Diagnosing Coeliac disease

The process of diagnosing coeliac disease typically involves a combination of serological testing (i.e. blood testing) and duodenal biopsy. Untreated coeliac disease can cause a variety of unpleasant symptoms and elevates the risk of long-term complications.

Establishing a definitive diagnosis of coeliac disease is important as it will guide you down the correct pathway of appropriate medical care and follow-up and exclude other causes for your symptoms. It will ensure that following a lifelong and strict gluten-free diet is the correct medical treatment for you. A diagnosis also has implications for family members.

Following a proper diagnosis, your doctor will be able to monitor the disease, ensure healing of the bowel, and screen for other health issues associated with coeliac disease (e.g. complications or associated autoimmune conditions). It is important to note that an absence of symptoms does not necessarily indicate a healthy bowel –individuals that self-diagnose do not have the means to determine their underlying disease state. Similarly, feeling better after removing gluten from the diet does definitively confirm coeliac disease.

In adults, the diagnosis of coeliac disease depends on demonstrating the typical changes that occur in the small bowel (villous atrophy and inflammation) while gluten is still in the diet. Blood tests to measure coeliac antibodies are also helpful in supporting the diagnosis. In children, the same criteria apply, however in some cases with very elevated coeliac antibody levels a diagnosis can be made by a specialist without a gastroscopy and biopsy.

If a gluten-free diet has already been adopted prior to diagnosis, the tests used to diagnose coeliac disease are unreliable, and can be falsely negative. In this case,

If gluten has been removed from the diet, a normal diet must be resumed for at least six weeks prior to testing. During this ‘gluten challenge’, a minimum of four slices of wheat based bread (or equivalent) should be consumed each day (for adults) (two slices of wheat based bread each day for children). It is important the gluten challenge is carried out properly to ensure reliable test results.

These tests can be less reliable in children under the age of four years, as their antibody levels can fluctuate. It is suggested the antibody tests be performed on two occasions three months apart.

Importantly, a diagnosis of coeliac disease SHOULD NOT be made on the basis of a blood test alone. A positive blood test always needs to be followed by a small bowel biopsy to confirm the diagnosis.

A small bowel biopsy is essential to confirm diagnosis

A diagnosis of coeliac disease can only be made by demonstrating the typical small bowel changes of coeliac disease (villous atrophy). This involves a gastroscopy procedure in which several tiny samples (biopsies) of the small bowel are taken. A gastroscopy is a simple day procedure done under light anaesthetic sedation that takes about 10 minutes. In the majority of cases, the bowel damage present in those with untreated coeliac disease is not visible to the naked eye. The biopsies are examined under a microscope to confirm the presence of villous atrophy.

is an essential part of treating and monitoring the underlying disease pathology (i.e. damage or recovery of the intestinal mucosa).