Measurement of high-density lipoprotein cholesterol in serum: comparison of six isolation methods combined with enzymic cholesterol analysis
Demacker, P.N.; Vos-Janssen, H.E.; Hijmans, A.G.; van't Laar, A.; Jansen, A.P.
Clinical Chemistry 26(13): 1780-1786
1980
ISSN/ISBN: 0009-9147 PMID: 6777082 Document Number: 156328
Six methods for isolating high-density lipoproteins serum are compared. Cholesterol was determined by 2 different enzymic methods. The values for HDL cholesterol obtained with 2 (centrifugation-speed) modifications of the heparin/Mn2+ method and with the phosphotungstate/Mg2+, the dextran sulfate/Mg2+ and the polyethylene glycol methods were compared with those obtained by ultracentrifugation. One cholesterol method, in which each determination was blank-corrected, was not interfered with by the various precipitation reagents. The other, in which there was no blank correction, was considerably interfered with by Mn2+ and dextran sulfate. Neither method was interfered with by phosphotungstate/Mg2+ or by polyethylene glycol. Use of EDTA in either cholesterol reagent was unhelpful (or deleterious). After correction for all interferences caused by the precipitation reagents and EDTA, values obtained for HDL cholesterol agreed well with those by ultracentrifugation (corrected for apo B-containing lipoproteins in the d > 1.063 kg/l fraction). Rocket immunoelectrophoresis showed no significant co-precipitation of HDL in any method. Various methods for complete removal of apo B-containing lipoproteins from lipemic serum appeared to vary widely in efficiency, but the optimized phosphotungstate method and the polyethylene glycol method appeared best. With them, only sera with triglyceride concentrations of 7.6 and 18.5 mmol/l or greater, respectively, could not be fractionated successfully. After ultrafiltration, accurate values were obtained with the other methods. The phosphotungstate method and the polyethylene glycol method are the best methods for HDL-cholesterol analysis when enzymic cholesterol analysis is used.