Cholesterol in high-density lipoprotein: use of Mg2+/dextran sulfate in its enzymic measurement.

We describe a method for measuring high-density lipoprotein cholesterol. MgCl2 and dextran sulfate are used to precipitate all low-density and very-low-density lipoproteins. The supernate contains only high-density lipoproteins, the cholesterol concentration of which is estimated by an enzymic method, with a discrete analyzer (Abbott Bichromatic Analyzer). Concentration and instrument response are linearly related to 50 mg/liter. The precision of the method is excellent in the range of clinical interest (100 to 1000 mg of cholesterol per liter). The precision and efficiency of the precipitation are shown at various concentrations of high-density lipoprotein cholesterol. The method was compared to that of two laboratories in the Cooperative Lipoprotein Phenotyping Study group by testing a number of split samples, and agreement was good.