Serum testosterone, dihydrotestosterone and estradiol concentrations in older men self-reporting very good health: the healthy man study

Lowered testosterone in male obesity: mechanisms, morbidity and management

With increasing modernization and urbanization of Asia, much of the future focus of the obesity epidemic will be in the Asian region. Low testosterone levels are frequently encountered in obese men who do not otherwise have a recognizable hypothalamic-pituitary-testicular (HPT) axis pathology. Moderate obesity predominantly decreases total testosterone due to insulin resistance-associated reductions in sex hormone binding globulin. More severe obesity is additionally associated with reductions in free testosterone levels due to suppression of the HPT axis. Low testosterone by itself leads to increasing adiposity, creating a self-perpetuating cycle of metabolic complications. Obesity-associated hypotestosteronemia is a functional, non-permanent state, which can be reversible, but this requires substantial weight loss. While testosterone treatment can lead to moderate reductions in fat mass, obesity by itself, in the absence of symptomatic androgen deficiency, is not an established indication for testosterone therapy. Testosterone therapy may lead to a worsening of untreated sleep apnea and compromise fertility. Whether testosterone therapy augments diet- and exercise-induced weight loss requires evaluation in adequately designed randomized controlled clinical trials.

Sex steroids and glucose metabolism

Testosterone levels are lower in men with metabolic syndrome and type 2 diabetes mellitus (T2DM) and also predict the onset of these adverse metabolic states. Body composition (body mass index, waist circumference) is an important mediator of this relationship. Sex hormone binding globulin is also inversely associated with insulin resistance and T2DM but the data regarding estrogen are inconsistent. Clinical models of androgen deficiency including Klinefelter's syndrome and androgen deprivation therapy in the treatment of advanced prostate cancer confirm the association between androgens and glucose status. Experimental manipulation of the insulin/glucose milieu and suppression of endogenous testicular function suggests the relationship between androgens and insulin sensitivity is bidirectional. Androgen therapy in men without diabetes is not able to differentiate the effect on insulin resistance from that on fat mass, in particular visceral adiposity. Similarly, several small clinical studies have examined the efficacy of exogenous testosterone in men with T2DM, however, the role of androgens, independent of body composition, in modifying insulin resistance is uncertain.

Are we testing appropriately for low testosterone?: Characterization of tested men and compliance with current guidelines

INTRODUCTION

Direct-to-consumer ads for testosterone replacement therapies have significantly increased over the past several years. Subsequently, testing for low serum testosterone has correspondingly increased.

AIMS

We sought to determine the testing behaviors of practitioners as well as the characteristics of men who are undergoing testing for low testosterone.

METHODS

Men aged 18-85 years were queried from the institutional electronic data warehouse from 2009 to 2012. Men were considered "tested" if their serum total testosterone level had been measured for any purpose. Tested men (TM) were compared with those not tested (NT).

MAIN OUTCOME MEASURES

The frequency and timing of testing for low testosterone as well as patient demographics and clinical characteristics were compared between TM and NT using multivariable logistic regression models.

RESULTS

Of the 321,674 total men, 10,133 (3.2%) underwent testing with a serum total testosterone (mean age of 55.2 ± 14.1 years). The frequency of testing increased from 2.5% to 3.6% during the study period (P < 0.001). Multivariable analysis demonstrated that TM were significantly (P < 0.001) more likely to be Caucasian and have increased body mass index. In addition, TM were significantly more likely to have comorbid conditions including decreased libido (adjusted odds ratio [aOR] 10.0, 95% confidence interval [CI] 8.5, 11.7), infertility (aOR 4.8, 95% CI 3.6, 6.6), erectile dysfunction (aOR 3.6, 95% CI 3.4, 3.8), osteoporosis (aOR 3.3, 95% CI 2.8, 3.8), depression (aOR 1.7, 95% CI 1.6, 1.8), prostate cancer (aOR 1.7, 95% CI 1.5, 1.8), hypertension (aOR 1.3. 95% CI 1.2, 1.4), chronic obstructive pulmonary disease (aOR 1.2, 95% CI 1.0, 1.4), and benign prostatic hyperplasia (aOR 1.2, 95% CI 1.1, 1.2). Among TM, only 889 (9%) men underwent testing between 7 am and 12 pm.

