GALLBLADDER EMPTYING IN-VIVO, BILE COMPOSITION, AND NUCLEATION OF CHOLESTEROL CRYSTALS IN PATIENTS WITH CHOLESTEROL GALLSTONES

Background/Aims: Impaired postprandial gallbladder emptying may provid e time for progressive bile concentration with formation of instable c holesterol-rich vesicles and fast nucleation of cholesterol crystals. The aim of this study was to assess postprandial gallbladder emptying, bile composition, and nucleation of cholesterol crystals in the same patient. Methods: In 30 patients with cholesterol gallstones, postpran dial gallbladder emptying was measured ultrasonographically. In each p atient, gallbladder bile composition (obtained at cholecystectomy) and nucleation of cholesterol crystals was determined. Patients were divi ded in 22 strong contractors (>50% postprandial gallbladder emptying) and 8 weak contractors. Results: In weak contractors, bile salt and ph ospholipid concentrations were much higher than in strong contractors (234.6 +/- 24.1 vs. 130.3 +/- 10.8 mmol/L [P < 0.001] and 44.5 +/- 3.5 vs. 30.2 +/- 3.1 mmol/L [P < 0.05], respectively). Cholesterol concen trations were comparable in strong and weak contractors. Consequently, total lipid concentration was significantly higher (15.5 +/- 1.4 and 9.2 +/- 0.7 g/dL; P < 0.001) and cholesterol saturation index signific antly lower (0.90 +/- 0.08 and 1.61 +/- 0.17; P < 0.001) in weak contr actors. Nucleation time, percentage of cholesterol in vesicles, bile s alt species, and molecular species of phosphatidylcholine were not sig nificantly different. Conclusions: Differences in bile composition can be linked to different patterns of postprandial gallbladder emptying and may point to two different pathways of gallstone formation.