A new method for the measurement of bile acid turnover and pool size by a double label, single intubation technique.

A new method is described for measuring the cholic acid turnover and pool size by a single duodenal intubation technique. The method is based on determination in a single bile sample of the ratio of the specific activities of [14C]cholic acid and [3H]cholic acid administered intravenously with an interval of 24 hr. With this ratio the fractional turnover rate (k) of cholic acid can easily be calculated as well as the half-life and pool size. Studies in ten normal subjects indicate that the cholic acid half life and pool size, determined by this single intubation technique, correlate very well (r greater than or equal to 0.98) with the results obtained by Lindstedt's method. Unlike the other methods using a single intubation, this method allows a good estimate of the bile acid turnover as well as the bile acid pool size.