Geographic variations in structure and composition of gallstones and their correlation with brittleness

Cholesterol gallstones obtained from different geographic regions have been reported to show significant differences in their minor chemical constituents. We undertook the present study with two objectives: (i) to investigate the possible physiochemical and radiological differences between cholesterol gallstones obtained from Indian and German patients; and (ii) to compare the brittleness of the two stone groups. Forty Indian and 36 German gallstones (matched in size and shape) were subjected to assessment of physical characteristics, in vitro computed tomography (CT) and chemical analysis. German stones more often had a stone density distribution index of > or = 50 Hounsfield units (HU) (26 vs 14; P < 0.01), peripheral calcification (18 vs 9; P < 0.02), maximum CT density > or = 90 HU (17 vs 9; P < 0.05) and significant calcium carbonate (9 vs 5; P < 0.05), compared to Indian stones. The in vitro lithotripsy performed with the Siemens Lithostar Plus machine at a constant energy level showed the German stones to be more brittle (easy to fragment), more often requiring < 1000 shocks for fragmentation (25/36; 69%) compared to Indian stones (18/40; 45%, P < 0.05). Gallstones from different geographic regions may show significant variations in their physicochemical characteristics that may explain the differences in their brittleness to lithotripsy.