OBJECTIVE: The limited understanding of venous thromboembolism (VTE) has hindered the development of novel treatment approaches. This study aimed to identify critical factors underlying VTE. METHODS: The isobaric tags for relative and absolute quantitation (iTRAQ) method was applied to identify differentially expressed proteins in plasma samples from patients with VTE and healthy volunteers. Gene overexpression and knockdown techniques were used for cultured human umbilical vein endothelial cells (HUVECs) and VTE mouse models. Thrombosis and apoptosis related to the identified proteins were verified using qRT-PCR, western blot, and flow cytometry analyses. RESULTS: iTRAQ analysis revealed significant upregulation of keratin 1, pro-platelet basic protein, and hemopexin (HPX) in the plasma of VTE patients. HPX was highly expressed in both plasma and GSE19151 and GSE48000 datasets. qRT-PCR and western blot results for HPX overexpressing HUVECs and VTE mouse models revealed that HPX positively regulated the expression of platelet endothelium aggregation receptor 1 and von Willebrand factor, but negatively regulated the expression of serpin family D member 1 and alpha-2-macroglobulin. Flow cytometry revealed that HPX exhibited pro-apoptotic activity in HPX overexpressing HUVECs. Furthermore, HPX elevated cleaved caspase-3 expression and inhibited B-cell lymphoma-2 expression in HUVECs and VTE mouse models. CONCLUSION: HPX exhibits possible prothrombotic activity by regulating thrombosis - apoptosis-related proteins.