Metabolic clearance rates and interconversions of estrone and 17beta-estradiol in normal males and females

The continuous infusion of (3)H-6,7-estrone and (3)H-6,7-estradiol has been used to study the metabolic clearance rate (MCR), the interconversions, and the red cell uptake of these steroids in normal males and females. The whole blood MCR of estrone is 1,990 +/- 120 liters per day/m(2) (SE) in males and 1,910 +/- 100 liters per day/m(2) in females. The whole blood MCR of estradiol is 1,600 +/- 80 liters per day/m(2) in males and 1,360 +/- 40 liters per day/m(2) in females. The values in females do not vary significantly when studied in the follicular or luteal phase of the cycle. At least 35% of the total estrone metabolism in both sexes is extrasplanchnic and at least 25% of the total estradiol metabolism in males, and 15% in females is extrasplanchnic. The [rho](BB) (2,1) [transfer constant of estradiol to estrone, which is equivalent to the fraction of the precursor (estradiol) converted to the product (estrone) when both the infusion of the precursor and the measurement of the product are in peripheral blood] is 15%; and the [rho](BB) (1,2) [transfer constant of estrone to estradiol, which is equivalent to the fraction of the precursor (estrone) converted to product (estradiol) when both the infusion of the precusor and the measurement of the product are in peripheral blood] is 5% in both males and females. Our findings concerning the radioactivity in whole blood, as measured by our procedure, were the following: 15-20% of estrone in both sexes and 15% of estradiol in males is associated with red cells. Only 2% of the whole blood radioactivity of estradiol in females is associated with red cells. Changes in the distribution of radioactivity between plasma and red cells will influence the MCR as calculated from plasma, but not as calculated from whole blood.

Body mass index, serum sex hormones, and breast cancer risk in postmenopausal women

BACKGROUND

Obesity is associated with increased breast cancer risk among postmenopausal women. We examined whether this association could be explained by the relationship of body mass index (BMI) with serum sex hormone concentrations.

METHODS

We analyzed individual data from eight prospective studies of postmenopausal women. Data on BMI and prediagnostic estradiol levels were available for 624 case subjects and 1669 control subjects; data on the other sex hormones were available for fewer subjects. The relative risks (RRs) with 95% confidence intervals (CIs) of breast cancer associated with increasing BMI were estimated by conditional logistic regression on case-control sets, matched within each study for age and recruitment date, and adjusted for parity. All statistical tests were two-sided.

RESULTS

Breast cancer risk increased with increasing BMI (P(trend) =.002), and this increase in RR was substantially reduced by adjustment for serum estrogen concentrations. Adjusting for free estradiol reduced the RR for breast cancer associated with a 5 kg/m2 increase in BMI from 1.19 (95% CI = 1.05 to 1.34) to 1.02 (95% CI = 0.89 to 1.17). The increased risk was also substantially reduced after adjusting for other estrogens (total estradiol, non-sex hormone-binding globulin-bound estradiol, estrone, and estrone sulfate), and moderately reduced after adjusting for sex hormone-binding globulin, whereas adjustment for the androgens (androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and testosterone) had little effect on the excess risk.

CONCLUSION

The results are compatible with the hypothesis that the increase in breast cancer risk with increasing BMI among postmenopausal women is largely the result of the associated increase in estrogens, particularly bioavailable estradiol.

Sex hormone levels in premenopausal African-American women with upper and lower body fat phenotypes

Body fat distribution may be a better marker of a hormonal pattern associated with increased breast cancer risk than obesity. This cross-sectional study of 106 healthy premenopausal African-American (AA) women compared the midfollicular phase sex hormone and sex hormone-binding globulin levels in upper body fat (UBF) and lower body fat (LBF) phenotype and obese and nonobese women. Multivariate regression analyses were used to control for various confounders, including dietary factors. UBF phenotype women had 37% (P = 0.02), 50% (P = 0.01), 52% (P = 0.007), and 50% (P = 0.009) higher levels of estradiol (E2), free E2, testosterone (T), and free T, respectively, than LBF phenotype women. Only %free T was higher in obese than in nonobese women (P = 0.02). The levels of E2, free E2, %free E2, T, and free T were higher [by 42% (P = 0.01), 68% (P = 0.001), 18% (P = 0.04), 36% (P = 0.04), and 61% (P = 0.01), respectively] and the level of sex hormone-binding globulin was lower [by 28% (P = 0.04)] in obese UBF than in nonobese LBF phenotype women. These findings support the hypothesis that body fat distribution may be a better marker of a hormonal pattern associated with increased breast cancer risk than obesity. Obese UBF phenotype AA women, in particular, have a high-risk hormonal profile. Future breast cancer studies might consider controlling for measures of obesity and body fat distribution to minimize confounding.

Longitudinal study of hormone levels and depression among women transitioning through menopause

OBJECTIVE

To address the association between depression and absolute levels of estradiol, and change in estradiol, among women during the menopausal transition.

METHODS

This was a prospective, observational study conducted in Massachusetts, USA. Analyses reported here are based on the first three interviews following baseline (T1-T3). The participants were 309 women aged initially 43-53 years, who contributed a total of 728 observations (mean number of observations per subject 2.36). The main outcome measure was depression as measured by the Center for Epidemiologic Studies-Depression (CES-D) scale.

RESULTS

CES-D score was not significantly associated with menopause status categories, nor was it associated with annual change in estradiol level (E2) (p = 0.19). The unadjusted association between log E2 and CES-D was negative (odds ratio 0.69) and statistically significant (p = 0.03). Upon adjustment for symptoms, however, the association remained negative but was no longer statistically significant (p = 0.26). Hot flushes/night sweats were positively associated with CES-D (p = 0.04), and trouble sleeping was strongly positively related to CES-D (p < 0.001).

CONCLUSIONS

Results provide strong support for the domino or symptom hypothesis, which posits that depressed mood is caused by vasomotor symptoms associated with changing estrogen levels. Estradiol did not have a direct effect, independent of symptoms. This study adds to the body of literature suggesting that any association found between menopause and depression is most likely to be explained by other factors, such as symptoms and sleep problems. Findings also highlight the importance of studying the complex relationship between hormone levels, sleep problems and vasomotor symptoms during the menopausal transition.

Regulation of sex hormone-binding globulin secretion in human hepatoma G2 cells

Our purpose was to examine the roles of natural (estradiol (E2) and estrone (E1)) and synthetic estrogens (ethinyl estradiol (EE), moxestrol (MOX), and tamoxifene (TAM)) in regulating production of sex hormone-binding globulin (SHBG) by human hepatoma G2 (Hep G2) cells, the rationale being that synthetic estrogens are less rapidly metabolized than natural estrogens and, thus, may alter SHBG levels more readily. In Hep G2 cells, E2, E1, and EE at 10(-7) M did not result in significantly greater SHBG secretion compared to control cells. The synthetic estrogens, MOX and TAM, caused significant, P < 0.001, increases of 30% and 51% in SHBG secretion at 10(-7) M compared to controls. However, when TAM and E2 were added together, each at 10(-7) M, no increase in SHBG secretion was noted. We conclude that natural estrogens at physiologic concentrations do not increase SHBG secretion by Hep G2 cells, but the increase of SHBG secretion caused by MOX and TAM suggests that the lack of effect of E2 and E1 may, in part, be due to their rapid metabolism. In addition, TAM stimulates SHBG secretion by interaction with the genome that is different, in certain respects, from that of E2.

