FACILITATED METHOD FOR MEASUREMENT OF BILIARY-SECRETION RATES IN HEALTHY HUMANS

We have developed a facilitated method for determining secretion of co nstituents into bile. The ratio of constituent/bilirubin was measured in gallbladder bile and multiplied by bilirubin secretion rate, estima ted by measuring endogenous production of carbon monoxide (V(CO)) by b reath sampling. Accuracy of this method was assessed by measuring secr etion rate of Technetium-99m-labeled disofenin during steady-state con stant intravenous infusion. In nine subjects, mean (+/- SEM) secretion of disofenin by the CO method was 104.2 +/- 7.2% of expected and by s tandard marker perfusion was 97.8 +/- 13.1% of expected. In ten subjec ts, secretion rate of cholesterol by the CO method averaged 103 mumol/ h by the CO method compared to 113 by marker perfusion (NS). Compared to marker perfusion (which is believed to reflect 24-h secretion rate) , the CO method significantly underestimated secretion rate of bile ac id (1110 vs. 1332 mumol/h, P = 0.076) and lecithin (295 vs. 413 mumol/ h, P = 0.01), probably because gallbladder bile contained a disproport ionate amount of fasting versus postprandial bile. Thus, this new meth od provides an accurate secretion rate for biliary constituents secret ed at a relatively constant rate, including cholesterol, with less var iability than marker perfusion. However, it can be used to estimate se cretion of bile acid and lecithin only when a 20-30% underestimation o f 24-h secretion is acceptable.