The effect of hemolysis and infection/stasis on pigment gallstones was assessed by comparing the composition of stones from (1) U.S. patients without hemolysis or cirrhosis, (2) U.S. patients with sickle cell disease, and (3) Japanese patients with biliary infections. Gallstone composition was quantitated by infrared spectroscopy and chemical analyses. Gallstones from patients with sickle cell anemia contained more pigment, carbonate, calcium, and measured components than stones from U.S. patients without hemolysis (P<0.05). However, the similar types of calcium salts in black stones from patients with and without sickle cell anemia suggested that intermittent hemolysis may be a potential mechanism in the formation of black stones found in the general population. In Japanese patients with brown pigment stones, there was an absence of calcium carbonate, low levels of calcium phosphate, and the presence of calcium salts of fatty acids (P<0.05). Thus, the accompanying stasis and/or infection in this latter group was associated with the formation of a distinctive stone type and was not involved in the formation of the black stones. The similarly small proportion of cholesterol in each of these groups suggested that it was present due to coprecipitation rather than to cholesterol supersaturation.
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