Androsterone Glucuronide Levels Research Articles

Unraveling the functional role of the orphan solute carrier, SLC22A24 in the transport of steroid conjugates through metabolomic and genome-wide association studies.

Variation in steroid hormone levels has wide implications for health and disease. The genes encoding the proteins involved in steroid disposition represent key determinants of interindividual variation in steroid levels and ultimately, their effects. Beginning with metabolomic data from genome-wide association studies (GWAS), we observed that genetic variants in the orphan transporter, SLC22A24 were significantly associated with levels of androsterone glucuronide and etiocholanolone glucuronide (sentinel SNPs p-value <1x10-30). In cells over-expressing human or various mammalian orthologs of SLC22A24, we showed that steroid conjugates and bile acids were substrates of the transporter. Phylogenetic, genomic, and transcriptomic analyses suggested that SLC22A24 has a specialized role in the kidney and appears to function in the reabsorption of organic anions, and in particular, anionic steroids. Phenome-wide analysis showed that functional variants of SLC22A24 are associated with human disease such as cardiovascular diseases and acne, which have been linked to dysregulated steroid metabolism. Collectively, these functional genomic studies reveal a previously uncharacterized protein involved in steroid homeostasis, opening up new possibilities for SLC22A24 as a pharmacological target for regulating steroid levels.

Bioanalytical LC-MS Method for the Quantification of Plasma Androgens and Androgen Glucuronides in Breast Cancer.

The physiological and pathological development of the breast is strongly affected by the hormonal milieu consisting of steroid hormones. Mass spectrometry (MS) technologies of high sensitivity and specificity enable the quantification of androgens and consequently the characterization of the hormonal status. The aim of this study is the assessment of plasma androgens and androgen glucuronides, in the par excellence hormone-sensitive tissue of the breast, through the application of liquid chromatography-mass spectrometry (LC-MS). A simple and efficient fit-for-purpose method for the simultaneous identification and quantification of dehydroepiandrosterone sulfate (DHEAS), androstenedione (A4), androsterone glucuronide (ADTG) and androstane-3α, 17β-diol-17-glucuronide (3α-diol-17G) in human plasma was developed and validated. The presented method permits omission of derivatization, requires a single solid-phase extraction procedure and the chromatographic separation can be achieved on a single C18 analytical column, for all four analytes. The validated method was successfully applied for the analysis of 191 human plasma samples from postmenopausal women with benign breast disease (BBD), lobular neoplasia (LN), ductal carcinoma in situ and invasive ductal carcinoma (IDC). DHEAS plasma levels exhibited significant differences between LN, IDC and BBD patients (P < 0.05). Additionally, ADTG levels were significantly higher in patients with LN compared with those with BBD (P < 0.05).

