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.