CONCLUSIONS

The rate of testosterone testing is increasing with most testing practices directed toward a subset of men with comorbidities that are associated with hypogonadism. Compliance of physicians obtaining early morning serum testosterone levels is low. Further education of practitioners is required to appropriately test patients for hypogonadism.

A validated age-related normative model for male total testosterone shows increasing variance but no decline after age 40 years

The diagnosis of hypogonadism in human males includes identification of low serum testosterone levels, and hence there is an underlying assumption that normal ranges of testosterone for the healthy population are known for all ages. However, to our knowledge, no such reference model exists in the literature, and hence the availability of an applicable biochemical reference range would be helpful for the clinical assessment of hypogonadal men. In this study, using model selection and validation analysis of data identified and extracted from thirteen studies, we derive and validate a normative model of total testosterone across the lifespan in healthy men. We show that total testosterone peaks [mean (2.5-97.5 percentile)] at 15.4 (7.2-31.1) nmol/L at an average age of 19 years, and falls in the average case [mean (2.5-97.5 percentile)] to 13.0 (6.6-25.3) nmol/L by age 40 years, but we find no evidence for a further fall in mean total testosterone with increasing age through to old age. However we do show that there is an increased variation in total testosterone levels with advancing age after age 40 years. This model provides the age related reference ranges needed to support research and clinical decision making in males who have symptoms that may be due to hypogonadism.

Diagnosing and managing low serum testosterone

Measuring testosterone levels became easier in the 1970s, and it wasn't long before levels were being checked in men across all age groups. At that time, several authors reported an age-associated decline of serum testosterone levels beginning in the fourth or fifth decades of life. Other studies found that the decline in testosterone with age might be more related to comorbidities that develop in many aging men. Aggressive marketing campaigns by pharmaceutical companies have led to increased awareness of this topic, and primary care physicians are seeing more patients who are concerned about "low T." Unfortunately, testosterone replacement therapy has not been straightforward. Many men with low testosterone levels have no symptoms, and many men with symptoms who receive treatment and reach goal testosterone levels have no improvement in their symptoms. The actual prevalence of hypogonadism has been estimated to be 39% in men aged 45 years or older presenting to primary care offices in the United States. As the US population ages, this number is likely to increase. This article, targeted to primary care physicians, reviews the concept of late-onset hypogonadism, describes how to determine the patients who might benefit from therapy, and offers recommendations regarding the workup and initiation of treatment.

The implications of low testosterone on mortality in men

Testosterone levels in men slowly decline with aging and also decline more abruptly due to medical illness or medications. Prescriptions for testosterone have increased dramatically over the past decade, since a testosterone-gel formulation was approved and since numerous studies reported an association between low serum testosterone and increased mortality. However, recent observational studies of testosterone treatment have reported conflicting results with some studies reporting decreased risks for mortality while others reported increased mortality risks with testosterone treatment. This paper will summarize recent studies of low serum testosterone and mortality and testosterone treatment and mortality and what the potential implications of these studies are for the clinician.

Differential associations of testosterone, dihydrotestosterone and oestradiol with physical, metabolic and health-related factors in community-dwelling men aged 17-97 years from the Busselton Health Survey

OBJECTIVES

Lower testosterone (T) levels are associated with poorer health outcomes in older men, but associations in younger or middle-aged men are uncertain, and data for dihydrotestosterone (DHT) and oestradiol (E2) are limited. We assessed the associations of circulating T, DHT and E2 with physical and health-related factors in a cohort comprising men aged 17-97 years.

PARTICIPANTS AND METHODS

Serum from 2143 community-dwelling men from the 1994/95 Busselton Health Survey was assayed for T, DHT and E2 using liquid chromatography-tandem mass spectrometry. Men receiving hormonal therapy or reporting the use of testosterone, or with prostate cancer or orchidectomy were excluded.

