High vesicular cholesterol and protein in bile are associated with formation of cholesterol but not pigment gallstones.

To examine the differentiating parameters between cholesterol and pigment gallstones, we compared the nucleation times, concentrations of biliary lipid and protein, and the distribution of vesicular cholesterol in gallbladder bile of 16 patients with cholesterol, eight patients with black pigment gallstones, and nine gallstone-free control patients. Cholesterol monohydrate crystals were present in the fresh bile of only the cholesterol gallstone group. The nucleation time was significantly faster in the cholesterol stone group (3.3 +/- 3.2 days) than in the other two groups (pigment stone: 15.8 +/- 6.6, control: 16.9 +/- 5.7). The cholesterol saturation indices and the distribution of vesicular cholesterol were significantly higher in the cholesterol gallstone group than those in the other two groups. The total biliary protein concentration was significantly (P < 0.01) higher in the cholesterol gallstone group [2.57 +/- 1.91 (SD) mg/ml] than that in the black pigment stone group (1.09 +/- 0.59). All parameters in patients with black pigment gallstone were essentially similar to the controls. We conclude that the presence of cholesterol crystals, rapid nucleation time, high vesicular cholesterol distribution, elevated cholesterol saturation index, and high protein concentration are associated with cholesterol gallstones but not with black pigment gallstones.