René Bérubé

Androgen glucuronides, instead of testosterone, as the new markers of androgenic activity in women

Despite the long series of cohort studies performed during the last 20 years, the correlation between serum testosterone and any clinical situation believed to be under androgen control in women has remained elusive. This is likely related to the recent finding that the androgens made locally in large amounts in peripheral tissues from the precursor dehydroepiandrosterone (DHEA) act in the same cells where synthesis takes place and are not released in significant amounts in the circulation, thus making unreliable the measurement of serum testosterone as marker of total androgenic activity. The objective is to determine if serum androgen glucuronides can be replaced by testosterone or another steroid as measure of androgenic activity. Since the glucuronide derivatives of androgens are the obligatory route of elimination of all androgens, these metabolites were measured by liquid chromatography tandem mass spectrometry under basal conditions in 377 healthy postmenopausal women aged 55-65 years as well as in 47 premenopausal women aged 30-35 years while testosterone was assayed by gas chromatography mass spectrometry. No correlation was found between the serum concentration of testosterone and that of androsterone glucuronide (ADT-G) or androstenediol glucuronide (3alpha-diol-G), the androgen metabolites which account for the total pool of androgens. The present data show that measurement of the total pool of androgens reflected by the serum levels of ADT-G and 3alpha-diol-G cannot be replaced by serum testosterone or any other steroid, including DHEA or DHEA sulphate. These findings may have implications for women with androgen deficiency involving osteoporosis, obesity, type 2 diabetes, sexual dysfunction, loss of muscular strength and a series of other clinical situations affecting womens health. Measuring ADT-G and 3alpha-diol-G might identify cases of true androgen deficiency and provide an opportunity to offer appropriate androgen therapy.

Metabolism of DHEA in postmenopausal women following percutaneous administration

The marked decline in serum dehydroepiandrosterone (DHEA) with age is believed to play a role in health problems associated with aging, these health issues being potentially preventable or reversible by the exogenous administration of DHEA. In the present study, liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) and gas chromatrography/mass spectrometry (GC/MS) were used to measure the serum levels of DHEA and 11 of its metabolites in seventy-five 60-65-year-old Caucasian women who received 3g of 0.1%, 0.3%, 1.0% or 2.0% DHEA cream or placebo applied twice daily on the face, upper chest, arms and legs. The serum levels of DHEA increased 574% over control at the 2.0% DHEA dose while the sum of the androgen metabolites androsterone glucuronide (ADT-G), 3alpha-androstenediol-3G (3alpha-diol-3G) and 3alpha-diol-17G increased by only 231%. On the other hand, serum testosterone and dihydrosterone were increased by 192% and 275%, respectively, above basal levels compared to 139% and 158% for estrone and estradiol. Such data show that the transformation of exogenous DHEA in postmenopausal women is preferentially into androgens rather than into estrogens. On the other hand, the present data indicate that serum DHEA measurements following DHEA supplementation in postmenopausal women are an overestimate of the formation of active androgens and estrogens and suggest a decreased efficiency of transformation of DHEA into androgens and estrogens with aging.

Comparable amounts of sex steroids are made outside the gonads in men and women: strong lesson for hormone therapy of prostate and breast cancer.

The objective of this study was comparison of circulating androgens and their metabolites as well as estrogens measured for the first time by a validated mass spectrometry technology in 60-80-year-old men and women of comparable age. Castration in men (n=34) reduces the total androgen pool by only about 60% as indicated by the decrease in the serum levels of the glucuronide metabolites of androgens compared to intact men (n=1302). Such data are in agreement with the 50 to 75% decrease in intraprostatic dihydrotestosterone (DHT) concentration after castration. Most interestingly, the same amounts of androgens and estrogens are found in postmenopausal women (n=369) and castrated men of comparable age. The most significant therapeutic implication of these findings is the absolute need to add a pure (nonsteroidal) antiandrogen to castration in men with prostate cancer in order to block the action of the 25 to 50% DHT left in the prostate after castration. Not adding an antiandrogen to castration in men treated for prostate cancer is equivalent to not prescribing a blocker of estrogens in women suffering from breast cancer because they are postmenopausal and have low circulating estradiol.

Effect of one-week treatment with vaginal estrogen preparations on serum estrogen levels in postmenopausal women

