Urinary steroid profile in relation to the menstrual cycle

Area of Science:

• Sports Science
• Endocrinology
• Anti-Doping

Background:

• Steroid module interpretation in the Athlete Biological Passport (ABP) is complex in female athletes due to endogenous steroid variations.
• The menstrual cycle is a major confounding factor in analyzing steroid profiles, with unpredictable phase durations.

Purpose of the Study:

• To precisely determine menstrual phases (follicular, ovulatory, luteal) in female athletes.
• To assess the impact of menstrual cycle phases on urinary steroid concentrations relevant to the ABP.
• To identify reliable biomarkers for detecting testosterone doping in women.

Main Methods:

• Serum samples from 17 women were analyzed to determine menstrual cycle phases.
• Urinary steroid concentrations were measured three times weekly over two cycles.
• Statistical analysis was performed to evaluate steroid variations across menstrual phases.

Main Results:

• Epitestosterone (E) showed significant variation, being 133% higher during ovulation compared to the follicular phase.
• High coefficients of variation in steroid profiles were consistent between cycles for individual athletes.
• Inter-individual differences in the testosterone/epitestosterone (T/E) ratio ranged widely (11%-230%).

Conclusions:

• Epitestosterone and T/E ratios are problematic biomarkers for detecting doping in female athletes due to menstrual cycle influence.
• The timing of sample collection relative to the menstrual cycle significantly affects steroid profile interpretation.
• Additional biomarkers are necessary for accurate testosterone doping detection in women.