QUANTIFICATION OF LIPOPROTEIN(A) IN PLASMA BY ASSAYING CHOLESTEROL INLECTIN-BOUND PLASMA FRACTION

Lipoprotein(a) [Lp(a)] is a low-density lipoprotein (LDL)-like particl e in which apolipoprotein(a) [apo(a)] is disulfide-linked to apolipopr otein B (apoB). High concentrations of Lp(a) in plasma are associated with an increased risk of coronary heart disease (CHD). Lp(a) has trad itionally been measured by immunoassay and expressed as total mass of Lp(a). Measuring Lp(a) by its cholesterol content will provide a way t o directly compare Lp(a) with other lipoproteins that are measured by cholesterol. We have developed an assay to quantify Lp(a) by its chole sterol content [Lp(a)-C], using lectin affinity to isolate Lp(a) from other lipoproteins, and then measuring the cholesterol within the isol ated fraction. We compared the Lp(a)-C assay with an ELISA for Lp(a) m ass in 47 plasma samples from normotriglyceridemic, fasting individual s with high Lp(a) contents (mean +/- SD, 446 +/- 350 mg/L). The mean L p(a)-C concentration was 110 +/- 89 mg/L and correlated very highly wi th Lp(a) mass (r = 0.9975). Lp(a)-C measurement is an alternative meth od to screen for this CHD risk factor.