[Serum serotonin concentration and urine 5-hydroxyindole acetic acid excretion in patients with irritable bowel syndrome]

Abstract

Serotonin (5-HT) is among other factors involved in gastrointestinal motility, secretion and visceral sensation. Available data suggest that secretion and metabolism of 5-HT may be disturbed in irritable bowel syndrome (IBS). Interpretation of these observations have been hampered by the variable methodology used and small numbers of patients involved in the previous studies. Aim of this study was to measure serum 5-TH concentration under fasting condition in patients with irritable bowel syndrome (IBS), compared with controls (K). The metabolite of serotonine--5-hydroxyindole acetic acid (5-HIAA) in urine was also assessed.

Methods: 71 subjects, aged 19-50 years were included in this study. Three groups were distinguished: group I (n=25)--healthy volunteers, group II (n=23)--patients with constipation predominant (IBS-C), group Ill (n=23)--subjects with diarrhea predominant irritable bowel syndrome (IBS-D). IBS was diagnosed according to Rome Ill Criteria. On the day of the experiment, patients received a standard meal (Nutridrink 6 x 300 kcal) and blood samples were collected during fasting. 5-HIAA concentration was determined in 24-hour urine collection. Concentration of 5-HT and 5-HIAA was measured by immunoenzyme ELISA method employing standard kits IBL nr RE59121 i RE59131 and Labsystems Multiscan detector.

Results: The average serotonin concentration during fasting was found in group I--156.67 +/- 49.12 ng/ml, in group II--221.73 +/- 91.56 ng/ml (p < 0.05), in group III--3.50 +/- 1.71 mg/24h. 5- HIAA concentration in urine was decreased in group Ill--3.50 +/- 1.71 mg/24 hrs (p < 0.05) and group II--4.37 +/- 2.95 mg/24 hrs compared with healthy volunteers--5.65 +/- 2.31 mg/24 hrs.

Conclusion: (1) Serotonin concentration is increased in C-IBS and D-IBS patients. (2) Urine 5-hydroxyindole acetic acid excretion is decreased in IBS-subjects. (3) Disturbed metabolism of serotonin probably may play role in pathogenesis of functional bowel diseases.