Pros and Cons of the SeHCAT Test in Bile Acid Diarrhea: A More Appropriate Use of an Old Nuclear Medicine Technique

Figure 2

Pathophysiology of enterohepatic circulation: bile acids (BAs) excreted in the intestinal lumen are mainly reabsorbed in the ileum through the apical sodium-dependent bile acid transporter (ASBT) and return to the liver through the portal vessels. Stimulation of the farnesoid X receptor (FXR) initiates the production of fibroblastic growth factor 15/19 (FGF-15/19) that interacts in the hepatocytes with cholesterol 7 alpha-hydroxylase (CYP7A/1) and reduces BA synthesis, with a negative feedback mechanism. Mutations in ASBT and klothoB have been demonstrated to be a cause of bile acid malabsorption (BAM).