O-055. Acromegalic patients have increased large bowel transit time (LBTT) and serum deoxycholic acid levels (% DCA) after long-term octreotide therapy

Background: Octreotide (OT) therapy causes the formation of gallbladder stones (GBS) in up to 50% of acromegalic patients, due to an increase in the % DCA and the cholesterol saturation of gallbladder bile, together with impairment of meal-stimulated gallbladder emptying. Prolongation of intestinal transit has been proposed as the mechanism for the increase in the % DCA, but our earlier unpaired studies did not show any significant effect of OT on large bowel transit - important since the colon is the site of DCA formation and absorption. Objective: To assess LBTT and biliary DCA before and during long-term (>3 months) OT treatment. Methods: LBTT was measured using radio-opaque marker shapes in 8 acromegalic patients (age range 22-69 yrs; 4 women). As there is an exchange, and ultimately an equilibrium, between bile acids in serum and bile, fasting serum levels of DCA provide an accurate estimate of biliary levels. The % DCA was therefore measured in fasting serum of 6 patients. Results: The mean LBTT increased from 42±SEM 4.3 h before to 55±5.1 h during OT treatment (p<0.0001) and the mean % DCA increased from 15±2.5% to 28±4.7% (p<0.05). There was a significant linear relationship between LBTT and % DCA (r = 0.87; p<0.0005). Conclusions: These results show that long-term OT therapy prolongs LBTT and that this prolongation is associated with an increase in % DCA in serum, and by implication in bile - factors important in the pathogenesis of OT-induced gallstones.