Table 2. Diagnostic criteria for non-celiac gluten sensitivity.

• Gluten ingestion typically elicits the rapid occurrence (in a few hours or days) of intestinal and extra-intestinal symptoms (Table 1)

• Symptoms disappear quickly (in a few hours or days) after the elimination of gluten from the diet

• Reintroduction of gluten causes the rapid recurrence of symptoms

• Celiac disease must be ruled out by means of negative serology (endomysial and tissue transglutaminase IgA antibodies) and a duodenal biopsy on a gluten-containing diet

• Wheat allergy tests (specific IgE as well as skin prick tests), performed on a gluten-containing diet, must be negative

• A double-blind, placebo-controlled gluten challenge test is needed in each suspected patient to confirm the diagnosis and to exclude a placebo effect induced by gluten exclusion

(i) Although no serological marker is available for non-celiac gluten sensitivity (NCGS), it must be emphasized that approximately 50% of NCGS pts are positive for first-generation anti-gliadin antibodies (AGA), mainly IgG; (ii) NCGS is unrelated to the celiac disease genetic markers (i.e., HLA-DQ2 and -DQ8), which are found in approximately 40% of NCGS patients vs. 30% in the general population.