title: Colonic Transit and Bile Acid Synthesis or Excretion in Patients With Irritable Bowel Syndrome-Diarrhea Without Bile Acid Malabsorption.
abstract: OBJECTIVE
  Bile acids (BAs) are passively absorbed to a different extent along the mammalian colon, so that levels are lower in the feces than in proximal colon. Our aim was to explore associations among total, primary, and secretory BA in stool and colonic transit in patients with irritable bowel syndrome-diarrhea (IBS-D) without overt BA malabsorption (BAM).
  
  
  METHODS
  In a cross-sectional observational study of 116 patients with IBS-D recruited from local communities in Minnesota, we measured total and individual main fecal BA excretion, fecal fat and fecal weight over 48 hours, fasting serum levels of C4 (surrogate for BA synthesis), and overall colonic transit by scintigraphy (geometric center at 24 hours and 48 hours). Patients without overt BAM were assigned to groups based on total fecal BA level below 2337 μmol/48 hours (n = 86) or serum levels of C4 below 47.1 ng/mL (n = 91). We used Spearman correlations to test study hypotheses with correction for 14 correlations tested (P < .0036). Data from 30 healthy volunteers were used as control subjects.
  
  
  RESULTS
  Patients with IBS-D who had increased or normal total BA excretion in stool or BA synthesis had higher stool proportions of primary BAs (especially chenodeoxycholate), compared with healthy control subjects. In patients with IBS-D without overt BAM (normal 48-hour total fecal BA or serum C4), there were significant positive correlations between total fecal BA, fecal primary and secretory BA, fecal weight, and increased geometric center at 24 and 48 hours (P < .0036). Normal and slightly increased levels of total fecal BA have greatest effects on colonic transit at 48 hours.
  
  
  CONCLUSIONS
  In the absence of overt BAM, the total, primary, and secretory BAs in stool contribute to the acceleration of colonic transit and fecal weight in the diarrhea of patients with IBS-D.
authors.affiliation: Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Cédric
authors.initials: C
authors.lastname: Peleman
authors.affiliation: Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota. Electronic address: camilleri.michael@mayo.edu.
authors.forename: Michael
authors.initials: M
authors.lastname: Camilleri
authors.affiliation: Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Irene
authors.initials: I
authors.lastname: Busciglio
authors.affiliation: Clinical Enteric Neuroscience Translational and Epidemiological Research, Mayo Clinic, Rochester, Minnesota.
authors.forename: Duane
authors.initials: D
authors.lastname: Burton
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Leslie
authors.initials: L
authors.lastname: Donato
authors.affiliation: Department of Health Sciences Research, Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota.
authors.forename: Alan R
authors.initials: AR
authors.lastname: Zinsmeister
mesh_terms: D000328:Adult; D001647:Bile Acids and Salts / Q000032:analysis*; D003106:Colon / Q000473:pathology*; D003430:Cross-Sectional Studies; D003967:Diarrhea / Q000473:pathology*; D005243:Feces / Q000737:chemistry*; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000473:pathology*; D008055:Lipids / Q000032:analysis; D008297:Male; D008875:Middle Aged; D008910:Minnesota
chemical_list: D001647:Bile Acids and Salts; D008055:Lipids
keywords: CDCA; Clinical Study; Intestine; Lithocholate