Currently, gluten challenge is no longer required to confirm the diagnosis in patients with intestinal lesions compatible with coeliac disease and a positive response to a gluten-free diet. Nevertheless, in some cases, a gluten challenge with a subsequent biopsy may be useful to support the diagnosis, for example in people with a high suspicion for coeliac disease, without a biopsy confirmation, who have negative blood antibodies and are already on a gluten-free diet. Gluten challenge is discouraged before the age of 5 years and during pubertal growth. The alternative diagnosis of non-coeliac gluten sensitivity may be made where there is only symptomatic evidence of gluten sensitivity. Gastrointestinal and extraintestinal symptoms of people with non-coeliac gluten sensitivity can be similar to those of coeliac disease, and improve when gluten is removed from the diet, after coeliac disease and wheat allergy are reasonably excluded.Up to 30% of people often continue having or redeveloping symptoms after starting a gluten-free diet. A careful interpretation of the symptomatic response is needed, as a lack of response in a person with coeliac disease may be due to continued ingestion of small amounts of gluten, either voluntary or inadvertent, or be due to other commonly associated conditions such as small intestinal bacterial overgrowth (SIBO), lactose intolerance, fructose, sucrose, and sorbitol malabsorption, exocrine pancreatic insufficiency, and microscopic colitis, among others. In untreated coeliac disease, these are often transient conditions derived from the intestinal damage.
Cause
Coeliac disease is caused by an inflammatory reaction to gliadins and glutenins (gluten proteins) found in wheat and to similar proteins found in the crops of the tribe Triticeae (which includes other common grains such as barley and rye) and to the tribe Aveneae (oats). Wheat subspecies (such as spelt, durum, and Kamut) and wheat hybrids (such as triticale) also cause symptoms of coeliac disease.A small number of people with coeliac disease react to oats. Oat toxicity in coeliac people depends on the oat cultivar consumed because the prolamin genes, protein amino acid sequences, and the immunoreactivities of toxic prolamins are different in different oat varieties. Also, oats are frequently cross-contaminated with other grains containing gluten. The term "pure oats" refers to oats uncontaminated with other gluten-containing cereals. The long-term effects of pure oat consumption are still unclear, and further studies identifying the cultivars used are needed before making final recommendations on their inclusion in a gluten-free diet. Coeliac people who choose to consume oats need a more rigorous lifelong follow-up, possibly including periodic intestinal biopsies. Other grains
Other cereals such as corn, millet, sorghum, teff, rice, and wild rice are safe for people with coeliac disease to consume, as well as noncereals such as amaranth, quinoa, and buckwheat. Noncereal carbohydrate-rich foods such as potatoes and bananas do not contain gluten and do not trigger symptoms. Risk modifiers
There are various theories as to what determines whether a genetically susceptible individual will go on to develop coeliac disease.