title: Alterations in serotonin metabolism in the irritable bowel syndrome.
abstract: BACKGROUND
  Alterations in serotonin (5-HT) metabolism have been postulated to play a role in the pathogenesis of irritable bowel syndrome (IBS). However, previous reports regarding 5-HT metabolism in IBS are contradicting.
  
  
  OBJECTIVE
  To compare platelet poor plasma (PPP) 5-HT and 5-hydroxyindole acetic acid (5-HIAA) levels and their ratio in a large cohort of IBS patients and healthy controls (HC), including IBS-subgroup analysis.
  
  
  METHODS
  Irritable bowel syndrome patients and HC were evaluated for fasting PPP 5-HT and 5-HIAA levels. Furthermore, GI-symptom diary, GSRS, quality of life, anxiety and depression scores were assessed in the 2 weeks before blood sampling.
  
  
  RESULTS
  One hundred and fifty four IBS patients and 137 HC were included. No differences were detected in plasma 5-HT between groups. The 5-HIAA concentrations and 5-HIAA/5-HT ratio were significantly lower in IBS compared to HC: 24.6 ± 21.9 vs. 39.0 ± 29.5 μg/L (P < 0.001) and 8.4 ± 12.2 vs. 13.5 ± 16.6 (P < 0.01), respectively. Subtype analysis for 5-HIAA showed all IBS subtypes to be significantly different from HC. The 5-HIAA/5-HT ratio was significantly lower in the IBS-M subtype vs. HC. Linear regression analysis points to an influence of gender but not of GI-symptoms, psychological scores or medication use.
  
  
  CONCLUSIONS
  We demonstrated that fasting 5-HT plasma levels are not significantly different in IBS patients compared to controls. However, decreased 5-HIAA levels and 5-HIAA/5-HT ratio in IBS patients may reflect altered serotonin metabolism in IBS. Gender affects 5-HIAA levels in IBS patients, but no effects of drugs, such as SSRIs, or higher GI-symptom or psychological scores were found.
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: A Y
authors.initials: AY
authors.lastname: Thijssen
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: Z
authors.initials: Z
authors.lastname: Mujagic
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: D M A E
authors.initials: DM
authors.lastname: Jonkers
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Ludidi
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: D
authors.initials: D
authors.lastname: Keszthelyi
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.|NUTRIM School for Nutrition, and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Hesselink
authors.affiliation: Department of Gastroenterology, Alrijne Zorggroep, Leiden, The Netherlands.
authors.forename: C H M
authors.initials: CH
authors.lastname: Clemens
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Conchillo
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Kruimel
authors.affiliation: Division of Gastroenterology-Hepatology, Department of Internal Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands.
authors.forename: A A M
authors.initials: AA
authors.lastname: Masclee
mesh_terms: D000328:Adult; D005215:Fasting; D005260:Female; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism*; D043183:Irritable Bowel Syndrome / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D012701:Serotonin / Q000378:metabolism*; D055815:Young Adult
chemical_list: D012701:Serotonin; D006897:Hydroxyindoleacetic Acid