Background: Ageing and degeneration are biologically distinct processes in intervertebral discs but are difficult to differentiate radiologically. Metabolomics reflects real-time biochemical activity, and age-stratified metabolomic profiling of normal and degenerated discs may identify pre-clinical degeneration and reveal molecular signatures distinguishing normal ageing from degeneration. 

Methods: Nucleus pulposus tissue from 21 healthy organ donors (Pfirrmann gradeI) was stratified by age: young(20–30yrs), middle-aged(31–50yrs), and old(>50yrs), and compared with 40 degenerated discs (grades III–V) from surgical specimens. Untargeted UHPLC–MS/MS was performed in both ionization modes. Metabolites were identified using Compound Discoverer v3.7, HMDB, KEGG. Statistical and pathway enrichment analyses were performed via MetaboAnalyst 6.0. 

Results: Untargeted UHPLC-MS/MS analysis revealed 831 significant metabolites (VIP >1). Lipids and lipid-like molecules, especially sphingolipids, fatty acyls, and steroids, constituted 39%. Four distinct metabolic trends observed:(i) progressive decline of antioxidants (ubiquinone, glutathione, N-acetyl seretonin);(ii) increased oxidative/inflammatory markers (4-HNE, prostaglandin E₂ ethanolamide, N1-acetylspermidine);(iii) transient midlife antioxidant elevation; (4OH benozoic acid, 4OH phenylpyruvic acid) (iv) partial recovery in older discs (Hypoxanthine, Paraxanthine, CerP(d18:1/18:0). In old-aged discs, accumulation of sphingolipids (sphingosine, ceramides) and redox drift indicated enhanced senescence and energy imbalance. Degenerated discs exhibited suppression of bioactive lipids, particularly resolvins, PGE2, and SOFAs, accompanied by disrupted sphingolipid metabolism and reduced redox capacity. 

Conclusion: Metabolomic shifts offer physio-pathological staging - “metabolically stable ageing,” “compensated ageing,” and “metabolic degeneration”. Unique sphingolipid and redox signatures clearly distinguished physiological ageing from degeneration and provide a strong foundation for biomarker discovery and therapeutic strategies to stop/reverse disc degeneration at the preclinical stage.