Metabolism of orally administered androstenedione in young men

Androstenedione is a steroid hormone and the major precursor to testosterone. It is available without prescription and taken with the expectation that it will be converted to testosterone endogenously and increase strength and athletic performance. The metabolism of orally administered testosterone has not been well studied. We randomly assigned 37 healthy men to receive 0, 100, or 300 mg oral androstenedione in a single daily dose for 7 d. Single 8-h urine collections were performed on the day before the start of the androstenedione administration and on d 1 and 7 to assess excretion rates of free and glucuronide- conjugated testosterone, androsterone, etiocholanolone, and dihydrotestosterone. Serum testosterone glucuronide concentrations were measured by frequent blood sampling over 8 h on d 1 in 16 subjects (5 each in the 0 and 100 mg group and 6 in the 300 mg group). In the control group, mean (+/-SE) d 1 and 7 excretion rates for testosterone, androsterone, etiocholanolone, and dihydrotestosterone were 3 +/- 1, 215 +/- 26, 175 +/- 26, and 0.4 +/- 0.1 microg/h, respectively. In the 100 mg group, mean d 1 and 7 excretion rates for testosterone, androsterone, etiocholanolone, and dihydrotestosterone were 47 +/- 11, 3,836 +/- 458, 4,306 +/- 458, and 1.6 +/- 0.2 microg/h, respectively. In the 300 mg group, mean d 1 and 7 excretion rates for testosterone, androsterone, etiocholanolone, and dihydrotestosterone were 115 +/- 39, 8,142 +/- 1,362, 10,070 +/- 1,999, and 7.7 +/- 1.5 microg/h, respectively. Urinary excretion rates of all metabolites were greater in both the 100 and 300 mg groups than in controls (P < 0.0001). Urinary excretion rates of testosterone (P = 0.007), androsterone (P = 0.009), etiocholanolone (P = 0.0005), and dihydrotestosterone (P < 0.0001) were greater in the subjects who received 300 mg androstenedione than in those who received 100 mg. In the treated groups, excretion of free testosterone accounted for less than 0.1% of the total excreted testosterone measured. Serum testosterone glucuronide levels increased significantly during frequent blood sampling in both the 100 and 300 mg groups compared with controls (P = 0.0005 for the 100 mg group; P < 0.0001 for the 300 mg group). The net mean changes in area under the curve for serum testosterone glucuronide were -18 +/- 25%, 579 +/- 572%, and 1267 +/- 1675% in the groups receiving 0, 100, and 300 mg/d androstenedione, respectively. We conclude that the administration of both 100 and 300 mg androstenedione increases the excretion rates of conjugated testosterone, androsterone, etiocholanolone, and dihydrotestosterone and the serum levels of testosterone glucuronide in men. The magnitude of these increases is much greater than the changes observed in serum total testosterone concentrations. These findings demonstrate that orally administered androstenedione is largely metabolized to testosterone glucuronide and other androgen metabolites before release into the general circulation.

Are serum hormones associated with the risk of prostate cancer? Prospective results from the Massachusetts Male Aging Study

OBJECTIVES

To determine whether prediagnostic serum hormones are predictive of prostate cancer risk in a sample of men 40 to 70 years old at baseline.

METHODS

Seventeen serum hormones, including androgens, estrogens, and adrenal and pituitary hormones, were measured at baseline (1987 to 1989) and used to predict incident prostate cancer by follow-up (1995 to 1997) using data from the Massachusetts Male Aging Study, a prospective, population-based random sample.

RESULTS

Seventy men (4%) of 1576 were diagnosed with prostate cancer between the baseline and follow-up periods (approximately 8 years). None of the hormones were associated with prostate cancer risk except for androstanediol glucuronide (AAG), which exhibited a nonlinear, inverse relationship with prostate cancer (P <0.003) when age, body mass index, alcohol use, dihydrotestosterone, and total prostate-specific antigen were controlled for. Men in the second, third, and fourth quartiles of AAG relative to the first were less likely to be diagnosed with prostate cancer, although only the comparison of the second versus the first achieved statistical significance (odds ratio 0.2, 99% confidence interval 0.04 to 0.6). No dose-response relationships were observed.

CONCLUSIONS

The lack of association with most hormones and the nonlinear association with AAG calls into question whether serum hormones collected during midlife are risk factors for prostate cancer.

Sources of elevated serum androgens in postmenopausal women who develop breast cancer

Postmenopausal women with elevated serum androgens are at an increased risk of breast cancer. High dehydroepiandrosterone sulfate concentrations in these women suggest increased adrenal secretion. Both the adrenals and ovaries could contribute to elevated concentrations of androstenedione (Delta4A). 11beta-Hydroxyandrostenedione (11betaOHA) is elevated, and the Delta4A:11betaOHA ratio is depressed when the adrenals are the primary source of elevated Delta4A in women. Conversely, Delta4A:11betaOHA is elevated when the ovaries are the primary source. We prospectively evaluated associations of serum 11betaOHA and Delta4A:11betaOHA with breast cancer in the Columbia, Missouri Serum Bank to identify the source of elevated Delta4A related to risk. Fifty-three postmenopausal women who were not taking estrogens when they donated blood and were diagnosed with breast cancer up to 10 years later (median, 2.9 years) served as cases. Two controls, who were also postmenopausal and not taking estrogens, were matched to each case on age, date, and time of blood collection. Serum Delta4A concentration was significantly (trend P = 0.02) positively associated with breast cancer risk. Adjusted risk ratios for women in the lowest to highest tertiles were 1.0, 1.6, and 2.4 [95% confidence interval (CI), 0.9-6.5]. However, neither 11betaOHA concentration nor Delta4A:11betaOHA was related to risk. Comparable risk ratios were 1.0, 1.2, and 1.4 (95% CI, 0.5-3.6) for 11betaOHA and 1.0, 1.2, and 1.2 (95% CI, 0.4-3.5) for Delta4A:11betaOHA. Our results suggest that neither the ovaries nor adrenals are the predominant source of elevated serum Delta4A in postmenopausal women who develop breast cancer, but rather both may contribute.

Macronutrient intake and estrogen metabolism in healthy postmenopausal women

The purpose of this study was to determine if dietary factors could bias estimates of the relationships between estrogen metabolites and breast cancer risk factors. A lower ratio of urinary 2-hydroxyestrone/16alpha-hydroxyestrone (2/16) has been associated with breast cancer diagnosis. However, both estrogen metabolism and breast cancer risk have been associated with dietary intake, and breast cancer patients may have different dietary patterns than healthy controls. An association between urinary 2/16 levels and breast cancer risk may be due to transitory dietary change after diagnosis, or due to other breast cancer risk factors which have been associated to steroid hormone metabolism. Thirty-seven healthy postmenopausal women provided two 24-h urine samples at a two-week interval. Six 24-h diet recalls were administered in this same time period. In linear regression analysis, dietary fat-to-fiber ratio (fat/fiber) and the saturated fat/soluble fiber ratio was inversely associated with urinary 2/16 values (b = -0.22, 95% CI (-0.43, -0.01); b= -0.26, 95% CI (-0.43, -0.09), respectively). The effects of these dietary factors on 2/16 were independent of body mass index or other breast cancer risk factors. These study results suggest that some of the variation in estrogen metabolite levels among postmenopausal Caucasian women may be due to dietary intake, and that dietary factors should be carefully measured and evaluated when investigating the relationship between estrogen metabolites and breast cancer risk.

Endocrine function of the postmenopausal ovary

The ovaries of postmenopausal women are smaller than those of premenopausal women and consist primarily of stromal cells. These cells have receptors for, and respond to, gonadotropins and secrete testosterone and lesser amounts of other androgens and estrogens. The ovaries of some postmenopausal women contain P-450 aromatase and secrete estradiol. There is little evidence that inhibins A or B are secreted by postmenopausal ovaries.

Low dehydroepiandrosterone and ischemic heart disease in middle-aged men: prospective results from the Massachusetts Male Aging Study

The adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) have been characterized as "protective" against ischemic heart disease (IHD), especially in men, on the basis of sparse epidemiologic evidence. The authors used data from the Massachusetts Male Aging Study, a random sample prospective study of 1,709 men aged 40-70 years at baseline, to test whether serum levels of DHEA or DHEAS could predict incident IHD over a 9-year interval. At baseline (1987-1989) and follow-up (1995-1997), an interviewer-phlebotomist visited each subject in his home to obtain comprehensive health information, body measurements, and blood samples for hormone and lipid analysis. Incident IHD between baseline and follow-up was ascertained from hospital records and death registries, supplemented by self-report and evidence of medication. In the analysis sample of 1,167 men, those with serum DHEAS in the lowest quartile at baseline (<1.6 microg/ml) were significantly more likely to incur IHD by follow-up (adjusted odds ratio = 1.60, 95 percent confidence interval: 1.07, 2.39; p = 0.02), independently of a comprehensive set of known risk factors including age, obesity, diabetes, hypertension, smoking, serum lipids, alcohol intake, and physical activity. Low serum DHEA was similarly predictive. These results confirm prior evidence that low DHEA and DHEAS can predict IHD in men.

