Comparison of improved precipitation methods for quantification of high-density lipoprotein cholesterol.

1985 ◽  
Vol 31 (2) ◽  
pp. 217-222 ◽  
Author(s):  
G R Warnick ◽  
T Nguyen ◽  
A A Albers

Abstract We compared the standard Lipid Research Clinics heparin-Mn2+ (46 mmol/L) method and five improved precipitation methods for quantification of high-density lipoprotein (HDL) cholesterol. Three of these methods--a dextran sulfate-Mg2+ procedure, reported as a Selected Method, a modified heparin-Mn2+ (92 mmol/L) method, and a modified phosphotungstate-Mg2+ procedure--all gave similar results. Three other methods--the standard heparin-Mn2+ (46 mmol/L) method and two polyethylene glycol methods (75 g/L or pH 10 reagent at 100 g/L final concentrations)--gave slightly higher values for HDL cholesterol. Addition of NaCl or glucose to specimens did not significantly change protein precipitation. In terms of sedimentation effectiveness with hypertriglyceridemic specimens, the methods were ranked in the following order: polyethylene glycol (pH 10, 100 g/L) greater than dextran sulfate-Mg2+ greater than heparin-Mn2+ (92 mmol/L) = polyethylene glycol (75 g/L) greater than phosphotungstate-Mg2+ greater than heparin-Mn2+ (46 mmol/L).

1997 ◽  
Vol 43 (6) ◽  
pp. 1048-1055 ◽  
Author(s):  
Yi-Chang Huang ◽  
Jau-Tsuen Kao ◽  
Keh-Sung Tsai

Abstract We evaluated the performance of two homogeneous assays for quantifying HDL cholesterol (HDL-C) and compared them with the phosphotungstic acid (PTA)/MgCl2 assay. Both homogeneous HDL-C assays were precise, having a within-run CV of <1.20% and a between-run CV of <4.07%. The HDL-C values (y) measured by the two homogeneous methods correlated well with those by the PTA/MgCl2 method (x): y = 1.00x + 64.98 mg/L, r = 0.987, Sy|x = 27.99 mg/L (n = 152) for the polyethylene glycol-modified enzymes/α-cyclodextrin sulfate (PEGME) assay (Kyowa), and y = 0.84x + 106.51 mg/L, r = 0.984, Sy|x = 26.10 mg/L (n = 152) for the polyanion–polymer/detergent (PPD) assay (Daiichi). The specificity of the PEGME method seemed better than that of the PPD method, as the PPD method was markedly interfered with by supplemental LDL-C. Addition of 20 g/L triglycerides produced a negative error of ∼18% in both homogeneous assays. Bilirubin and hemoglobin had little influence on the PEGME method; hemoglobin had little effect on the PPD method. Bilirubin, however, markedly decreased the readings by the PPD method. We found the PEGME assay superior to the PPD assay for routine HDL-C testing, because the PPD assay is relatively inaccurate and not specific.


1979 ◽  
Vol 25 (4) ◽  
pp. 596-604 ◽  
Author(s):  
G R Warnick ◽  
M C Cheung ◽  
J J Albers

Abstract We compared six precipitation methods for high-density-lipoprotein cholesterol quantitation with an ultracentrifugation method, the accuracy of which was improved by correcting for 4% manipulative loss in the d greater than 1.063 fractions. For purposes of comparison, the apoprotein B-associated cholesterol (average 56 mg/L) measured by immunoassay in the d greater than 1.063 fractions was subtracted. In 65 plasma samples from men, women, and children, a heparin-Mn2+ procedure with Mn2+ at 46 mmol/L produced results slightly higher (+16 mg/L), while results with Mn2+ at 92 mmol/L averaged slightly lower (-8 mg/L) than the comparison ultracentrifuge method. Results that were about 5% low were obtained by the dextran sulfate 500-Mg2+ (-25 mg/L) and phosphotungstate-Mg2+ (-31 mg/L) methods. A heparin-Ca2+ method produced results 10% high (+58 mg/L). Results by a polyethylene glycol-6000 precipitation method were 12% low (-64 mg/L). Precision was better with the two heparin-Mn2+ and the dextran sulfate 500-Mg2+ procedures, with CVs of 4%, intermediate with phosphotungstate-Mg2+ and polyethylene glycol-6000 (CV 6-7%), and poorest with heparin-Ca2+ (CV 10%). Precipitation by phosphotungate-Mg2+ appeared more sensitive to reagent concentration and temperature variations than either the heparin-Mn2+ or dextran sulfate 500-Mg2+ methods. We conclude that these precipitation methods are not equivalent, but give rise to significant systematic differences in high-density-lipoprotein cholesterol quantitation.