RESULTS

Of the men, 43% had never smoked, 6·1% had diabetes and 16·8% cardiovascular disease (CVD). Mean (±SD) age was 50·3 ± 17·0 years. Total T was moderately correlated with DHT (r = 0·56), E2 (r = 0·35) and sex hormone-binding globulin (r = 0·53). In age-, smoking-, body mass index (BMI)- and sex hormone-binding globulin (SHBG)-adjusted analyses, T was inversely associated with metabolic syndrome score, while DHT and E2 were not associated. In multivariable models, higher total T was associated with lower age, BMI and C-reactive protein, and with higher creatinine and haemoglobin, independently of SHBG. Higher DHT was associated with lower age, BMI and glucose level, and higher creatinine and haemoglobin. E2 was positively associated with age, BMI and haemoglobin.

CONCLUSIONS

In men spanning younger, middle and older ages, circulating androgens are more related to age and metabolic factors than CVD or chronic disease. Further investigation is required to clarify whether androgens and oestrogens have contrasting roles as risk predictors for CVD.

Human metabolome associates with dietary intake habits among African Americans in the atherosclerosis risk in communities study

The human metabolome is a measurable outcome of interactions among an individual's inherited genome, microbiome, and dietary intake. We explored the relationship between dietary intake and serum untargeted metabolomic profiles in a subsample of 1,977 African Americans from the Atherosclerosis Risk in Communities (ARIC) Study in 1987-1989. For each metabolite, we conducted linear regression to estimate its relationships with each food group and food category. Potential confounding factors included age, sex, body mass index (weight (kg)/height (m)(2)), energy intake, kidney function, and food groups. We used a modified Bonferroni correction to determine statistical significance. In total, 48 pairs of diet-metabolite associations were identified, including multiple novel associations. The food group "sugar-rich foods and beverages" was inversely associated with 5 metabolites in the 2-hydroxybutyrate-related subpathway and positively associated with 5 γ-glutamyl dipeptides. The hypothesized mechanism of these associations may be through oxidative stress. "Sugar-rich foods and beverages" were also inversely associated with 7 unsaturated long-chain fatty acids. These findings suggest that the contribution of a sugar-rich dietary pattern to increased cardiovascular disease risk may be partially attributed to oxidative stress and disordered lipid profiles. Metabolomics may reveal novel metabolic biomarkers of dietary intake and provide insight into biochemical pathways underlying nutritional effects on disease development.

Testosterone therapy in older men with late-onset hypogonadism: a counter-rationale

OBJECTIVE

The past decade has seen a surge in referrals of older men for consideration of testosterone therapy for late-onset hypogonadism (LOH) to treat symptoms such as fatigue, sexual dysfunction and decreased vitality. Prescription sales of testosterone have accordingly increased by 20-fold over the same period, due mainly to marketing campaign as well as to the failure of clinicians to distinguish organic hypogonadism from LOH. This review seeks to provide a counter-rationale for testosterone therapy in LOH.

METHODS

A retrospective review of English-language epidemiologic studies, clinical trials and their relevant cited studies related to testosterone and older men was carried out.

RESULTS

Shortcomings of population studies on LOH include use of multiple numeric definitions and non-standard testosterone assays, and measurement of testosterone at a single time point. In contrast to higher estimates of prevalence based solely on numeric values, the syndromic prevalence of LOH is only 2%. Although attrition of testicular Leydig cells and slowing of gonadotropin-releasing hormone neurons both contribute to LOH, obesity and other comorbidities strongly influence testosterone levels, suggesting that testosterone is a biomarker of health. Testosterone therapy in LOH has consistently resulted in improvements in muscle mass and strength, although data regarding effects on physical function and improvements in fall and fracture rates remain unknown. Eythrocytosis is the most common adverse effect of testosterone therapy in older men, while long-term risks in the prostate and cardiovascular system remain unclear.

CONCLUSION

Considering the paucity of data on clinically meaningful outcomes, the number of uncertain risks, and the fact that modifiable risk factors adversely influence testosterone levels, healthy lifestyle and treatment of comorbidities might attenuate age-related declines in testosterone levels.

