“…The serum concentrations of cholesterol, lanosterol, desmosterol, sitosterol, campesterol, stigmasterol, sitostanol, 24S-hydroxycholesterol, 27-hydroxycholesterol, and 7a-hydroxy-4-cholesten-3-one were quantified using HPLC eMS/MS in all subjects according to the method previously described [15], and they were expressed as mmol/l as well as normalized to mmol/l of total cholesterol. Briefly, 100 ml of serum was transferred to a screw-capped vial, and 6 ml of deuterium-labeled internal standard, [ …”