NHD CPD eArticle SPONSORED BY
NETWORK HEALTH DIGEST
Volume 8.06 - 12th April 2018
BILE ACID MALABSORPTION Rebecca Gasche Registered Dietitian, Countess of Chester Hospital NHS Trust Rebecca has a keen interest and specialises in gastroenterology dietetics. She currently works in the community setting in the Chester area, running clinics and group sessions to manage a wide range of gastroenterology conditions.
This article will focus on a specific type of malabsorption - bile acid malabsorption (BAM) - with the aim of raising awareness of the signs and symptoms, to improve recognition and early diagnosis. Malabsorption is a word we often come across when working in a clinical setting. It can be defined as the poor absorption of nutrients in the small intestine and may be nutrient specific (i.e. affecting only the absorption of fats), or generalised (i.e. affecting the absorption of many nutrients).1 There are a number of causes for malabsorption, such as intestinal resections, mucosal damage, pancreatic insufficiency, inflammatory bowel disease or coeliac disease.1 WHAT IS BILE ACID MALABSORPTION?
Bile contains bile acids, which are manufactured in the liver and stored in the gallbladder. The ingestion of dietary fat causes the gallbladder to contract and the bile acids are secreted into the upper small bowel to aid the breaking down and absorbing of fats and vitamins. They are then reabsorbed in the terminal ileum, and around 97% of bile acids are recycled for re-use back to the liver (the last 3% are excreted in faeces), a process called enterohepatic circulation.2 If the terminal ileum is diseased or has been
resected, or if hepatic bile production is increased so much so that it overwhelms normal absorptive mechanisms, excess bile can enter the colon and cause erratic, chronic diarrhoea.3 BAM is best diagnosed by a SeHCAT test or by the 7ɑ-hydroxy-4-cholesten3-one blood test.3 The SeHCAT test involves the patient swallowing a capsule containing a synthetic bile salt with a small amount of ionising radiation, which tests the function of the bowel by measuring how well the compound is retained or lost in the body.2 The SeHCAT test involves two scans one week apart to assess the amount of the compound retained, and results will be as follows: • retention values of 10-15% (mild bile acid malabsorption) • retention values of 5-10% (moderate bile acid malabsorption) • retention values of 0-5% (severe bile acid malabsorption)2 The SeHCAT test is advised in the British Society of Gastroenterology (BSG) guidelines.4
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