Is there an association between menopause status and sexual functioning?

OBJECTIVE

The purpose of this study was to address whether: (1) there is an association between menopause status and various aspects of sexual functioning, and (2) the relative contributions of menopause status and other variables to various aspects of sexual functioning.

DESIGN

Analyses are based on 200 women from the Massachusetts Women's Health Study II, a population-based sample of women transitioning through the menopause who were not HRT users, who had not had a surgical menopause, and who had partners. The women were classified as pre-, peri-, or postmenopausal according to menstrual cycle characteristics. Estradiol, estrone, and follicle-stimulating hormone were also measured. Sexual functioning was measured in terms of satisfaction, desire, frequency of sexual intercourse, belief that interest declines with age, arousal compared with a younger age, difficulty reaching orgasm, and pain. Predictor variables included sociodemographics, health, vasomotor symptoms, psychological variables, partner variables, and lifestyle behaviors.

RESULTS

Menopause status was significantly related to lower sexual desire, a belief that interest in sexual activity declines with age, and women's reports of decreased arousal compared with when in their 40s. Menopause status was unrelated to other aspects of sexual functioning in either unadjusted or multiple regression analyses. In analyses in which log estradiol (E2) was included in addition to menopause status, log E2 was only related to pain. In multiple regression analyses, other factors such as health, marital status (or new partner), mental health, and smoking had a greater impact on women's sexual functioning than menopause status.

CONCLUSIONS

Menopause status, but not E2, is related to some, but not all, aspects of sexual functioning. This may be due to menopause per se or other factors associated with menopause and aging (e.g., increased sexual dysfunction among aging men). Menopause status has a smaller impact on sexual functioning than health or other factors.

Brassica vegetable consumption shifts estrogen metabolism in healthy postmenopausal women

Previous studies suggest that the estrogen metabolite 16alpha-hydroxyestrone acts as a breast tumor promoter. The alternative product of estrogen metabolism, 2-hydroxyestrone, does not exhibit estrogenic properties in breast tissue, and lower values of the ratio 2-hydroxyestrone:16alpha-hydroxyestrone (2:16) in urine may be an endocrine biomarker for greater breast cancer risk. Vegetables of the Brassica genus, such as broccoli, contain a phytochemical, which may shift estrogen metabolism and increase the 2:16 ratio. Adding 500 g/day of broccoli to a standard diet shifts 2:16 values upward in humans; however, it is unknown as to whether healthy women are able to consume a sufficient quantity of Brassica to affect breast cancer risk through this mechanism. In this study, 34 healthy postmenopausal women participated in an intensive intervention designed to facilitate the addition of Brassica to the daily diet. The diet was measured by repeated 24-h recall, and estrogen metabolites were measured by enzyme immunoassay in 24-h urine samples. In a crude analysis, there was a nonsignificant increase in the urinary 2:16 ratio associated with greater Brassica consumption. With adjustment for other dietary parameters, Brassica vegetable consumption was associated with a statistically significant increase in 2:16 values, such that for each 10-g/day increase in Brassica consumption, there was an increase in the 2:16 ratio of 0.08 (95% confidence interval, 0.02-0.15). To the extent that the 2:16 ratio, as measured in urine, is associated with breast cancer risk, future research should consider Brassica vegetable consumption as a potentially effective and acceptable dietary strategy to prevent breast cancer.

Oral androstenedione administration and serum testosterone concentrations in young men

CONTEXT

Androstenedione, a steroid hormone and the major precursor to testosterone, is available without prescription and is purported to increase strength and athletic performance. The hormonal effects of androstenedione, however, are unknown.

OBJECTIVE

To determine if oral administration of androstenedione increases serum testosterone levels in healthy men.

DESIGN

Open-label randomized controlled trial conducted between October 1998 and April 1999.

SETTING

General clinical research center of a tertiary-care, university-affiliated hospital.

PARTICIPANTS

Forty-two healthy men aged 20 to 40 years.

INTERVENTION

Subjects were randomized to receive oral androstenedione (either 100 mg/d [n = 15] or 300 mg/d [n = 14]) or no androstenedione (n = 13) for 7 days.

MAIN OUTCOME MEASURES

Changes in serum testosterone, androstenedione, estrone, and estradiol levels, measured by frequent blood sampling, compared among the 3 treatment groups.

RESULTS

Mean (SE) changes in the area under the curve (AUC) for serum testosterone concentrations were -2% (7%), -4% (4%), and 34% (14%) in the groups receiving 0, 100, and 300 mg/d of androstenedione, respectively. When compared with the control group, the change in testosterone AUC was significant for the 300-mg/d group (P<.001) but not for the 100-mg/d group (P = .48). Baseline testosterone levels, drawn 24 hours after androstenedione administration, did not change. Mean (SE) changes in the AUC for serum estradiol concentrations were 4% (6%), 42% (12%), and 128% (24%) in the groups receiving 0, 100, and 300 mg/d of androstenedione, respectively. When compared with the control group, the change in the estradiol AUC was significant for both the 300-mg/d (P<.001) and 100-mg/d (P = .002) groups. There was marked variability in individual responses for all measured sex steroids.

CONCLUSIONS

Our data suggest that oral androstenedione, when given in dosages of 300 mg/d, increases serum testosterone and estradiol concentrations in some healthy men.

Diet and sex hormone-binding globulin

The serum concentration of sex hormone-binding globulin (SHBG) is inversely related to weight and in animal studies is inversely related to protein intake. As SHBG can affect the biological activity of testosterone and estradiol, we wished to determine the role of protein intake on SHBG levels in men. Using data from the Massachusetts Male Aging Study we examined cross-sectional relationships between dietary components and SHBG levels in 1552 men (aged 40-70 yr) for whom these factors were known. Analyzed by multiple regression, controlling for testosterone and estradiol levels, age (P<0.001) and fiber intake (P = 0.02) were positively correlated to SHBG concentration, whereas body mass index (P<0.001) and protein intake (P<0.03) were negatively correlated to SHBG concentration. The intakes of calories, fat (animal or vegetable), and carbohydrate were not related to SHBG concentration. We conclude that age and body mass index are major determinants of SHBG concentrations in older men, and fiber and protein intake are also significant contributors to SHBG levels, but total caloric intake and the intake of carbohydrate or fat are not significant. Thus, diets low in protein in elderly men may lead to elevated SHBG levels and decreased testosterone bioactivity. The decrease in bioavailable testosterone can then result in declines in sexual function and muscle and red cell mass, and contribute to the loss of bone density.

Plasma steroid hormones, surgery for benign prostatic hyperplasia, and severe lower urinary tract symptoms

Because benign prostatic hyperplasia (BPH) may be influenced by plasma steroid hormones, we examined their relation in the Health Professionals Follow-up Study. In 1993-1995, 18,000 cohort members provided blood. We selected as cases men who had had surgery for BPH (n=174) or who scored 20-35 points (n=126) on the American Urological Association index of severity of lower urinary tract symptoms. Cases were matched by age to men who scored</=3 points and without an enlarged prostate or elevated prostate-specific antigen. We estimated the odds ratio (OR) of BPH surgery and severe lower urinary tract symptoms for plasma testosterone (T), dihydrotestosterone (DHT), androstanediol glucuronide (AAG), estradiol (E2), and sex hormone binding globulin (SHBG) in multivariable conditional logistic regression models. Compared to the lowest tertiles, men in the middle (OR=1.42) and top (OR=1.78) tertiles of AAG were at increased risk for having either BPH surgery or severe lower urinary tract symptoms (P-trend=0.02). Men in the middle (OR=0.58) and top (OR=0.60) tertiles of E2 were at lower risk. T level was unrelated to surgery and symptoms. Our findings support opposing roles for DHT, reflected by its metabolite AAG, and E2 in the etiology of BPH.