Hormonal changes and their impact on cognition and mental health of ageing men

Demographic changes resulting in ageing of the world's population have major implications for health. As men grow older, circulating levels of the principal androgen or male sex hormone testosterone (T) decline, while the prevalence of ill-health increases. Observational studies in middle-aged and older men have shown associations between lower levels of T and poorer mental health in older men, including worse cognitive performance, dementia and presence of depressive symptoms. The role of T metabolites, the more potent androgen dihydrotestosterone (DHT) and the oestrogen receptor ligand estradiol (E2) in the pathophysiology of cognitive decline are unclear. Studies of men undergoing androgen deprivation therapy in the setting of prostate cancer have shown subtle detrimental effects of reduced T levels on cognitive performance. Randomised trials of T supplementation in older men have been limited in size and produced variable results, with some studies showing improvement in specific tests of cognitive function. Interventional data from trials of T therapy in men with dementia are limited. Lower levels of T have also been associated with depressive symptoms in older men. Some studies have reported an effect of T therapy to improve mood and depressive symptoms in men with low or low-normal T levels. T supplementation should be considered in men with a diagnosis of androgen deficiency. Beyond this clinical indication, further research is needed to establish the benefits of T supplementation in older men at risk of deteriorating cognition and mental health.

Testosterone, aging and survival: biomarker or deficiency

PURPOSE OF REVIEW

The purpose of this study is to review recent studies that examined the association of endogenous and exogenous testosterone and mortality in older men.

RECENT FINDINGS

Over the past several years, there has been a steep rise in testosterone prescriptions. The increased use of testosterone occurred in the context of several studies that reported an association between low serum testosterone and increased cardiovascular events and mortality. In contrast, recent studies have reported an association between testosterone treatment and adverse events. A testosterone treatment trial of mobility-impaired elderly men with prevalent cardiovascular disease was stopped due to increased cardiovascular events in the T-treated men and a meta-analysis reported increased cardiovascular events in T-treated men. In two recent large observational studies, testosterone treatment was associated with an increased risk for serious adverse cardiovascular events.

SUMMARY

Low testosterone is associated with mortality in multiple cohort studies; however, it is unclear if this is a causal association or due to low testosterone being a biomarker of poor health. Given recent reports of adverse outcomes associated with testosterone treatment, a conservative use of testosterone is warranted in men with cardiovascular disease who may be at greater risk for adverse outcomes.

Testosterone and cardiovascular disease

PURPOSE OF REVIEW

Use of testosterone among men is increasing rapidly. Low serum testosterone is positively associated with cardiovascular disease and its risk factors. No large randomized controlled trial (RCT) has assessed the effects of testosterone on cardiovascular outcomes. Here recent evidence accumulating from other sources - pharmacoepidemiology, Mendelian randomization studies and meta-analysis of small RCTs - is reviewed to inform current testosterone usage.

RECENT FINDINGS

In a large, well conducted pharmacoepidemiology study specifically testosterone prescription was associated with myocardial infarction. Two Mendelian randomization studies did not corroborate beneficial effects of higher endogenous testosterone on cardiovascular risk factors, but suggested higher endogenous testosterone raised LDL cholesterol and lowered HDL cholesterol. A comprehensive meta-analysis of RCTs summarizing 27 trials including 2994 men found increased risk of cardiovascular-related events on testosterone (odds ratio 1.54, 95% confidence interval 1.09-2.18).

SUMMARY

Contrary to expectations from observational studies, current indications suggest testosterone causes ischemic cardiovascular disease with corresponding implications for practice. A large RCT would undoubtedly settle the issue definitively. Given mounting evidence of harm and the urgency of the situation assembling all the evidence from completed RCTs of testosterone or androgen deprivation therapy and use of Mendelian randomization might generate a definitive answer most quickly.

Longitudinal and cross-sectional relationships of circulating reproductive hormone levels to self-rated health and health-related quality of life in community-dwelling older men

CONTEXT

Self-rated health and health-related quality of life are inversely associated with increased morbidity and mortality; however, the temporal relationship with reproductive hormones is poorly understood.

