The first step towards diagnosis is a blood test. Following a positive blood test, the most conclusive way to diagnose coeliac disease is by taking a biopsy from the small intestine.
It is important to be on a gluten containing diet before testing in order to ensure the most accurate result. Four slices of ordinary bread a day for six weeks or more should be sufficient.
It is important not to self diagnose. A life long gluten-free diet is a big commitment which should only be undertaken if necessary. An official diagnosis is required to take advantage of the financial support available.
Your GP can take a blood test for antibodies – Immunoglobulin A (IgA) anti-tissue transglutaminase antibodies(IgA tTGA) and anti-endomysial antibodies (IgA EMA). If results show raised tTG or positive EMA then you should be referred to a consultant gastroenterologist for a biopsy. Bear in mind that negative screening blood tests do not always exclude coeliac disease, as a small minority of coeliacs may also have IgA deficiency and the screening test results will be misleading. In children under the age of three the blood tests can be particularly unreliable.
There are some do it yourself test blood test kits available from abroad. The Coeliac Society recommend that you have a blood test organised by your doctor.
The biopsy procedure is called an upper gastro-intestinal endoscopy or oesophagastroduodenoscopy (OGD). A gastroscope (a small tube) is passed through the mouth and down into the duodenum or jejunum. A very small piece of tissue is taken from the wall of the intestine. The tissue is examined under a microscope to check for damage to the villi.
Having the Biopsy
The biopsy is usually carried out in an outpatient clinic. You will be asked to fast overnight beforehand and the procedure itself takes 10 – 15 minutes (excluding waiting and preparation time). In adults it is usually carried out under light sedation, children are given a general anaesthetic. There is no pain when the biopsy is taken.
Guidelines for diagnosis
Further information regarding adult diagnosis and management of coeliac disease coeliac-disease-recognition-assessment-and-management-1837325178565
Further information regarding diagnosis in children European_Society_for_Pediatric_Gastroenterology_.28