PHILIDELPHIA — Children with irritable bowel syndrome have a unique breathprint that could eventually be used to diagnose the syndrome simply, cheaply, and noninvasively, preliminary findings suggest.

There were significantly more biomarkers of bacterial fermentation and oxidative stress from volatile organic compounds in the breath of pediatric irritable bowel patients than in healthy control subjects, reported lead investigator Sophia Patel, MD, a gastroenterology fellow at the Cleveland Clinic Children's Hospital.

"Irritable bowel syndrome is a tough diagnosis in pediatrics because it involves a lot of invasive endoscopic and radiologic testing. It would be really nice if we could do a single test and say for certain whether the patient has irritable bowel syndrome or not," Dr Patel told Medscape Medical News.

The study results were presented here at the American College of Gastroenterology 2014 Annual Scientific Meeting.

"One percent of the human breath contains volatile organic compounds, which reflect the metabolic state of the body," Dr Patel explained. "Our hope is that, in the future, a simple breath sample could diagnose irritable bowel syndrome with good accuracy."

In previous research, investigators from the Cleveland Clinic Children's Hospital found that organic compounds differ in children with and without fatty liver disease. Dr Patel and colleagues hypothesized that the same would hold true for irritable bowel syndrome.

They evaluated 22 children with irritable bowel syndrome and 55 healthy control subjects. Mean age was about 12 years. The irritable bowel syndrome children were diagnosed with the ROME III criteria, and the healthy children were recruited during well-child visits.

There were more girls in the irritable bowel group than in the control group (68% vs 44%), and body mass index was higher in the irritable bowel group.

"Breath collection is a very simple process," Dr Patel said. Subjects rinse their mouth with water to help decrease the endogenous organic compounds found in mouth flora, and then inhale through a filter and exhale into a small bag. Samples are analyzed with mass spectrometry within 4 hours of collection.

"The filter also helps eliminate some of the exogenous compounds that are collected," Dr Patel explained.

The four compounds significantly higher in the irritable bowel group than in the placebo group were dimethyl sulfide (a biomarker of bacterial fermentation), 1-octene, 3-methylhexane, and benzene (an exogenous composite).

Table: Comparison of Breath Compounds Between Pediatric Groups

Compound Irritable Bowel Group (ppb) Placebo Group (ppb) P Value Dimethyl sulfide 3.2 1.3 <.01 1-octene 10.3 5.9 <.026 3-methylhexane 33.3 16.4 <.015 Benzene 2.9 1.9 <.02

"We also did a performance discriminate analysis," Dr Patel noted. Using mass scanning ion peaks, all but 3 patients were classified into the correct group.

Further analysis revealed that the specificity and sensitivity of the four compounds are very good, suggesting that they are good markers for irritable bowel syndrome.

"We've now expanded the study to include 40 to 50 patients with irritable bowel syndrome to get a more complete look at the two groups," she reported. "With a higher-powered study, we may be able to delineate between different types of irritable bowel syndrome and to generalize our findings to a greater population. So we're really excited about the test."

The findings are still very early, said Brian Lacy, MD, from the Geisel School of Medicine, Dartmouth–Hitchcock Medical Center, in Lebanon, New Hampshire.

"They are also in children and adolescents, so they may not be applicable to adults," he told Medscape Medical News. Investigators also need to compare these particular compounds with a hydrogen breath test, which is widely used to explore the pathophysiology of functional gastrointestinal disorders, such as irritable bowel syndrome.

"Still, it's fascinating early work that may lend some new insight into the pathophysiology of irritable bowel syndrome," Dr Lacy said. "Then we will have to determine if this will translate into a change in treatment or a better diagnosis. It's a brand new way of thinking about irritable bowel syndrome, which his kind of neat."

Dr Patel and Dr Lacy have disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2014 Annual Scientific Meeting: Abstract 12. Presented October 20, 2014.