OBJECTIVES

The objective of the study was to examine relationships between reproductive hormones, self-rated health, and quality of life in older men at baseline as well as changes over a 2-year follow-up.

DESIGN, SETTING, AND PARTICIPANTS

One thousand six hundred thirty-seven men aged 70 years and older from the Concord Health and Ageing in Men Project were assessed at baseline and 1316 men returned for the 2-year follow-up. Serum T, dihydrotestosterone, estradiol, and estrone (E1) were measured by liquid chromatography-tandem mass spectrometry and SHBG, LH, and FSH by immunoassay. Logistic regression and multivariate linear regression models were performed.

OUTCOME MEASURES

Self-rated health and health-related quality of life measures (12-Item Short Form Health Survey) were determined.

RESULTS

In the cross-sectional baseline data, univariate analyses revealed significant associations between many of the hormones and quality-of-life scores and self-rated health. In a multivariable analysis, the associations between T, E1, and calculated free T and self-rated health remained statistically significant. Compared with men in the highest T quartile, men in the lowest T quartile had an odds ratio of 1.47 (95% confidence interval 1.04-2.06) for reporting fair, poor, or very poor health vs excellent or good health. The findings for E1 and calculated free T were similar. In the longitudinal data, the only significant relationship was that between E1 and self-rated health. Compared with those in the highest E1 quartile, those in the lowest quartile experienced deterioration in self-rated health: adjusted odds ratio of 1.84 (95% confidence interval 1.10-3.06).

CONCLUSION

Low serum T and E1 are associated with poorer self-rated health in older men, whereas lower serum levels of E1 are predictive of subsequent deterioration in self-rated health over time. Therefore, serum E1 is a novel potential risk factor for poor self-rated health in older men that warrants further investigation.

Serum sex steroids and steroidogenesis-related enzyme expression in skeletal muscle during experimental weight gain in men

OBJECTIVES

Low-circulating testosterone is associated with development of type 2 diabetes in obese men. In this study, we examined the effects of experimental overfeeding and weight gain on serum levels of sex hormones and skeletal muscle expression of steroidogenic enzymes in healthy men with (FH+) and without (FH-) a family history of type 2 diabetes.

METHODS

Following a 3-day lead in energy balanced diet, FH+ (n = 9) and FH- men (n = 11) were overfed by 5200 kJ/day (45% fat) for 28 days. Body weight, fasting glucose, insulin, sex steroid, sex hormone binding globulin (SHBG) levels, insulin sensitivity (hyperinsulinaemic-euglycaemic clamp) and body fat (DXA) were assessed in all individuals at baseline and day 28, and sex steroidogenesis-related enzyme expression in vastus lateralis biopsies was examined in a subset (n = 11).

RESULTS

Body weight, fat mass and fasting insulin levels were increased by overfeeding (P < 0.01) and insulin was increased significantly more in FH+ men (P<0.01). Serum sex hormone binding globulin (SHBG) and 5α-dihydrotestosterone (DHT) were reduced with overfeeding (P < 0.05), and serum testosterone and DHT were reduced to a greater extent in FH+ men (P < 0.05). Overfeeding reduced mRNA expression of 3β-hydroxysteroid dehydrogenase (HSD) and 17βHSD (P ≤ 0.007), independently of group. 5α-Reductase (SRD5A1) mRNA expression was not changed overall, but a time by group interaction was observed (P = 0.04).

CONCLUSION

Overfeeding reduced SHBG and muscle expression of enzymes involved in the formation of testosterone in skeletal muscle. Men with a family history of T2DM were more susceptible to deleterious outcomes of overfeeding with greater reductions in serum testosterone and DHT and greater increases in markers of insulin resistance, which may contribute to increased risk of developing type 2 diabetes.

