Salivary testosterone across the menstrual cycle.

Area of Science:

• Reproductive Endocrinology
• Behavioral Neuroendocrinology
• Hormonal Physiology

Background:

• Testosterone production in women is hypothesized to fluctuate across the menstrual cycle, potentially impacting behavior.
• Testosterone is a precursor to estradiol, crucial for ovulation, but its peripheral exposure is not fully elucidated.
• Salivary testosterone is frequently used as a biomarker in behavioral studies, presumed to mirror serum levels.

Purpose of the Study:

• To investigate the temporal pattern of salivary testosterone across the menstrual cycle in women.
• To determine the extent of within-subject variability in testosterone levels during the ovulatory window and luteal phase.
• To assess the relationship between salivary testosterone and the ovulatory phase.

Main Methods:

• Salivary testosterone was measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
• Samples were collected from 339 women with confirmed ovulation (via LH tests) four times during the mid-cycle and luteal phases.
• Within-subject analyses were conducted to examine individual testosterone patterns across the cycle.

Main Results:

• Aggregate analysis revealed a statistically significant, albeit small, pattern of mid-cycle testosterone peak and luteal phase decrease.
• Individual-level analysis demonstrated considerable variability in both the direction and magnitude of testosterone fluctuations across the menstrual cycle.
• The study highlights inconsistencies between aggregate trends and individual hormonal profiles.

Conclusions:

• While a general mid-cycle testosterone peak exists in women, individual variations are substantial, complicating behavioral interpretations.
• Researchers should consider the high degree of individual variability when studying testosterone levels and behavior in women.
• Further research is needed to understand the physiological mechanisms driving individual differences in testosterone secretion and peripheral exposure.