1996 ◽  
Vol 42 (5) ◽  
pp. 738-743 ◽  
Author(s):  
N Harris ◽  
V Galpchian ◽  
N Rifai

Abstract We compared the performance of three methods for quantifying high-density lipoprotein cholesterol (HDL-C) with the Reference Method for HDL-C, using samples with a wide range of triglyceride (TG) concentrations (290-18000 mg/L). All three comparison assays-- utilizing a magnetic dextran sulfate precipitating reagent, a direct method, and a standard MgCl2-dextran sulfate reagent--were precise, with a run-to-run CV of less than or equal to 4.1%. However, the systematic error of these assays exceeded the National Cholesterol Education Program (NCEP) performance goal of less than or equal to 10% in half of the concentration ranges tested. Nevertheless, the total error of the assays generally meets the current 22% limit set by the NCEP. Although both the magnetic dextran sulfate precipitation reagent and the direct assay can be performed more rapidly than the MgCl2-dextran sulfate assay, the direct assay involves no sample preparation and requires only 4 microL of sample excluding 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.


1984 ◽  
Vol 30 (1) ◽  
pp. 127-129 ◽  
Author(s):  
N N Rehak ◽  
R J Elin ◽  
R Chesler ◽  
E Johnson

Abstract We compared the Du Pont aca (phosphotungstate-enzymic cholesterol) and the Dow (dextran sulfate/Mg2+-enzymic cholesterol) methods for the determination of high-density lipoprotein cholesterol (HDLC) and total cholesterol in serum from 113 patients. The aca results for both total cholesterol and HDLC were significantly greater (p less than 0.0001) than the Dow results, the aca method overestimating the HDLC concentration (mean recovery 107.2% in serum samples with values assigned by the Centers for Disease Control). The precision of the aca method for HDLC was essentially the same as that of the Dow method. Bilirubin (up to 0.17 g/L), hemoglobin (up to 4 g/L), and slight lipemia (triglycerides up to 5.4 g/L) did not interfere with the aca method.


1983 ◽  
Vol 65 (6) ◽  
pp. 669-672 ◽  
Author(s):  
R. S. Elkeles ◽  
S. R. Khan ◽  
V. Chowdhury ◽  
M. B. Swallow

1. Changes in serum triglyceride and high density lipoprotein (HDL) cholesterol after a fatty meal have been studied in smokers and non-smokers. 2. Average serum triglyceride during the study was higher in smokers than in non-smokers. 3. In non-smokers there was a rise in the HDL2/HDL3 cholesterol ratio after oral fat, but not in smokers. 4. These findings are compatible with the hypothesis that smoking interferes with the lipolysis of triglyceride rich lipoproteins and the conversion of HDL3 into HDL2.


1984 ◽  
Vol 30 (6) ◽  
pp. 839-842 ◽  
Author(s):  
P S Bachorik ◽  
R E Walker ◽  
D G Virgil

Abstract Manganese interferes with enzymic cholesterol methods. In this study, we enzymically measured high-density-lipoprotein (HDL) cholesterol in heparin-Mn2+ supernates that had been treated with NaHCO3 (91 mmol/L) to precipitate Mn2+, and compared results with those by an automated Liebermann- Burchard method. For untreated supernates of 96 fresh plasma samples, the enzymic values were 10.4% higher than comparison-method values, a bias that declined to +2.3% for treated supernates. For 72 sera promptly frozen and stored after collection, the enzymic values for untreated and treated supernates were, respectively, 6.0% and 0.5% higher than comparison-method values. In all cases, the magnitude of the bias was independent of the concentrations of cholesterol, triglyceride, and HDL-cholesterol. Enzymic HDL-cholesterol measurements in NaHCO3-treated heparin-Mn2+ supernates prepared from four pooled serum controls agreed within 21 mg/L with values established for these pools by the Centers for Disease Control. We conclude that the accuracy of enzymic HDL cholesterol measurements in heparin-Mn2+ supernates in considerably increased by treatment with NaHCO3.


Author(s):  
Catherine J Briggs ◽  
Deborah Anderson ◽  
P Johnson ◽  
T Deegan

Treatment of fresh sera with polyethylene glycol 6000 at a final concentration of 100 g/l produced selective precipitation of low-density lipoproteins with only traces of contamination with high-density lipoproteins, as determined by electroimmunoassay using antisera to human α1-lipoprotein and human β-lipoprotein. Supernatants collected for high-density lipoprotein-cholesterol estimation were free from low-density lipoproteins. Precipitates sedimented readily from specimens with high triglyceride contents, and secondary precipitation during enzymatic cholesterol determinations was absent. Values obtained by this method correlated well with those obtained by precipitation of low-density lipoproteins with heparin and manganous ions at concentrations optimal for discrete separation of lipoprotein classes (r = 0·975; P<0·001).


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