Response to Dr Simes and Dr Snabes

I thank Dr Simes and Dr Snabes for the information regarding the longer-term safety study of testosterone (T) gel (LibiGel) clarifying that by February 2011 data from some 2800 women-years of exposure have been gathered giving an average per subject exposure of 12 months. I note that enrollment is expected to be complete in the first half of 2011 and women will be followed for 5 years. Very appropriately the women have cardiovascular risk factors that are commonly present in postmenopausal women including hypertension, smoking, and diabetes. It is not clear to me whether the women are also supplemented with estrogen, nor could I find this information on the company website or in a recent abstract from the annual conference of the International Society for the Study of Women's Sexual Health. However, I will assume not. Nevertheless, issues of safety involve both androgen and estrogen from the aromatization of testosterone. Current data support the ‘critical window’ hypothesis [Whitmer et al. 2011] such that early postmenopausal estrogen therapy (ET) protects against cardiovascular disease, dementia, and cancer, whereas ET in later life increases these risks [Shumaker et al. 2003] and continued ET from mid to later life offers no protection [Shumaker et al. 2003]. Time since surgical or natural menopause, or duration of any prior ET, may also have an important influence on the safety of supplemental T. It would be useful to know whether the safety study includes accurate baseline studies of androgen activity using androgen metabolites, principally androsterone glucuronide (ADT-G). It is of note that at any given age there is a broad range of ADT-G amongst women [Labrie et al. 2006] and that risks from T supplementation may vary with endogenous T activity. It remains important to recall that women carefully diagnosed with hypoactive sexual desire disorder (HSDD) have ADT-G levels comparable to carefully assessed controls [Basson et al. 2010]. Recent research identifies certain hormonal milieus that predispose to, or conversely protect from, progression of carotid artery intima media thickness during ET [Karim et al. 2008]. Assessment of hormonal milieu during sex hormone treatment is advocated [Karim et al. 2008]. The expectation is that in some 5 years time much more will be known on the safety of marked alteration to the androgen:estrogen ratio in women. Compared with premenopausal women this ratio becomes highly nonphysiological in T-supplemented women. The theoretical concern is of course that when endogenous androgens are high, cardiovascular risk increases [Wild, 2007]. The major issue with any hormonal supplementation for sexual dysfunction is that the duration of requirement is indefinite: women continue their sexual lives as long as there is an available sexually competent partner. If lack of androgen activity is assumed to be causing the disorder, this lack is only going to increase with age, given the continued reduction of intracrine production of androgen [Labrie et al. 1997]. Although a 5-year study of women with cardiovascular risk factors is an excellent start, the statement that ‘determination of the long-term cardiovascular and breast safety of testosterone will be known once the blind is broken and the data analyzed, which should occur in the next twelve months’ is misleading. The company will know in the next 12 months the safety of exposure to 12 months of supplemental T in a cohort of women with variable prior exposure to postmenopausal ET and variable (possibly unknown) endogenous androgen activity. In a further 5 years they will have data on exposure of a proportion of the initial 2800 women who continued T for the full 5 years. The debacle over postmenopausal hormonal therapy in general stemming from the Women's Health Initiative study in 2002 [Clarkson, 2008; Writing Group for the Women's Health Initiative Investigators, 2002] encourages caution and it encourages full discussion with our patients concerning the limited knowledge of the safety of hormonal therapy with testosterone.

Role of androgens in women's sexual dysfunction

Although suspected, androgen deficit in women with sexual dysfunction has never been established. Given that serum testosterone levels are of limited value, we sought to compare total androgen activity in women with and without hypoactive sexual desire disorder (HSDD). Intracellular production in target tissues is the major source of testosterone in older women and can now be measured. Androgen metabolites, specifically androsterone glucuronide (ADT-G), reflect intracellular and ovarian sources of testosterone. Thus, we predicted significantly lowered levels of metabolites in women with sexual dysfunction. A detailed assessment of the sexual function of women without depression, without serious relationship discord, or receiving medications affecting sexual function included 121 women with HSDD and 124 sexually healthy community controls. Sexual function was assessed using structured interviews, validated questionnaires, and steroid analysis-mass spectrometry levels of ADT-G, testosterone, and precursor hormones. No group differences in serum levels of testosterone or ADT-G were found. Significantly lower levels of two precursor hormones, dehydroepiandrosterone sulfate and androstene-3β,17β-diol, were found in women with sexual dysfunction (P = 0.006 and P = 0.020, respectively). The variability of metabolite and precursor levels was substantial for all women. Significantly lower levels of the two precursor steroids dehydroepiandrosterone sulfate and androstene-3β,17β-diol but not the major androgen metabolite ADT-G were found in women with HSDD. Although the significance of the former awaits further study, androgen deficiency in women with HSDD was not confirmed. Given the unknown long-term effects of testosterone supplementation, women receiving testosterone therapy should be informed that a deficit of testosterone activity in women with HSDD has not been identified.

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 (3α-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 3α-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 women's health. Measuring ADT-G and 3α-diol-G might identify cases of true androgen deficiency and provide an opportunity to offer appropriate androgen therapy.

Androstane-3alpha,17beta-diol glucuronide as a steroid correlate of visceral obesity in men.

