Evidence for diminished midcycle ovarian androgen production in older reproductive aged women

Abstract

To test the hypothesis that reproductive aging is associated with menstrual cycle-related decreases in androgen secretion. Comparison of cross-sectional data. University teaching hospital. Two groups of seven women were studied; midreproductive aged (19 to 37 years old) and older reproductive aged (43 to 47 years old). All patients were cycling regularly and had normal PRL and TSH. Patients underwent blood sampling during selected days of the menstrual cycle. After establishing the date of the midcycle surge, specimens were measured on selected days for androstenedione (A), total T, free T, and sex hormone-binding globulin (SHBG) using commercially available reagents. Sex hormone-binding concentrations did not vary across the menstrual cycle and did not differ between older and younger women. Total T did not differ significantly at any cycle stage between older and younger women. However, the midcycle rise in free T and A seen in younger women was consistently and significantly absent in the older women. In the absence of significant changes in SHBG associated with older reproductive age, the finding of diminished concentrations of both free T and A suggests that these hormones are produced in lesser quantity at midcycle in older women. Because the changes we noted depended on menstrual cycle stage, our findings suggest that an ovarian and not adrenal process is involved.