Diagnosis

There is a clearly defined diagnostic pathway for coeliac disease. If a patient presents with symptoms that are suggestive of coeliac disease, there are specific tests that can be done.

Click here to see our diagnostic flowchart in pdf format

Two types of antibodies are tested for in the patient's serology; endomysial antibodies (EMA) and tissue transglutaminase antibodies (tTGA) which are produced in response to gluten ingestion.

Therefore it is essential that the patient has not removed gluten from their 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 depends largely on the patient, but as a rough guide an adult should aim to eat 4 slices of bread per day, or the equivalent amount of pasta, pizza base, biscuits etc.

Some research has shown that these blood tests are around 95% sensitive when performed in isolation, but when performed together are nearer to 99% accurate (1). However, other studies have suggested that the sensitivity is lower, nearer to 80%.

Although most seronegative results suggest coeliac disease is not present, it needs to be considered that patients with coeliac disease are more likely to be IgA deficient than the general population (2), so a seronegative result does not necessarily mean that the patient does not have coeliac disease and further investigations should be carried out in patients whose symptoms are strongly suggestive of coeliac disease.

A small bowel biopsy is still considered the gold standard for diagnosis of coeliac disease (3), so a referral to a gastroenterologist needs to be made in patient with positive antibodies and in those with negative antibodies but in whom CD is still suspected. Previously CD was diagnosed only in those with total or sub-total villous atrophy, but now there are several grades of gut damaged that are recognised. These have been classified by Marsh, and include the infiltration of lymphocytes without villous atrophy and crypt hyperplasia, as well as various stages of villous atrophy (4).

Following diagnosis it is essential that the patient is referred to a dietitian for expert advice on following a gluten-free diet which will be tailored to the individual patient. Follow-up care is also important and it is recommended that patients with coeliac disease are followed up at least annually (5)

References

(1)Scoglio R, Di Pasquale G, Pagano G, Lucanto MC, Magazzu G, Sflerlazzas C (2004), Is intestinal biopsy always needed for diagnosis of celiac disease? American Journal of Gastroenterology, 98(6):1325-31.

(2)Lenhardt A. Plebani A. Marchetti F. et al. Role of human-tissue transglutaminase IgG and anti-gliadin IgG antibodies in the diagnosis of coeliac disease in patients with selective immunoglobulin A deficiency. Digestive & Liver Disease 2004;36(11):730-4

(3)Abdulkarim AS & Murray JA. Review article: the diagnosis of coeliac disease. Alimentary Pharmacology and Therapeutics 2003;17:987-995.

(4)Marsh MN . Gluten, major histocompatibility complex, and the small intestine. A molecular and immunobiologic approach to the spectrum of gluten sensitivity ('celiac sprue'). Gastroenterology 1992;102:330-54.

(5)British Society of Gastroenterology. Guidelines for the management of patients with coeliac disease 2002 www.bsg.org.uk