The nature and incidence of gallstones containing calcium.

The crystalline constituents of gallstones determined by x-ray powder diffraction can be broadly classified as cholesterols and calcium salts. On this basis there are three main types of stones consisting of cholesterol, calcium salts, and mixtures of these. In a study of the composition of 481 gallstones from 11 countries, the percentage incidence of each was 59.9, 13.1, and 27.0 respectively. The presence of calcium compounds in 40.1% of the calculi showed the importance of these constituents in the nucleation and/or growth of many specimens. Men are just as likely as women to form stones consisting entirely of calcium salts, but female patients outnumber males by about 3:1 for both calculi of cholesterol and those of cholesterol with calcium salts. A description is given of the appearance, texture, and structure of calcium-containing stones subdivided according to the calcium salt(s) present.