Osteoporosis in men: a review

Osteoporosis and consequent fracture are not limited to postmenopausal women. There is increasing attention being paid to osteoporosis in older men. Men suffer osteoporotic fractures about 10 years later in life than women, but life expectancy is increasing faster in men than women. Thus, men are living long enough to fracture, and when they do the consequences are greater than in women, with men having about twice the 1-year fatality rate after hip fracture, compared to women. Men at high risk for fracture include those men who have already had a fragility fracture, men on oral glucocorticoids or those men being treated for prostate cancer with androgen deprivation therapy. Beyond these high risk men, there are many other risk factors and secondary causes of osteoporosis in men. Evaluation includes careful history and physical examination to reveal potential secondary causes, including many medications, a short list of laboratory tests, and bone mineral density testing by dual energy X-ray absorptiometry (DXA) of spine and hip. Recently, international organizations have advocated a single normative database for interpreting DXA testing in men and women. The consequences of this change need to be determined. There are several choices of therapy for osteoporosis in men, with most fracture reduction estimation based on studies in women.

Testosterone and glucose metabolism in men: current concepts and controversies

A wealth of observational studies show that low testosterone is associated with insulin resistance and with an increased risk of diabetes and the metabolic syndrome. Experimental studies have identified potential mechanisms by which low testosterone may lead to insulin resistance. Visceral adipose tissue is an important intermediate in this relationship. Actions of testosterone or its metabolite oestradiol on other tissues such as muscle, liver, bone or the brain, and body composition-independent effects may also play a role. However, definitive evidence from randomised controlled trials (RCTs) to clarify whether the association of low testosterone with disordered glucose metabolism is causative is currently lacking. It therefore remains possible that this association is due to reverse causation, or simply originates by association with common health and lifestyle factors. RCTs of testosterone therapy in men with or without diabetes consistently show modest metabolically favourable changes in body composition. Despite this, testosterone effects on glucose metabolism have been inconsistent. Recent evidence suggests that the hypothalamic-pituitary-testicular axis suppression in the majority of obese men with metabolic disorders is functional, and may be, at least in part, reversible with weight loss. Until further evidence is available, lifestyle measures with emphasis on weight reduction, treatment of comorbidities and optimisation of diabetic control should remain the first-line treatment in these men. Such measures, if successful, may be sufficient to normalise testosterone levels in men with metabolic disorders, who typically have only modest reductions in circulating testosterone levels.

Impact of moderate calorie restriction on testicular morphology and endocrine function in adult rhesus macaques (Macaca mulatta)

We previously reported that moderate calorie restriction (CR) has minimal impact on testicular gene expression in young adult rhesus macaques, and no obvious negative impact on semen quality or plasma testosterone levels. We now extend these findings by examining the influence of CR on various aspects of the reproductive axis of older males, including 24-h circulating testosterone levels, testicular gene expression, and testicular morphology. Young adult and old adult male rhesus macaques were subjected to either 30 % CR for 5-7 years, or were fed a standard control diet. Analysis of the 24-h plasma testosterone profiles revealed a significant age-associated decline, but no evidence for CR-induced suppression in either the young or old males. Similarly, expression profiling of key genes associated with testosterone biosynthesis and Leydig cell maintenance showed no significant CR-induced changes in either the young or old animals. The only evidence for CR-associated negative effects on the testis was detected in the old animals at the histological level; when old CR animals were compared with their age-matched controls, there was a modest decrease in seminiferous tubule diameter and epithelium height, with a concomitant increase in the number of depleted germ cell lines. Reassuringly, data from this study and our previous study suggest that moderate CR does not negatively impact 24-h plasma testosterone profiles or testicular gene expression. Although there appear to be some minor CR-induced effects on testicular morphology in old animals, it is unclear if these would significantly compromise fertility.

Performance of direct estradiol immunoassays with human male serum samples

BACKGROUND

Steroid immunoassays originally required solvent extraction, chromatography, and structurally authentic tracers to avoid interference from steroid cross-reactivity and matrix effects. The demand for steroid assays has driven assay simplification, bypassing this triplet of validity criteria to allow use of unextracted serum, which has introduced bias and nonspecificity at low steroid concentrations. We aimed to evaluate the performance of commercial direct estradiol (E2) immunoassays relative to the reference method of LC-MS and compared serum E2 measurements from each assay with biomarkers of estrogen action.

