Analyte Annotation and Marker Identification
Table S2 presents the annotated metabolite ions discussed in this study. The metabolite ions of interest were first searched through HMDB (http://hmdb.ca) and Metlin (https://metlin.scripps.edu) with the 5.0 ppm mass tolerance. The type of adduct ions included [M+H]+, [M+Na]+, [M+K]+, [M-H2O+H]+, [M+2Na-H]+, [M+2K-H]+, and [M+NH4]+. Only those candidates with a reported presence in humans were given consideration. For those unknown significantly changed ions, MS/MS experiments were performed to match the collision-induced dissociation (CID) fragmentation patterns either with given standards or recorded MS/MS spectra in HMDB and Metlin.