An X-ray diffraction study of the crystalline composition of gallstones.

The crystalline composition of gallstones removed from 30 patients from southwestern Finland was determined by the X-ray powder method. A total of eight crystalline compounds, varying from one to four per stone, were identified. Anhydrous cholesterol was by far the most abundant compound, occurring in 29 patients (97%), and calcium salts occurred in half the material studied. The stones could be classified on the basis of crystalline composition: pure cholesterol stones (40%), stones of cholesterol and calcium carbonate (37%), stones of cholesterol and sodium chloride or/and calcium palmitate (20%), and a stone of apatite and calcium carbonate (3%). The average amount of crystalline components per stone was as follows: cholesterols, 82%; calcium carbonates, 14%; and the rest, apatite, calcium palmitate, and sodium chloride. The crystalline composition of the stones related to the sex and age of the patients indicated several trends, including the occurrence of calcium carbonates in the stones of patients over 50 years of age and their simultaneous occurrence in small stones and with the cholesterols. Calcium palmitate was also more frequently present in the calculi of male patients.