Ability of Mayo Clinic High-performance Liquid Chromatography (HPLC) Method to Measure Fecal Bile Acids

Patients with IBS-diarrhea with prior evidence of increased fecal 48 hour total bile acid and increased fasting serum 7alphaC4 who meet the following: INCLUSION CRITERIA * Bowel disease questionnaire (BDQ) - IBS symptoms: Positive by Rome lll criteria * No restrictions on Hospital Anxiety/Depression Score (HADS). * Gender: Men or women. Women of childbearing potential will have a negative pregnancy test before initiation of medication. EXCLUSION CRITERIA * Use of drugs or agents within the past 1 week or planned use in the subsequent 2 weeks during the study period (Birth control pill, estrogen replacement therapy, and thyroxine replacement are permissible exceptions): * Agents that alter GI transit including opioids, narcotics, anticholinergics, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors (SNRI) antidepressants. * Analgesic drugs including opiates, nonsteroidal anti-inflammatory drugs (NSAID), cyclooxygenase-2 (COX 2) inhibitors * Intake of medication that could interfere with the interpretation of the study. * Female subjects who are pregnant or breast-feeding. Females must be either surgically sterilized, postmenopausal (\>12 months since last menses), or, if of childbearing potential, using reliable methods of contraception as determined by the physician. * Abdominal surgery (except Appendectomy) * Patients with known chronic liver disease or history of elevated aspartate aminotransferase (AST)/ alanine transaminase (ALT) 2.0 X upper limit of normal. * Bile acid (BA) synthesis and possible false positive or negative fecal bile acid or serum 7alpha-hydroxy-4-cholesten-3-one (7alphaC4) result. If there is no AST or ALT values in the medical record, the study physicians will determine if the tests need to be run.