Evidence that the CAG repeat in the androgen receptor gene is associated with the age-related decline in serum androgen levels in men

In men over 30 years old, serum levels of testosterone (T) decrease with age. A shorter polymorphic CAG repeat length in exon 1 of the androgen receptor (AR) gene is associated with higher transcription activation by the AR. We determined the number of CAG repeats for 882 men aged between 40 and 70 years from the Massachusetts Male Aging Study (MMAS). MMAS is a population-based random sample survey of men for whom baseline (1987-1989, mean age 53+/-8 years) and follow-up (1995-1997, mean age 61+/-8 years) serum hormone levels were available. Multiple linear regression was used to determine if CAG repeat length would be predictive of hormone levels at follow-up. Hormone levels measured included T, free T, albumin-bound T, dihydrotestosterone (DHT), sex hormone-binding globulin (SHBG) and luteinizing hormone (LH). The CAG repeat length was significantly associated with T (P=0.041), albumin-bound T (P=0.025) and free T (P=0.003) when controlled for age, baseline hormone levels and anthropometrics. Follow-up levels of T decreased by 0.74%+/-0.36 per CAG repeat decrement. Likewise, the percentages of free and albumin-bound T decreased by 0.93%+/-0.31 and 0.71%+/-0.32 per CAG repeat decrement respectively. These results suggest that androgen levels may be modulated by AR genotype.

Plasma prolactin levels and subsequent risk of breast cancer in postmenopausal women

BACKGROUND

In animal studies, prolactin has been found to be important for mammary epithelial development and its administration has been shown consistently to increase the rate of mammary tumor formation. Previous epidemiologic studies of prolactin and breast cancer risk in postmenopausal women have been limited in size, and the results have been inconsistent. We conducted a nested case-control study within the prospective Nurses' Health Study cohort to better determine the relationship between plasma prolactin levels and postmenopausal breast cancer risk.

METHODS

Blood samples were collected from cohort members during the period from 1989 through 1990. Prolactin levels were measured by use of a microparticle enzyme immunoassay. Included in this analysis were 306 postmenopausal women who were diagnosed with breast cancer after blood donation but before June 1994. One or two postmenopausal control subjects were matched per case subject on the basis of age, postmenopausal hormone use, and time of day and month of blood collection; the study included a total of 448 control subjects.

RESULTS

In conditional logistic regression analyses, a significant positive association was observed between plasma level of prolactin and postmenopausal breast cancer risk (highest versus lowest quartile, multivariate relative risk = 2.03; 95% confidence interval = 1.24-3.31; two-sided P for trend = .01). The relationship was independent of plasma sex steroid hormone levels and was similar after excluding case subjects diagnosed in the first 2 years after blood collection.

CONCLUSIONS

These prospective data suggest that higher plasma prolactin levels are associated with an increased risk of breast cancer in postmenopausal women.

Relation of dehydroepiandrosterone and dehydroepiandrosterone sulfate with cardiovascular disease risk factors in women: longitudinal results from the Massachusetts Women's Health Study

Low circulating levels of the adrenal steroids dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) are thought to be associated with increased risk of cardiovascular disease (CVD) in men. In women, either a positive or null association with CVD has been found. The nature of the relation between DHEAS and CVD risk factors in women is unclear and is based on cross-sectional data. We present results from a longitudinal investigation of serum DHEA and DHEAS and cardiovascular disease risk factors in 236 women, initially 50-60 years old, from a population-based prospective (1986-1995) study of the menopausal transition. We used generalized estimating equations to model the relation of serum DHEA and DHEAS to systolic and diastolic blood pressure and serum levels of total cholesterol, high density lipoprotein cholesterol, and apolipoproteins A and B, adjusting for other factors related to CVD. Both DHEA and DHEAS were positively related to diastolic and systolic blood pressure, and DHEAS was negatively related to apolipoprotein A. DHEA and DHEAS were also positively related to smoking, alcohol use, estrone, and estradiol levels, and inversely related to age. Our results suggest that higher levels of DHEA and DHEAS in middle-aged women may indicate increased CVD risk.

Androgen metabolism and the menopause

The concentration of androgens in the blood peaks in early adulthood. While the concentrations of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) decline steadily, the concentrations of androstenedione (A) and testosterone (T) decline just before or at the menopause. DHEAS is bound strongly to albumin, resulting in a very low metabolic clearance rate (MCR) of about 12 L/day. DHEA and A are bound weakly to albumin and their MCRs are 1800 to 2000 L/day. T is bound strongly to sex hormone-binding globulin (SHBG), and the MCR of T is about 500 L/day. There are no significant changes in the MCRs at the menopause or with age. The pathways of metabolism are not altered at the menopause but aromatization of DHEA, A, and T to estrone and estradiol all increase with age. Thus, androgen metabolism in general is affected more by age than by the menopause itself.

Changes in reproductive hormones and sex hormone-binding globulin in a group of postmenopausal women measured over 10 years

OBJECTIVE

As part of a study on hormones and bone density in older women, we measured a number of steroid and polypeptide hormones at 4- to 6-month intervals in 32 women over a 10-year period.

DESIGN

All women were postmenopausal during this time and all measurements from 12 months after the menopause to the end were used in the analysis. To determine whether there was a significant trend in steroid or polypeptide hormones over the years, the data were analyzed by random coefficient linear regression against number of months since menopause.

RESULTS

There was no significant trend in the concentrations of estrone, estrone sulfate, dehydroepiandrosterone, and follicle stimulating hormone. There was a significant decline in the concentrations of estradiol, dihydrotestosterone, dehydroepiandrosterone sulfate, and luteinizing hormone. There was a rise in the levels of androstenedione and testosterone.

CONCLUSIONS

The changes in the concentration of sex hormone-binding globulin could be fitted to a quadratic equation with an initial rise in the concentration followed by a decline. Thus, the trend in hormone concentrations shows no set pattern with aging in the postmenopausal years.

Dehydroepiandrosterone sulfate does not prevent spontaneous and iodine-induced lymphocytic thyroiditis and diabetes mellitus in the BB/Wor rat

Chronic feeding of dehydroepiandrosterone (DHEA) and its sulfated metabolite, dehydroepiandrosterone sulfate (DHEAS), has previously been reported to decrease hyperglycemia, obesity, cancer, and autoantibody generation in a number of animal models and to increase muscle mass and physiological and psychological well-being in elderly humans, although these latter studies remain controversial. The present study was carried out to determine whether large amounts of DHEAS given orally would prevent the occurrence of spontaneous and iodine-induced autoimmune lymphocytic thyroiditis (LT) and/or spontaneous insulin-dependent diabetes mellitus (DM) in male and female BB/Wor rats. DHEAS was administered by gavage (44 mg/rat/day) or in the chow (133 mg/rat/day) to LT- and DM-prone rats from 30 to 120 days of life; some of these rats also received iodine in the drinking water to enhance the incidence and intensity of LT. Onset of DM requiring protamine zinc insulin and its maintenance dose were assessed. Rats were killed at 90 or 120 days of age and blood, thyroid, adrenals, pancreases, testes, and ovaries were removed. Serum glucose, DHEA, DHEAS, thyroxine (T4), tri-iodothyronine (T3) and thyrotropin (TSH) concentrations were measured in all rats in both experiments. Serum DHEAS concentrations were 10-fold higher in the rats given the steroid by gavage or in the diet compared with levels in control rats. DHEAS administered over a prolonged period of time had no significant effect on body weight, incidence and severity of DM, incidence and intensity of spontaneous and iodine-induced LT, and thyroid, pancreas and testes weights but did significantly decrease adrenal and ovarian weights. Serum T4, T3, and TSH concentrations were similar in control and DHEAS-treated rats. In conclusion, DHEAS did not prevent the occurrence of iodine-induced or spontaneous autoimmune LT or spontaneous DM in the BB/Wor rat, at variance with its reported immunosuppressive effects in other animal models.