Plasma levels of androstane-3alpha,17beta-diol glucuronide (3alpha-DIOL-G) and androsterone glucuronide (ADT-G) as well as testosterone and adrenal C19 steroid concentrations were measured in a sample of 80 men in whom visceral adipose tissue (AT) accumulation was also determined by computed tomography. Plasma 3alpha-DIOL-G concentrations showed significant positive correlations with total body fat mass (r = 0.31; P < 0.05) and percent body fat (r = 0.28; P < 0.05). Furthermore, plasma 3alpha-DIOL-G levels were significantly associated with visceral adipose tissue accumulation (r = 0.41; P < 0.0005) as well as fasting plasma insulin (r = 0.35; P < 0.005) and glycemic and insulinemic responses to an oral glucose load (r = 0.39; P < 0.0005 and r = 0.32; P < 0.005, respectively). However, associations between 3alpha-DIOL-G and plasma glucose-insulin homeostasis indexes were no longer significant after adjustment for visceral AT area. ADT-G levels were not significantly associated with any of the adiposity variables. Subjects matched for abdominal sc AT area but with either low or high levels of visceral AT area showed significant differences in 3alpha-DIOL-G concentrations (P < 0.05), whereas subjects with low or high levels of abdominal sc AT but similar levels of visceral AT had similar 3alpha-DIOL-G concentrations. Among men with high testosterone levels, subjects with reduced 3alpha-DIOL-G concentrations had lower visceral adipose tissue accumulation than subjects with increased 3alpha-DIOL-G levels. The present results indicate that plasma 3alpha-DIOL-G, but not ADT-G, is a steroid correlate of visceral obesity. Excess visceral adipose tissue and/or concomitant alterations in insulin levels or in vivo insulin action could be responsible for the increased 3alpha-DIOL-G formation observed in this condition.

Metabolism of dihydrotestosterone to 5α-androstane-3α,17β-dioI glucuronide is greater in the peripheral compartment than in the splanchnic compartment

To compare the peripheral versus the splanchnic contribution to the formation of 3 alpha-diol G. Prospective study in various groups of women and men. Reproductive Endocrine service of our University Medical Center. Six normal ovulatory women, five hirsute women with polycystic ovary syndrome, and six normal men. All subjects received IV dihydrotestosterone (DHT) infusions as well as percutaneous administration of DHT. Serum was obtained at multiple time points before and after each administration of DHT. Comparison of serum levels of DHT, 3 alpha-androstanediol (3 alpha-diol), 3 alpha-diol G, and androsterone glucuronide in the three groups. Steady-state levels of DHT were similar in the three groups and were also similar after the two different routes of administration. However, ratios of 3 alpha-diol G to DHT were significantly greater after percutaneous gel than after IV administration in all three groups. This also was the case for the ratio of unconjugated serum 3 alpha-diol to DHT. Levels of androsterone glucuronide were similar with the different routes of administration. Using normal routes of administration and, in attempting to assess in vivo metabolism of DHT, our data confirm that the skin is the major site of unconjugated 3 alpha-diol and 3 alpha-diol G formation. Serum 3 alpha-diol G, therefore, appears largely to reflect skin DHT metabolism.

Pathogenesis of the decreased androgen levels in obese men.

In obese men, sex hormone-binding globulin levels (SHBG) as well as total plasma testosterone (T) levels are decreased. Data concerning the levels of nonprotein-bound testosterone (FT) are discordant, with some researchers reporting normal levels, and other reporting decreased levels. The latter imply an impairment of the feedback regulation mechanism of FT levels. We investigated whether an eventual decrease in FT levels and, hence, functional impairment of the gonadostat might occur only at a more severe degree of obesity than that required for a decrease in SHBG and total T levels. We, therefore, determined androgen and precursor levels in three groups of male subjects: nonobese controls [body mass index (BMI), G (kg)/L2 (m) < 26; n = 70]; moderately (BMI, 30-35; n = 18), and severely (BMI, > 40; n = 22) obese men, respectively. In a subgroup of these controls, moderately and severely obese subjects, respectively, we studied LH levels as well as LH pulsatility. Moreover, as a decrease in FT levels might affect the metabolic pattern of the androgens and, more specifically, 5 alpha-reductase activity, we determined the plasma levels of the major 5 alpha-reduced metabolites, androstanediol glucuronide and androsterone glucuronide (AG), as well as the urinary excretion of the major 5 alpha (androsterone glucuronide) and the major 5 beta (etiocholanolone glucuronide) metabolite of the androgens. In moderately obese men, T levels were decreased, which was the consequence of the decreased SHBG-binding capacity. FT levels, however, were normal as were LH levels and both pulse amplitude and frequency of LH pulses, suggesting a normal hypothalamic control of LH secretion. In severely obese men (BMI, > 40), total T, FT, and LH levels as well as LH pulse amplitude were decreased, indicating a functional impairment of the gonadostat. Even in massively obese subjects with decreased FT levels, androgen metabolism and 5 alpha-reductase activity appeared to be normal, as suggested by similar androstanediol glucuronide and AG levels, determined by RIA or calculated from the conversion rates of precursors obtained in nonobese subjects. This was confirmed by the similar AG/eticholanolone glucuronide ratios in obese and nonobese men.(ABSTRACT TRUNCATED AT 400 WORDS)

Origin and significance of plasma androsterone glucuronide levels: a parameter of adrenal androgen secretion and hepatic 5 alpha-reductase activity.

