Biliary lathosterol and other cholesterol precursor sterols are increased in patients with ileal exclusion

The human bile contains several noncholesterol sterols, of which the cholesterol precursor sterols are quantitatively the most important. Detailed data on factors that regulate the amount of these sterols in the bile have not been available. In this study the effect of chronic stimulation of cholesterol synthesis on biliary cholesterol precursor sterol content was evaluated by measuring these sterols in the bile and plasma of familial hypercholesterolemia patients with and without ileal exclusion. In the operated patients cholesterol synthesis was fivefold increased, and cholesterol precursor sterols comprised 7% of the biliary sterols, compared with 2% in the control patients. All eight biliary cholesterol precursor sterols measured were significantly increased in the operated patients, and the increase was similar to that of respective sterols in plasma. Hence, the biliary methyl sterols were increased 2 to 4 times, the lathosterols 5 times, but demosterol only 1.5 times. The proportion of lathosterol was higher and that of lanosterol lower in the bile of the operated than in that of the control patients. We conclude that activation of cholesterol synthesis increases the amount of cholesterol precursor sterols in the bile in proportion to the increase of these sterols in plasma and to the overall cholesterol synthesis.