Can Follicle-Stimulating Hormone be used to Define Menopausal Status?

OBJECTIVE

To assess the ability of the level of follicle-stimulating hormone (FSH) to distinguish among premenopausal, perimenopausal, and postmenopausal women.

METHODS

We examined cross-sectional and longitudinal data from the second phase of the Massachusetts Women's Health Study (1986 to 1995), a population-based cohort of 427 premenopausal and perimenopausal women identified from the first phase of the Massachusetts Women's Health Study (1981 to 1986).

RESULTS

Boxplots of FSH levels throughout the menopausal transition displayed considerable overlap. Logistic regressions and their resulting receiver operating characteristic curves further demonstrated that, although FSH is a statistically significant predictor of menopausal status, no single value of FSH is expedient for distinguishing premenopausal from perimenopausal or perimenopausal from postmenopausal women.

CONCLUSION

FSH alone is not an effective predictor of transition into the perimenopausal or postmenopausal period. Specifically, the frequently recommended FSH cutoff of 40 IU/L is inappropriate by itself for clinical determination of postmenopausal status.

Low dehydroepiandrosterone sulfate and heart disease in middle-aged men: cross-sectional results from the Massachusetts Male Aging Study

PURPOSE

Serum concentrations of the adrenal androgen dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS), both of which decline with age more markedly than other sex hormone levels, have been alternately credited and discredited as "protective" correlates of heart disease. Baseline data from the Massachusetts Male Aging Study (MMAS), collected in 1987-89, provided a large population-based random sample (n = 1709) in which to examine cross-sectionally the relation of DHEA and DHEAS levels to heart disease, while controlling for a comprehensive set of potential confounders including serum lipid and hormone levels as well as smoking, alcohol intake, obesity, hypertension, diabetes, diet, medication, physical activity, and psychological measures.

METHODS

The subjects were men aged 40-70 years, randomly sampled from the Massachusetts state census listing, measured and interviewed at home. Nonfasting blood samples were assayed for hormones and lipids.

RESULTS

In all strata of age, smoking, and alcohol intake, the age-adjusted odds ratio for self-reported heart disease was between 0.55 and 0.85 per standard deviation (SD) of log DHEA and DHEAS concentration. Multiple logistic regression analysis indicated a strong independent role for DHEAS as a predictor of self-reported heart disease, controlling for age and the potential confounders listed above. The multiply-adjusted odds ratio for heart disease was 0.64 per SD log DHEAS concentration, with 95% confidence interval (CI) 0.50-0.83 (P = 0.0002). The DHEAS effect was not diminished by controlling for use of cardiac, vasodilator, antihypertensive, or lipid-lowering medication.

CONCLUSIONS

These findings suggest that serum DHEAS levels bear an inverse relationship to heart disease, independently of a large set of established cardiovascular risk factors. The cross-sectional nature of this study requires that the findings be interpreted with caution.

Sex steroids and bone mass in older men. Positive associations with serum estrogens and negative associations with androgens

The purpose of this study was to determine whether bone density in older men was associated with serum sex steroids or sex hormone binding globulin (SHBG). Bone density and sex steroids were measured in men over age 65 at 6-mo intervals for an average of 2.1 yr. Bone density was significantly positively associated with greater serum E2 concentrations (+0.21 < r < +0.35; 0.01 < P < 0.05) at all skeletal sites. There were weak negative correlations between serum testosterone and bone density (-0.20 < r < -0.28; 0.03 < P < 0.10) at the spine and hip. SHBG was negatively associated only with bone density in the greater trochanter (r = -0.26, P < 0.05). Greater body weight was associated with lower serum testosterone and SHBG, and greater E2. Because of these associations, regression models which adjusted for age, body weight, and serum sex steroids were constructed; these accounted for 10-30% of the variability in bone density, and showed consistent, significant positive associations between bone density and serum E2 concentrations in men, even after adjustments for weight and SHBG. These data suggest that estrogens may play an important role in the development or maintenance of the male skeleton, much as is the case for the female skeleton. These data also indicate that, within the normal range, lower serum testosterone concentrations are not associated with low bone density in men.

Assay reproducibility of hormone measurements in postmenopausal women

As part of a breast cancer case-control study of serum hormones conducted in Columbia, MO, we included several replicate quality control samples to monitor the consistency of laboratory assays. Sera were obtained from three postmenopausal women; from each woman, three samples were placed randomly in each of nine batches with the laboratory unaware of which sample corresponded to whom. Laboratory assays for estrone (E1), estradiol (E2), testosterone, androstenedione (Adione), E1SO4, dehydroepiandrosterone sulfate (DHEAS), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), and percentages of free and albumin-bound E2 were done at a single academic facility. ANOVA results showed that hormone values varied considerably from one batch to the next. The overall coefficients of variation (CVs) estimated for E2, percentage of unbound E2, and percentage of albumin-bound E2 were higher than 15%, but of these, only percentage of unbound E2 had both inter- and intra-assay CVs greater than 10%. Intraclass correlations (ICC) for FSH, SHBG, and DHEAS were high, suggesting that these assays are suitable for population-based studies attempting to link hormone levels to disease risk. The ICC estimated for E1SO4 was quite low due to aberrant values reported in a single batch. For the remaining hormones, the ICCs were fair (ranging from 47% for albumin-bound E2 to 67% for Adione), and studies using these assays would require a substantial increase in the sample size to detect small case-control differences.

Serum sex hormone levels are related to breast cancer risk in postmenopausal women

We conducted a nested case-control study to prospectively evaluate the relationship of serum estrogens and androgens to risk of breast cancer in postmenopausal women. From 1977 to 1987, 3375 postmenopausal women free of cancer and not taking replacement estrogens donated blood to the Breast Cancer Serum Bank in Columbia, Missouri. Of these, 72 were subsequently diagnosed with breast cancer. For each case, two controls matched on age and date and time of day of blood collection were selected using incidence density matching. The median age of subjects at blood collection was 62 years; the time from blood collection to diagnosis ranged from less than 1 to 9.5 years with a median of 2.9 years. Risk of breast cancer was positively and significantly associated with serum levels of estrogens and androgens. Compared to women in the lowest quartile, those in the highest quartile for non-sex hormone-binding globulin (non-SHBG) bound (bioavailable) estradiol had a relative risk of 5.2 (95% confidence interval [CI] = 1.5-18.5) and those in the highest quartile for testosterone had a relative risk of 6.2 (95% CI = 2.0-19.0). Our results lend considerable support to the hypothesis that serum concentrations of estrogens and androgens are related to the subsequent diagnosis of breast cancer in postmenopausal women.

Relationship of serum dehydroepiandrosterone (DHEA), DHEA sulfate, and 5-androstene-3 beta, 17 beta-diol to risk of breast cancer in postmenopausal women

Laboratory evidence suggests a role for dehydroepiandrosterone (DHEA) and its metabolite 5-androstene-3 beta, 17 beta-diol (ADIOL) in mammary tumor growth. Serum DHEA also has been related to breast cancer in postmenopausal women, but the relationship of ADIOL to risk has not been evaluated previously. To assess the relationship of serum DHEA, its sulfate (DHEAS), and ADIOL with breast cancer risk in postmenopausal women, we conducted a prospective nested case-control study using serum from the Columbia, MO Breast Cancer Serum Bank. Cases included 71 healthy postmenopausal volunteers not taking replacement estrogens when they donated blood and who were diagnosed with breast cancer up to 10 years later (median, 2.9 years). Two randomly selected controls, who also were postmenopausal and not taking estrogens, were matched to each case on exact age, date (+/-1 year), and time (+/-2 h) of blood collection. Significant (trend P = 0.02) gradients of increasing risk of breast cancer were observed for increasing concentrations of DHEA and ADIOL, and women whose serum levels of these hormones were in the highest quartiles were at a significantly elevated risk compared to those in the lowest; their risk ratios were 4.0 [95% confidence interval (CI), 1.3-11.8) and 3.0 (95% CI, 1.0-8.6), respectively. The relationship of DHEAS to breast cancer was less consistent, but women whose serum DHEAS concentration was in the highest quartile also exhibited a significantly elevated risk ratio of 2.8 (95% CI, 1.1-7.4). Results of this prospective study support a role for the adrenal androgens, DHEA, DHEAS, and ADIOL, in the etiology of breast cancer.

Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study

We conducted a controlled feeding study to evaluate the effects of fat and fiber consumption on plasma and urine sex hormones in men. The study had a crossover design and included 43 healthy men aged 19-56 y. Men were initially randomly assigned to either a low-fat, high-fiber or high-fat, low-fiber diet for 10 wk and after a 2-wk washout period crossed over to the other diet. The energy content of diets was varied to maintain constant body weight but averaged approximately 13.3 MJ (3170 kcal)/d on both diets. The low-fat diet provided 18.8% of energy from fat with a ratio of polyunsaturated to saturated fat (P:S) of 1.3, whereas the high-fat diet provided 41.0% of energy from fat with a P:S of 0.6. Total dietary fiber consumption from the low- and high-fat diets averaged 4.6 and 2.0 g.MJ-1.d-1, respectively. Mean plasma concentrations of total and sex-hormone-binding-globulin (SHBG)-bound testosterone were 13% and 15% higher, respectively, on the high-fat, low-fiber diet and the difference from the low-fat, high-fiber diet was significant for the SHBG-bound fraction (P = 0.04). Men's daily urinary excretion of testosterone also was 13% higher with the high-fat, low-fiber diet than with the low-fat, high-fiber diet (P = 0.01). Conversely, their urinary excretion of estradiol and estrone and their 2-hydroxy metabolites were 12-28% lower with the high-fat, low-fiber diet (P < or = 0.01). Results of this study suggest that diet may alter endogenous sex hormone metabolism in men.

Analysis of differential gene regulation in adequate versus inadequate secretory-phase endometrial complementary deoxyribonucleic acid populations from the rhesus monkey

The ability to create artificial menstrual cycles in the rhesus monkey provides a model for studies on the regulation of genes and gene networks by estradiol or progesterone (P) in the primate endometrium. This model allowed us to create both a normal level of secretory phase P or an inadequate level of secretory phase P, i.e. endometria that cannot support implantation. The objective of our present study focused on PCR analyses of genes for several factors that are believed to be important in the proper maturation of the endometrium. Complementary DNA (cDNA) populations were prepared from endometria harvested on day 13 (peak E level), days 21-23 of an adequate secretory phase (PcDNA) and days 21-23 of an inadequate secretory phase (IcDNA). Although placental protein 14, leukemia inhibitory factor and 17-beta hydroxysteroid dehydrogenase displayed highly upregulated levels in PcDNA (P-activated genes), there was little or no up-regulation in IcDNA. Transforming growth factor-beta 2 and its receptor and insulin growth factor-I and its receptor were up-regulated in PcDNA, whereas little or no expression was observed in IcDNA. Regulators of the cell cycle and transcription, such as retinoblastoma, c-fos, and c-jun genes, were also greatly underexpressed in IcDNA compared with PcDNA. Interestingly, one gene that we studied, keratinocyte growth factor, that was up-regulated by P (peak E levels vs. PcDNA) was more highly expressed in IcDNA. This latter result suggests that low levels of circulating P are sufficient for expression of this gene, whereas high sustained P levels result in an autologous down-regulation. These data show that the regulation of genes that may play pivotal roles in endometrial maturation are differentially expressed in IcDNA vs. PcDNA and may, in part, characterize improper endometrial maturation.

Hormone levels during dietary changes in premenopausal African-American women

BACKGROUND

In the United States, 5-year survival rates of 69% and 84%, respectively, have recently been reported for African-American and Caucasian women diagnosed with breast cancer. Differences in the levels of endogenous sex hormones in these populations could explain some of the variation in survival rates, since estrogen is recognized as a risk factor for this type of cancer.

PURPOSE

Dietary factors are known to affect endogenous hormone levels; therefore, our study was designed to determine the serum hormone levels of African-American women consuming a typical North American diet, to determine the effect of a low-fat and high-fiber diet on their serum hormone levels, and to compare the base-line serum hormone levels in the African-American women with hormone data from our study of Caucasian women (n = 68) consuming the same control diet.

METHODS

Twenty-one healthy, premenopausal, African-American women who agreed to eat only food prepared in a clinical study unit were recruited into the study. The control diet was similar to their usual diet, being high in fat (40% of calories from fat) and low in fiber (12 g/day), and was consumed on average for 3 weeks. The concentrations of estrone (E1), estrone sulfate (E1SO4), estradiol (E2), free E2, androstenedione, and sex hormone-binding globulin (SHBG) in serum samples obtained from the participants during the last week of the control diet and during the follicular phase of their menstrual cycle were determined. The women were then switched to a diet low in fat (20% of calories as fat) and high in fiber (40 g/day); they consumed this diet for two menstrual cycles before blood samples were collected for determination of serum hormone levels. Repeated-measures regression modeling was used to investigate the relationship between diet and hormone levels in African-American and Caucasian women. All P values resulted from two-sided statistical tests.

RESULTS

Analysis of serum hormone levels in the African-American women indicated that the change in diet caused a significant decrease in E2 (-8.5%; 95% confidence interval [CI] = -16.1% to -0.3%; P < or = .03) and E1SO4 (-16.2%; 95% CI = -22.1% to -9.8%; P < .0001) and a significant increase in androstenedione levels (+18.3%; 95% CI = +10.3% to +26.8%; P < .0001). SHBG levels of the African-American women were 5.6% (95% CI = -14.0% to +3.7%) lower for those on the experimental diet compared with those on the control diet, but the difference was not statistically significant. Comparison of control serum hormone values in the African-American women in this study with those in Caucasian women previously studied indicated that the Caucasian women had statistically significant lower levels of E1 (-37%; 95% CI = -61.2% to -16.4%; P < or = .0002), E2 (-54.5%; 95% CI = -90.9% to -25.1%; P < or = .0001), free E2 (-30.2%; 95% CI = -65.7% to -2.3%; P < .03), and androstenedione (-48.3%; 95% CI = -83.7% to -19.7%; P < or = .0004).

CONCLUSION

African-American women appear to have higher levels of serum hormones than Caucasian women, and dietary modification can result in a lowering of serum estrogens.

Dehydroepiandrosterone metabolism

Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) circulate in the blood mostly bound to albumin but with a small amount not bound to a protein. DHEA is cleared rapidly from the blood, with a metabolic clearance rate (MCR) in the range of 2000 I/day, but the clearance of DHEAS is much slower and its MCR is in the range of 131/day. DHEA and DHEAS interconvert and about 6% of DHEA will re-enter the blood as DHEAS, while 60-70% of DHEAS will re-enter as DHEA. Both DHEA and DHEAS can be converted in peripheral tissues to androstenedione, testosterone and dihydrotestosterone, and both are aromatized to estrogens. DHEAS enters the ovarian follicle and can be an important source of ovarian testosterone.

Prospective study of sex hormone levels and risk of prostate cancer

BACKGROUND

Sex steroids, particularly androgens, have been implicated in the pathogenesis of prostate cancer. Data from previous studies comparing circulating hormone levels in men with and without prostate cancer are difficult to interpret, since the studies were limited in size, hormone levels were analyzed in blood drawn after the diagnosis of cancer, nonrepresentative control subjects were used, and hormone and hormone-binding protein levels were not simultaneously adjusted.

PURPOSE

We conducted a prospective, nested case-control study to investigate whether plasma hormone and sex hormone-binding globulin (SHBG) levels in healthy men were related to the subsequent development of prostate cancer.

