Making a diagnosis of coeliac disease

Coeliac disease can easily be missed or misdiagnosed in primary care, according to Dr Sohail Butt.

The numbers of people diagnosed with coeliac disease appears to be increasing. It is estimated that it may affect 1 per cent of people in the UK.

Coeliac disease is a chronic and permanent inflammatory disease of the upper small intestinal mucosa. It is triggered in susceptible people by eating the proteins known as gluten found in wheat, rye, barley and possibly oats.

What are the symptoms?
People with coeliac disease may present with a range of symptoms and signs, and these can be divided into intestinal features and those caused by malabsorption. Many patients, especially those presenting in adulthood, have minimal or atypical symptoms such as anaemia and chronic fatigue.

Is coeliac disease common?
Ten years ago coeliac disease was considered a comparatively uncommon disorder, with a prevalence of one in 1,000 quoted. Several recent serological population studies have shown a much higher prevalence. Recent work has suggested that the subclinical form of the disease may be present from childhood, as 1 per cent of children were found to have positive endomysial antibodies and had no symptoms.

Coeliac disease can occur at any age. Data from Coeliac UK suggest the average age at diagnosis of new members joining Coeliac UK in 2000 was 45 years. Studies suggest that 3-5 per cent of first-degree family members of people with coeliac disease are also affected by the condition.

Diagnosis
GPs can assess patients with symptoms suggestive of coeliac disease with initial serological tests. The usual process for diagnosis involves a serological test, which looks for antibodies produced in response to gluten, followed by a small bowel biopsy.

Two types of antibodies are in common use by GPs to assess coeliac disease: endomysial antibodies and tissue transglutaminase antibodies, which are produced in response to gluten ingestion.

Therefore it is essential that the patient has not started a gluten-free diet, and if they have it should be re-introduced for at least six weeks prior to blood being taken. The amount of gluten that should be eaten is variable, but as a rough guide an adult should aim to eat six slices of bread per day, or the equivalent in cereal-based products.

Research has shown that these blood tests are around 86-95 per cent sensitive when performed in isolation. Most sero-negative results suggest coeliac disease is not present; false negative results may arise due to IgA deficiency. Hence sero-negative patients whose symptoms are suggestive of coeliac disease should have a small bowel biopsy.

A small bowel biopsy is considered the gold standard for diagnosis of coeliac disease, when a loss of small bowel villi is found on histological examination of the small bowel mucosa.

Referral to a gastroenterologist should be made in patients with positive antibodies and in those with negative antibodies, but in whom coeliac disease is still clinically suspected.

Initial management
Following diagnosis it is essential that the patient is referred to a dietitian for expert advice on following a gluten-free diet. Keeping to a gluten-free diet for life is the main treatment for coeliac disease.

Gluten is found in wheat, barley, rye and possibly oats. After starting a gluten-free diet most patients show a rapid clinical response, with improvement of symptoms within weeks.

Keeping to a gluten-free diet can be difficult because there are often hidden sources of gluten in processed food. Guidelines and food lists provided by Coeliac UK are helpful. Adherence to a gluten-free diet can be monitored by serial measurement of antigliadin or antiendomysial antibodies.

In addition to wheat, barley and rye cereal products, oat cereals are also traditionally excluded in a gluten-free diet. Recent clinical studies have, however, provided evidence that oats do not damage the mucosa of patients with coeliac disease. But it is important to advise patients that the oats must be free of other contaminating cereals.

GPs can prescribe some gluten-free foods to patients with coeliac disease. Patients are not exempt from prescription charges. A list of gluten-free prescribable items is available in MIMS.

Early diagnosis
Coeliac disease is a common, under-diagnosed condition with significant morbidity and mortality. The availability of serological tests for diagnosis may allow GPs to make an early diagnosis of people with symptoms and arrange dietary treatment to improve their health.

Dr Butt is a GP in Ashford, Middlesex.

SYMPTOMS OF COELIAC DISEASE

Adulthood

  • Chronic diarrhoea, weight loss and lethargy.
  • Anaemia.
  • Fatigue.

Infancy (<2 years)

  • Diarrhoea.
  • Abdominal distension.
  • Failure to thrive.

Childhood

  • Diarrhoea or constipation.
  • Anaemia.
  • Loss of appetite (short stature, osteoporosis).

 

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