Objective: Approximately 50% of postmenopausal women suffer from vaginal atrophy, and a large proportion of them choose intravaginal estrogen preparations administered for local action to avoid systemic exposure to estrogens and its associated risk of breast and uterine cancer. The primary objective of this study was the evaluation of the systematic bioavailability of estradiol and estrone and the pharmacokinetics of two of the most frequently used intravaginal estrogen preparations, namely Vagifem and Premarin cream. Design: While immunobased assays could not previously provide accurate measurement of serum estrogen concentrations in postmenopausal women, we have used validated mass spectrometry assays to measure the pharmacokinetics of serum estradiol and estrone during the 24 hours following the seventh daily application of 25 µg estradiol (Vagifem) and 1 g (0.625 mg) conjugated estrogens (Premarin) cream in 10 postmenopausal women in each group. Results: Serum estradiol was increased on average by 5.4-fold from 3 to 17 pg/mL during the 24-hour period after daily administration of 25 &mgr;g estradiol or 1 g (0.625 mg) conjugated estrogens cream. Serum estrone, conversely, increased 150% with Vagifem and 500% with Premarin cream. Conclusions: The present data using validated, accurate, and sensitive mass spectrometry assays of estrogens show that the Vagifem pill and Premarin cream, after 1 week of daily treatment, cause an approximately fivefold increase in serum estradiol in postmenopausal women, thus indicating that the effects are unlikely to be limited to the vagina and that systemic actions are expected after application of these intravaginal estrogen preparations.

Serum steroid levels during 12-week intravaginal dehydroepiandrosterone administration.

Objective: Because a previous 1-week study has shown no or minimal changes in the serum levels of dehydroepiandrosterone (DHEA) and its metabolites after up to daily 1.8% (23.4 mg) intravaginal DHEA, the objective of the present study was to investigate the serum steroid levels during a 12-week daily intravaginal administration of 0%, 0.25%, 0.5%, and 1.0% DHEA (Prasterone) 1.3 mL ovules. Methods: In a double-blind, placebo-controlled phase III study, 218 postmenopausal women (age range, 42-74 y) were randomized to receive daily one of four DHEA concentrations intravaginally. Serum steroids were measured by a Good Laboratory Practice-validated mass spectrometry technology in samples obtained at time of visit. Results: The serum levels of DHEA and 11 of its metabolites measured at screening, day 1, and weeks 2, 4, 8, and 12 in women showed no or minimal changes during the whole observation period, with all values remaining well within the limits of normal postmenopausal women. No accumulation of the steroid metabolites nor change in DHEA bioavailability was detected. Conclusions: The present data show that local daily intravaginal DHEA administration at DHEA doses of 3.25-13 mg was able to rapidly and efficiently achieve correction of all the signs and symptoms of vaginal atrophy and improve sexual function and caused no or minimal changes in serum sex steroid levels, which all remain within the normal postmenopausal range, thus avoiding the risks of all estrogen formulations.

Effect of intravaginal DHEA on serum DHEA and eleven of its metabolites in postmenopausal women.

The primary objective of this study was measurement of the systemic bioavailability of DHEA and its metabolites following daily intravaginal application of the sex steroid precursor. Forty postmenopausal women were randomized to receive a daily dose of one ovule of the following DHEA concentrations: 0.0%, 0.5%, 1.0% or 1.8%. After only 7 days of treatment, the maturation value of the vaginal epithelial cells was significantly increased while the vaginal pH was significantly decreased at all DHEA doses. These important local effects were observed while the serum concentrations of estradiol and testosterone remained within the values found in normal postmenopausal women at all DHEA doses. Similar observations were made for serum androstenedione, estrone, estrone-sulfate and DHEA-sulfate. Even at the highest 1.8% DHEA dose, serum DHEA was increased at the levels found in normal premenopausal women. The present data show that the intravaginal administration of DHEA permits to rapidly achieve the local beneficial effects against vaginal atrophy without significant changes in serum estrogens, thus avoiding the increased risk of breast cancer associated with the current intravaginal or systemic estrogenic formulations. In addition, the recent observation that DHEA is transformed into both androgens and estrogens in the vagina permits to exert benefits on all the three layers of the vaginal wall.

Exposure to free and conjugated forms of bisphenol A and triclosan among pregnant women in the MIREC cohort.

Background: Bisphenol A (BPA) and triclosan (TCS) are two nonpersistent chemicals that have been frequently measured in spot urine samples from the general population but less so in pregnant women; however, data are limited on the free (bioactive) and conjugated forms of these phenols. Objectives: The Maternal-Infant Research on Environmental Chemicals (MIREC) Study addressed these data gaps by utilizing stored maternal urine samples from a large multicenter cohort study of Canadian pregnant women. Methods: Concentrations of free and conjugated forms of BPA and TCS were measured in about 1,890 first-trimester urine samples by ultra performance liquid chromatograpy–tandem mass spectrometry using isotope dilution. Results: The glucuronides of BPA and TCS were the predominant forms of these chemicals measured (detected in 95% and 99% of samples, respectively), whereas the free forms were detected in 43% and 80% of samples, respectively. The geometric mean urinary concentrations for glucuronides of BPA and TCS were 0.80 μg/L (95% CI: 0.75, 0.85) and 12.30 μg/L (95% CI: 11.08, 13.65), respectively. Significant predictors of BPA included maternal age < 25 vs. ≥ 35 years, current smoking, low vs. high household income, and low vs. high education. For TCS, urinary concentrations were significantly higher in women ≥ 25 years of age, never vs. current smokers, and women with high household income and high education. Conclusions: The results from this study represent the largest national-level data on urinary concentrations of free and conjugated forms of BPA and TCS in pregnant women and suggest that maternal characteristics predicting elevated urinary concentrations of these phenols largely act in opposite directions. Citation: Arbuckle TE, Marro L, Davis K, Fisher M, Ayotte P, Bélanger P, Dumas P, LeBlanc A, Bérubé R, Gaudreau É, Provencher G, Faustman EM, Vigoren E, Ettinger AS, Dellarco M, MacPherson S, Fraser WD. 2015. Exposure to free and conjugated forms of bisphenol A and triclosan among pregnant women in the MIREC cohort. Environ Health Perspect 123:277–284; http://dx.doi.org/10.1289/ehp.1408187

