poorer pregnancy outcomes; sepsis; and some forms of malignancy, especially lymphoproliferative disorders, such as lymphoma. 
  • Strict removal of dietary gluten – a protein found in wheat, rye, barley and oats – can arrest the damaging inflammatory immune response caused by gluten and is important to reduce morbidity and mortality. 

Symptoms and signs that should prompt testing for coeliac disease: 

  • Chronic or intermittent gastrointestinal symptoms, such as diarrhoea, constipation, abdominal pain, bloating or flatulence 
  • Prolonged fatigue (“tired all the time”) 
  • Iron deficiency anaemia or nutritional deficiency 
  • Sudden or unexpected weight loss 
  • Dental enamel defects or mouth ulcers 
  • Low-trauma fracture or premature osteoporosis 
  • Unexplained infertility or recurrent miscarriage 
  • Abnormal liver function tests (especially elevated transaminases) 
  • Peripheral neuropathy, ataxia or epilepsy 

High-risk associations that should prompt testing for coeliac disease:

  • Family history of coeliac disease (10-20% risk) 
  • Autoimmune thyroid disease 
  • Type 1 diabetes 
  • Other autoimmune disease, e.g. Addison’s disease, Sjogren’s syndrome, autoimmune liver disease 
  • Dermatitis herpetiformis (an itchy, blistering skin condition) 
  • Immunoglobulin A (IgA) deficiency 
  • Down’s syndrome 
  • Turner syndrome

How to test for coeliac disease: 

  1. Confirm your patient is consuming a gluten- containing diet for accurate results (see box below for management if they are already following a gluten free diet). 
  2. Request coeliac disease serology
  • Transglutaminase-IgA (tTG-IgA) and deamidated gliadin peptide-IgG (DGP-IgG) 
  • Transglutaminase-IgA (tTG-IgA) with total IgA level (to exclude the 2-3% of people with coeliac disease who are IgA deficient) 
  1. In select cases, HLA-DQ2/8 genotyping may be performed on blood or buccal scrape. 

The HLA DQ2/8 gene test can be useful when screening high-risk individuals,  e.g. those with a positive family history, to guide the need for further clinical work-up. 

How to interpret these tests:

  • If tTG-IgA and/or DGP-IgG is positive refer to a gastroenterologist for confirmatory small bowel biopsy. Serology alone is insufficient to diagnose coeliac disease
  • A positive HLA-DQ2/8 gene test is not diagnostic of coeliac disease in isolation (approximately half of the general population are positive). 
  • A negative HLA-DQ2/8 gene test has strong negative predictive value (<1% likelihood of coeliac disease being present) and means coeliac disease can be excluded
  • If coeliac serology is negative but the patient is symptomatic and positive for HLA-DQ2 and/or HLA-DQ8 then consider referral to a gastroenterologist for further work-up. 
  • A HLA-DQ2 and/or HLA-DQ8 positive relative with normal coeliac serology is at-risk for future development of coeliac disease and follow-up is warranted. Repeat screening is recommended if they become symptomatic (suggestive symptoms indicated over the page). 

If your patient is following a gluten free diet prior to testing:

Option 1 – Recommend a gluten challenge. One option is to recommend 8-10g gluten per day for 6 weeks prior to testing. This is equivalent to approximately 4 slices of wheat-based bread per day. Our fact sheet, Gluten Challenge , has more information.

Option 2 – If your patient is reluctant or unable to complete a gluten challenge, offer HLA-DQ2/8 gene testing. If HLA DQ2/8 gene testing is negative coeliac disease can be safely excluded. If it is positive, then option 1 is the only feasible diagnostic approach. 

Once coeliac disease has been diagnosed:

  1. Refer to a dietitian with a special interest in coeliac disease for nutritional education.
  2. Download the chronic disease management template ​​​​​​​ to guide ongoing follow-up.
  3. Provide a Coeliac Australia membership referral letter for ongoing support.


  1. Anderson RP. Aust Fam Physician. 2005 Apr;34(4):239-42;
  2. Kenrick K and Day AS. Aust Fam Physician. 2014 Oct;43(10):674-8;
  3. Steele R et al. Postgrad Med J. 2011 Jan;87(1023):19-25;
  4. Tye-Din JA et al. Intern Med J. 2015 Apr;45(4):441-50;
  5. NICE (UK) guidelines: Coeliac disease: recognition, assessment and management (2015).