METHODS

Among participants in the Physicians' Health Study who provided plasma samples in 1982, we identified 222 men who developed prostate cancer by March 1992. Three hundred ninety control subjects, matched to the case patients on the bases of age, smoking status, and length of follow-up, were also identified. Immunoassays were used to measure the levels of total testosterone, dihydrotestosterone (DHT), 3 alpha-androstanediol glucuronide (AAG), estradiol, SHBG, and prolactin in the stored (at -82 degrees C) plasma samples. Correlations between individual hormone levels and between hormone levels and SHBG in the plasma of control subjects were assessed by use of Spearman correlation coefficients (r). Odds ratios (ORs) and 95% confidence intervals (CIs) specifying the prostate cancer risk associated with quartile levels of individual hormones, before and after adjustment for other hormones and SHBG, were calculated by use of conditional logistic regression modeling. Reported P values are two-sided.

RESULTS

No clear associations were found between the unadjusted levels of individual hormones or SHBG and the risk of prostate cancer. However, a strong correlation was observed between the levels of testosterone and SHBG (r = .55), and weaker correlations were detected between the levels of testosterone and the levels of both estradiol (r = .28) and DHT (r = .32) (all P < .001). When hormone and SHBG levels were adjusted simultaneously, a strong trend of increasing prostate cancer risk was observed with increasing levels of plasma testosterone (ORs by quartile = 1.00, 1.41, 1.98, and 2.60 [95% CI = 1.34-5.02]; P for trend = .004), an inverse trend in risk was seen with increasing levels of SHBG (ORs by quartile = 1.00, 0.93, 0.61, and 0.46 [95% CI = 0.24-0.89]; P for trend = .01), and a non-linear inverse association was found with increasing levels of estradiol (ORs by quartile = 1.00, 0.53, 0.40, and 0.56 [95% CI = 0.32-0.98]; P for trend = .03). No associations were detected between the levels of DHT or prolactin and prostate cancer risk; for AAG, a marker of 5 alpha-reductase activity, only suggestive evidence of a positive association was found. The results were essentially unchanged when case patients diagnosed within 4 years of plasma collection, case patients diagnosed with localized (i.e., nonaggressive) disease, or control subjects with elevated prostate serum antigen levels (> 2.5 ng/mL) were excluded from the analyses.

CONCLUSIONS

High levels of circulating testosterone and low levels of SHBG-both within normal endogenous ranges-are associated with increased risks of prostate cancer. Low levels of circulating estradiol may represent an additional risk factor. Circulating levels of DHT and AAG do not appear to be strongly related to prostate cancer risk.

Relation of energy, fat, and fiber intakes to plasma concentrations of estrogens and androgens in premenopausal women

To evaluate whether diet may influence the incidence of hormone-dependent cancers through an effect on blood estrogen and androgen concentrations, we analyzed diet-blood hormone relations in a cross-sectional study. Dietary energy, fat, and fiber intakes were estimated from 7-d food records completed by 90 premenopausal women on days 14-20 of their menstrual cycles. Fasting blood specimens were collected on days 5-7, 12-15, and 21-23 of each participant's cycle and pooled to create follicular-, midcycle-, and luteal-phase samples, respectively, for analysis. Energy intake was associated inversely with plasma androstenedione and dehydroepiandrosterone sulfate (DHEAS), averaged across the three menstrual cycle phases, and directly with the probability of a luteal-phase rise in progesterone. For each additional 1 MJ (239 kcal) consumed, androstenedione decreased by 6.0% (95% CI: -8.4%, -3.6%), DHEAS decreased by 5.1% (95% CI: -9.6%, -0.4%), and the probability of a progesterone rise increased by 60% (95% CI: 5%, 145%). After energy intake was adjusted for, the ratio of polyunsaturated to saturated fat (P:S) in the diet was significantly inversely associated with plasma estradiol and estrone during the luteal phase of the menstrual cycle. For each 0.1 increment in the P:S, there was a 7.6% (95% CI: -14.3%, -0.5%) decrease in estradiol and a 6.8% (95% CI: -12.7%, -0.6%) decrease in estrone. Results of this cross-sectional study support a relation between both energy and fat ingestion and plasma sex hormone concentrations in premenopausal women.

Relation of prediagnostic serum estrogen and androgen levels to breast cancer risk

To evaluate the relation of serum sex hormones to breast cancer risk, we conducted a prospective nested case-control study using the Breast Cancer Serum Bank (Columbia, MO). This bank included serum from 3375 postmenopausal women free of cancer and not taking replacement estrogens when they donated blood between 1977 and 1987. Of these, 71 were diagnosed subsequently with breast cancer. For each case, two women alive and free of cancer at the age of the case's diagnosis and matched to the case on age and on date and time of day of blood collection were selected as controls. The median age of subjects at blood collection was 62 years, and the time from blood collection to diagnosis ranged from less than 1 to 9.5 years, with a median of 2.9 years. Postmenopausal women with elevated serum levels of total and non-sex hormone-binding globulin-bound E2 were at an increased risk of developing breast cancer. For non-sex hormone-binding globulin-bound E2, risks were elevated 4-5 fold for women in the upper three quartiles relative to those in the lowest quartile. Although breast cancer was not related to estrone or estrone sulfate concentration, the ratio of estrone sulfate to estrone was significantly inversely associated with risk, suggesting that women who develop breast cancer may be less able to metabolize estrone to its less active form. Serum testosterone was significantly positively associated with postmenopausal breast cancer; the relative risk for women in the highest versus the lowest quartile was 6.2 (95% confidence interval, 2.0-19.0). Our results support the hypothesis that prediagnostic serum estrogens and androgens are related to the subsequent diagnosis of breast cancer in postmenopausal women.

Does collecting repeated blood samples from each subject improve the precision of estimated steroid hormone levels?

Measuring levels of steroid hormones in epidemiologic studies is difficult because pulsatile release can cause the levels of many hormones to vary markedly over short intervals, leading to a loss of precision in between-subject comparisons. Clinicians often control this variation by collecting several samples from each subject at defined intervals and pooling these samples for assay. The number of samples per subject that would adequately control such variation in an epidemiologic study has not been fully investigated. This study examines the effects of collecting 1, 2, or 3 samples per subject on the variances of 11 hormones and sex hormone binding globulin in men and 6 hormones in women. Three samples were collected at 30-minute intervals from each of 20 men and 59 women and were assayed separately. Variances that would be obtained in studies collecting one, two, or three samples per subject were then estimated. Collecting more than one sample substantially reduced the variances of several hormones in men but not in women.

Dehydroepiandrosterone metabolism in the female rhesus monkey: oral versus intravenous administration

Because of the biologic effects on a variety of end points reported for dehydroepiandrosterone (DHA) and its sulfate (DHAS) after oral administration, we studied the metabolism of DHA in six female rhesus monkeys after oral and after intravenous administration. We administered [4-14C]DHA p.o. and [7-3H]DHA i.v. simultaneously, drawing blood samples at increasingly longer intervals for 24 h. The mean +/- SE metabolic clearance rate of the intravenous DHA was 404 +/- 49 L/day. The mean metabolic clearance rate was 2,601 +/- 261 L/day after oral administration, and the calculated absorption was 16.3 +/- 2.5%. There was rapid conversion of p.o. DHA to DHAS, as the conversion ratio of the orally administered DHA measured in the blood as [4-14C]DHAS was 63.3 +/- 13.6, whereas the conversion ratio of intravenously administered DHA to DHAS was 9.3 +/- 2.0. Small amounts of DHA were measured in the blood as testosterone and androstenedione after both forms of administration. We conclude that there is marked metabolism in splanchnic tissue of orally administered DHA to DHAS prior to its entry into the bloodstream, and the absorption of DHA itself is minimal when administered by mouth to the rhesus monkey.

Sex steroids, bone mass, and bone loss. A prospective study of pre-, peri-, and postmenopausal women

Although bone loss around the time of menopause is driven by estrogen deficiency, the roles of estrogens and androgens in the preservation of skeletal mass at other stages of life are less well understood. To address this issue we studied 231 women between the ages of 32 and 77 with multiple measurements of sex steroids and bone mass over a period of 2-8 yr. In all women bone mass was negatively associated with concentrations of sex-hormone binding globulin, and positively associated with weight. Bone loss occurred from all skeletal sites in peri- and postmenopausal women, but premenopausal women lost bone only from the hip (-0.3%/yr) and had positive rates of change in the radius and spine. Bone loss was significantly associated with lower androgen concentrations in premenopausal women, and with lower estrogens and androgens in peri- and postmenopausal women. Sex steroids are important for the maintenance of skeletal integrity before menopause, and for as long as 20-25 yr afterwards.

