PRECIPITATION METHODS FOR HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL MEASUREMENT COMPARED, AND FINAL EVALUATION UNDER ROUTINE OPERATING-CONDITIONS OF A METHOD WITH A LOW SAMPLE-TO-REAGENT RATIO

We evaluated six precipitation methods for high-density lipoprotein ch olesterol (HDL-chol) determination: the heparin/Mn2+ precipitation rea gent method (Hep), two variants of the phosphotungstic acid/Mg2+ metho d (Tung-L and Tung-B), the dextran sulfate 50,000/Mg2+ method (Dex), t he PEG 6000 method (PEG), and the PEG 6000/dextran sulfate 15,000 (PEG /Dex) method. The Tung-B and PEG/Dex precipitation methods have a low sample/precipitation reagent volume ratio (<0.4). The Tung-B, Dex, PEG , and PEG/Dex methods gave similar values, averaging within 0.1 mmol/L of each other, showing that the precipitation selectivity of these me thods is comparable. The precipitation efficiency of Tung-B and Peg/De x, however, was superior. Ultrafiltration of the supernatants was need ed only at triglyceride concentrations >16.4 mmol/L (undiluted sample) or >28.0 mmol/L (sample diluted twofold); however, ultrafiltration wi thout dilution was the most accurate method. Results of Tung-B under r outine conditions (33 technicians) agreed well with those of the PEG m ethod for 406 normo- and hyperlipidemic plasma samples. By comparison with the HDL-chol method from the Centers for Disease Control and Prev ention, the Tung-B method showed a total error of 10.6%, which fulfill s the criteria of the National Cholesterol Education Program for HDL-c hol analysis. In conclusion, with motivated personnel, Tung-B is a rel iable, cost-effective method for routine HDL-chol analysis.