Noncholesterol sterols in bile and stones of patients with cholesterol and pigment stones

Human bile and cholesterol gallstones contain sterols including methylated (lanosterol and other dimethyl and monomethyl sterols), and demethylated cholesterol precursor sterols (delta 8-lathosterol, lathosterol, and desmosterol), plant sterols (campesterol and sitosterol), and cholestanol. The aim of the study was to analyze the noncholesterol sterols in gallbladder bile and stones from female and male patients with cholesterol stones (CS) and pigment stones (PS) to ascertain whether any sterol fraction contributes to the gallstone formation. Classification of gallstones to CS and PS was performed on the basis of the stone cholesterol content. The study group consisted of 165 consecutive cholecystectomized patients, 150 with CS and 15 with PS. Bile acids and sterols were quantitated using gas-liquid chromatography (GLC). The biliary lipid and noncholesterol sterol/cholesterol proportions were similar in the CS and PS patients. The proportions of methylated and plant sterols were significantly lower in the CS than in bile, whereas those of delta 8-lathosterol, lathosterol, and cholestanol were significantly higher. The PS, in contrast to the CS, were neither sex nor weight related. The bile acid and phospholipid concentrations and the proportions of lanosterol, delta 8,24-dimethylsterol, and sitosterol were up to 50 times higher and those of delta 8-lathosterol and lathosterol twice lower in the PS than in the CS. The results suggest that, in general, the stones with low cholesterol content are proportionately richer in nonpolar precursor and plant sterols and lower in demethylated precursors, the situation being opposite for the CS. The stone/bile ratios suggest that in both stone groups, but especially in the CS, levels of the polar precursor sterols and cholestanol were enriched in the stone, whereas levels of the nonpolar precursor sterols, and to a lesser extent plant sterols, were not enriched in the stone despite their high biliary proportions.