Bowel Functions, Fecal Unconjugated Primary and Secondary Bile Acids, and Colonic Transit in Patients With Irritable Bowel Syndrome

Abstract

Background & Aims There is an unclear relationship among bowel symptoms, excretion of unconjugated fecal bile acid (UBA), and colonic transit in irritable bowel syndrome (IBS). We measured total and main individual UBA in fecal samples of patients with IBS, and assessed relationships among stool frequency or consistency, fecal UBA (total and individual), and colonic transit. Methods In a study of 30 healthy volunteers (controls), 31 subjects with IBS with diarrhea (IBS-D), and 30 with IBS with constipation (IBS-C) were placed on 4-day diets containing 100 g fat; we measured stool characteristics, total fecal UBA and fat levels, and overall colonic transit. We assessed univariate associations of total and individual levels of fecal UBA with phenotype (controls, IBS-D, IBS-C) using the Kruskal-Wallis test; associations between endpoints were assessed using Spearman correlations. With response surface regression models, we assessed relationships between stool, colonic transit, and fecal total and secretory UBA. Results There was a significant association between total fecal UBA and phenotype (P=.029); the association was greater for IBS-D than IBS-C, compared with controls. Fecal levels of primary UBAs (cholic and chenodeoxycholic acids) were higher in subjects with IBS-D, compared with controls (both P<.01). Levels of fecal secretory UBAs (chenodeoxycholic acids, P=.019; deoxycholic acid, P=.025) were lower in subjects with IBS-C compared with controls, whereas levels of the nonsecretory UBA, lithocholic acid, were higher (P=.020). There were significant univariate associations between stool number and form and total fecal UBA (including percentages of lithocholic acid, chenodeoxycholic acids, and cholic acid), fecal fat, and colonic transit at 24 and 48 h after eating. In the regression models, the relative contribution of colonic transit was consistently greater, and largely independent of the contribution of bile acids. Conclusions Measurements of individual UBAs identify changes associated with stool characteristics in patients with IBS; these effects are independent of the effects of colonic transit.

High Prevalence of Idiopathic Bile Acid Diarrhea Among Patients With Diarrhea-Predominant Irritable Bowel Syndrome Based on Rome III Criteria

“…17 However, in the current climate, as none of these tests are routinely available in countries such as the USA, there is interest in the development of a simple, cheap, and readily available biomarker that will help screen for patients that potentially have BAD who can then subsequently be referred on for confirmatory tests. Of these, measurement of serum FGF-19, 18 identification of the primary bile acids cholate and chenodeoxycholate in a single stool sample, 19,20 or detection of volatile organic compounds in a single urine sample (presumed to be a consequence of dysbiosis secondary to elevated levels of colonic bile acids), 21 have all shown initial promising results, but require further work to validate their clinical applicability.…”

Emerging Pharmacologic Therapies for Constipation-predominant Irritable Bowel Syndrome and Chronic Constipation

“…57 Recently, a study showed that measurements of individual urinary bile acids were associated with stool characteristics in patients with IBS; these effects were independent of the effects of colonic transit. 58 A similar study demonstrated that serum and stool levels of bile acids were increased in diarrhea-predominant IBS patients compared to healthy controls. 59 Thus, the modulation of luminal bile acid concentrations represents a novel treatment strategy for patients with bowel disturbances.…”

Diarrea pos colecistectomía, enfoque diagnóstico y terapéutico

“…Los AB primarios, el ácido cólico y el ácido quenodesoxicólico son sintetizados en el hígado a partir del colesterol, se conjugan con glicina y taurina que aumentan su hidrosolubilidad y su secreción biliar (11). Los AB secundarios, como el ácido desoxicóli-co y el ácido litocólico, son generados a partir de los AB primarios por modificaciones realizadas por las bacterias, esto aumenta su absorción pasiva a nivel colon (12)(13)(14). La circulación enterohepática de AB fue descrita hace más de 40 años (15,16).…”

“…La demostración de mala-absorción de AB es difícil y clásicamente se han utilizado dos exámenes: la medición AB en materia fecal de 24 horas y el test respiratorio con glicocolato marcado con 14 C. En esta prueba se ingiere el glicocolato marcado con 14 C con una co- Tipo IV -idiopática No se encuentra la causa AB -ácidos biliares; ASBT -transportador apical activo dependiente de sodio de ácidos biliares; FGF19 -factor de crecimiento del fibroblasto 19; FGFR4 -receptor de membrana del hepatocito FGF tipo 4; GPBAR1 -receptor 1 de ácidos biliares unido a proteína G mida estándar, las bacterias rompen el enlace entre la glicina y el ácido cólico, se absorbe la glicina 14 C y se metaboliza a nivel hepático con la posterior exhalación de 14 CO 2 , en el test de aliento se evalúa cada hora por seis horas (30). La otra prueba es la evaluación del glicocolato marcado con 14 C en la materia fecal de 24 horas, la cual se recolecta y se realiza combustión para crear 14 CO 2 (30).…”

“…La otra prueba es la evaluación del glicocolato marcado con 14 C en la materia fecal de 24 horas, la cual se recolecta y se realiza combustión para crear 14 CO 2 (30). Ambos estudios son dispendiosos y exponen al paciente a radiación (31).…”