O1 Faecal volatile organic compounds in paediatric inflammatory bowel disease

Faecal volatile organic compounds (VOCs) result from the metabolism of the intestinal mucosa, gut microbiota and the environment. Profiling of faecal VOCs in children with different IBD sub-types and disease distribution and activity may shed light on underlying disease mechanisms. Method We assessed faecal VOCs by gas chromatography-mass spectrometry in a prospective, observational study of children with suspected inflammatory bowel disease (IBD) attending 3 specialist clinics. We tested whether the abundance of faecal VOCs differed according to IBD versus other gastrointestinal disorders, IBD subtype and response to treatment in IBD. Results We characterised faecal VOCs in 132 children in whom IBD was diagnosed and 132 non-IBD controls. 162 (61.4%) were boys. Mean age was 12.2 years (SD 3.0). In total 214 (81.1%) were white, 35 (13.3%) were Asian and 15 (5.7%) of other ethnic background. There were 78 (29.5%) children with Crohn’s disease (CD), 38 (14.4%) with ulcerative colitis (UC) and 16 (6.1%) IBD-unclassified. The most common diagnosis in controls was a functional gastrointestinal disorder. The mean abundance of 16 VOCs was significantly lower in IBD than controls whereas phenol and propan-1-ol were higher in IBD (p=0.001). Some short chain fatty acids (butanoic, pentanoic and hexanoic acids) were lower in IBD than controls (p The two compounds that were more abundant in IBD than control (propan-1-ol and phenol) returned to control levels post-treatment (figure 1). Within IBD, the subtype (CD versus colitis (UC and IBD-unclassified)) described a small amount of variation (3%, p=0.006), with three faecal VOCs (6-methylhept-5-en-2-one; benzaldehyde; 4-methylphenol) significantly different in abundance between CD and colitis (t-test, p Conclusion/interpretation Propan-1-ol and phenol, higher in abundance in IBD than controls and returning to control levels post-treatment, may indicate abnormal amino-acid metabolism in pre-treatment IBD; phenol may be pro-inflammatory. Further analysis of VOCs may provide insights into underlying disease mechanisms in paediatric IBD.