Objective: Serum paraoxonase (PON1) is a HDL associated esterase and inhibits LDL oxidation. The oxidative modification of LDL plays an important role in the pathogenesis of atherosclerosis. In hemodialysis patients, the increased oxidative stress induces oxidative modification of LDL and causes an increased risk for developing atherosclerosis. In keeping with this hypothesis, we aimed to evaluate the PON1 activities in hemodialysis patients.

Material and Methods: We measured PON activity, Apo A1, HDL, LDL levels in 52 hemodialysis patients and in 42 healthy control subjects.

Results: The serum PON activities were found to be decreased in hemodialysis patients (95.88 U/L) compared to control subjects (126.38 U/L) (p<0.001). The Apo A1 and HDL levels were also lower in hemodialysis patients. To assess whether the observed reduction in PON activity was due to HDL and Apo A1 level decreases, we standardized the enzyme activity for HDL and Apo A1 concentrations. The standardized serum PON1 activities in hemodialysis patients did not show a significant decrease when compared with the control group.

Conclusion: This study shows that the decreased PON1 activities may lead to a reduction in the antioxidant capacity of HDL and contribute to the accelerated development of atherosclerosis in hemodialysis patients.