[7] People who present minor damage of the small intestine often have negative blood antibodies titers and many patients with coeliac disease are missed when a duodenal biopsy is not performed.
[2] 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.
[4] European guidelines suggest that in children and adolescents with symptoms which are compatible with coeliac disease, the diagnosis can be made without the need for an intestinal biopsy if anti-tTG antibodies titres are very high (10 times the upper limit of normal).
To exclude a placebo effect, a double-blind placebo-controlled gluten challenge is a useful tool, although it is expensive and complicated in routine clinical ground, and therefore, is only performed in research studies.
Nevertheless, recent studies have shown that 2-week challenge of 3 g of gluten per day may induce histological and serological abnormalities in most adults with proven coeliac disease.
[3][5] This newly proposed protocol has shown higher tolerability and compliance, and it has been calculated that its application in secondary-care gastrointestinal practice would identify celiac disease in 7% patients referred for suspected non-coeliac gluten sensitivity, while in the remaining 93% would confirm non-coeliac gluten sensitivity,[3] but is not yet universally adopted.