Table 2. Relative levels of VOCs differentially expressed in CD patients and healthy subjects (median (IQR)).
| Metabolite | CD patients | Detected (n/45) | HC | Detected (n/40) | FDR-adjusted P-value |
|---|---|---|---|---|---|
| Benzeneacetaldehyde | 0.004 (0.001–0.006) | 40 | 0.000 (0.000–0.000) | 7 | <0.0001 |
| Dimethyl sulfide | 0.000 (0.000–0.001) | 5 | 0.026 (0.004–0.045) | 31 | <0.0001 |
| 2-Butanone | 0.000 (0.000–0.000) | 10 | 0.325 (0.157–0.472) | 37 | <0.0001 |
| 1-Methoxy-4-methylbenzene | 0.001 (0.000–0.002) | 24 | ND | 0 | <0.0001 |
| 2-Methylpropanal | 0.370 (0.235–0.520) | 45 | 0.098 (0.025–0.289) | 35 | <0.0001 |
| Phenol | 0.003 (0.000–0.018) | 44 | 0.000 (0.000–0.001) | 27 | <0.0001 |
| 3-Methyl-1H-indole | 0.000 (0.000–0.001) | 11 | 0.016 (0.001–0.045) | 33 | <0.0001 |
| 1-Ethyl-2,4-dimethylbenzene | <0.000 | 1 | 0.001 (0.000–0.013) | 19 | <0.0001 |
| Heptanoate | 0.000 (0.000–0.002) | 19 | 0.054 (0.001–0.241) | 35 | <0.0001 |
| 1-Hexanol | 0.000 (0.000–0.000) | 3 | 0.001 (0.000–0.002) | 20 | <0.0001 |
| Hexanoate | 0.009 (0.003–0.057) | 45 | 0.230 (0.030–0.809) | 39 | <0.0001 |
| Methyl propyl disulfide | 0.000 (0.000–0.000) | 6 | 0.001 (0.000–0.003) | 25 | <0.0001 |
| 2,5-Dimethyl furan | 0.000 (0.000–0.000) | 6 | 0.007 (0.000–0.013) | 23 | <0.0001 |
| 2-Pentyl furan | 0.000 (0.000–0.000) | 2 | 0.001 (0.000–0.002) | 18 | <0.0001 |
| Nonyl-cyclopropane | ND | 0 | 0.001 (0.000–0.005) | 14 | <0.0001 |
| 1-Methyl-4-(1-methylethenyl)-benzene | 0.000 (0.000–0.001) | 9 | 0.002 (0.000–0.006) | 22 | <0.001 |
| 1-Ethyl-3-methyl-benzene | 0.026 (0.018–0.043) | 45 | 0.008 (0.001–0.028) | 39 | <0.001 |
| Hexane | 0.000 (0.000–0.000) | 2 | 0.002 (0.000–0.540) | 15 | <0.001 |
| α-Terpinene | ND | 0 | 0.001 (0.000–0.002) | 11 | <0.001 |
| Methyl alcohol | <0.000 | 1 | 0.000 (0.000–0.051) | 13 | 0.001 |
| Octanoate | 0.000 (0.000–0.003) | 17 | 0.004 (0.000–0.042) | 30 | 0.002 |
| 2-Methyl-2-propenyl-benzene | 0.000 (0.000–0.001) | 15 | <0.000 | 1 | 0.002 |
| 5-Methyl-2-(1-methylethyl)-cyclohexanol | 0.000 (0.000–0.005) | 14 | <0.000 | 1 | 0.004 |
| Furan | 0.057 (0.039–0.083) | 44 | 0.033 (0.023–0.053) | 39 | 0.005 |
| 2,2,4-Trimethyl-pentane | ND | 0 | 0.000 (0.000–0.001) | 9 | 0.005 |
| Carbon disulfide | 0.022 (0.011–0.046) | 35 | 0.005 (0.000–0.017) | 28 | 0.005 |
| 2-Methylbutyrate | 0.300 (0.102–0.482) | 44 | 0.656 (0.337–1.189) | 36 | 0.007 |
| Methyl 2-propenyl disulfide | ND | 0 | 0.000 (0.000–0.001) | 8 | 0.009 |
| Methanethiol | 0.000 (0.000–0.000) | 9 | 0.009 (0.000–0.029) | 22 | 0.009 |
| Pentanoate | 0.248 (0.019–0.426) | 45 | 0.427 (0.240–0.606) | 40 | 0.011 |
| 3-Methyl-2-pentene | 0.000 (0.000–0.000) | 9 | ND | 0 | 0.014 |
| α-Methylstyrene | <0.000 | 1 | 0.000 (0.000–0.000) | 9 | 0.018 |
| Hexanal | 0.000 (0.000–0.021) | 23 | 0.000 (0.000–0.001) | 11 | 0.024 |
| 5-Methyl-2-furancarboxaldehyde | 0.003 (0.002–0.005) | 45 | 0.002 (0.000–0.004) | 35 | 0.024 |
| Cyclohexanone | 0.000 (0.000–0.001) | 16 | 0.001 (0.000–0.007) | 20 | 0.027 |
| 6-Methyl-3,5-heptadiene-2-one | <0.000 | 1 | 0.000 (0.000–0.000) | 8 | 0.027 |
| Acetone | 1.062 (0.631–2.031) | 45 | 0.699 (0.572–1.022) | 39 | 0.030 |
| Acetophenone | 0.002 (0.000–0.009) | 30 | 0.007 (0.002–0.018) | 33 | 0.030 |
| Hydrogen sulfide | 0.005 (0.000–0.009) | 27 | 0.000 (0.000–0.002) | 13 | 0.044 |
| 3-Phenyl-2-propenal | 0.000 (0.000–0.000) | 2 | 0.000 (0.000–0.001) | 9 | 0.045 |
Abbreviations: CD, Crohn's disease; FDR, false discovery rate; HC, healthy control; IQR, interquartile range; n, number out of the total number of individuals/group; ND, non-detectable; VOC, volatile organic compound.