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

Abstract

We evaluated six precipitation methods for high-density lipoprotein cholesterol (HDL-chol) determination: the heparin/Mn2+ precipitation reagent method (Hep), two variants of the phosphotungstic acid/Mg2+ method (Tung-L and Tung-B), the dextran sulfate 50 000/Mg2+ method (Dex), the 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 methods is comparable. The precipitation efficiency of Tung-B and Peg/Dex, however, was superior. Ultrafiltration of the supernatants was needed only at triglyceride concentrations >16.4 mmol/L (undiluted sample) or >28.0 mmol/L (sample diluted twofold); however, ultrafiltration without dilution was the most accurate method. Results of Tung-B under routine conditions (33 technicians) agreed well with those of the PEG method for 406 normo- and hyperlipidemic plasma samples. By comparison with the HDL-chol method from the Centers for Disease Control and Prevention, the Tung-B method showed a total error of 10.6%, which fulfills the criteria of the National Cholesterol Education Program for HDL-chol analysis. In conclusion, with motivated personnel, Tung-B is a reliable, cost-effective method for routine HDL-chol analysis.