To evaluate the reliability of plasma androsterone glucuronide (ADTG) as a parameter of androgenicity at the target tissue level, we studied the origin of ADTG in women, by measuring the plasma conversion rate of different possible precursors as well as by measuring ADTG levels in ovariectomized women and women with Addison's disease. In women, ADTG levels reflect essentially adrenal androgen secretion, dehydroepiandrosterone sulfate (DHEAS) being the major precursor, accounting for 70%-80% of ADTG levels. As estimated from the ADTG/DHEAS ratio in hirsute women (increased peripheral 5 alpha-reductase) and hyperthyroid women (increased hepatic 5 alpha-reductase), it appears that hepatic 5 alpha-reductase is a major determinant of the conversion of precursors to plasma ADTG. In men, plasma testosterone and DHEAS appear to contribute to a comparable extent to plasma ADTG levels, as suggested by data obtained in orchidectomized men and men with Addison's disease. In accordance with the role of DHEAS as a precursor, plasma levels of ADTG decrease significantly with age in both men and women. Our data do not support the concept that plasma ADTG levels reflect primarily peripheral androgen formation.

Androsterone Glucuronide is a Marker of Adrenal Hyperandrogenism in Hirsute Women

Androsterone glucuronide (Andros-G), a dihydrotestosterone metabolite, is present in serum at concentrations at least tenfold greater than those of androstanediol glucuronide. To investigate the significance of serum androsterone glucuronide, we developed a direct radioimmunoassay for this compound and measured its levels in normal women, women with mild or severe idiopathic hirsutism (IH), hirsute women with polycystic ovarian syndrome (PCO), and non-hirsute obese women. To determine the source of Andros-G precursors, serum levels were measured before and after selective ovarian suppression with leuprolide, combined ovarian and adrenal suppression with leuprolide and dexamethasone, and adrenal stimulation with ACTH. Androsterone glucuronide levels (nmol/l; mean +/- SD) were significantly higher (P less than 0.025) in women with mild idiopathic hirsutism (IH) (185 +/- 91), severe IH (173 +/- 97), and hirsute women with polycystic ovarian syndrome (PCO) (178 +/- 102) than in normal women (110 +/- 26). Levels in non-hirsute obese women (64 +/- 19) were lower than in normal women (P less than 0.01). Baseline levels (mean +/- SEM) in hirsute women given 20 micrograms/kg/day leuprolide for 5-9 months (171 +/- 15) were not significantly changed after leuprolide alone (153 +/- 18), and were decreased after adding dexamethasone (19 +/- 6; P less than 0.001). Andros-G levels did not increase significantly in normal women 60 min after i.v. ACTH (112 +/- 14 to 126 +/- 19), but rose in IH (170 +/- 24 to 216 +/- 26; P less than 0.001) and in PCO (179 +/- 26 to 238 +/- 31; P = 0.002). We conclude that Andros-G in women arises primarily from adrenal gland precursors and is elevated in hirsute women as a group. Its levels do not correlate with the severity of hirsutism, or the presence or absence of PCO, but reflect an increased production of adrenal androgens in both IH and PCO.

