The enriched low mass proteome is unexplored as a source of differentiators for diagnosing and monitoring Inflammatory Bowel Disease (IBD) activity, less invasively than colonoscopy and histopathology. Differences in the enriched low mass plasma proteome (<25kDa) were assessed by label-free quantitative mass-spectrometry. A panel of marker candidates were progressed to validation phase and ‘Tier-2’ FDA-level validated quantitative assay. Proteins important in maintaining gut barrier function and homeostasis at the epithelial interface have been quantitated by Multiple Reaction Monitoring (MRM) in plasma and serum including both inflammatory rheumatoid arthritis controls (RA) and non-inflammatory healthy controls (C), ulcerative colitis (UC) and crohn’s disease (CD) patients. Detection by immunoblot confirmed presence at the protein level in serum. Correlation analysis and receiver operator characteristics were used to report the sensitivity and specificity. Five peptides discriminating IBD activity and severity had very little-to-no correlation to Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), white cell or platelet counts. Three of these peptides were found to be binding partners to SPP24 protein alongside other known matrix proteins. These Proteins have the potentially improve effective diagnosis and evaluate IBD activity, reducing the need for more invasive techniques.