Coeliac Disease

What is Coeliac disease?

Coeliac disease is an autoimmune condition that attacks the intestine. Normally, your immune system protects your body by attacking foreign substances such as disease-causing organisms. In autoimmune diseases, your immune system erroneously recognises parts of your body as foreign; it produces autoantibodies that attack healthy tissues. In coeliac disease, your immune system reacts against your intestine when food and drink containing gluten (a protein found in grains: wheat, barley and rye) are consumed.

Why is Coeliac disease important?

The intestine of a person with coeliac disease is unable to digest gluten protein. The immune response to gluten causes chronic inflammation within the intestines and destruction of the finger-like projections (called villi) lining the inside the small intestines. Damage to the villi impairs the absorption of nutrients from food, causing vitamin deficiencies and malnutrition. Damage to the intestine normalises when gluten is excluded from the diet, but reappears when gluten is eaten again. Continued gluten consumption can lead to permanent intestinal damage. It may also lead to lactose (milk sugar) intolerance, osteoporosis, and cancer.

Who should be tested for Coeliac disease?

Why some people develop coeliac disease is not fully understood. However, it is more common in people with a first-degree relative with the condition and people who have other autoimmune disease, e.g., type 1 diabetes and autoimmune thyroid disease. You should therefore be screened if you have a family member with coeliac disease or you have an autoimmune disease. Nevertheless, any adult or child aged over 3 years experiencing symptoms of coeliac disease should be tested for the condition.

Coeliac disease can cause a wide range of symptoms in the intestinal tract and elsewhere in the body, including diarrhoea/constipation, wind, nausea/vomiting, stomach pain/cramps/bloating, mouth ulcers, fatigue, anaemia, vitamin deficiencies, nerve problems, and skin rash (dermatitis herpetiformis). Symptoms vary in severity among individuals, ranging from none through mild to severe.

How to test for Coeliac disease?

Blood tests can determine if you are sensitive to gluten. The immune system makes antibodies called immunoglobulins (IgA and IgG), which attack:

• an enzyme in the intestines called tissue transglutaminase (tissue transglutaminase IgA antibody [tTG-IgA] test)
• tissues in the muscle of the intestinal wall (IgA endomysial antibody [EMA] test), and
• gluten protein (deamidated gliadin peptide IgA and IgG antibodies [DGP IgA and IgG] test)

A test may be carried out to detect each of these antibodies, and they are all tested when profiling coeliac disease or gluten allergy/sensitivity. Additionally, measuring total IgA or tTG-IgG enables cases with an IgA deficiency to be detected. Profiling may also detect IgE antibodies that are produced in people with immediate onset gluten allergy, and genes implicated in celiac disease (HLA DQ2/DQ8).

Blood tests for coeliac disease require the patient to be consuming gluten in their diet. If on a gluten-free diet, then the healthcare professional will recommend a diet containing gluten for several weeks before the test; generally, this means consuming foods containing gluten in 2 meals/day for over 6 weeks, although specific instructions on diet will be provided. This is important for the test to be accurate.

The blood test can be done from a blood sample taken by you (the patient). The self-collection sample pack is provided by the healthcare professional, who will also provide details of where you must send the sample for laboratory analysis. Detailed instructions on how to collect a sample of your own blood from a finger are provided in the sample pack; these must be read and followed carefully. In brief, a lancet is used to pierce the skin and blood droplets (600 ml) are collected into a collection tube up to the marked upper line. The blood collection tube is then sealed and gently inverted 5-10 times, before labelling with your details and mailing for analysis. Your healthcare professional will receive, and advise you on, your test results.

Results take 2 days to process.

What do Coeliac disease test results indicate?

These antibody tests are about 95% accurate, and used to help diagnose coeliac disease and/or to monitor treatment. Your healthcare provider will explain your test results and what they mean for you.

Most people do not have coeliac disease and have negative test results, which means that no antibodies were found in the blood. Very rarely, a person with coeliac disease has a negative test result. Should this be the case but symptoms continue, contact your healthcare professional for further evaluation of your condition.

A positive test and high levels of IgA antibodies indicate gluten sensitivity and suggest coeliac disease. A diagnosis of coeliac disease is further indicated if you also have typical coeliac symptoms, which improve on a gluten-free diet. A biopsy of the small intestine may be required to examine any inflammation of the small intestine, and necessary to confirm your condition.

How to live well with Coeliac disease

Coeliac disease is not curable; its treatment is the life-long commitment to a gluten-free diet. While it is demanding, the condition is manageable and there are many lifestyle changes that will greatly impact your well-being. Your healthcare professional will refer you to a dietician who can advise on dietary modifications to ensure a balanced gluten-free diet. Gluten-free foods are available through pharmacies and at supermarkets. Many foods are naturally gluten free, such as fruit, vegetables and dairy products, but it is necessary to check the label on processed foods. Make your kitchen 'safe' by storing and cooking gluten-free foods separate from other foods. So that they understand, it is important to explain to relatives and friends about coeliac disease and the risk to you of food cross-contamination. Your social life can continue, with many eating places offering a gluten-free menu or suggesting to modify dishes using gluten-free produce; be sure to ask if you have any doubts or questions about your choice of food and its cooking.

Reviewed by: Dr Loraine Haslam MBBS, DRCOG, DFSRH, LoC SDI, LoC IUT, MRCGP
GMC registration number: 4524038
Date: 16 August 2022
Next review: 15 August 2024
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