Daily luteal serum and urinary hormone profiles in the menopause transition: Study of Women's Health Across the Nation.

Objective: To further characterize the endocrinology of the menopause transition, we sought to determine: whether relationships between urine and serum hormones are maintained as women enter their sixth decade; whether a single luteal phase serum progesterone (P) is reflective of integrated-luteal urinary pregnanediol glucuronide (uPdg); and whether serum P, like luteal uPdg, declines as women approach their final menses (FMP).
Methods: The Study of Women's Health Across the Nation (SWAN) Daily Hormone Study's (DHS) is a community-based observational study. A subset of participants underwent a timed, luteal blood draw planned for cycle days 16 to 24 during the same month of DHS collection. Serum-luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol and P, and urine LH, FSH, estrone conjugates (E1c), and daily and integrated luteal uPdg were measured in 268 samples from 170 women. Serum/urine hormone associations were determined using Pearson's correlation and linear regression, adjusted for concurrent age, body mass index, smoking status, and race/ethnicity.
Results: Pearson's r ranged from 0.573 (for LH) to 0.843 (for FSH) for serum/urine correlations. Integrated luteal uPdg weakly correlated with serum P (Pearson's r = 0.26, P = 0.004) and explained 7% of the variability in serum P in adjusted linear regression (total R 0.09, P = 0.002). Serum P demonstrated a marginally significant decline with approaching FMP in adjusted analysis (P = 0.04).
Conclusions: Urine and serum hormones maintain a close relationship in women into their sixth decade of life. Serum luteal P was weakly reflective of luteal Pdg excretion.