Section of Hepatology & Gastroenterology, Department of Medicine, Imperial College London and, Imperial College Healthcare, London, UK.
Expert Rev Gastroenterol Hepatol. 2010 Oct;4(5):561-7. doi: 10.1586/egh.10.54.
Chronic diarrhea due to bile acid malabsorption may be considered as contributing to the diagnosis when it results from secondary causes, such as ileal resection affecting the enterohepatic circulation. However, the primary form (also known as idiopathic bile acid malabsorption) is not well recognized as a common condition and patients are left undiagnosed. Primary bile acid diarrhea can be diagnosed by the nuclear medicine 75Se-homocholyltaurine (SeHCAT) test, although this is unavailable or underutilized in many settings. A systematic review suggests that approximately 30% of patients who would otherwise be diagnosed with diarrhea-predominant irritable bowel syndrome or functional diarrhea have abnormal SeHCAT retention. Serum 7α-hydroxy-4-cholesten-3-one can also be measured to show increased bile acid synthesis. The reasons for the lack of recognition of primary bile acid diarrhea are discussed, and these are compared with the other common cause of malabsorption, celiac disease. The lack of a clear pathophysiological mechanism has been a problem, but recent evidence suggests that impaired feedback control of hepatic bile acid synthesis by the ileal hormone FGF19 results in overproduction of bile acids. The identification of FGF19 as the central mechanism opens up new areas for development in the diagnosis and treatment of primary bile acid diarrhea.
由胆酸吸收不良引起的慢性腹泻，如果是继发于某些原因，如影响胆汁肠肝循环的回肠切除术，则可能有助于诊断。然而，原发性（也称为特发性胆酸吸收不良）并没有被很好地认为是一种常见病症，导致许多患者未被诊断。核医学 75Se-同型胆酸牛磺酸盐（SeHCAT）试验可诊断原发性胆酸腹泻，但在许多情况下，该试验不可用或未被充分利用。一项系统评价表明，否则可能被诊断为腹泻为主的肠易激综合征或功能性腹泻的患者中，约有 30%存在异常的 SeHCAT 保留。还可以测量血清 7α-羟基-4-胆甾烯-3-酮以显示胆汁酸合成增加。讨论了未识别原发性胆酸腹泻的原因，并将其与其他常见的吸收不良原因——乳糜泻进行了比较。缺乏明确的病理生理机制一直是一个问题，但最近的证据表明，回肠激素 FGF19 对肝胆汁酸合成的反馈控制受损导致胆汁酸过度生成。FGF19 作为中心机制的发现为原发性胆酸腹泻的诊断和治疗开辟了新的领域。
