Measurement of fat absorption utilizing 131iodine-triolein and nonabsorbable radioactive markers

To eliminate many of the practical problems inherent in the collection of feces and in the chemical determination of fecal fat, a radioactive marker (131Ba) was combined with a labeled fat (131l-triolein) to measure fat absorption in man. The ratios of radioactivity of 131Ba/131l in a prepared capsule and that found in a random "grab" stool specimen after oral administration of the capsule were compared to determine the amount of fat absorbed. In an initial 36 patients, this double-label technique accurately separated normal from abnormal fat absorption as determined by the usual methods of quantitative fecal fat measurement. Results in an additional 102 patients and in 26 normals accurately reflected their clinical states. In addition, in vitro studies demonstrated more complete recovery of added lipid (99 percent) by radioactive techniques than by chemical analysis (86 per cent). The double-label technique not only seems more accurate than usual quantitative fecal fat determinations, but also greatly simplifies the measurement of fat absorption in man by eliminating the need for special diets, quantitative stool collections, and chemical analysis of stool.