As you may know, celiac disease is a chronic autoimmune condition caused by a response to gluten (a protein naturally found in some grains). The only treatment option offered to those with celiac disease is a strict, lifelong gluten-free diet (GFD).   

Current evaluation methods of GFD adherence include a dietary assessment, blood tests, and the assessment of clinical symptoms. Recently, biochemical tests have been developed to measure gluten immunogenic peptides (GIPs). GIPs are smaller versions of proteins (short strings of amino acids) resistant to digestion that are excreted through the stool and urine. Specific GIPs, such as one called “33-mer,” are linked to gastrointestinal inflammation. 

A recent study, co-authored by CDF Young Investigator Prize winners Dr. Maureen Leonard and Dr. Jocelyn Silvester, evaluated the prevalence of detectable GIPs in urine and stool to gauge accidental gluten exposure and adherence to a gluten-free diet in children with celiac disease in the United States.   

How did they do it? 

Two groups of children and adolescents (a total of 84 participants), one from Massachusetts General Hospital and one from Boston Children’s Hospital, were studied. The group from Massachusetts General Hospital ranged in age, 6-21 years old, and only samples from follow-up endoscopies were used. Consented participants were not told what their urine samples would be used for, and they completed a GFD compliance questionnaire. Based on their answers, participants were labeled either adherent or nonadherent.   

The group from Boston Children’s Hospital was composed of children, ages 6-18, with biopsy-confirmed celiac disease who had been on a GFD for at least six months. Both stool and urine samples were collected during follow-up visits and random home sample collections. Consented patients were aware of what their samples would be used for, and participants (or their parents) used Gluten-Free Eating Assessment Tools to rank their level of adherence to a GFD and completed the ObsRo Celiac Disease Daily Symptom Diary. 

Immunoassay testing was used to analyze serum (blood), urine, and stool samples.  

What did they find? 

Compared to previously published studies, researchers found less detectable gluten exposure using GIPs in stool and urine samples in children with celiac disease who had been on a gluten-free diet for at least six months. GIPs were found in about 9% of the stool samples and in about 5% of urine samples, and most participants did not present with symptoms at the time of sample collection. Additionally, all the participants who had ongoing damage or irritation and swelling of the small intestine had no detectable GIPs in their urine samples, which could be related to timing of sample collection, gluten exposure, or recovery of the intestinal lining. 

What does this mean? What does this change? 

These results are quite useful supporting the idea that symptoms are not the only screen for gluten exposure; GIPs offer an additional screening method for gluten exposure in patients with celiac disease on a gluten-free diet. 

While gauging adherence to a gluten-free diet isn’t an exact science, studies like these put us one step closer to understanding gluten digestion. 

Keep reading to learn more about the study. 

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