Department of Medicine, Johns Hopkins University, Baltimore, MD 21287, USA.
J Clin Lipidol. 2012 Jul-Aug;6(4):368-73. doi: 10.1016/j.jacl.2012.01.004. Epub 2012 Jan 21.
There is little known about the relative predictive value of different lipoprotein(a) [Lp(a)] assays in clinical use, although each has been shown to predict similar incremental risk over conventional clinical and lipid risk factors. Thus, we examined the classification behavior of two commonly used Lp(a) assays and their associations with other lipid parameters. Serum lipid and Lp(a) concentrations were measured in 144 primary and secondary prevention patients. Lp(a) cholesterol [Lp(a)-C] was measured with the Vertical Auto Profile (upper limit of normal, 10 mg/dL). Lp(a) particle concentrations [Lp(a)-P] were measured with an isoform-independent molar assay (upper limit of normal, 70 nmol/L). The subjects were divided into the following four groups on the basis of their Lp(a)-C and Lp(a)-P levels: normal Lp(a)-P and Lp(a)-C; high Lp(a)-P and normal Lp(a)-C; normal Lp(a)-P and high Lp(a)-C; and high Lp(a)-P and Lp(a)-C. The proportion of subjects with values above the upper limit of normal was similar with both assays (P = .15). However, the Lp(a)-C and Lp(a)-P assays discordantly classified 23% of the study's subjects. In addition, the four Lp(a)-defined groups displayed differences in their relationships with other lipoproteins. The two groups with elevated Lp(a)-C showed significant associations with higher high-density lipoprotein cholesterol, apolipoprotein AI, and high-density lipoprotein cholesterol/apolipoprotein AI ratios. Triglycerides were also noted to be above normal in discordant and normal within concordant Lp(a) groups. Finally, the amount of cholesterol per Lp(a) particle [Lp(a)-C/Lp(a)-P] varied widely across the four groups. These findings suggest that the four Lp(a)-defined groups are physiologically discrete. Further investigation is warranted to assess which parameters among Lp(a)-P, Lp(a)-C, and Lp(a)-C/Lp(a)-P can be used to more accurately characterize Lp(a)-associated cardiovascular risk.
关于在临床应用中不同脂蛋白(a) [Lp(a)]检测方法的相对预测价值知之甚少，尽管每种方法都已被证明可以预测比传统临床和血脂危险因素更显著的增量风险。因此，我们研究了两种常用的 Lp(a)检测方法的分类行为及其与其他脂质参数的关系。在 144 名一级和二级预防患者中测量了血清脂质和 Lp(a)浓度。使用垂直自动分析(Vertical Auto Profile)（正常值上限为 10mg/dL）测量 Lp(a)胆固醇[Lp(a)-C]。使用同工型独立摩尔测定法（正常值上限为 70nmol/L）测量 Lp(a)颗粒浓度[Lp(a)-P]。根据 Lp(a)-C 和 Lp(a)-P 水平，将受试者分为以下四组：正常 Lp(a)-P 和 Lp(a)-C；高 Lp(a)-P 和正常 Lp(a)-C；正常 Lp(a)-P 和高 Lp(a)-C；高 Lp(a)-P 和 Lp(a)-C。两种检测方法检测到的超过正常值上限的受试者比例相似（P=.15）。然而，Lp(a)-C 和 Lp(a)-P 检测方法将研究对象的 23%分类不一致。此外，四个基于 Lp(a)的分组在与其他脂蛋白的关系上显示出差异。两个 Lp(a)-C 升高的组与较高的高密度脂蛋白胆固醇、载脂蛋白 AI 和高密度脂蛋白胆固醇/载脂蛋白 AI 比值呈显著相关。在 Lp(a) 不一致和一致的组中，甘油三酯也高于正常值。最后，每个 Lp(a)颗粒的胆固醇量[Lp(a)-C/Lp(a)-P]在四个组中差异很大。这些发现表明，四个基于 Lp(a)的分组在生理学上是不同的。需要进一步研究评估 Lp(a)-P、Lp(a)-C 和 Lp(a)-C/Lp(a)-P 之间的哪些参数可以更准确地描述与 Lp(a)相关的心血管风险。
