Vnitr Lek 2026, 72(1):E6-E14 | DOI: 10.36290/vnl.2026.011

Serotonin as a biomarker in inflammatory bowel diseases

Zuzana Cingelová^{1, 2}, Stanislava Blažíčková^{1, 2}

¹ Katedra laboratórnych vyšetrovacích metód v zdravotníctve, Fakulta zdravotníctva a sociálnej práce, Trnavská univerzita v Trnave, Slovenská republika

² Laboratórium klinickej biochémie, hematológie a transfuziológie, AGEL Lab s.r.o., Bratislava, Slovenská republika

Background: Non-specific inflammatory bowel disease (IBD) - Crohn's disease and ulcerative colitis are chronic diseases of the gastrointestinal tract. Diagnosis requires endoscopic examination with histology sampling. In addition to calprotectin, serotonin is also being discussed in professional circles as a suitable non-invasive biomarker for the diagnosis of IBD.

Objective: The aim was to assess the possibility of using serotonin as a biomarker in the diagnosis of inflammatory bowel disease (IBD).

Patients and methods: Serum and stool samples were collected from a Slovak cohort of 60 patients with active and remitting MC and UC. Serum serotonin and CRP levels were measured, and stool calprotectin levels were determined. Serotonin sampling was then repeated after 1 and 2 months in a group of 30 patients whose samples were available.

Results: When comparing the groups, the statistically most significant increases in CRP and calprotectin levels were found in the group of patients with MC relapse. Interestingly, serotonin levels were significantly elevated in patients with MC relapse, but not in patients with UC relapse. In remission of both diseases, the values were not statistically significant. In repeated serotonin samples, patients with MC and UC who had entered remission showed a downward trend in serotonin levels. In patients with relapsed MC and UC, we determined persistently higher serum serotonin levels. There was a difference between serotonin levels in patients who were still in relapse after two months. In MC, the average values showed a slight downward trend, in contrast to serotonin levels in patients with relapsed UC. Here, the average values showed an upward trend.

Conclusion: It is becoming increasingly clear that serotonin plays a key role and is associated with inflammatory processes that lead to many GIT disorders. Serum serotonin levels are often elevated in active IBD, particularly in Crohn's disease, and may serve as a useful non-invasive biomarker of disease activity. Further research is needed to standardize its clinical use and clarify its role in ulcerative colitis as well as Crohn's disease.

Keywords: Crohn's disease, CRP, IBD, calprotectin, serotonin.

Accepted: February 5, 2026; Published: February 12, 2026  Show citation