Pulmonary hypertension (PH) often leads to poor survival outcomes and encompasses diverse subtypes with distinct underlying causes. Specifically, PH resulting from fibrosing mediastinitis (FM-PH) presents significant diagnostic challenges due to nonspecific symptoms and overlap of clinical characterization with other PH subtypes, leading to frequent misdiagnosis and delayed treatment. Moreover, the complex diagnostic procedures impose a significant burden on FM-PH patients, many of whom already experience mobility difficulties. This study represents a single test-based diagnosis of FM-PH, using the plasma metabolites obtained through ferric particle-enhanced laser desorption/ionization mass spectrometry analysis. Distinct metabolic alterations in FM-PH are identified compared to healthy controls and other PH subtypes, achieving an area under the curve (AUC) of 0.987 for FM-PH diagnosis and 0.728 for differentiating FM-PH from other subtypes. By addressing existing gaps in diagnostic strategies, this research highlights the potential of metabolic analysis in elucidating the metabolic landscape of PH.