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Coeliac disease update



GP Dr Sohail Butt discusses who to screen, how to diagnose and the importance of an effective avoidance diet

Coeliac disease is a condition in which children and adults develop a lifelong intolerance to gluten, found in wheat, barley and rye.

The prevalence of coeliac disease is thought to be one in 100 of the general population, although only about 10-15% are thought to have been clinically diagnosed. Although many of the remainder will feel well, a significant minority will have chronic health problems such as gastrointestinal symptoms, the effects of anaemia and lethargy. These may result in recurrent consultations with GPs and extensive investigations without a clear diagnosis.

The prevalence of coeliac disease seems to be increasing. This may be attributable to several factors including: a true increase in prevalence in line with other food intolerances; wider availability of serological assessment; the development and wider availability of endoscopy and duodenal biopsy; and the wider awareness of the non-gastrointestinal features of coeliac disease.

Which patients should GPs assess for coeliac disease?

Historically, GPs have seen coeliac disease present with the classical gastrointestinal symptoms of chronic diarrhoea, abdominal pain and weight loss. More recently, atypical presentations have been recognised, with patients having limited or no gastrointestinal symptoms.

In May 2009, NICE published guidelines on the recognition and assessment of coeliac disease1 (see box 1).

Diagnosing coeliac disease in primary care

 

41269971GPs should initially arrange serological tests for people with suggestive signs, symptoms and relevant co-existing conditions. Testing for antibodies to tissue transglutaminase (TTG) is widely used in primary care and is the serological test of choice. It has a sensitivity of 91-95% and a specificity of approaching 100%.2 TTG antibodies may be negative in the presence of IgA deficiency, as it is an IgA-based test. So IgA immunoglobulin levels should be measured when there is a high index of clinical suspicion and a negative TTGtest.

Clinicians should refer patients with a positive TTG test to a specialist for further assessment, including a duodenal biopsy. Serological tests alone are not sufficient to replace duodenal biopsy.

It is very important that patients are advised to continue to eat a gluten-containing diet prior to testing, as exclusion of gluten from the diet can produce misleading results. Gluten should be eaten more than once a day for at least six weeks before testing.

Antibody-negative coeliac disease may occur in 6.4- 9.1% of all diagnosed cases.3 So anyone with a negative TTG antibody test – but in whom the index of suspicion is high – should be referred.

The risks of coeliac disease

People with coeliac disease – particularly those who are yet to be diagnosed and those who do not adhere to a gluten-free diet – risk complications such as malignancy, osteoporosis and subfertility. Studies suggest that people with coeliac disease have a modestly increased risk of malignancy, particularly lymphoma. This risk appears to fall after diagnosis in those people who keep to a gluten-free diet.4, 5

At diagnosis, 40% of patients have reduced bone mineral density. This translates to a modestly increased fracture risk6, so patients with coeliac disease should be considered for dual X- ray absorptionometry at diagnosis and then subsequently at appropriate specified intervals. Bone mineral density in coeliac patients has been shown to improve after treatment with a gluten-free diet.7

Subfertility, increased risk of miscarriage and intra-uterine growth retardation have been attributed to undiagnosed coeliac disease. It is thought that adhering to a gluten-free diet can reduce these risks.

Although the diagnosis of coeliac disease and the diet may have a psychological impact and be socially restrictive, most symptomatic people have an improved quality of life once the diagnosis is made and they start on a gluten-free regime. Studies suggest that higher quality of life scores are maintained for at least one year – and longer in coeliacs who keep to the diet than in those who do not.

Management

The gluten-free diet is the cornerstone of the management of coeliac disease. Most patients struggle with the requirements of the diet – therefore education and support from a dietician and GP are vital.

The dietician can advise about the variety of social situations patients face (home, work, school, restaurants and holidays) and ensure adequate intake of calcium, iron, fibre, folate and vitamin B12. Some patients eating a gluten-free diet gain weight and so need advice on appropriate macronutrient and calorific intake.

Patient compliance with the gluten-free diet may be assessed via repeat duodenal biopsy, repeat antibody testing, dietary history and a resolution of symptoms.

Most consultants do not repeat duodenal biopsies if symptoms resolve, serology is negative and the diagnosis is clear. Repeat duodenal biopsies are more commonly done in young children where the diagnosis is less secure.

Guidelines suggest that patients should have an annual follow-up with a clinician, as this improves dietary compliance.8

Practices should consider setting up a disease register of coeliac patients, recalling them annually and recording information including dietary compliance, BMI, symptoms, haematology and serology results, pneumococcal immunisation and bone densitometry. Recent studies suggest that patients on an established gluten-free diet may be able to introduce modest amounts of oats (<50g a day) under clinical supervision without adverse effects.9

If symptoms continue despite a gluten-free diet, careful dietary evaluation is required. Persisting symptoms, or new alarm symptoms such as weight loss, rectal bleeding or change of bowel habit, may require referral to a gastroenterologist.

Studies suggest breast-feeding infants reduces the risk of the child developing coeliac disease in later life. This is another reason for GPs to encourage breast-feeding in the general population and in particular in those parents who are coeliac themselves for at least the first six months of life.

Current Department of Health guidelines recommend that gluten-containing foods should be gradually introduced to infants after age six months, as earlier introduction may increase the risk of developing coeliac disease.

Dr Sohail Butt is a GP in Ashford, Middlesex, and a member of Coeliac UK health advisory committee.

Coeliac UK is the leading charity working for people with coeliac disease and dermatitis herpetiformis. The helpline number is 0845 305 2060.

 

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– Consider coeliac disease – it’s commoner than you think
– Check TTG if patients have IBS symptoms or unexplained anaemia.
– Make sure patients are eat gluten at least twice a day for at least six weeks before their small bowel biopsy.
– Ensure patients have an annual review to help dietary compliance