A longitudinal study of antioxidant status in phenylketonuric patients

Objectives: To investigate the implications of the three main factors of the antioxidant system reported in relation to oxidative damage in phenylketonuric patients: selenium, ubiquinone-10 (Q10) and antioxidant enzymes over 3 years of metabolic follow-up. Design and methods: Longitudinal study of 46 phenylketonuric patients (age range: 6 months–34 years). Antioxidants were measured by atomic absorption spectrophotometric, chromatographic and spectrophotometric procedures. Results: Plasma selenium concentrations in phenylketonuria (PKU) were not different from those of a healthy population. Decreased plasma Q10 concentrations were mainly related to the dietary control and the age of patients. Erythrocyte catalase activity was significantly decreased in PKU while the other enzyme activities were not different from those of a healthy population. Conclusions: Selenium status is not impaired in phenylketonuric patients under dietary treatment. Q10 values tend to decrease with increased patient age. Catalase activity was negatively associated with plasma phenylalanine values.