Coeliac Disease — Symptoms, Diagnosis and Why You Must Not Stop Gluten Before Testing
TL;DR — Coeliac disease is an autoimmune reaction to gluten that damages the lining of the small bowel. About 1 in 70 Australians has coeliac disease; around 80% are undiagnosed. The diagnosis requires both a positive blood test (coeliac serology) and confirmation by duodenal biopsy at gastroscopy — while you are still eating gluten. Treatment is a strict, lifelong gluten-free diet. Dr Goutham performs diagnostic gastroscopy with duodenal biopsy across Brisbane, Redland and Logan.
Important: if you suspect coeliac disease, do not start a gluten-free diet until all testing is complete. Stopping gluten causes the blood test and biopsy to normalise, which means the diagnosis cannot be made. See the patient PDF: Coeliac Disease Diagnosis Pathway.
What is coeliac disease?
Coeliac disease is an autoimmune condition triggered by gluten — a protein found in wheat, rye, barley and to a lesser extent oats. In affected people, the immune system mistakenly attacks the lining of the small bowel whenever gluten is eaten. Over time this flattens the absorptive surface (villous atrophy), reducing the absorption of iron, calcium, folate, B12 and other nutrients.
Symptoms
Coeliac disease can present in many ways — some classic, many subtle.
- Chronic diarrhoea, constipation, bloating, abdominal pain
- Iron-deficiency anaemia (often the only sign)
- Vitamin D, folate or B12 deficiency
- Unexplained weight loss; failure to thrive in children
- Mouth ulcers, dental enamel defects
- Dermatitis herpetiformis (an itchy, blistering rash on elbows / knees / buttocks)
- Unexplained osteoporosis or fractures
- Subfertility, recurrent miscarriage
- Family history of coeliac disease in a first-degree relative
- Type 1 diabetes, autoimmune thyroid disease, Addison’s disease
Causes and risk factors
Coeliac disease has a strong genetic component. Around 95% of people with coeliac disease carry the HLA-DQ2 gene; most of the remainder carry HLA-DQ8. However, the genes alone are not sufficient — around 30–40% of the general population carries DQ2/DQ8 but only a small fraction develops coeliac disease. The trigger is environmental (gluten exposure) plus likely other factors not yet fully understood. First-degree relatives of someone with coeliac disease have a 10–15% lifetime risk.
How is coeliac disease diagnosed?
The diagnostic pathway has three core steps:
- Keep eating gluten — do not start a gluten-free diet until both tests are complete.
- Coeliac serology — blood test for tissue transglutaminase IgA (tTG-IgA) and total IgA. A positive tTG-IgA suggests coeliac disease but does not confirm it.
- Gastroscopy with duodenal biopsy — Dr Goutham performs a 10-minute upper endoscopy under sedation and takes multiple biopsies from the duodenum. Pathology takes 7–14 days. A diagnosis is made when biopsies show villous atrophy and increased intraepithelial lymphocytes (Marsh classification 3a/b/c) in someone with positive serology while on a gluten-containing diet.
If you have already started a gluten-free diet, you will need a gluten challenge — eating at least 4 slices of bread (or equivalent) per day for 6–8 weeks — before retesting. This is the only way to confirm or exclude coeliac disease if gluten has already been excluded.
How is coeliac disease treated?
Treatment is a strict, lifelong gluten-free diet. Even small amounts of gluten cause ongoing intestinal damage, even when no symptoms are felt. The treatment plan includes:
- Referral to an accredited dietitian familiar with coeliac disease
- Bone density (DXA) scan — coeliac disease increases osteoporosis risk; baseline and follow-up scans are recommended
- Replacement of any deficient nutrients (iron, B12, folate, vitamin D, calcium)
- Coeliac Australia membership for community support and updated food information
- Testing of first-degree relatives — 10–15% will also have coeliac disease, often without classic symptoms
- Follow-up gastroscopy at 12–24 months in some cases, to confirm mucosal healing
When to see a specialist
- Positive coeliac serology (tTG-IgA) — needs biopsy confirmation before lifelong dietary change
- Unexplained iron-deficiency anaemia, B12 deficiency, folate deficiency, or vitamin D deficiency
- Persistent GI symptoms (bloating, diarrhoea, abdominal pain) without an explanation
- First-degree relative diagnosed with coeliac disease
- Type 1 diabetes, autoimmune thyroid disease, or Down syndrome (higher risk)
- Already started a gluten-free diet but want a definitive diagnosis — needs a gluten challenge
What to expect at your appointment with Dr Goutham
At consultation Dr Goutham will review your symptoms, family history, prior pathology and any current dietary changes. If serology has not yet been done, he will arrange it. If serology is positive (or if symptoms are highly suggestive and you have already had a positive screen via your GP), the next step is gastroscopy with duodenal biopsy. The procedure itself takes 10 minutes under sedation; you’ll spend 2–3 hours at the day-surgery facility from arrival to discharge. Results take 7–14 days; a written report goes to your GP and a copy to you. If confirmed, Dr Goutham will discuss the next steps including dietitian referral, DXA scan, and first-degree relative testing.
Frequently asked questions
Is gluten sensitivity the same as coeliac disease?
No. Non-coeliac gluten sensitivity (NCGS) is a separate, less well defined condition. It does not cause intestinal damage and is diagnosed only after coeliac disease and wheat allergy have been excluded by appropriate testing.
Can a normal blood test rule out coeliac disease?
Usually yes — tTG-IgA has good sensitivity, especially when combined with total IgA to check for IgA deficiency. However, the test can occasionally be normal in early or atypical disease. If clinical suspicion is high (positive family history, classic symptoms, dermatitis herpetiformis), gastroscopy is still appropriate.
Are oats gluten-free?
Pure oats contain a different protein from wheat and are tolerated by most people with coeliac disease — but most commercial oats are cross-contaminated with wheat during growing or processing. Only certified gluten-free oats are safe, and only after discussion with your dietitian.
If I’m diagnosed with coeliac disease, do my children need to be tested?
Yes. First-degree relatives (parents, siblings, children) have a 10–15% lifetime risk of coeliac disease. Testing is recommended even in those without symptoms, because untreated coeliac disease causes long-term harm even when silent.
Book a consultation
Phone 07 3733 1551 or send a referral via the contact form. Download the patient PDF: Coeliac Disease Diagnosis Pathway. See also: about Dr Goutham | cost & no-gap.
