Background/aims: Increased oxidative stress in chronic kidney disease (CKD) was suggested to be both a cause and an effect of renal injury. However, the evolution of oxidant stress from early stages of renal function decline is not fully clear. This study aimed to determine the oxidant-antioxidant balance across the whole range of renal function.

Methods: A total of 116 patients with CKD (85 predialysis patients divided into groups according to CKD stage, and 31 patients with end-stage renal disease (ESRD) on hemodialysis treatment), as well as 29 healthy subjects were evaluated. Plasma levels of 15-F(2t)-isoprostane (15-F(2t)-IsoP), a valid marker of oxidant stress, as well as total antioxidant capacity (TAC) and serum levels of vitamin E were measured in all participants.

Results: Plasma 15-F(2t)-IsoP levels were higher in predialysis and ESRD patients compared to healthy subjects and were progressively increasing with advancing CKD stages (p < 0.001). In contrast, plasma TAC was similar between healthy subjects and predialysis patients, and presented a small reduction in ESRD patients (p < 0.001). Vitamin E levels were higher in healthy subjects compared to any other group (p < 0.001) and slightly higher in ESRD patients compared to predialysis patients (p < 0.01), but did not differ significantly between the groups of predialysis patients. Plasma 15-F(2t)-IsoP levels were inversely correlated with estimated glomerular filtration rate in predialysis patients (r = -0.65, p < 0.001).

Conclusions: This study shows that 15-F(2t)-IsoP levels increase progressively with advancing CKD stages, whereas TAC and vitamin E levels remain rather stable with the loss of renal function and change only in patients with ESRD.