EVALUATION OF PRECIPITATION AND DIRECT-METHODS FOR HDL-CHOLESTEROL ASSAY BY HPLC

HDL-cholesterol (HDL-C) values measured by precipitation (sodium phosp hotungstate-MgCl2) and direct methods were compared with those obtaine d by HPLC with a new column (TSKgel Lipopropak) and an eluent (TSKelue nt LP-1). The HDL-C values determined by the precipitation method were significantly (P < 0.001) lower than those by the HPLC method, wherea s the HDL-C values by the direct method were slightly but significantl y higher (P < 0.02) than those by the HPLC method. A quantitative HPLC analysis of the cholesterol concentration in HDL and non-HDL fraction s in the supernatant of serum separated by precipitation reagents with different MgCl2 concentrations ranging from 7.3 to 44 mmol/L revealed that reagents with >22 mmol/L MgCl2 precipitated part of HDL as well as non-HDL lipoproteins. The HPLC method providing quantitative and qu alitative information with high precision was regarded as being a reli able approach for HDL-C assay. The HPLC can be also used to evaluate a lternative methods for cholesterol assay.