[Postprandial serum bile acid level and 75SeHCAT retention in diagnosis of bile acid malabsorption syndrome. A comparative study].

Postprandial serum bile acids (expressed as integrated bile acid response [IR]) after a standardized test meal were compared with 75SeHCAT retention, measured in a whole body counter, in healthy controls (n = 20), in 44 patients with ileal disease or resection and in 23 patients with colitis without ileal involvement. In the controls the IR after 180 min was 736 +/- 186 mumol x min x 1(-1) (mean +/- standard deviation), the 75SeHCAT retention 31 +/- 9%. 80% of the patients with ileal disease or resection had a decreased 75SeHCAT retention, indicating bile acid malabsorption, but only 59% had a diminished IR. One of the 23 patients with colitis and radiologically normal ileum had a decreased 75SeHCAT retention but a normal IR, reflecting a dysfunction of the morphologically normal ileum. The characteristics of the two tests are: 75SeHCAT retention test: sensitivity 80%, specificity 98%, accuracy 89%; postprandial serum bile acids: sensitivity 64%, specificity 74%, accuracy 69%. With respect to chronic inflammatory bowel disease the positive predictive value of the 75SeHCAT retention test is 1.0%, for postprandial serum bile acids 0.1%, whereas the negative predictive values amount to 99% for both tests. Thus 75SeHCAT retention is more reliable in detecting bile acid malabsorption than the determination of postprandial serum bile acids, although both tests are not usefull for screening the population for ileal disease.