Referral guideline – Coeliac disease diagnosis
Coeliac disease is common (1/100) and has a wide spectrum of presentations.
Accurate diagnosis is important as the disease is life-long.
An empirical gluten free diet makes diagnosis difficult or sometimes impossible.
Coeliac serology is used to test for coeliac disease (antibodies are elevated in the majority of coeliacs and a small minority of the general population). False positive elevation of coeliac antibodies is not unusual. Seronegative coeliac disease occurs but is rare.
When testing for coeliac disease, a patient must be on a diet containing adequate gluten. Ensure each of the following tests are performed:
- tissue transglutaminase – TTG IgA
- IgG dependent antibody (also known as deamidated antigliadin – DAG IgG)
- total IgA (as IgA deficiency can interfere with IgA antibodies).
In additional to coeliac serology, a duodenal biopsy is essential for diagnosis in most patients.
The “gene test”
HLA DQ2 or 8 is present in all patients with coeliac disease, but also in 30% of the general population. It should NOT be used to make a diagnosis or to justify gluten restriction.
HLA testing is primarily used to exclude coeliac disease in first degree relatives of index cases.
If HLA DQ2 or 8 negative, they will never develop coeliac disease and can be reassured. Specialist referral is unnecessary.
If HLA DQ2 or 8 positive, but seronegative for coeliac antibodies and without symptoms, they should not be placed on a gluten free diet. They may still develop coeliac disease in the future but specialist referral is unnecessary at this stage. In such patients, coeliac antibodies should be re-tested if symptoms develop, with appropriate referral at that point.
Request the following blood tests while maintaining gluten in the diet:
- TTG IgA (tissue transglutaminase antibodies)
- DAG IgG (deamidated antigliadin antibodies)
- Total IgA.
Do not stop gluten. Emphasize the importance of continuing a normal diet with gluten until the diagnosis is confirmed, usually by duodenal biopsy.
When to refer
- If abnormal coeliac serology is identified
- Do not refer patients on the basis of HLA testing without serology
Essential referral info
- Details and severity of any clinical symptoms
- Results of coeliac serology
- Height/Weight or BMI, if type 2 diabetes suspected
- Confirmation that the patient has been recommended to continue a normal diet
- Patient details
- Medicare number
- Parent/carer name and contact details
- Referring clinician details (name, contact details, provider number, date and length of referral)
Helpful referral info
- Family history of coeliac disease, autoimmune conditions or gastrointestinal malignancy