Bisphenol A and phthalate metabolite urinary concentrations: Daily and across pregnancy variability

Phthalates and bisphenol A (BPA) are high production volume and ubiquitous chemicals that are quickly metabolized in the body. Traditionally, studies have relied on single spot urine analyses to assess exposure; ignoring variability in concentrations throughout a day or over a longer period of time. We compared BPA and phthalate metabolite results from urine samples collected at five different time points. Participants (n=80) were asked to collect all voids in a 24 h period on a weekday and then again on a weekend before 20 weeks of pregnancy. During the second and third trimesters and in the postpartum period, single spot urines were collected. Variability over time in urinary concentrations was assessed using intraclass correlation coefficients (ICCs) and the sensitivity to correctly classify a single sample as high or low versus the geometric mean (GM) of all samples was calculated. We found low reproducibility and sensitivity of BPA and all phthalate metabolites throughout pregnancy and into the postpartum period but much higher reproducibility within a day. Time of day when the urine was collected was a significant predictor of specific gravity adjusted exposure levels. We concluded that, if the interest is in average exposures across pregnancy, maternal/fetal exposure estimation may be more accurate if multiple measurements, collected across the course of the entire pregnancy, rather than a single spot measure, are performed.

Intravaginal prasterone (DHEA) provides local action without clinically significant changes in serum concentrations of estrogens or androgens

In order to avoid the risks of non-physiological systemic exposure, serum concentrations of estradiol (E2) and testosterone (as measured by mass spectrometry-based assays) should remain below the 95th centiles measured at 9.3pg/ml and 0.26ng/ml for these respective sex steroids in normal postmenopausal women. To document the possibility of achieving this therapeutic objective, we have measured individual 24h serum E2 and testosterone concentrations in women with vulvovaginal atrophy (VVA) receiving daily intravaginal administration of a clinically effective dose of 6.5mg prasterone (dehydroepiandrosterone, DHEA). Serum E2 and testosterone, as well as DHEA and nine of its other metabolites, were assayed at ten time intervals over 24h on the first and seventh days of daily vaginal administration of 6.5mg prasterone. No significant change from baseline of average 24h serum E2 or testosterone concentrations was observed. Moreover, average 24h serum DHEA remained within the normal postmenopausal range. Estrone sulfate and the androgen metabolites androsterone glucuronide and androstane-3α, 17β-diol glucuronide did not change, thus confirming the absence of any biologically relevant systemic exposure to estrogens and androgens, respectively. Serum concentrations of metabolites of both estrogens and androgens remain within the normal postmenopausal range following daily intravaginal administration of 6.5mg prasterone. As other studies have shown, local formation of sex steroids in peripheral tissues without significant release of E2 or testosterone in the circulation can be achieved with intravaginal prasterone. Thus, prasterone is a promising physiological and attractive solution to treating VVA symptoms.

Determination of bisphenol A, triclosan and their metabolites in human urine using isotope-dilution liquid chromatography-tandem mass spectrometry.

Bisphenol A (BPA) and triclosan (TCS) are ubiquitous environmental phenols exhibiting endocrine disrupting activities that may be involved in various health disorders in humans. There is a need to measure separately free forms and conjugated metabolites because only the former are biologically active. We have developed sensitive methods using isotope-dilution liquid chromatography-tandem mass spectrometry for individual measurements of free BPA and TCS as well as their metabolites, BPA glucuronide (BPAG), BPA monosulfate (BPAS), BPA disulfate (BPADS), TCS glucuronide (TCSG) and TCS sulfate (TCSS) in urine. Comparative analyses of urine samples from 46 volunteers living in the Quebec City area using the new methods and a GC-MS/MS method previously used in our laboratory revealed very strong correlations for total BPA (Spearmans rs=0.862, p<0.0001) and total TCS concentrations (rs=0.942, p<0.0001). Glucuronide metabolites were the most abundant BPA and TCS species in urine samples (>94% of total urinary concentrations). Unconjugated TCS concentrations represented a small proportion of total TCS species (median=1.6%) but its concentration was likely underestimated due to losses by adsorption to the surface of polypropylene tubes used for sample storage. To our knowledge, we are the first to report levels of free, sulfated and glucuronidated TCS levels in human urine.