Ferric Reducing Ability of Plasma and Lipid Peroxidation in Hemodialysis patients: Intradialytic changes

Background and Aims:

Patients on maintenance hemodialysis are at an increased risk of cardiovasculardisease. Oxidative stress has a negative impact on endothelial functions producing endothelial dysfunction which contributes to cardiovascular risk. FRAP assay has been shown to be a simple cost effective tool for estimating antioxidant capacity. Hence the present study was taken up to evaluate total antioxidant capacity as ferric reducing ability of plasma (FRAP) and malondialdehyde (MDA), in patients during hourly intervals of a single hemodialysis session. During hemodialysis, FRAP is subjected to alterations, due to intradialytic changes in various molecules that contribute FRAP. This study was aimed to assess the utility of FRAP as a measure of the antioxidant capacity during hemodialysis.

Methods:

Twenty seven patients with end stage renal disease on maintenance hemodialysis were recruitedinto the study. Time course changes in plasma MDA, FRAP, uric acid, total bilirubin, vitamin C and vitamin E were evaluated. Statistical evaluation of changes in the biochemical parameters during the whole period of dialysis was done using Friedman's test. Linear regression using generalized estimating equations (GEE) model for repeated measures was applied to study the association between parameters on intradialytic FRAP.

Results: Intradialytic increase in plasma MDA (p<0.01), decrease in FRAP (<0.01) and uric acid (p<0.001) levels were found. Uric acid was found to have significant association with FRAP as found by GEE (p<0.001).

Conclusions:

A single session of hemodialysis contributes substantially to oxidative stress. Decreasedintradialytic FRAP levels can be due to a decrease in uric acid levels. Assessment of antioxidant status in hemodialysis patients by FRAP method may not truly represent the actual antioxidant status, as changes in uric acid levels are reflected in FRAP levels. Hence measurement of individual antioxidants would give a better picture of the antioxidant status during hemodialysis.