Serum antioxidant capacity is preserved in peritoneal dialysis contrary to its robust depletion after hemodialysis and hemodiafiltration sessions

Oxidation State in Peritoneal Dialysis in Patients with Type 2 Diabetes Mellitus

End-stage renal disease (ESRD) progression is closely related to oxidative stress (OS). The study objective was to determine the oxidant and antioxidant status in peritoneal dialysis (PD) patients with type 2 diabetes mellitus (DM). An analytical cross-sectional study from the PD program was carried out with 62 patients, 22 with and 40 without DM. Lipoperoxides (LPO) levels in patients with DM, 3.74 ± 1.09 mM/L, and without DM, 3.87 ± 0.84 mM/L were found to increase compared to healthy controls (HC) 3.05 ± 0.58 mM/L (p = 0.006). The levels of the oxidative DNA damage marker (8-OH-dG) were found to be significantly increased in patients with DM, 1.71 ng/mL (0.19-71.92) and without DM, 1.05 ng/mL (0.16-68.80) front to 0.15 ng/mL (0.15-0.1624) of HC (p = 0.001). The antioxidant enzyme superoxide dismutase (SOD) activity was found to be significantly increased in patients with DM, 0.37 ± 0.15 U/mL, and without DM, 0.37 ± 0.17 compared to HC, 0.23 ± 0.05 U/mL (p = 0.038). The activity of the enzyme glutathione peroxidase (GPx) showed a significant increase (p < 0.001) in patients with DM, 3.56 ± 2.18 nmol/min/mL, and without DM, 3.28 ± 1.46 nmol/min/mL, contrary to the activity obtained in HC, 1.55 ± 0.34 nmol/min/mL. In conclusion, we found an imbalance of oxidative status in patients undergoing PD with and without DM through the significant increase in LPO oxidants and the marker of oxidative damage in DNA. The activity of the antioxidant enzymes SOD and GPx were significantly increased in patients with and without DM undergoing PD, possibly in an attempt to compensate for the deregulation of oxidants. Antioxidant enzymes could be promising therapeutic strategies as a complement to the management of chronic kidney diseases.

Do HDL and LDL subfractions play a role in atherosclerosis in end-stage renal disease (ESRD) patients?

BACKGROUND

Significantly increased cardiovascular mortality in patients with chronic kidney (CKD) disease cannot be explained by traditional risk factors. Recent studies revealed that the quality of HDL and LDL cholesterol may be more important than their serum levels. The aim of this study was to assess which LDL and HDL subfractions were more abundant in end-stage renal disease (ESRD) patients and to analyse whether subfraction distribution could be associated with accelerated atherosclerotic processes.

METHODS

This study included 50 ESRD patients undergoing dialysis and 20 healthy volunteers. LDL and HDL subfractions were analysed in serum with the use of Lipoprint system. All patients had intima-media thickness (IMT) measured.

RESULTS

Statistically significant differences in subfractions between control and study group were observed in case of: HDL1 (p < 0.0001), HDL2 (p = 0.009), HDL3 (p < 0.0001), HDL4 (p = 0.003), HDL5 (p = 0.01), HDL7 (p < 0.0001), HDL8 (p < 0.0001), HDL9 (p < 0.0001), HDL10 (p < 0.0001), large HDL (p < 0.0001), HDL Small (p < 0.0001) as well as IDL-B (p = 0.014), IDLA (p = 0.011), LDL2 (p = 0.007). Significant differences were also observed in HDL and LDL subfraction distribution between haemodialysis patients with normal and increased IMT: HDL6 (p = 0.020), HDL Large (HDL1-3) (p = 0.017), HDL Intermediate (HDL4-7) (p = 0.017).

CONCLUSIONS

This study revealed that ESRD influenced HDL subfractions. In HD patients, large HDL subfractions are more abundant while small HDL fraction is more frequent in healthy persons. It failed to show the influence of end-stage disease on LDL subfraction levels. Shift in HDL subfractions might be responsible for the increased risk of atherosclerosis in CKD patients.

Evaluation of assays for measurement of serum (anti)oxidants in hemodialysis patients

Background. Various biomarkers and assays have been used for assessment of (anti)oxidant status in hemodialysis patients, including those intended for measurement of serum total (anti)oxidants, most often as a part of panel biomarkers. Methods. Serum (anti)oxidant status was measured in 32 chronically hemodialyzed patients and in 47 healthy persons, using two oxidations and three antioxidant assays. Results. The patients before the hemodialysis session have had higher values of total oxidants in comparison to the healthy persons, with a further increase during the hemodialysis. These findings were confirmed with both oxidation assays, but they differ in the percentage of increase and the statistical significance. All three antioxidant assays showed significantly higher values of the total serum antioxidants in the patients before the hemodialysis session in comparison to the healthy persons, and their significant decrease during the hemodialysis. However, the assays differ in the percentage of decrease, its statistical significance, and the correlations with uric acid. Conclusion. The variability of results of total (anti)oxidants which are obtained using different assays should be taken into account when interpreting data from clinical studies of oxidative stress, especially in complex pathologies such as chronic hemodialysis.

Greater risk of hip fracture in hemodialysis than in peritoneal dialysis

Several differences may have existed between patients treated with peritoneal dialysis and hemodialysis because of the difference in dialysis modality. This nationwide population-based cohort study demonstrated that patients on hemodialysis had an increased risk of hip fracture compared to patients on peritoneal dialysis; the hazard ratio was 1.52.

INTRODUCTION

Numerous debates on which dialysis modality is "superior" have taken place in recent decades. However, no large-scale study has ever mentioned about the relationship between dialysis modality and risk of hip fracture.

METHODS

We identified 64,124 incident end-stage renal disease patients from the National Health Insurance Research Database in Taiwan between 1998 and 2008, including 59,457 (92.72%) hemodialysis (HD) and 4,667 (7.28%) peritoneal dialysis (PD) patients. After 8:1 propensity score matching, 31,554 patients, of whom 28,048 were HD and 3,506 were PD patients, were included in the study. We conducted the Cox proportional hazards model to examine the effects of dialysis modality and other variables on hip fracture risk.

RESULTS

A total of 2,587 hip fractures were identified in 64,124 dialysis patients. The incidence rate of hip fracture was 13.60 per 1000 patient-years in the HD group and 6.25 in the PD group. Dialysis modality, sex, age, presence of cardiovascular disease, diabetes, medication with antiepileptic drugs, diuretics, steroids, and vitamin D had statistically significant associations with hip fracture. Patients on HD had an increased risk of hip fracture compared to patients on PD; the hazard ratio (HR) was 1.52 (95% CI: 1.09-2.12, P = 0.02).

CONCLUSIONS

In this population-based cohort study, HD had a greater hip fracture risk compared to PD; the HR was 1.52. We should focus more on reducing the risk of hip fractures in hemodialysis patients.

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.