Kostner K M, Banyai S, Banyai M, Bodlaj G, Maurer G, Derfler K, Hörl W H, Oberbauer R
Department of Medicine, University of Vienna, Austria.
Ann Med. 1998 Oct;30(5):497-502. doi: 10.3109/07853899809002492.
Increased plasma lipoprotein (a) (Lp(a)) levels are strongly associated with premature cardiovascular disease and stroke. Recently we, as well as other groups, found that apolipoprotein (a) (apo(a)) fragments appear in the urine of healthy individuals, and that renal transplant patients with impaired renal function excrete fewer apo(a) fragments into their urine compared with controls. As the excretion mode of apo(a) is presently unknown, we determined plasma Lp(a) levels and urinary apo(a) excretion in relation to kidney function in 58 proteinuric patients and 58 healthy controls. For the first time, urinary apo(a) excretion was related to apo(a) isoforms. Plasma Lp(a) values were higher in the proteinuric patients compared with the controls, independent of their renal function. The patients with low-molecular-weight apo(a) isoforms had higher Lp(a) plasma levels, whereas the patients with high-molecular-weight apo(a) isoforms had lower Lp(a) plasma levels. Urinary apo(a) showed a very similar pattern to that of plasma Lp(a), being significantly higher in patients with low-molecular-weight isoforms as compared with patients with high-molecular-weight isoforms. Urinary apo(a) excretion was significantly decreased in the patient group when compared with healthy controls. There was a close correlation (P < 0.001) between the plasma Lp(a) and urinary apo(a) excretion in both the patient group and the control group. Urinary apo(a) excretion did not correlate with protein excretion, creatinine clearance or plasma creatinine levels. We conclude that urinary apo(a) excretion correlates with plasma Lp(a) and Lp(a) isoforms, and that proteinuric patients excrete significantly less apo(a) into their urine than healthy controls, a factor that might contribute to increased plasma Lp(a) levels in these patients.
血浆脂蛋白(a) [Lp(a)] 水平升高与早发性心血管疾病和中风密切相关。最近，我们以及其他研究团队发现，载脂蛋白(a) [apo(a)] 片段出现在健康个体的尿液中，并且与对照组相比，肾功能受损的肾移植患者尿液中排出的apo(a) 片段较少。由于目前尚不清楚apo(a) 的排泄方式，我们测定了58例蛋白尿患者和58例健康对照者的血浆Lp(a) 水平及尿apo(a) 排泄情况，并将其与肾功能进行关联分析。首次将尿apo(a) 排泄与apo(a) 异构体联系起来。与对照组相比，蛋白尿患者的血浆Lp(a) 值更高，且与他们的肾功能无关。低分子量apo(a) 异构体的患者血浆Lp(a) 水平较高，而高分子量apo(a) 异构体的患者血浆Lp(a) 水平较低。尿apo(a) 呈现出与血浆Lp(a) 非常相似的模式，低分子量异构体患者的尿apo(a) 明显高于高分子量异构体患者。与健康对照组相比，患者组的尿apo(a) 排泄显著减少。患者组和对照组的血浆Lp(a) 与尿apo(a) 排泄之间均存在密切相关性（P < 0.001）。尿apo(a) 排泄与蛋白排泄、肌酐清除率或血浆肌酐水平均无相关性。我们得出结论，尿apo(a) 排泄与血浆Lp(a) 和Lp(a) 异构体相关，并且蛋白尿患者尿液中apo(a) 的排泄量明显低于健康对照组，这可能是导致这些患者血浆Lp(a) 水平升高的一个因素。
