Introduction Emerging evidence in the literature has suggested fibroblast growth factor 19 (FGF19) and the farnesoid X receptor (FXR) are integral in bile acid synthesis, glucose and lipid metabolism. Reduced level of FGF19 and reduced feedback via the FXR are associated with idiopathic bile acid malabsorption (BAM) and non-alcoholic fatty liver disease (NAFLD), leading to the research and development of FXR agonists as potential treatment.
In this retrospective case control study, we examined the correlation between BAM and NAFLD in the district general hospital population in light of recent findings in the literature.
Method Patients who had tauroselcholic [ 75selenium] acid (SeHCAT) scan (Defined as <15% bile acid retention at day 7) between December 2012 to March 2016, with additional liver imaging (Ultrasound, CT, MRI) were included in the study. Patients with normal SeHCAT and fatty liver disease on imaging were identified as the control group. Patients with incomplete SeHCAT scans, and patients who had SeHCAT scan but no additional liver imaging were excluded from the study. Clinic letters were subsequently reviewed to ascertain cause of BAM and fatty liver disease. Patients with a diagnosis of alcoholic fatty liver disease were excluded.
Results BAM subgroup analysis- 93 type 2 (idiopathic), 39 type 1 (Terminal ileal pathology), 25 type 3 (Other GI causes). Further subgroup analysis was not possible, but the majority of the included patients had Type 2 BAM.
Conclusion Our study has shown that in patients with BAM who subsequently had liver imaging, 34% were also diagnosed with NAFLD. In comparison only 11.96% in the control group were diagnosed with NAFLD (p=0.0003, OR=3.8). It is likely that patients with Type 2 BAM are over represented, but that is reflective of our clinical experience. An expanded bile acid pool in these patients may be mechanistic by increasing LDL cholesterol and reducing HDL cholesterol. A number of other factors have recognised influences on hepatic fat metabolism and the progressive impact of bile acid sequestration on the hepatic bile acid pool and subsequent hepatic fat load is uncertain.
In summary, the increased prevalence of NAFLD in patients with BAM may indicate clinical value in screening these malabsorptive patients with hepatic ultrasound. Bile acid sequestration may have little impact on reducing hepatic fat, but there may be benefit from addressing lifestyle factors such as exercise and weight loss.
- bile acid malabsorption