Determination of high-density lipoproteins: screening methods compared.

Factors reflecting the concentration of high-density lipoproteins in serum were assessed for 108 men and 106 women participating in a Venetian screening program for hyperlipoproteinemia. The methods applied, optimized in our laboratory, were: (a) cholesterol in high-density lipoproteins, determined in the supernate after sedimentation of the very-low-density lipoproteins + low-density lipoproteins with dextran sulfate or sodium phosphotungstate; and (b) immunochemical quantitation of apolipoprotein A-I and apolipoprotein A-II by Laurell's "rocket" technique. The latter determinations were performed with total serum before and after delipidation with diispropyl ether/n-butanol (6/4 by vol). The dextran sulfate method gave about 5% higher values than did the phosphotungstate method, but the correlation between the two was excellent (r = 0.95). Results of the immunochemical quantitation indicate that delipidation of lipoproteins before Laurell electrophoresis may not be necessary if only freshly drawn sera are used.