METHODS

We measured serum E2 in duplicate using 5 commercial direct immunoassays and LC-MS in a nested cohort of 101 healthy, asymptomatic men >40 years old from the Healthy Man Study. For each immunoassay, we evaluated the detectability and distribution of serum E2 measurements, CV, and bias (relative to LC-MS) by Passing-Bablok regression and deviance plots.

RESULTS

Three assays detected E2 in all samples, whereas E2 was detected in only 53% and 72% of samples by 2 other assays. All 5 assays had positive biases, ranging from 6% to 74%, throughout their ranges. CVs were lower with 4 immunoassays than with LC-MS. LC-MS, but none of the direct immunoassays, correlated with serum testosterone and sex steroid-binding globulin.

CONCLUSIONS

The positive bias of direct E2 immunoassays throughout their working range reflects the nonspecific effects of steroid cross-reactivity and/or matrix interference arising from the violation of the triplet validity criteria for steroid immunoassay.

Obesity and age as dominant correlates of low testosterone in men irrespective of diabetes status

Although men with type 2 diabetes (T2D) frequently have lowered testosterone levels, it is not well established whether this is ascribable to the diabetic state per se, or because of other factors, such as obesity. Our objective was to determine the prevalence and correlates of low testosterone in middle-aged men with diabetes. We conducted a cross-sectional study in 240 men including 80 men with type 1 diabetes (T1D), 80 men with T2D and 80 men without diabetes. Prevalence of a total testosterone ≤8 nmol/L was low, occurring in none of the men with T1D, 6.2% of men with T2D and 2.5% of men without diabetes. Men with T1D had higher testosterone levels compared with men without diabetes (p < 0.001), even after adjustment for body mass index (BMI) and age (p < 0.02). While men with T2D had lower testosterone compared with controls (p = 0.03), this was no longer significant when BMI and age were taken into account (p = 0.16). In the entire cohort, TT remained inversely associated with BMI independent of age, sex hormone-binding globulin and diabetic status (p = 0.01), whereas calculated free testosterone (cFT) was independently and inversely associated with age (p < 0.001), but not with BMI (p = 0.47). These results suggest that marked reductions in circulating testosterone are uncommon in middle-aged men with diabetes. Increasing BMI and age are dominant drivers of lowered total and cFT, respectively, independent of the presence or absence of diabetes.

Genome-wide association study of sex hormones, gonadotropins and sex hormone-binding protein in Chinese men

BACKGROUND

Sex hormones and gonadotropins exert a wide variety of effects in physiological and pathological processes. Accumulated evidence shows a strong heritable component of circulating concentrations of these hormones. Recently, several genome-wide association studies (GWASs) conducted in Caucasians have identified multiple loci that influence serum levels of sex hormones. However, the genetic determinants remain unknown in Chinese populations. In this study, we aimed to identify genetic variants associated with major sex hormones, gonadotropins, including testosterone, oestradiol, follicle-stimulating hormone (FSH), luteinising hormone (LH) and sex hormone binding globulin (SHBG) in a Chinese population.

METHODS

A two-stage GWAS was conducted in a total of 3495 healthy Chinese men (1999 subjects in the GWAS discovery stage and 1496 in the confirmation stage).

RESULTS

We identified a novel genetic region at 15q21.2 (rs2414095 in CYP19A1), which was significantly associated with oestradiol and FSH in the Chinese population at a genome-wide significant level (p=6.54×10(-31) and 1.59×10(-16), respectively). Another single nucleotide polymorphism in CYP19A1 gene was significantly associated with oestradiol level (rs2445762, p=7.75×10(-28)). In addition, we confirmed the previous GWAS-identified locus at 17p13.1 for testosterone (rs2075230, p=1.13×10(-8)) and SHBG level (rs2075230, p=4.75×10(-19)) in the Chinese population.

CONCLUSIONS

This study is the first GWAS investigation of genetic determinants of FSH and LH. The identification of novel susceptibility loci may provide more biological implications for the synthesis and metabolism of these hormones. More importantly, the confirmation of the genetic loci for testosterone and SHBG suggests common genetic components shared among different ethnicities.

