Testing for Faecal Gluten Immunogenic Peptides: Is It Useful to Evaluate Adherence to Gluten-Free Diet?

Aim: Determination of faecal gluten immunogenic peptides (f-GIP) has recently been proposed as new noninvasive method to detect gluten intake in celiac disease (CD). Our aim was to evaluate the use of f-GIP for the adherence to gluten-free diet (GFD) and to compare this new marker with traditional methods. Methods: We enrolled both newly diagnosed cases and children in follow-up with CD. Adherence to the GFD was assessed using the Biagi score, IgA anti-transglutaminase (tTG IgA) and f-GIP. Results: Seventy-one CD children, 40.8% new diagnosis and 59.2% in follow-up, were enrolled. Significant differences were found in the levels of faecal GIP between new diagnosis and follow up (median 185.7 ng/mL, IQR 67.8–318.8 ng/mL and 16.6 ng/mL, IQR 6.9–61 ng/mL respectively, p < 0.001). A significant direct correlation was found between faecal GIP and tTG IgA in the total cohort of enrolled patients (r = 0.5, p < 0.001). In the follow up group, 21.4% tested positive for GIP and, of these GIP + patients, 78% had a high Biagi score. Conclusion: Our data shows that faecal GIP offers a precise assessment of even occasional exposure to gluten and suggests it might represent a less invasive instrument to check dietary adherence compared to traditional methods.