Metabolomic Profiling Reveals Distinct Signatures in Primary and Secondary Polycythemia

<b>Background/Objectives</b>: The differential diagnosis between primary polycythemia vera (PV) and secondary polycythemia (SP) presents significant clinical challenges owing to substantial phenotypic overlap. This investigation utilized untargeted metabolomic approaches to elucidate disease-specific metabolic perturbations and evaluate the metabolic consequences of cytoreductive therapeutic interventions. <b>Methods</b>: Plasma specimens obtained from PV patients (<i>n</i> = 40) and SP patients (<i>n</i> = 25) underwent comprehensive metabolomic profiling utilizing liquid chromatography-mass spectrometry (LC-MS) platforms. Multivariate statistical analyses, including principal component analysis (PCA), were employed in conjunction with pathway enrichment analyses to characterize disease-associated metabolic dysregulation. Additionally, receiving treatment (tPV) (<i>n</i> = 25) and not receiving treatment (ntPV) (<i>n</i> = 15) PV patients were compared to assess therapeutic metabolic effects. <b>Results</b>: Comprehensive metabolomic analysis identified 67 significantly altered metabolites between PV and SP patients, with 36 upregulated and 31 downregulated in PV. Key upregulated metabolites in PV included thyrotropin-releasing hormone, 3-sulfinoalanine, nicotinic acid adenine dinucleotide, and protoporphyrin IX, while 4-hydroxyretinoic acid and deoxyuridine were notably downregulated. Pathway enrichment analysis revealed disruptions in taurine, glutamate, nicotinate, and cysteine metabolism in PV. ntPV patients exhibited higher glucose and octanoyl-CoA levels compared to treated patients, indicating the normalization of glucose and fatty acid metabolism with cytoreductive therapy. ntPV was also associated with altered B-vitamin metabolism, including decreased nicotinic acid adenine dinucleotide and increased nicotinamide ribotide levels. Cross-comparison analysis revealed overlapping pathway enrichment in glutamate metabolism, nicotinate and nicotinamide metabolism, and cysteine metabolism between both comparisons. <b>Conclusions</b>: This study demonstrates that PV and SP exhibit fundamentally distinct metabolic signatures, providing novel insights into disease pathogenesis and potential diagnostic biomarkers. The identification of oxidative stress signatures, disrupted energy metabolism, and altered B-vitamin cofactor pathways distinguishes PV from SP at the molecular level. Cytoreductive therapy significantly normalizes metabolic dysregulation, particularly glucose and nucleotide metabolism, validating current therapeutic approaches while revealing broader systemic treatment effects. The metabolic signatures identified, particularly the combination of deoxyuridine, thyrotropin-releasing hormone, and oxidative stress metabolites, may serve as complementary diagnostic tools to traditional morphological and molecular approaches. These findings advance our understanding of myeloproliferative neoplasm pathophysiology and provide a foundation for developing metabolically targeted therapeutic strategies and precision medicine approaches in PV management.