Serum uric acid levels in patients with Parkinson's disease: Their relationship to treatment and disease duration

There is evidence to support that oxidative stress is increased in Parkinson's disease (PD) and contributes to degeneration of dopaminergic neurons. Uric acid (UA), a natural antioxidant in blood and brain tissue, scavenging superoxide, peroxynitrite and hydroxyl radical, was found reduced in the serum of PD patients. In addition low plasma uric acid (UA) levels have been associated with an increased risk of PD. Objectives: The aim of our study was to investigate serum UA levels in PD patients compared with age-matched healthy controls and their possible relationship with several clinical parameters of PD and pharmaceutical treatment. Patients and methods: We measured serum UA levels in 43 PD patients and 47 healthy volunteers, age and sex-matched. UA levels were correlated with disease duration, severity and treatment. Results: Low UA levels were observed in PD patients compared with controls (p = 0.009). Age, Body Mass Index (BMI) and UPDRS III score did not significantly affect serum UA concentrations, whereas gender was found to contribute significantly to UA level (p < 0.000). Strong and significant inverse correlations of UA with disease duration (R-s = -0.397, p = 0.009) and daily levoclopa dosage (R-p = -0.498, p = 0.026) were observed. These associations were significant for men (R-s = -0.441, p = 0.04 and R-s = -0.717, p = 0.03 respectively), but not for women (R-s = -0.221, p = 0.337 and R-s = -0.17, p = 0.966 respectively). Conclusion: Our results suggest that there may be increased consumption of UA as a scavenger in PD, possibly heightened by dopaminergic drug treatment. Given the antioxidant properties of UA, manipulation of its concentrations should be investigated for potential therapeutic strategies of the disease. (C) 2009 Elsevier B.V. All rights reserved.