Nutrients. 2024 Jan 17;16(2):279. doi: 10.3390/nu16020279

Amy K Russell ¹, Erin C Lucas ¹, Lee M Henneken ², Catherine J Pizzey ², Dean Clarke ³, Anna Myleus ⁴, Jason A Tye-Din ^1 2 5 6

Author information

¹Immunology Division, The Walter and Eliza Hall Institute, Parkville, VIC 3052, Australia.

²Department of Gastroenterology, The Royal Melbourne Hospital, Parkville, VIC 3052, Australia.

³National Measurement Institute, Port Melbourne, VIC 3207, Australia.

⁴Department of Public Health and Clinical Medicine, Family Medicine, Umea University, 901 87 Umea, Sweden.

⁵Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.

⁶The Murdoch Children's Research Institute, Parkville, VIC 3052, Australia.

Abstract

Monitoring adherence to a gluten-free diet is an important goal of coeliac disease management. Urine and stool gluten immunogenic peptide (GIP) assays provide an objective readout of gluten ingestion, with the former favoured due to its convenience and acceptability. This study assessed stool GIP excretion after low-dose gluten challenge designed to mimic accidental gluten exposure. A total of 52 coeliac participants undertook a randomised, double-blind gluten (50-1000 mg) or placebo challenge. Stool and urinary GIP, serology, dietary adherence and symptoms were assessed. Stool GIP was 100% sensitive for gluten intake ≥250 mg and 71% for 50 mg. Peak GIP detection was 12-36 h after gluten exposure. The mean stool GIP after 1000 mg gluten ingestion remained above the limit of quantification for 5 days. Urine GIP assessment had poor sensitivity for GIP excretion compared to stool. Serology, dietary adherence score and symptoms did not correlate with gluten excretion during lead-in. We conclude that stool GIP detection is highly sensitive, with levels related to gluten dose and time from ingestion. Weekly or bi-weekly testing will detect low-level exposure more effectively than urine GIP assessments or traditional methods. In this seronegative, apparently well-treated cohort, a high frequency of baseline-positive GIP suggests ongoing gluten exposure, but the assessment of patient behaviour and assay specificity is needed.