Kostner K M, Huber K, Stefenelli T, Rinner H, Maurer G
Department of Cardiology, University Hospital of Vienna, Austria.
Atherosclerosis. 1997 Feb 28;129(1):103-10. doi: 10.1016/s0021-9150(96)06011-x.
Increased plasma lipoprotein (a) (Lp(a)) levels are associated with premature cardiovascular diseases and stroke. Since Lp(a) immune reactivity is found in urine we compared urinary apolipoprotein (a) (apo(a)) with plasma Lp(a) levels in 116 patients suffering from angiographically proven coronary artery diseases with that of 109 controls. Urinary apo(a) investigated by immuno blotting, revealed a distinct apo(a) fragmentation pattern with molecular weights between 50 and 160 kDa. Apolipoprotein B however was not secreted into urine. Lp(a) and apo(a) were measured by a fluorescence immuno assay. Within single individuals, urinary apo(a) levels correlated significantly with creatinine (Rho, 0.98; P < 0.0005). Medians and 25/75 percentiles of urinary apo(a) in coronary artery disease (CAD) patients were 5.70, 3.25 and 10.35 microg/dl and in controls 2.64, 1.43 and 3.50 microg/dl respectively. At cut-off levels of 30 mg/dl for plasma Lp(a) and 10 microg/dl of urinary apo(a) respectively, both paramenters showed comparable sensitivities (33.8% vs. 26.7%), yet the specificity (76.1% vs. 91.7%) and the positive predictive value (60.0% vs.76.4%) of urinary apo(a) were much higher. In receiver-operating characteristic plots, urinary apo(a) was much more sensitive at high specificities i.e. greater than 60% as compared to Lp(a). Urinary secretion of apo(a) fragments normalized to creatinine is stable in a given individual and significantly associated with coronary artery disease.
血浆脂蛋白(a)[Lp(a)]水平升高与心血管疾病早发及中风相关。鉴于尿液中存在Lp(a)免疫反应性，我们比较了116例经血管造影证实患有冠状动脉疾病的患者及109例对照者的尿载脂蛋白(a)[apo(a)]与血浆Lp(a)水平。通过免疫印迹法检测尿apo(a)，发现其具有明显的apo(a)片段化模式，分子量在50至160 kDa之间。然而，载脂蛋白B未分泌到尿液中。采用荧光免疫分析法测定Lp(a)和apo(a)。在个体内部，尿apo(a)水平与肌酐显著相关（Rho，0.98；P<0.0005）。冠状动脉疾病（CAD）患者尿apo(a)的中位数及25/75百分位数分别为5.70、3.25和10.35μg/dl，对照者分别为2.64、1.43和3.50μg/dl。血浆Lp(a)的截断水平为30 mg/dl，尿apo(a)的截断水平为10μg/dl时，这两个参数显示出相当的敏感性（33.8%对26.7%），但尿apo(a)的特异性（76.1%对91.7%）和阳性预测值（60.0%对76.4%）要高得多。在受试者工作特征曲线中，与Lp(a)相比，尿apo(a)在高特异性（即大于60%）时更为敏感。以肌酐标准化的apo(a)片段的尿分泌在给定个体中是稳定的，且与冠状动脉疾病显著相关。
