Bile Acid Diarrhea: An Etiology of Chronic Diarrhea Easily Overlooked

Chronic diarrhea is a symptom frequently noted in patients with various diseases. In addition to organic conditions, such as inflammatory bowel and neoplastic diseases, functional diseases including irritable bowel syndrome are important etiological factors related to chronic diarrhea. According to recent reports, approximately one-third of cases with suspected irritable bowel syndrome are actually diagnosed as bile acid diarrhea, which is characterized by decreased absorption of bile acids from the terminal ileum as well as their hepatic overproduction. Clinical signs and symptoms of bile acid diarrhea do not differ from those of other diseases complicated with chronic diarrhea, and reliable laboratory tests for proper diagnosis are not available in Japan. On the other hand, effective treatment is possible with oral administration of bile acid sequestrants. Therefore, in cases of irritable bowel syndrome with diarrhea and functional diarrhea, the possibility of bile acid diarrhea should always be considered, with a treatment trial with bile acid sequestrants discussed herein as an option.