Plasma and biliary cholestanol related to steroid metabolism in familial hypercholesterolemia patients with and without ileal exclusion

Plasma cholestanol is increased in cerebrotendinous xanthomatosis and in sitosterolemia with xanthomatosis. We measured plasma and biliary cholestanol in heterozygous familial hypercholesterolemia patients with (n = 10) and without (n = 12) ileal exclusion. In the unoperated patients plasma cholestanol concentration (12.9 mumol/l) and content (1.2 mmol/mol cholesterol) were slightly higher than in the nonhypercholesterolemic control subjects studied by us. Ileal exclusion had lowered plasma cholestanol concentration but only in proportion to the lowering of plasma cholesterol concentration, and plasma cholestanol content (mmol/mol cholesterol) was similar in the operated and unoperated subjects. Plasma and biliary cholestanol contents were positively associated. In the unoperated patients the fractional cholesterol absorption and plasma plant sterols, also reflecting sterol absorption, were positively correlated with plasma cholestanol content. Our study suggests, that plasma cholestanol is slightly elevated in familial hypercholesterolemia and that, in addition to plasma lipoprotein level, sterol absorption is important in the regulation of plasma cholestanol level. Ileal exclusion decreases plasma cholestanol in proportion to the decrement in the plasma cholesterol concentration.