Urinary Biopyrrin Levels and Their Relationship with the Menstrual Cycle and Concomitant Symptoms Among Healthy Nonpregnant Women of Reproductive Age: A Cohort Study

Background

Urinary biopyrrin (UBP) is an oxidative metabolite formed from the reaction of bilirubin with reactive oxygen species. Previous studies have explored the relationship between UBP levels and certain diseases or pregnancy. However, UBP levels in healthy nonpregnant women have not been well examined. We aimed to clarify the representative value of UBP in healthy nonpregnant women and explore its relationship with menstrual cycles and concomitant symptoms.

Methods

We included healthy, nonpregnant Japanese women aged 20-39 years with normal body mass index and menstrual cycle. In total, 1260 urine samples collected during 43 menstrual cycles of 36 women were analyzed to determine the representative values and reference intervals of UBP levels. The correlation between daily UBP levels and the order of the day was explored, and median UBP levels of 5-day clusters were compared using Friedman and Mann-Whitney U tests. These analyses were also conducted in women with concomitant symptoms during the menstrual cycle.

Results

The median UBP level in all samples was 0.2291 (reference: 0.0102-2.9335) μmol/gCr. There was no significant relationship between the median UBP level and menstrual cycle, regardless of the presence of self-manageable symptoms during or before menstruation.

Conclusions

The representative UBP value and its reference interval can serve as standards for comparison with other populations. Our findings suggest that the UBP level may be an objective oxidative stress indicator that is less sensitive to menstrual cycle and concomitant symptoms. UBP levels in healthy nonpregnant women could be assessed regardless of the menstrual cycle and concomitant symptoms.

Effects of lifestyle factors on urinary oxidative stress and serum antioxidant markers in pregnant Japanese women: A cohort study

Oxidative stress plays a major pathological role in pregnancy-related complications. Although oxidative stress is induced by exogenous toxins in association with a poor lifestyle in normal subjects, there is little information on the factors altering oxidative stress and antioxidant levels during pregnancy. The purpose of this study was to determine the relationship between lifestyle factors and oxidative stress/antioxidant levels during each trimester and 1-month postpartum. This prospective cohort study followed 54 healthy women through pregnancy; first, second, and third trimester and 1-month postpartum. Participants were administered a questionnaire on characteristics and lifestyle factors. Morning blood and urine samples were obtained to measure urinary biopyrrins and serum coenzyme Q10 (CoQ10) levels. The levels of urinary biopyrrins and serum CoQ10 increased significantly throughout pregnancy, with peak values registered during the third trimester. Higher biopyrrin levels were significantly associated with non-consumption of morning meal during the first trimester, smoking during the third trimester and 1-month postpartum, alcohol consumption during the third trimester, high food-based polyunsaturated fatty acid intake during the third trimester, and poor mental health scores during the first and third trimesters. Higher CoQ10 levels were significantly associated with no smoking during pregnancy and at 1-month postpartum, and with a high frequency of exercise during the third trimester and 1-month postpartum. Thus, pregnancy represents a state of oxidative stress, which can be counterbalanced by increased levels of antioxidants, such as CoQ10. We speculate that certain lifestyle choices such as avoiding smoking can reduce oxidative stress and increase antioxidant levels during pregnancy.

Ubiquinol-10 and ubiquinone-10 levels in umbilical cord blood of healthy foetuses and the venous blood of their mothers

Despite their being good markers of oxidative stress for clinical use, little is known about ubiquinol-10 (reduced coenzyme Q10) and ubiquinone-10 (oxidized coenzyme Q10) levels in foetuses and their mothers. This study investigates oxidative stress in 10 healthy maternal venous, umbilical arterial and venous bloods after vaginal delivery by measuring ubiquinol-10 and ubiquinone-10 levels. Serum ubiquinol-10 and ubiquinone-10 levels were measured by HPLC with a highly sensitive electrochemical detector. Maternal venous ubiquinol-10 and ubiquinone-10 levels were significantly higher than umbilical arterial and venous levels (all p < 0.001). However, the ubiquinone-10/total coenzyme Q10 (CoQ10) ratio, which reflects the redox status, was significantly higher in umbilical arterial and umbilical venous blood compared to maternal venous blood (all p < 0.001). The ubiquinone-10/total CoQ10 ratio was higher in umbilical arterial than in umbilical venous blood (p < 0.01). The present study demonstrated that foetuses were under higher oxidative stress than their mothers.