Bile Salt Malabsorption

Bile salt malabsorption is a condition which often (but not always) causes watery diarrhoea). Usually bile is produced in the liver, stored in the gallbladder and released from there via the bile duct and into the small bowel where it facilitates the digestion of fats and fat dependant vitamins. Normally the majority of bile is then reabsorbed in the last part of the small bowel and re-circulated back to the liver. The effectiveness of this re-capture and re-circulation is what is measured in the SecHAT test, In this investigation a radiolabelled bile precursor is administered and then the amount of retained material is measured a week later. Usually at least 15% of the initial bile is still retained after a week. This retention is what is measured in the second part of the SecHAT test.

If too much bile escapes to reach the large bowel (colon), where it cannot be reabsorbed it draws water from the bowel wall into the lumen, making the contents more watery and thence causes watery diarrhoea. Patients with bile salt malabsorption which can arise at any time but may occur more frequently after gut infection or removal of the gallbladder, usually present with loose watery diaorrhea. This is sometimes worse after fatty foods, perhaps because this stimulates the release of more bile. 

Treatment is usually with bile sequestrants, like questran or cholestagel which bind to the bile salts and stop them from causing loose stools.