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:
- 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).
- 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)
- 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 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:
- Refer to a dietitian with a special interest in coeliac disease for nutritional education.
- Download the chronic disease management template to guide ongoing follow-up.
- Provide a Coeliac Australia membership referral letter for ongoing support.
- Anderson RP. Aust Fam Physician. 2005 Apr;34(4):239-42;
- Kenrick K and Day AS. Aust Fam Physician. 2014 Oct;43(10):674-8;
- Steele R et al. Postgrad Med J. 2011 Jan;87(1023):19-25;
- Tye-Din JA et al. Intern Med J. 2015 Apr;45(4):441-50;
- NICE (UK) guidelines: Coeliac disease: recognition, assessment and management (2015). www.nice.org.uk/guidance/ng20