Does dialysis modality influence the oxidative stress of uremic patients?

BACKGROUND/AIMS: Since peritoneal membrane is more compatible and residual renal function better preserved during peritoneal dialysis, we questioned whether the oxidative burden in chronic kidney disease (CKD) is influenced by dialysis modality. METHODS: 49 stable CKD patients, 17 on continuous ambulatory peritoneal dialysis (CAPD), 16 on hemodialysis (HD), and 16 non-dialyzed, and 13 healthy subjects were enrolled. Plasma thiobarbituric acid-reactive substances (TBARS; nmol/g protein), serum total antioxidant activity (TAA), total plasma-free thiols (Pt-SH; µmol/g protein), albumin and uric acid were measured by spectrophotometry. Serum residual antioxidant activity (RAA) was calculated. RESULTS: TBARS were higher in HD (78.3 ± 20.3) versus both non-dialyzed (53.1 ± 27.9, p = 0.007) and CAPD groups (58.3 ± 19.8, p = 0.008). Pt-SH was reduced in CKD patients, but showed comparable values between dialysis groups. TAA and RAA were similarly increased in HD and CAPD patients than in the other two groups. CONCLUSION: Oxidative stress occurs in all CKD patients and worsens as renal function declines. Lipid peroxidation seems more augmented during chronic HD as compared to CAPD, but the plasma antioxidant status did not differ between the investigated dialysis methods. Therefore, dialysis modality appears to influence lipid peroxidation without changing the extracellular antioxidant defense of CKD patients.

The success story of peritoneal dialysis in Romania: analysis of differences in mortality by dialysis modality and influence of risk factors in a national cohort.

BACKGROUND: This report describes the status of renal replacement therapy (RRT), particularly continuous ambulatory peritoneal dialysis (CAPD), in Romania (a country with previously limited facilities), outlines the fast development rate of CAPD, and presents national changes in a European context. METHODS: Trends in the development of RRT were analyzed in 2003 on a national basis using annual center questionnaires from 1995 to 2003. Survival data and prognostic risk factors were calculated retrospectively from a representative sample of 2284 patients starting RRT between 1 January 1995 and 31 December 2001 (44% of the total RRT population investigated). RESULTS: The annual rate of increase in the number of RRT patients (11%) was supported mainly by an exponential development of the CAPD population (+600%); the hemodialysis (HD) growth rate was stable (+33%) and renal transplantation had a marginal contribution. The characteristics of both HD and PD incident patients changed according to current European epidemiology (increasing age and prevalence of diabetes and nephroangiosclerosis). There were significant differences between PD and HD incident populations, PD patients being significantly older and having a higher prevalence of diabetic nephropathy and baseline comorbidities, probably reflecting different inclusion policies. The estimated overall survival of RRT patients in Romania was 90.6% at 1 year [confidence interval (CI) 89.4 - 91.8] and 62.2% at 5 years (CI 59.4 - 65.0). The initial treatment modality did not significantly influence patients' survival. There was no difference in unadjusted technique survival during the first 2 years; afterwards, there was a clear advantage for HD, with more patients being transferred from PD to HD. Several factors seemed to significantly and negatively influence PD patients' survival (Cox regression analysis): male gender, lack of predialysis erythropoietin treatment, and initial comorbidities. Stratified analysis to discover the influence of these factors on patients' survival revealed that HD was associated with an increased risk of death in the younger nondiabetic end-stage renal disease population, regardless of other coexisting comorbid conditions. However, in older patients (>65 years) and in diabetics, regardless of the presence or absence of associated comorbid conditions, there was no significant difference in death rates between HD and PD patients. CONCLUSIONS: We report an impressive quantitative and qualitative development of CAPD in one of the rapidly growing Central and Eastern Europe countries. CAPD should be the method of choice for young nondiabetic end-stage renal disease patients. Improvement in predialysis nephrologic care and in transplantation rates is required to further ensure the ultimate success of the Romanian PD program.

Global assessment of serum antioxidant status in hemodialysis patients.

BACKGROUND: Since chronic renal failure (CRF) was described as a state of oxidant/antioxidant imbalance augmented after hemodialysis (HD) initiation, we assessed the total antioxidant activity and single antioxidants in sera from uremic patients dialyzed or not, compared to subjects with normal renal function. METHODS: Serum total antioxidant activity (TAA--measured as Trolox equivalent antioxidant capacity; mmol/L), total plasma free thiols (Pt-SH; micromol/g protein), albumin (g/dL) and uric acid (mg/dL) were determined in 19 hemodialyzed patients, 15 CRF non-dialyzed patients (serum creatinine (Cr) = 4.4 +/- 2.7 mg/dL) and in 16 healthy controls. The "antioxidant gap" (mmol/L), as a measure of the combined activity of plasma antioxidants other than albumin and uric acid, was calculated. RESULTS: TAA and the "antioxidant gap" were higher in HD patients (1.21 +/- 0.12 vs. 0.96 +/- 0.13 in the non-HD group, p<0.001, and vs. 0.9 +/- 0.14 in controls, p<0.001, respectively, for TAA; 0.46 +/- 0.15 vs. 0.2 +/- 0.15, p<0.001, and vs. 0.21 +/- 0.16, p<0.001, respectively, for residual antioxidant activity). However, no differences existed in major plasma antioxidant levels (albumin and uric acid) among uremic patients, hemodialyzed or not. Pt-SH were reduced in nondialyzed patients as compared to controls (6.21 +/- 1.1 vs. 7.33 +/- 0.83, p=0.002), but were elevated in HD patients (11.9 +/- 1.1). CONCLUSIONS: These results suggest that HD patients appear to have improved plasma antioxidant status, hyperuricemia not being the sole contributor. Therefore, it seems reasonable to speculate that other antioxidants (thiols or some as yet unrecognized substances) could also be contributors. However, more reliable assays for extracellular antioxidant defense evaluation are required to validate this hypothesis.

Influence of epoietinum therapy on the oxidative stress in haemodialysis patients.

BACKGROUND: The causes of oxidative stress in haemodialysis (HD) patients are still controversial. Beside the uraemic state and dialysis-related factors, adjuvant drug therapies such as epoietinum (rHuEpo) and intravenous iron were involved. METHODS: Several parameters related to oxidative stress were assessed by spectrophotometry in stable HD patients, treated for at least 2 months with epoietinum (n = 14; mean dose = 97.7 +/- 19.1 U/kg/week) or not (n = 15), none of them on iron therapy, and in 13 controls. Plasma thiobarbituric acid-reactive substances (TBARS) were used as markers of reactive species generation. Erythrocyte and plasma antioxidant systems, reflected by non-protein erythrocyte thiols, and erythrocyte enzyme activities -- superoxide dismutase (SOD), glutathione peroxidase, catalase and plasma total thiols, respectively -- were also investigated. RESULTS: There were no differences between HD subgroups regarding haemoglobin levels. Plasma TBARS was increased in all HD patients as opposed to controls, irrespective of rHuEpo therapy. In addition, no change in antioxidant status parameters between rHuEpo-treated and -untreated patients was observed. Except for SOD, the other antioxidant indices were higher in all HD patients versus controls. CONCLUSIONS: These results suggest that (1) chronic HD patients appear to have simultaneously enhanced reactive species generation and antioxidative systems efficiency, and (2) epoietinum therapy did not change their oxidative status, at least in the absence of concomitant iron supplementation and at similar haemoglobin levels.