Assessment of paraoxonase 1 activity and malondialdehyde levels in patients with rheumatoid arthritis

Objectives: We aimed to evaluate antioxidant paraoxonase 1 activity together with malondialdehyde (MDA) (an oxidative stress parameter) levels in patients with rheumatoid arthritis. Design and methods: Fifty-seven rheumatoid arthritis patients were included in the study and subgrouped according to disease activity (active, n = 31; inactive, n = 26) and compared with healthy controls (n = 25). Serum paraoxonase 1 activity and MDA levels were measured according to an enzymatic spectrophotometric method. Results: Serum MDA level was higher (P = 0.001) whereas paraoxonase 1 activity was lower (P = 0.001) in the patient group than the controls. When active and inactive subgroups were compared with the control group, there was a statistically significant difference between each parameter. Serum MDA levels were significantly higher, while paraoxonase 1 activity was lower in the active and inactive rheumatoid arthritis groups than the control group. But there was not any difference between active and inactive patients with RA. There was a negative correlation between MDA levels and paraoxonase 1 activity. Conclusions: Increased reactive oxygen species levels in rheumatoid arthritis may result in a pro-oxidation environment, which in turn could result in decreased antioxidant paraoxonase 1 activity and increased MDA levels