3 ROUTINE METHODS FOR MEASURING HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL COMPARED WITH THE REFERENCE METHOD

We compared the performance of three methods for quantifying high-dens ity lipoprotein cholesterol (HDL-C) with the Reference Method for HDL- C, using samples with a wide range of triglyceride (TG) concentrations (290-18 000 mg/L). All three comparison assays-utilizing a magnetic d extran sulfate precipitating reagent, a direct method, and a standard MgCl2-dextran sulfate reagent-were precise, with a run-to-run CV of le ss than or equal to 4.1%. However, the systematic error of these assay s exceeded the National Cholesterol Education Program (NCEP) performan ce goal of less than or equal to 10% in half of the concentration rang es tested. Nevertheless, the total error of the assays generally meets the current 22% limit set by the NCEP. Although both the magnetic dex tran sulfate precipitation reagent and the direct assay can be perform ed more rapidly than the MgCl2-dextran sulfate assay, the direct assay involves no sample preparation and requires only 4 mu L of sample exc luding the dead space. Although precipitation is frequently inadequate with the MgCl2-dextran sulfate reagent at TG concentrations > 6000 mg /L, both the magnetic and the direct reagent show no interference from high TG concentrations as great as 18 000 mg/L.