Celiac Test

Coeliac disease is genetic in nature, has a high prevalence and is characterised by intolerance to gluten. Gluten is a protein that gives cohesiveness and the characteristic viscous and elastic texture to the dough of wheat, barley, rye, malt, semolina, oats, derivatives and variants. The ingestion of gluten causes lesions in the intestinal mucosa that result in digestive symptoms and may also present symptoms in other organs and systems (dermatitis herpetiformis, headache, tiredness, anaemia, osteoporosis, repeated miscarriages, etc.). Genetically predisposed individuals who develop the disease do not digest this protein, giving rise to protein fragments (prolamins), which are capable of activating the immune system and triggering symptoms. Non-coeliac gluten sensitivity presents symptoms very similar to coeliac disease but characteristically the antibodies are negative so the immune system does not intervene. Gluten and wheat allergy is also mediated by the immune system triggering a hypersensitivity reaction. Symptoms vary, and can cause oral itching, urticaria, lip oedema, difficulty breathing, etc.

According to the latest 2020 guidelines of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN), children and adolescents can be diagnosed with coeliac disease without biopsy if they have IgA anti-transglutaminase antibodies (more sensitive) 10 times higher than normal or IgA anti-endomysial antibodies (more specific). It is not necessary to present symptoms or to request a genetic study (HLA DQ2/8) in this case. A negative serology with compatible symptoms does not exclude the diagnosis of coeliac disease. However, in the event of a positive serology, you should see your specialist doctor for a duodenal biopsy (or the accessory tests that your doctor deems appropriate) that will allow a definitive diagnosis to be made.

This test is indicated to initiate the diagnosis of CD as it measures the presence of the main antibodies that people with coeliac disease develop. Once a diagnosis has been made and a gluten-free diet has been started, it is more appropriate to test for immunogenic gliadin peptides in urine or faeces to evaluate the diet.

• Total IgA
• Anti-tissue transglutaminase antibody - IgA

Screening for coeliac disease is based on the measurement of serum anti-transglutaminase IgA antibodies, as this provides a high sensitivity (true positive rate). If there is a selective IgA deficiency, which is 20 times more frequent in coeliacs, IgG class antibodies (anti-transglutaminase, anti-endomysial or anti-gliadin deamidated peptides) will be assessed. In turn, this deficit must be confirmed with the rest of the immunoglobulins. According to the Spanish Society of Digestive Pathology, around 78% of the population is not yet diagnosed with coeliac disease, which means 1 in 357 adults in Spain and 1 in 71 children. Given its high prevalence and under-diagnosis, early detection is necessary.

The coeliac condition test does not require any special preparation. However, if you have symptoms consistent with coeliac condition (e.g. diarrhoea, constipation, bloating, abdominal discomfort, foul-smelling stools, gas, nausea or vomiting), you should continue to eat gluten-containing foods before taking the test. If you have previously eliminated gluten from your diet, it is possible that the results will be negative, so you should see your specialist doctor for a gluten re-exposure by consuming 8-10g/day of gluten for several weeks before repeating this test. If there is a high suspicion of a gluten-related disorder, you should see your medical specialist.

If you have already been diagnosed with CD by your doctor, it is advisable to monitor the level of anti-transglutaminase antibodies 3-6 months and 12 months after starting the gluten-free diet.