Fig. 5

Discovery of the metabolic biomarkers for IgG4-RD relapse. The volcano plot for the differently expressed metabolites between relapsed (n = 21) and non-relapsed (n = 21) patients in ESI+ and ESI− modes. B–F The expression levels of the metabolic biomarkers for IgG4-RD relapse (n = 30): B phenylalanine betaine; C 1-(1z-hexadecenyl)-sn-glycero-3-phosphocholine; D Pi 40:8; E uracil; F N1-methyl-2-pyridone-5-carboxamide. The Mann–Whitney test was used for the comparison of the relative abundance between groups. *P < 0.05, **P < 0.01, ***P < 0.001. G The cumulative AUC of the differently expressed metabolites between relapsed and non-relapsed IgG4-RD patients. M208T204, phenylalanine betaine; M480T184, 1-(1z-hexadecenyl)-sn-glycero-3-phosphocholine; M906T194, Pi 40:8; M113T164, uracil; M153T126, N1-methyl-2-pyridone-5-carboxamide; M485T30, andrastin a; M811T197, 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphoserine; M263T102, (+)-abscisic acid; M243T169, uridine; M430T173, (e,2s,3r,4r,5s)-4-acetyloxy-2-amino-3,5,14-trihydroxyicos-6-enoic acid. H The importance scores of each differently expressed metabolite and selected metabolite between relapsed and non-relapsed IgG4-RD patients. I ROC curve of the selected metabolites between relapsed and non-relapsed IgG4-RD patients. IgG4-RD, immunoglobulin G4-related disease