Background: The role of attenuation in antioxidant capacity or expansion of pro-oxidant/oxidant is well known for the development of stress oxidative. The aim of this study was to evaluate the plasma antioxidant capacity along with uric acid in patients with diabetic nephropathy (DN+) and without diabetic nephropathy (DN-).

Materials and Methods: The research population included 88 patients with DN, 66 patients without DN and 54 healthy people who were matched for age, gender, and body mass index (BMI). In all groups, total antioxidant capacity of plasma by the ferric reducing antioxidant power (FRAP) assay and serum uric acid by commercial kit, respectively.

Results: The mean age of patients in DN+, DN- and control groups were 59.3± 9.4, 60 ±11.2, and 54.6±6.9 years, respectively. Plasma antioxidant capacity was higher in patients with DN+, (1589±330&mu mol/l Fe2+)  and DN- (1344± 347 &mu mol/l Fe2+) than that in healthy controls (1187±271 &mu mol/l Fe2+ ) (P<0.001). The mean plasma uric acid in patients with DN+ was significantly higher (8.7±1.3 mg/dl) compared with DN- (7.3±1.2 mg/dl) (P<0.01), and significantly lower in control group (4.1±1.4 mg/dl) (P<0.001).

Conclusion: According to our results, despite innate antioxidant activity of uric acid and increase of total antioxidant capacity and concentration of uric acid in diabetic patients with or without nephropathy, it cannot compensates the severity of oxidative stress. Further studies are required to determine the value of other antioxidant factors in increasing the power of total antioxidant capacity.