Serum LDL- and HDL-cholesterol determined by ultracentrifugation and HPLC.

Simple and precise methods for LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) measurements are essential for assessment of cardiovascular disease (CVD) risks and for lipid and lipoprotein studies. We report here an ultracentrifugation (UC) and HPLC method that requires substantially less specimen volume and provides the necessary reliability and throughput required by large-volume, high-quality research and clinical studies. 2-Mercaptoethanol (ME) was used to dissociate serum lipoprotein [a] (Lp[a]) into apolipoprotein [a] and Lp[a] remnant (Lp[a-]) and eliminated the contamination of Lp[a] in HDL separated by UC. Serum aliquots were centrifuged at a density of 1.006 kg/l for the separation of HDL plus LDL, and in the presence of ME at a density of 1.063 kg/l for the separation of HDL. Cholesterol concentrations of the bottom fractions were analyzed by HPLC. LDL-C and HDL-C determined using this method were equivalent to those with β-quantification and the designated comparison method of the Centers for Disease Control. The total coefficient of variations for LDL-C and HDL-C were 0.65-1.12% and 0.96-2.07%, respectively. This method requires a small amount of specimen and is easy to operate. This method may be used in research or in clinical laboratories where precise and specific lipoprotein cholesterol analysis is needed.