title: Chemical nature and distribution of calcium compounds in radiolucent gallstones.
abstract: A high failure rate for radiolucent cholesterol gallstones to dissolve with oral bile acids may be due to the presence of insoluble calcium compounds. Twenty sets of radiolucent gallstones, 7-20 mm in diameter, obtained from 20 patients undergoing cholecystectomy, were cut, and the outer surface, outer rim, middle portion, and central core areas were scanned for calcium by energy-dispersive X-ray microanalysis (EDX) and scanning electron microscopy (SEM). Scrapings from the four areas of each stone were analysed by infrared spectroscopy. A sample of the crushed stone was used for chemical estimation of cholesterol. Eleven (55%) of the 20 cholesterol (84-96% dry weight of cholesterol) stones showed presence of calcium by EDX; the distribution was peripheral in 5, homogeneous in 4, and central in 2. The chemical compound was calcium bilirubinate in 10 and calcium carbonate in 8 stones. Calcium compounds are present in a high proportion of radiolucent gallstones considered suitable for chemodissolution by conventional criteria. Their unrecognized presence may explain the high failure rate of such stones to respond to medical therapy.
authors.affiliation: Dept. of Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
authors.forename: D K
authors.initials: DK
authors.lastname: Agarwal
authors.forename: G
authors.initials: G
authors.lastname: Choudhuri
authors.forename: J
authors.initials: J
authors.lastname: Kumar
mesh_terms: D000328:Adult; D001663:Bilirubin / Q000032:analysis; D002118:Calcium / Q000032:analysis*; D002119:Calcium Carbonate / Q000032:analysis; D002130:Calcium Phosphates / Q000032:analysis; D002769:Cholelithiasis / Q000737:chemistry* / Q000000981:diagnostic imaging / Q000473:pathology; D002784:Cholesterol / Q000032:analysis; D004577:Electron Probe Microanalysis; D005260:Female; D006801:Humans; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D011859:Radiography
chemical_list: D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D002784:Cholesterol; C020243:calcium phosphate; D002119:Calcium Carbonate; C485829:calcium phosphate, dibasic, anhydrous; D001663:Bilirubin; D002118:Calcium