Open comparison study of oxidative stress markers between patients with chronic renal failure in conservative therapy and patients in haemodialysis

Abstract

Aims: Oxidative stress is defined as tissue damage caused by an imbalance between the excessive production of the oxidant components and an insufficient defence mechanism. It has been observed, as in patients with chronic kidney failure, that there exists a pro-oxidant state characterised by a higher level of reactive oxygen species (ROS), and that oxidative stress in dialysis patients can be aggravated by the activation of neutrophils associated with the production of free radicals. In patients undergoing dialysis even the molecules other than those of cytokines can accumulate and provoke an inflammatory response. This study proposes an analysis based on the total antioxidant capacity (TAC), thiol concentration (TC) and pro-oxidant capacity (POC) in the serum of various groups of patients: one group of dialysis subjects who had been undergoing substitutive treatment for more than ten years at the time of the study; one group of subjects with chronic renal insufficiency in its pre-terminal stage and subjected to conservative therapy; and the control group consisting of healthy volunteers.

Materials and methods: Three types of tests were employed to assess the level of oxidative stress: oxy-adsorbent test, d-ROMS test, and SHp- test. Thirty-three subjects were selected: 11 undergoing haemodialysis for over then years; 14 patients with chronic kidney failure in its pre-terminal stage, and 8 normal subjects. In patients undergoing renal substitutive treatment, the serum levels (mean±sd) of TAC were 272.98±20.54; TC, 249.19±92.48, and POC, 95.06±15.70. In patients with chronic renal insufficiency in its pre-terminal stage and undergoing conservative treatment, the value of TAC was 226.5±27.89; TC, 336.42±102.08; and POC, 80.78±15.69. The levels of TAC in the serum of the controls were 335.62±46.35; TC, 434.09±22.23; and POC, 56.31±7.41.

Conclusion: The analysed data suggest that in dialysis the patients with chronic kidney failure, whether undergoing conservative therapy during its pre-terminal stage or in substitution treatment during its terminal stage, there is a reduction in the antioxidant defence (in terms of TAC and thiolic barrier) and an increase in POC compared to the healthy subjects in the control group. Uraemia and haemodialysis increase the inflammatory response: an initial signal provokes the inflammatory state with the production of cytokines and free radicals or reactive oxygen, so that the lack of an antioxidant defence mechanism can bring about a vicious circle with the continual production of other free radicals.