Treatment for celiac disease (CD) is a lifelong strict gluten-free diet (GFD). Patients should be followed-up with dietary interviews and serologic tests for CD markers to ensure adherence to the diet. However, none of these methods offer an accurate measure of dietary compliance. Our aim was to evaluate the measurement of gluten immunogenic peptides (GIP) in stools as a marker of GFD adherence in CD patients and compare it with traditional methods of GFD monitoring.

We performed a prospective, non-randomized, multicentre study including 188 CD patients on a GFD and 73 healthy controls on a gluten-containing diet. Subjects were given a dietary questionnaire and fecal GIP quantified by ELISA (iVYLISA GIP-S kit). Serological anti-tissue transglutaminase (anti-tTG) IgA and anti-deamidated gliadin peptide (anti-DGP) IgA antibodies were measured simultaneously.

Inclusion Criteria:

• The study group consisted of celiac patients following a GFD for at least one year prior to the inclusion in the study and they were required to have an HLA-DQ2 or HLA-DQ8 haplotype and an histologically abnormal duodenal biopsy (grade Marsh IIIB or IIIC) at the time of diagnosis, supported by positive serum anti-endomysium IgA antibodies and/or anti-tissue transglutaminase (anti-tTG) IgA antibodies.
• The positive and negative control groups was comprised of healthy asymptomatic subjects in whom CD had been ruled out and who were not suspected of having any other gastrointestinal condition

Exclusion Criteria:

• All study patients included history of kidney or liver disease, and history of severe psychiatric disease or seizure disorder.

Celiac patients following a GFD for at least one year prior to the inclusion in the study