Factors associated with serum levels of estradiol and sex hormone-binding globulin among premenopausal Japanese women.

Abstract

We measured serum levels of estadiol (E2) and sex mn e-binding globulin (SHBG) among 50 healthy premenopausal Japanese women in 1994 in Gif Japan, to iiwestigate the reltionships between potential risk factor for brenst sncer and hormone levels. Using a self-adminis- No subject had a history of diabetes or endocrine diseases and none had ever taken oral contraceptives. There were no current users of other types of hormonal medication. One women had used hormonal medication about 2 years before the study, but only for a few months.Two blood samples were drawn from each subject in the mornings of the 11th and 22nd days of her menstrual cycle. Day 1 of the menstrual cycle was defined as the day of onset of menstrual bleeding. After centrifugation, the serum was separated and stored at -80°C until assayed. Hormone assays were carried out in one batch in one laboratory. Serum levels of total E2 and SHBG were measured radioimmunologically with kits purchased from Diagnostic Products Corporation (Los Angeles, CA). The intra-assay coefficients of variation, based on control pools, were 9.8% for E2 and 5.3% for SHBG.Hormone concentration was log-transformed for statistical analysis to reduce departures from the normal distribution. To assess the association between the logarithm of E2 or SHBG level and the study variables, we calculated the Pearson correlation coefficients. The variables examined in this way were height, weight, body mass index [BMI; weight (kg)/height (mi2)], age at menarche, age at start of regular cycle, birth order, and ages at menarche and delivery for the subject's mother. Although we restricted the sampling days according to the menstrual cycle, higher plasma E2 levels were observed for women with shorter cycles. Therefore, adjustments for cycle length and age were performed by regressing the logarithms of hormones and study variables separately on these potential confounders. The correlation coefficients between the two sets of residuals were then calculated. The relationships between categorical variables [i.e., length of the menstrual cycle (<27, 28-29, 30, 31-35 days, and irregular), smoking status, and

Birthweight and Body Size throughout Life in Relation to Sex Hormones and Prolactin Concentrations in Premenopausal Women

“…We and numerous previous investigators (28,(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)42) observed a strong inverse association between SHBG and BMI in premenopausal women. Consistent with this finding, we also observed that free testosterone levels were higher among overweight and obese women compared with normal weight women.…”

“…Interestingly, we did not observe a similar association with free estradiol, likely due to the lower total estradiol levels in women with high BMI. Although several studies have examined the relationship between current BMI and premenopausal estrogens and androgens, the results are relatively inconsistent (28,(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)42). Possible reasons for this may be the small sample sizes (n < 110; refs.…”

“…31-35, 37, 39, 42) and not having collected samples timed in the menstrual cycle (30,33,35,36,40,42). Among six studies collecting timed follicular or luteal samples or conducting phase-specific analyses, four smaller studies (n = 28, 48, 50, and 107) reported no association with follicular or luteal estradiol, DHEAS, androstenedione, or testosterone (31,32,37,39). A fifth small study (n = 88) observed an inverse relationship between follicular estradiol and BMI (29).…”

“…However, few studies have looked at these factors in relation to mid-to late-premenopausal hormone levels. Some studies have examined the associations between childhood (24)(25)(26)(27) and adult (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41) body mass index (BMI) with premenopausal sex hormones, but the results have been inconsistent. This may be due to the small sample size of many studies and because blood samples were collected without regard to timing in the menstrual cycle in many studies, and although some studies accounted for this in the statistical analyses (30,40), others did not (33,35,36,42).…”

Association of Physical Activity with Reproductive Hormones: The Penn Ovarian Aging Study

“…It is also possible that the associations detected among the late transition period were due to chance. Physical activity has been shown to be inversely associated with estrogen levels among postmenopausal women in some (13,(28)(29)(30), but not all, observational studies (31)(32)(33). Six cross-sectional studies have examined the association of exercise and hormone levels within postmenopausal women (28)(29)(30)(31)(32)(33).…”