'journal of Guscroenterology and Hepacology zyxwvutsrq (1994) 9, 452-456 zyxwvut LIVER AND BILIARY Geographic variations in structure and composition of gallstones and their correlation with brittleness G. CHOUDHURI, D. K. AGARWAL, R. V. PHADKE,* V. RAMESH,+ W. HAUSER,' A. K. KULSHRESHTHA* AND T. zyxw S. NEGI Departments of Gastroenterology, *Radiodiagnosis and +Biochemistry,Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India and 'Department of Internal Medicine, Kreiskrankenhaus Volklingen, Volklingen, Germany Abstract 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 physicochemical and radiological differences beween 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 350 Hounsfield units (HU) (26 vs zyxw 14; P zyxw < 0.01), peripheral calcification (18 zyxwvuts vs 9; P < 0.02), maximum C T density 3 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 (1 8/40; 45'/0, 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. Key words: computed tomography, extracorporeal shockwave lithotripsy, gallstones. INTRODUCTION The nature and proportion of minor constituents of cholesterol gallstones obtained from different geographic regions have been reported to show considerable varia- tion. Besides cholesterol, which is the predominant con- stituent, significant variations, especially in the presence and proportion of inorganic calcium compounds, have been noted in stones obtained from different geographic regions.' In a comparative study of gallstones obtained from eight countries, these regional differences were highlighted, although their implication was not clear.' Our preliminary clinical experienceZ had shown that biliary stones in Indian patients were more diffcult to fragment by extracorporeal shock wave lithotripsy com- pared to similar sized stones in German patient^.^ This difference was difficult to explain as both Indian and German stones were predominantly composed of choles- terol. Whether other unrecognized physicochemical or radiological characteristics could account for this observa- tion required further study. Hence in this prospective study we undertook to evaluate the physicochemical and radiological differences of cholesterol gallstones obtained from two different populations, that is, Indian and German, and tried to investigate whether these variations were associated with any difference in their brittleness to shockwave litho- tripsy. METHODS Gallstones Gallstones were harvested during cholecystectomy from consecutive zyxwv 45 Indian and 40 German patients in two hospitals, in two countries (Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India and Kreiskrankenhaus Volklingen, Volklingen, Germany) and maintained in normal saline solution until radiologi- cal study. Consecutive gallstones that appeared on visual inspection to be cholesterol-rich and measured 9-30 mm Correspondence: Dr G. Choudhuri, Associate Professor, Department of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Accepted for publication 26 March 1994. Medical Sciences, Raebareli Road, Lucknow 2260 14, India.