A Randomized, Triple-blind, Placebo-controlled, Clinical Trial on the Diagnostic Performance of Gluten Immunogenic Peptides in the Evaluation of Gluten-free Diet Adherence: the GRRES Study.

A strict and permanent gluten free diet (GFD) is the only effective treatment resulting in full clinical, serological and histological remission, avoiding long-term complications in celiac disease (CD) patients. Gluten immunogenic peptides (GIP) are fragments of gluten proteins resistant to gastrointestinal digestion and detectable in urine after intestinal digestion, providing direct evidence of recent gluten ingestion. A significant variability in the amount of excreted urinary GIP has been reported in individuals administered with similar doses of gluten and, so far, inadequate information is available about the amount of excreted GIP in subjects ingesting traces or low amount of gluten. This is an important issue, as even a strict GFD could be contaminated by traces of gluten, e.g. in wheat starch and processed food. The aim of this study is to assess the clinical usefulness of urinary GIP as a marker of GFD adherence using a rapid immunochromatographic assay based on anti-gliadin 33-mer monoclonal antibodies. This is a prospective, randomized, triple-blind, placebo-controlled, clinical trial. In this study, healthy volunteers following a normal diet will be requested to be on strict GFD for 5 days. On day 4th, participants will be requested to collect a baseline urine sample and in case of a negative GIP test result they will be assigned to ingest a specific dose of purified gluten incorporated in a capsule (0 mg, 10 mg, 50 mg, 100 mg, 500 mg and 1000 mg, according to randomization). Participants will be requested to collect urine samples in a container and take a 5 mL aliquote for the GIP test at the 9th and 24th hour from the time of the administration of the dose. During the collection, volunteers will also be requested to record the volume of the excreted urine and to store the collected urine at 4°C. Urine tubes will be stored at -20°C until the quantitative evaluation of GIP. GIP test will be performed using the rapid immunochromatographic assay based on anti-gliadin 33-mer monoclonal antibodies iVYCHECK GIP Urine™ test (Biomedal, Spain) according to the manufacturer's instructions.