Kim S B, Yang W S, Min W K, Lee S K, Park J S
Department of Internal Medicine, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.
Perit Dial Int. 2000 May-Jun;20(3):290-4.
Albumin is one of the plasma antioxidants. The higher incidence of cardiovascular disease in dialysis patients with hypoalbuminemia may be related to decreased antioxidant capacity resulting from low serum albumin. We evaluated malondialdehyde (MDA), a marker of oxidative stress, and total antioxidant capacity (TAC) in relation to serum albumin in continuous ambulatory peritoneal dialysis (CAPD) patients.
In this cross-sectional study, we measured MDA, TAC, albumin, uric acid (another important plasma antioxidant), prealbumin, and C-reactive protein (CRP) in the blood of 66 CAPD patients and 30 normal controls.Twenty-two CAPD patients with albumin less than or equal to 3.5 g/dL were divided into two groups: In the experimental group (n = 11), MDA,TAC, and CRP were measured before and after repeated infusion of 20% albumin 100 mL daily for 7 days. In the control group (n = 11), the same parameters were measured without albumin infusion.
CAPD patients had lower albumin and higher MDA,TAC, and uric acid than normal controls. There were positive correlations between albumin and TAC or uric acid in CAPD patients. Contrary to our expectation, there was also positive correlation between albumin and MDA in CAPD patients (r = 0.37, p = 0.004). MDA showed a positive correlation with TAC. Uric acid was correlated with TAC. It did not, however, show correlation with MDA. Log CRP was negatively correlated with albumin, but did not show correlation with MDA or TAC. Prealbumin was correlated with MDA, TAC, albumin, and uric acid. Serum albumin in the experimental group increased from 2.5+/-0.3 g/dL to 3.6+/-0.2 g/dL (p < 0.001) at the end of repeated infusions. No changes were seen in MDA, TAC, and CRP in either group.
The present study suggests that lipid peroxidation is increased in CAPD patients and that this is not due to weakening of antioxidant defenses of plasma. Increased TAC was mainly caused by a higher level of uric acid. Reduced, rather than increased, MDA in hypoalbuminemic patients and lack of effects of albumin infusion on levels of MDA suggest that the frequent occurrence of cardiovascular disease in dialysis patients with hypoalbuminemia is not due to the decrease in antioxidant capacity resulting from low serum albumin.
白蛋白是血浆抗氧化剂之一。低白蛋白血症的透析患者心血管疾病发病率较高，可能与血清白蛋白水平低导致抗氧化能力下降有关。我们评估了持续性非卧床腹膜透析（CAPD）患者中丙二醛（MDA，氧化应激标志物）和总抗氧化能力（TAC）与血清白蛋白的关系。
在这项横断面研究中，我们测量了66例CAPD患者和30例正常对照者血液中的MDA、TAC、白蛋白、尿酸（另一种重要的血浆抗氧化剂）、前白蛋白和C反应蛋白（CRP）。22例白蛋白小于或等于3.5 g/dL的CAPD患者被分为两组：实验组（n = 11），每天重复输注100 mL 20%白蛋白，共7天，在输注前后测量MDA、TAC和CRP；对照组（n = 11），在不输注白蛋白的情况下测量相同参数。
CAPD患者的白蛋白水平低于正常对照者，而MDA、TAC和尿酸水平高于正常对照者。CAPD患者中白蛋白与TAC或尿酸呈正相关。与预期相反，CAPD患者中白蛋白与MDA也呈正相关（r = 0.37，p = 0.004）。MDA与TAC呈正相关。尿酸与TAC相关，但与MDA不相关。Log CRP与白蛋白呈负相关，但与MDA或TAC不相关。前白蛋白与MDA、TAC、白蛋白和尿酸相关。重复输注结束时，实验组血清白蛋白从2.5±0.3 g/dL升至3.6±0.2 g/dL（p < 0.001）。两组的MDA、TAC和CRP均无变化。
本研究表明，CAPD患者脂质过氧化增加，且这并非由于血浆抗氧化防御减弱所致。TAC升高主要是由较高的尿酸水平引起的。低白蛋白血症患者的MDA降低而非升高，且白蛋白输注对MDA水平无影响，这表明低白蛋白血症的透析患者心血管疾病频繁发生并非由于血清白蛋白水平低导致抗氧化能力下降。
