Plasma cholecystokinin in obese patients before and after jejunoileal bypass with 3:1 or 1:3 jejunoileal ratio--no role in the increased risk of gallstone formation.

Background And Aim: Jejunoileal bypass surgery for obesity increases the risk of gallstone formation, and, contrary to expectations, the incidence is greater in patients with a long as compared to a short ileum left in continuity. Impaired gallbladder motility due to reduced cholecystokinin (CCK) stimulation could be an explanation. The aim of this study was to investigate the CCK levels in such patients.

Setting: The randomized trial of bypass surgery named The Danish Obesity Project.

Design And Methods: We compared plasma levels of CCK in obese patients at three, nine or 15 months after jejunoileal bypass surgery with either a 1:3 jejunoileal ratio (n = 14) or a 3:1 ratio (n = 15), and in unoperated obese patients (n = 7). Plasma CCK levels were determined during fasting and during 150 min following ingestion of a liquid test meal.

Results: There were no significant changes over time following surgery. Basal CCK levels were significantly increased after surgery, and significantly higher in those with a 3:1 than in those with a 1:3 jejunoileal ratio. The postprandial AUC (mean +/- SEM) was 935 +/- 71 pM x min in the 3:1 ratio group and 891 +/- 100 pM x min in the 1:3 ratio group. This difference was not significant, but both bypass groups were significantly higher than the unoperated group (515 +/- 79 pM x min). The integrated increase in plasma CCK above basal level showed a similar pattern, but the difference between the unoperated and the bypass groups was insignificant.

Conclusion: Postoperative changes in plasma CCK levels neither explain the increased risk of gallstone formation after bypass surgery nor the higher incidence with a long compared to a short ileum left in continuity in the bypass.