Serum gonadotropins and steroid hormones and the development of ovarian cancer

OBJECTIVE

To prospectively examine the association between endogenous hormones and development of ovarian cancer.

DESIGN

Nested case-control study.

SETTING

A population-based serum bank in Washington County, Maryland.

PARTICIPANTS

Serum samples were collected in 1974 from 20305 county residents and stored at -70 degrees C. From 1975 through 1989, a total of 31 cases of ovarian cancer were identified in women who were not taking hormones at the time of blood collection. These cases were matched to 62 controls on age, menopausal status, and, for premenopausal women, number of days from the beginning of the last menstrual period.

MAIN OUTCOME MEASURE

Prediagnostic endogenous hormone levels of cases and controls were compared.

RESULTS

Mean follicle-stimulating hormone levels were lower among cases (43.3 IU/L) compared with controls (54.4 IU/L) (P = .04), and increasing levels were associated with significantly lower risk (P for trend = .01), particularly among postmenopausal women. Luteinizing hormone levels were 9% lower among cases than controls, but the difference was not statistically significant (P = .39). Compared with controls, cases had higher androstenedione levels (4.5 nmol/L vs 3.3 nmol; P = .03) and higher dehydroepiandrosterone (DHEA) levels (15.9 nmol/L vs 9.7 nmol/L; P = .02). The risk of ovarian cancer increased with higher levels of androstenedione and DHEA sulfate (P for trend = .008 and .11, respectively). These associations were not materially different between premenopausal and postmenopausal women.

CONCLUSION

The results suggest that women with low serum gonadotropin levels or high androgen levels have an increased risk of ovarian cancer. These findings do not support the hypothesis that pituitary gonadotropins increase the risk of ovarian cancer. Replication of the study in other populations is highly desirable.

Alcohol, height, and adiposity in relation to estrogen and prolactin levels in postmenopausal women

BACKGROUND

Alcohol use, height, and postmenopausal adiposity have each been positively associated with postmenopausal breast cancer risk in most epidemiologic studies. The mechanism underlying these associations is unclear, although an effect of these factors on hormone levels has been hypothesized. Few previous studies have evaluated the relationship of either alcohol consumption or height with plasma hormone levels. A positive association between adiposity and plasma estrogen levels in postmenopausal women has been reported consistently.

PURPOSE

Using archived frozen plasma samples and corresponding data from participants in the Nurses' Health Study, we determined plasma hormone levels and assessed these levels in relation to alcohol consumption, height, and adiposity among postmenopausal women.

METHODS

Blood samples were collected from a subset of participants in the Nurses' Health Study in 1989 and 1990, then stored in liquid nitrogen. Hormone concentrations in 217 archived plasma samples (from healthy postmenopausal women) were analyzed in 1993. Spearman correlation coefficients were calculated to assess the linear association between alcohol consumption during the previous year (mean daily intake in grams per day ascertained from semiquantitative food-frequency questionnaires completed in 1990 or 1991), height, and adiposity (as measured by body mass index [BMI] in kg/m2, with weight reported at time of blood collection), and plasma hormone levels. Two-sided P values were also calculated.

RESULTS

After controlling for age, height, smoking status, and BMI, alcohol consumption was positively associated with estrone sulfate concentrations (r = .17; P = .02); no statistically significant association was noted for the other plasma hormones measured. Mean plasma estrone sulfate levels were 159 pg/mL in women who reported no alcohol use versus 211 pg/mL in women consuming 30 g or more of alcohol per day. After adjusting for the other covariates, we observed a strong positive correlation between BMI and plasma estrogens (r ranging from .37 for estrone and estrone sulfate to .63 for bioavailable estradiol, with all P values < or = .01; prolactin was the only hormone unassociated with BMI, r = -.01). Height was unrelated to either plasma estrogens or prolactin.

CONCLUSIONS

BMI and alcohol use were positively associated with postmenopausal plasma estrogen and estrone sulfate levels, respectively.

IMPLICATIONS

The association of alcohol consumption and postmenopausal obesity with subsequent breast cancer risk might be mediated, at least in part, through an influence on postmenopausal plasma estrogen levels. Additional studies are needed to further quantify the relationship between alcohol consumption and plasma hormone levels and to elucidate the physiologic basis for this association.

Reproducibility of plasma hormone levels in postmenopausal women over a 2-3-year period

We evaluated the reproducibility of plasma hormone levels over time in 79 healthy postmenopausal women, ages 51-69 years at baseline, who were not using postmenopausal hormones. Three blood samples were collected between 1989 and 1992 from each of these women. We assessed plasma levels of estradiol, free estradiol, percentage of free estradiol, bioavailable estradiol, percentage of bioavailable estradiol, estrone, estrone sulfate, sex hormone-binding globulin (SHBG), androstenedione, testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and prolactin at each of three sample collections. The means and SD for each of the plasma estrogens, SHBG, and prolactin were similar at each collection. For the androgens, plasma levels tended to decrease over time consistent with an aging effect; decreases with increasing age were statistically significant for androstenedione, dehydroepiandrosterone, and dehydroepiandrosterone sulfate. Intraclass correlation coefficients (ICCs) ranged from 0.92 (95% confidence interval = 0.89-0.95) for SHBG to 0.53 (95% confidence interval = 0.43-0.69) for prolactin. Most correlations were at least 0.70. The ICCs did not vary by age or time since menopause. Women who changed weight over the course of the study tended to have lower ICCs for a number of the hormones, although these differences were not statistically significant. These data indicate that, for most of these plasma hormones, a single measurement can reliably categorize average levels over at least a 3-year period in postmenopausal women.

Binding of 17-alpha-methyltestosterone in vitro to human sex hormone binding globulin and rat ventral prostate androgen receptors

We measured the relative binding affinity (RBA) of 17-alpha-methyltestosterone (MET) for the rat prostate androgen receptor and human sex hormone-binding globulin (SHBG) in vitro. The reference compound in both instances was dihydrotestosterone (DHT), the RBA of which was set at 100%. The RBA of methyltestosterone was 44% for the androgen receptor, but 11% for SHBG. The androgen receptor, therefore, would appear to recognize a different part of an androgen compared to the recognition site on SHBG. The difference in RBAs may amplify the biologic action of methyltestosterone.

Relationships of age and reproductive characteristics with plasma estrogens and androgens in premenopausal women

We used data from a cross-sectional study of 107 premenopausal women to evaluate the relation of age, menarcheal age, parity, and age at first live birth with plasma estrogen and androgen levels in premenopausal women. Fasting blood specimens were collected on each of days 5-7, 12-15, and 21-23 of menstrual cycles of the participants and pooled to create follicular, midcycle, and luteal phase samples, respectively, for each woman. Age was associated significantly and positively with plasma estradiol levels during the follicular phase [percentage difference/year = 2.6; 95% confidence interval (CI) = 1.0-4.2] and midcycle (percentage difference/year = 2.7; 95% CI = 0.9-4.7) but not the luteal phase (percentage difference/year = -0.4; 95% CI = -1.9-1.3) of the menstrual cycle. The relation of age to plasma estradiol varied by parity, with significant interactions during midcycle and luteal phase. Among nulliparous women, plasma estradiol levels increased with age midcycle and during the luteal phase, but among parous women estradiol levels decreased with age during these phases of the menstrual cycle. Plasma estrone increased with age in all women during the follicular phase of the menstrual cycle (percentage difference/year = 1.5; 95% CI = 0.2-2.8). During the luteal phase there was a significant interaction with parity; estrone levels in nulliparous women varied only slightly with age, but levels in parous women decreased significantly as age increased. The androgens, androstenedione and dehydroepiandrosterone sulfate decreased, and sex hormone-binding globulin increased as age increased. The results of this cross-sectional study suggest that pregnancy may modify age-related changes in plasma estrogen levels.