Oxidative stress, endothelial function, carotid artery intimal thickness and their correlates among chronic peritoneal dialysis patients

We evaluated important nontraditional cardiovascular risk factors, endothelial function and oxidative stress (OS) among stable peritoneal dialysis (PD) patients. Their association with carotid intimal medial thickness (CIMT) was also assessed. Thirty-eight adult patients (13 diabetics, 20 males) on PD for >6 months and 15 age and sex-matched controls were studied. Duration of dialysis (DOD), residual urine output (UO), weekly Kt/V urea, detailed biochemical and lipid profile were noted. OS was measured by serum concentration of antioxidants; vitamin C and ferric reducing ability of plasma (FRAP) and pro-oxidant; thiobarbituric acid-reactive substances (TBARS). High-resolution ultrasonography was used to determine CIMT and flow-mediated dilatation of brachial artery [endothelium-dependent dilatation (EDD)] and dilatation subsequent to nitrate spray [endothelium-independent dilatation (EID)]. Mean age, DOD, UO and Kt/V of study population were 49.3 ± 11.6 years, 19.4 ± 11.8 months, 508.2 ± 422.9 ml/day and 1.73 ± 0.24, respectively. As compared to controls PD patients had higher CIMT (0.46 ± 0.05 vs 0.50 ± 0.07 mm, P = 0.003) and TBARS (1.5 ± 0.4 vs 5.1 ± 2.3 nM/ml, P < 0.001) but lower Vitamin C (1.7 ± 0.3 vs 0.6 ± 0.2 mg%, P < 0.001), FRAP (990.8 ± 78.1 vs 328.7 ± 183.5 μM/L, P < 0.001) and EDD (26.2 ± 5.4 vs 9.8 ± 4.6 %, P < 0.001). TBARS correlated positively with DOD and negatively with hemoglobin. Vitamin C and FRAP correlated positively with serum albumin. EDD correlated positively with UO, Kt/V and hemoglobin. CIMT correlated negatively with Kt/V and hemoglobin. Among themselves CIMT correlated negatively with EDD and vitamin C. EDD correlated positively with vitamin C, while FRAP correlated positively with vitamin C and negatively with TBARS. PD patients have higher OS, poorer endothelial function and higher structural atherosclerosis. These parameters are closely linked to each other, hemoglobin, DOD, residual UO, serum albumin and small solute clearances.