Coeliac Disease — Symptoms, Diagnosis and Why You Must Not Stop Gluten Before Testing

Coeliac disease is an autoimmune reaction to gluten that damages the small-bowel lining. Coeliac Australia estimates that about 1 in 70 Australians has coeliac disease, and most are undiagnosed. In adults, diagnosis usually involves blood tests (coeliac serology) and biopsies taken during gastroscopy while you are still eating gluten. Treatment is a strict, lifelong gluten-free diet. Dr Goutham Sivasuthan performs diagnostic gastroscopy with duodenal biopsy across Brisbane, Redland and Logan.

Keep eating gluten until testing is complete. Reducing or avoiding it can make blood tests and biopsies less reliable. If you have already changed your diet, arrange an individual testing plan with your doctor before restarting gluten.

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. HLA-DQ2 and HLA-DQ8 are genes associated with susceptibility; having either gene does not establish a diagnosis. Gene testing can help clarify an uncertain diagnosis, including when gluten has already been removed from the diet. Family history is also part of the assessment.

How is coeliac disease diagnosed?

The diagnostic pathway has three core steps:

1. Keep eating gluten — do not start a gluten-free diet until both tests are complete.
2. 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.
3. Gastroscopy with duodenal biopsy — Dr Goutham takes small samples from the duodenum, the first part of the small bowel, during a gastroscopy under sedation, which takes about 10 minutes. The biopsy findings are assessed together with your blood tests (coeliac serology) and gluten intake to establish the diagnosis.

If you already avoid gluten, an individual testing plan is needed before you change your diet. Gene testing can sometimes help exclude coeliac disease. When a gluten challenge is needed, your doctor will set out how to do it and when to repeat testing.

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 reviews your symptoms, family history, previous test results and any dietary changes. He arranges coeliac blood tests if needed and considers whether gastroscopy with duodenal biopsy is appropriate. Your GP receives the procedure report on the day; biopsy results follow separately. If coeliac disease is confirmed, Dr Goutham discusses the next steps, including dietitian referral, bone-density assessment and testing for close relatives.

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?

A normal coeliac blood test (tTG-IgA) makes coeliac disease less likely but does not always rule it out. Gluten intake, the test used, persistent symptoms and family history all help determine whether gastroscopy or further testing is needed.

Are oats gluten-free?

Most people with coeliac disease tolerate oats produced without wheat, rye or barley contamination, although some react to oats themselves. In Australia and New Zealand, oats cannot be labelled gluten-free. An individual plan with your medical team can establish whether uncontaminated oats suit you and how to monitor your response.

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. See also: about Dr Goutham | cost & no-gap.