Bile acid malabsorption (BAM), clinically manifesting as hologenic diarrhea, is one of the common but often overlooked symptoms of inflammatory bowel diseases (IBD).
OBJECTIVE
To assess the level of fecal excretion of BA in patients with IBD and the possibility of using the determination of BA in feces in the diagnosis of diarrhea and the clinical course of Crohn’s disease (CD) and ulcerative colitis (UC).
MATERIAL AND METHODS
The study included 62 stool samples from clinically examined patients with CD, 26 — with UC, 20 — with IBD unclassified (IBDU), and 15 stool samples from healthy individuals, in which concentrations of fecal BA, fecal calprotectin (FC) and stool osmotic gap (SOG) were measured. The associations of these markers with diarrhea, localization, severity, disease phenotype, and surgical treatment of IBD were determined.
RESULTS
The mean concentration of fecal BA was significantly higher in patients with CD (113.3±303.1 µmol/g), UC (41.72±112.5 µmol/g) and IBDU (44.41±99, 6 µmol/g) compared with the control group (0.9±1.35 µmol/g) (p<0.05). An increased concentration of fecal BA in 51.3% of cases was observed in the group of patients with CD with diarrheal syndrome compared with patients with CD without diarrhea (26%) with mean concentrations of 162±371.6 µmol/g vs. 30.8±70.84 µmol/g (p<0.001). In 67.2% of IBD patients with diarrheal syndrome, low SOG values (23.16±12.64 mOsmol/kg) were noted, which had an inverse correlation with high concentrations of fecal BA (181.7±364.4.1 µmol/g) (r= –0.48, p=0.002). In 51.2% of patients with IBD with diarrhea and low values of SOG, high concentrations of fecal BA (134.7±321.8 µmol/g) and FC (1035±774.4 µg/g) were combined (r=0.29, p=0.03). The level of faecal excretion of fatty acids was significantly higher in patients with terminal ileitis (226±566.5 µmol/g) and stenosing CD phenotype (150±479.8 µmol/g) compared with patients with colitis, ileocolitis and involvement of the upper gastrointestinal tract and luminal CD phenotype, respectively. In CD patients with ileocecal resection, the frequency of detection and the mean concentration of fecal BA were higher compared with patients without removal of the terminal ileum — 85.7% (127.7±116.4 µmol/g) vs. 18.1% (21.82±53.13 µmol/g), respectively (p=0.01).
CONCLUSIONS
Determination of the concentration of fecal BA allows diagnosing type BAM, as well as identifying subgroups of patients with chologenoic and chologeno-inflammatory types of diarrheal syndrome in IBD. Clinically significant BAM is associated with terminal ileitis, a stricture phenotype, and ileocecal resection in CD. Assessment of faecal FA excretion can serve as a potential therapeutic target for the development of new treatments for IBD.
