Tauroselcholic acid Se-75 (SeHCAT) is an analog of naturally occurring bile acid conjugate taurocholic acid. It contains a radioactive isotope of selenium, which decays with a half-life of 120 days by emitting gamma-radiation. Tauroselcholic acid is used in clinical tests to diagnose bile acid malabsorption. This is achieved by determining either the excretion of activity in feces or the retention of the activity in the body over a period of days. Tauroselcholic acid is useful in the assessment of ileal involvement in, Crohn's disease, in assessing reduction of ileal absorptive function following certain surgical interventions and in assisting in the classification of patients suffering from chronic diarrhea.