ANDROSTERONE GLUCURONIDE IS A MARKER OF ADRENAL HYPERANDROGENISM IN HIRSUTE WOMEN

Androsterone glucuronide (Andros-G), a dihydrotestosterone metabolite, is present in serum at concentrations at least tenfold greater than those of androstanediol glucuronide. To investigate the significance of serum androsterone glucuronide, we developed a direct radioimmunoassay for this compound and measured its levels in normal women, women with mild or severe idiopathic hirsutism (IH), hirsute women with polycystic ovarian syndrome (PCO), and non-hirsute obese women. To determine the source of Andros-G precursors, serum levels were measured before and after selective ovarian suppression with leuprolide, combined ovarian and adrenal suppression with leuprolide and dexamethasone, and adrenal stimulation with ACTH. Androsterone glucuronide levels (nmol/l; mean +/- SD) were significantly higher (P less than 0.025) in women with mild idiopathic hirsutism (IH) (185 +/- 91), severe IH (173 +/- 97), and hirsute women with polycystic ovarian syndrome (PCO) (178 +/- 102) than in normal women (110 +/- 26). Levels in non-hirsute obese women (64 +/- 19) were lower than in normal women (P less than 0.01). Baseline levels (mean +/- SEM) in hirsute women given 20 micrograms/kg/day leuprolide for 5-9 months (171 +/- 15) were not significantly changed after leuprolide alone (153 +/- 18), and were decreased after adding dexamethasone (19 +/- 6; P less than 0.001). Andros-G levels did not increase significantly in normal women 60 min after i.v. ACTH (112 +/- 14 to 126 +/- 19), but rose in IH (170 +/- 24 to 216 +/- 26; P less than 0.001) and in PCO (179 +/- 26 to 238 +/- 31; P = 0.002). We conclude that Andros-G in women arises primarily from adrenal gland precursors and is elevated in hirsute women as a group. Its levels do not correlate with the severity of hirsutism, or the presence or absence of PCO, but reflect an increased production of adrenal androgens in both IH and PCO.

Effect of MK‐906, a Specific 5α‐reductase Inhibitor, on Serum Androgens and Androgen Conjugates in Normal Men

To determine the hormonal effects of MK-906, an orally active 5 alpha-reductase inhibitor, on serum androgens and androgen conjugates, 12 healthy men were given 10, 20, 50, and 100 mg MK-906 2 weeks apart in randomized order in a 4-period crossover design. Serum testosterone (T), dihydrotestosterone (DHT), androstanediol glucuronide, and androsterone glucuronide were measured before and 24 hours after each dose. The effect of MK-906 on glucuronyl transferase activity, the enzyme responsible for androstanediol glucuronide and androsterone glucuronide formation, was assessed in vitro using rat prostate tissue. Serum T levels were unchanged after all doses. Serum DHT, androstanediol glucuronide, and androsterone glucuronide were suppressed by 70, 40, and 56%, respectively, after the 10-mg dose, and by 82, 52, and 66% after the 100-mg dose (P less than 0.02 for the comparison between the 10 and 100-mg doses for all three steroids), respectively. Baseline serum T and DHT levels were strongly correlated (R = 0.89, P = 0.0002), as were androstanediol glucuronide and androsterone glucuronide levels (R = 0.78, P = 0.003), but there was no correlation between DHT levels and the levels of either conjugated steroid. MK-906 had no effect on glucuronyl transferase activity in vitro. It was concluded that single doses of MK-906 suppress both conjugated and unconjugated 5 alpha-reduced androgens. While all three steroids appeared to be good markers of systemic 5 alpha-reductase inhibition, further research will be needed to determine which steroid best reflects tissue DHT levels in patients receiving these inhibitors.

Abnormal hormone levels in men with coronary artery disease.

Plasma concentrations and urinary excretions of various hormones and hormone metabolites were measured in four groups. Group 1 was composed of 13 men with prior myocardial infarction; Group 2 contained 35 clinically normal men; Group 3 consisted of 44 men with normal coronary arteriograms; and Group 4 was composed of 25 men with severe coronary artery disease shown on arteriogram but no infarction. There were four major findings: Group 1 had significantly higher 24-hour mean plasma concentrations of estrone (E1), dehydroisoandrosterone (DHA), and dehydroisoandrosterone sulfate (DHAS) than Group 2, while Group 3 had the same levels as Group 4; Group 4 had significantly lower urinary excretion of androsterone glucuronide (AG) than Group 3, while Group 1 excreted normal amounts. There are three possible explanations for these findings: 1) myocardial infarction occurring in men with coronary artery disease may elevate the plasma levels of E1, DHA, and DHAS and eliminate the preinfarction depression of urinary AG levels; 2) higher than average levels of E1, DHA, DHAS, and AG may favor the development of infarction in men with coronary artery disease; 3) higher than average levels of E1, DHA, DHAS, and AG may favor survival from any infarction that occurs in men with coronary artery disease. Experimental and epidemiological evidence seems to favor the third possibility.