Effects of Psychological Stress from a National License Examination on the Urine 8-Hydroxy-Deoxyguanosine Levels in Young Female Students, Taking into Account the Menstrual Cycle

Objective: Urine 8-hydroxy-deoxyguanosine (U8-OHdG) was a marker of oxidative stress-induced DNA damage; it was increased by psychological stress. Since the menstrual cycle may confound or modify the association between psychological stress and U8-OHdG. The aim of this study was to verify the effect of psychological stress from a national license examination on levels of U8-OHdG, which is a biomarker of oxidative stress. And the effects of women’s menstrual cycles, which should be considered in mental and physical assessments, on U8-OHdG, were evaluated. Methods: The subjects were 18 female university students at a medical university in whom Self-rating Depression Scale (SDS) scores, State-Trait Anxiety Inventory (STAI) scores, and U8-OHdG levels were measured in 3 phases of the menstrual cycle, the follicular phase, ovulatory phase, and luteal phase. The mean values were taken for the group during a time of classroom learning. The same measurements were also made one week before and the day after a national license examination and the measurements were compared among the three periods. Results and Conclusion: State anxiety and U8-OHdG levels were significantly higher in those with a week before the national license examination than in those with classroom lecture (State anxiety: p = 0.002, U8-OHdG levels: p = 0.007). The menstrual cycle did not show a significant correlation with U8-OHdG levels. This study demonstrated that levels of the oxidative stress biomarker U8-OHdG are not affected by changes in the menstrual cycle. It also showed that U8-OHdG levels increased with the psychological stress of a national license examination.