Menstrual cycle effects on urinary estrogen metabolites

Area of Science:

• Endocrinology
• Oncology
• Metabolomics

Background:

• Endogenous estrogen metabolism is implicated in hormone-related cancers, particularly breast cancer.
• Estrogen metabolite profiles throughout the menstrual cycle remain largely uncharacterized.
• Understanding these profiles is vital for accurate research in premenopausal women.

Purpose of the Study:

• To investigate the impact of the menstrual cycle on endogenous estrogen metabolism.
• To analyze urinary estrogen metabolite profiles during distinct menstrual cycle phases.
• To assess the levels of potentially genotoxic estrogen metabolites.

Main Methods:

• Collected 24-hour urine samples daily from 6 healthy premenopausal women across 4 defined menstrual cycle phases.
• Analyzed 15 endogenous estrogens and metabolites using ion exchange chromatography and capillary gas chromatography-mass spectrometry.
• Correlated urinary metabolite patterns with plasma estradiol and estrone levels.

Main Results:

• Urinary estrogen metabolite patterns mirrored plasma estradiol and estrone, increasing in periovulatory and midluteal phases.
• Potentially genotoxic metabolites like 16alpha-hydroxyestrone were elevated during later cycle phases.
• Ratios of protective 2-hydroxyestrogens to 16alpha-hydroxyestrogens and 4-hydroxyestrogens significantly increased in periovulatory and midluteal phases.

Conclusions:

• Menstrual cycle phase significantly influences endogenous estrogen metabolism in premenopausal women.
• Estrogen metabolite profiles, including those of genotoxic compounds, vary predictably throughout the cycle.
• Future studies on estrogen metabolism in premenopausal women must account for menstrual cycle phase.