Decreased serum selenium concentrations in patients with Parkinson's disease

Selenium is an essential component of the antioxidant enzyme glutathione peroxidase. The activity of this enzyme is reduced in the substantia nigra of patients with Parkinson's disease (PD), but the results of studies on erythrocytes are controversial. We compared the serum levels of selenium and the 24 h urinary selenium excretion (measured by hydride generation atomic absorption spectrophotometry) in 29 PD patients and 30 matched controls. Serum selenium levels were significantly lower in PD patients than in controls (34.6 ± 2.35 and 45.2 ± 3.83 μg/l, p < 0.05) while urinary excretion was similar for both groups (47.1 ± 6.25 and 45.5 ± 5.38 μg/24 h). These values were not influenced by antiparkinsonian drugs, and they did not correlate with age, age at onset and duration of the PD, scores of the Unified PD Rating Scale or the Hoehn and Yahr staging in the PD group. These results might suggest a possible role of low serum selenium levels in the risk for, or a consequence of the oxidative stress in PD.