Objective: Whether serum androgen levels can identify women with "androgen insufficiency" or "androgen excess" is unresolved; thus, what constitutes "normal" remains uncertain. We sought to determine whether androgens, including 11-oxygenated C19 steroids, vary with age, menstrual cycle, or body mass index (BMI), during the reproductive years.
Design and setting: Cross-sectional study recruited from eastern Australian states.
Participants: A total of 588 women, aged 18 to 39 years, who were not pregnant, lactating, or using systemic hormone therapy, with regular menstrual cycles and no previous diagnosis of polycystic ovarian syndrome.
Main outcome measures: Sex steroids measured using liquid chromatography-tandem mass spectrometry.
Results: Testosterone and androstenedione concentrations were significantly higher during the menstrual cycle mid- and luteal phases than in the early follicular phase, with median values across the cycle of 0.34 nmol/L (range, 0.04 to 1.01) and 1.97 nmol/L (range, 0.53 to 7.89), respectively. No cyclical variations were found in dehydroepiandrosterone (DHEA; 4.91 nmol/L; range, 0.08 to 23.51), 11-ketoandrostenedione (11KA; 7.99 nmol/L; range, 0.07 to 31.67), or 11-ketotestosterone (11KT; 1.27 nmol/L; range, 0.03 to 7.61). Overweight women had lower median testosterone (P < 0.05), DHEA (P < 0.05), and 11KA (P < 0.01) levels than normal-weight women. All C19 steroids were significantly lower (P < 0.01) in those aged 35 to 39 years than in those aged 18 to 25 years. The median 11KA/androstenedione (4.3:1) and 11KT/testosterone (3.9:1) ratios did not change with age, after adjustment for BMI and cycle stage.
Conclusions: We have demonstrated that 11KA and 11KT are stable across the menstrual cycle and make major quantitative contributions to the circulating androgen pool. All C19 androgens declined with age before menopause; hence, age-specific reference ranges are required for the interpretation of androgen levels in premenopausal women.
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