Coeliac disease (pronounced See-Lee-Yak, and sometimes spelled 'celiac') is not a food allergy, or a wheat intolerance, but a serious, lifelong autoimmune, gastrointestinal disorder that can cause a wide spectrum of clinical symptoms.
Symptoms of coeliac disease can differ from person to person but often these include diarrhoea, bloating, wind, weight loss, malnutrition and skin disorders. The cause is a permanent intolerance to gluten, which is a complex mixture of storage proteins found in wheat, barley and rye. Once diagnosed, it is necessary to follow a strict gluten free diet. Any food or drink containing wheat, barley or rye can trigger symptoms if you have coeliac disease.
The main symptoms of coeliac disease are similar to, and often confused with irritable bowel syndrome (IBS);
- bloating
- wind
- abdominal pain
- diarrhoea
Other more general symptoms may also be present which may include;
- tiredness
- weight loss
- itchy rash (dermatitis herpetiformis)
- infertility
- nerve damage
The presence of high levels of tTG IgA antibodies in your blood are a reliable sign that you have coeliac disease. If you get a positive result with this test you should speak with your GP who may refer you to a gastroenterologist for follow-up tests. Do not start a gluten free diet until your diagnosis is confirmed by your doctor.
If you do have coeliac disease, and you start a gluten free diet, the level of IgA tTG antibodies in your blood are likely to decrease to levels that may become undetectable after a few weeks. If you have been on a strict gluten free diet for longer than a few weeks, most doctors recommend that you follow a normal, gluten containing diet for at least six weeks before taking any test for coeliac disease, whether a self test kit, laboratory test or intestinal biopsy. Blood tests that detect IgA tTG antibodies can also be used to monitor your compliance with a gluten free diet.
A small proportion of people (1 in 600) have selective IgA deficiency(1) which means they may get a false negative result with the tTG IgA test. Even if you have a negative result, it is important to speak with your doctor if you are concerned about your symptoms.
NICE Guideline NG20 Coeliac Disease: recognition, assessment and management (2015) includes the following priorities for implementation(2,3).
Specific serological testing (such as tTG IgA) for coeliac disease should be offered to patients with any of the following;
- irritable bowel syndrome (IBS) in adults
- persistent unexplained abdominal or gastrointestinal symptoms
- prolonged fatigue
- faltering growth
- unexpected weight loss
- severe or persistent weight loss
- unexplained iron, vitamin B or folate deficiency
- type 1 diabetes, at diagnosis
- autoimmune thyroid disease, at diagnosis
Serological testing for coeliac disease should also be considered in people with any of the following;
- metabolic bone disorder (reduced bone mineral density or osteomalacia)
- unexplained neurological symptoms (particularly peripheral neuropathy or ataxia)
- unexplained subfertility or recurrent miscarriage
- persistently raised liver enzymes with unknown cause
- dental enamel defects
- Down's syndrome
- Turner syndrome
The NICE Guidelines also emphasises that people should be advised to follow a normal (gluten containing) diet and to eat some gluten in more than one meal every day for at least six weeks before testing for coeliac disease.
Treatment for coeliac disease is a lifelong gluten-free diet under the supervision of a dietitian with experience of coeliac disease.
References
(1) Selective IgA deficiency. Patient information sheet. www.piduk.org
(2) Coeliac disease: recognition, assessment and management (NICE guideline NG20) www.nice.org.uk
(3) 2019 surveillance of coeliac disease: recognition, assessment and management (NICE guideline NG20) www.nice.org.uk