SeCHAT Test

A SeCHAT study is a nuclear Medicine test that assess how well the body absorbs bile salts. It is usually undertaken in patients with loose stools. Bile salts are made in the liver, stored in the gall bladder and then released into the upper gut (duodenum) in order to facilitate the digestion of fats and fat dependant vitamins (A,D, E and K). Bile is then largely reabsorbed with the fats and transported in the portal circulation (The blood which drains from the gut to the liver) back to the liver. Some of the bile remains in the lumen (passage) of the gut where it causes the stool to have its characteristic brown colour. Most of the bile makes its way back to the liver and is further re-cycled to be secreted into the bile ducts again. Usually patients retain at least 15% of the bile from week to week. In patients who do not re-absorb the bile in the small bowel an excess of bile in the effluent moving from the small into the large bowel draws water into the bowel, making the stool more liquid and sometimes leading to diarrhoea. A SeCHAT test uses bile labelled with a radioactive nucleotide, to assess the extent to which bile is retained as it should be. It is sometimes done to assess diarrhoea, to exclude bile salt malabsorption as a cause. Patients may need to stop a number of medicines prior to the test (for example cholestagel, cholestyramine, colesevelam, loperamide amongst others). Those patients who are pregnant or breast feeding should not undergo the test.