Endothelial Function and Oxidative Stress in Chronic Kidney Disease of Varying Severity and the Effect of Acute Hemodialysis

Aim: Oxidative stress (OS) and endothelial dysfunction are implicated in accelerated atherosclerosis in chronic kidney disease (CKD). We assessed endothelial function, OS, and carotid intimal medial thickness (CIMT) and their correlates in 44 CKD stage 5 patients (group III) before and after hemodialysis (HD), 40 patients of CKD stages 3 and 4 (group II), and 25 matched controls (group I). Methods: OS was measured by serum concentration of antioxidants; vitamin C and fractional reducing ability of plasma (FRAP) and pro-oxidant; thiobarbituric acid reactive substances (TBARS). Ultrasonography of carotid artery for CIMT and of brachial artery for flow-mediated dilatation (endothelium-dependent dilatation, EDD) was done. Results: TBARS increased significantly with severity of CKD. Antioxidants FRAP and vitamin C were significantly lower in CKD patients as compared with controls, but there was no significant difference between groups II and III. EDD decreased significantly with severity of CKD, whereas CIMT though higher in CKD patients as compared with controls was not significantly different between groups II and III. After a session of HD as compared with predialysis, levels of TBARS decreased, whereas those of FRAP, vitamin C, and EDD increased. On multivariate analysis, there was negative correlation of TBARS with glomerular filtration rate (GFR), serum albumin, hemoglobin, and EDD. Vitamin C had positive correlations with GFR, serum albumin, hemoglobin, and EDD. EDD had direct correlation with GFR, whereas CIMT correlated negatively with EDD. Conclusions: Endothelial dysfunction and OS occur early in CKD, are closely related to each other and structural atherosclerosis, and are proportional to decline in GFR.