The prevalence of couple infertility in the United States from a male perspective: evidence from a nationally representative sample

Infertility is a couple-based fecundity impairment, although population level research is largely based upon information reported by female partners. Of the few studies focusing on male partners, most focus on the utilization of infertility services rather than efforts to estimate the prevalence and determinants of infertility as reported by male partners. Data from a nationally representative sample of men aged 15-44 years who participated in the 2002 National Survey of Family Growth (NSFG) were used to estimate the prevalence of infertility and determinants of longer time-to-pregnancy (TTP) using the novel current duration (CD) approach. Using backward recurrence time parametric survival methods, we estimated infertility prevalence (TTP > 12 months) and time ratios (TR) associated with TTP as derived from males' reported CD of their pregnancy attempt. The estimated prevalence of infertility was 12.0% (95% CI: 7.0, 23.2). Longer TTP was associated with older male age (35-45 vs. 17-24 years) (TR: 2.49; 95% CI: 1.03, 6.03), biological childlessness (TR: 1.53; 95% CI: 1.07, 2.19) and lack of health insurance (TR: 1.73; 95% CI: 1.02, 2.94) after controlling for the differences in couples' age and other socioeconomic factors. The prevalence of infertility based on male reporting is consistent with estimates of infertility in the US found in prospective cohort studies and CD studies based on female reporting. Our findings suggest that male partners can reliably inform about couple infertility. Interventions and services aimed at reducing couple infertility should include attention to male factors associated with longer TTP identified in this study.

Osteoporosis in men: recent progress

As osteoporosis in men has been recognized as an important clinical problem, new information is being accumulated on its scope, pathophysiology, evaluation, and treatment. Fracture risk calculators, such as FRAX, identify a large proportion of the older male population to be at heightened risk for fracture. The classification of osteoporosis into primary and secondary forms, while still useful, is affected by the fact that many men have multiple contributing factors to their fracture risk. The role of sex steroids is being better defined as other risk factors for fracture are delineated. As longevity continues to increase in men and until osteoporotic fracture is truly recognized as a potentially fatal disorder, many men will be undiagnosed and untreated. Two recent studies provide more evidence that treatments which decrease fracture risk in women do the same in men. With the publication of guidelines and increasing strength of evidence for treatment efficacy, it is hoped that more men will be evaluated and treated for this often neglected disorder.

Revisiting hyper- and hypo-androgenism by tandem mass spectrometry

Modern endocrinology is living a critical age of transition as far as laboratory testing and biochemical diagnosis are concerned. Novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for steroid measurement in biological fluids have abundantly demonstrated their analytical superiority over immunometric platforms that until now have dominated the world of steroid hormones determination in clinical laboratories. One of the most useful applications of LC-MS/MS is in the hypogonadism and hyperandrogenism field: LC-MS/MS has proved particularly suitable for the detection of low levels of testosterone typical of women and children, and in general more reliable in accurately determining hypogonadal male levels. This technique also offers increased informative power by allowing multi-analytical profiles that give a more comprehensive picture of the overall hormonal asset. Several LC-MS/MS methods for testosterone have been published in the last decade, some of them included other androgen or more comprehensive steroid profiles. LC-MS/MS offers the concrete possibility of achieving a definitive standardization of testosterone measurements and the generation of widely accepted reference intervals, that will set the basis for a consensus on the diagnostic value of biochemical testing. The present review is aimed at summarizing technological advancements in androgen measurements in serum and saliva. We also provide a picture of the state of advancement of standardization of testosterone assays, of the redefinition of androgen reference intervals by novel assays and of studies using LC-MS/MS for the characterization and diagnosis of female hyperandrogenism and male hypogonadism.

Sex steroid hormone levels and body composition in men

BACKGROUND

Previous studies indicate that testosterone (T) is positively correlated with lean mass and inversely correlated with fat mass in men; however, the directionality of these associations, as well as the association with other hormones including estradiol (E2) and SHBG, is unclear.

METHODS

We examined cross-sectional and longitudinal associations of E2, T, SHBG, and E2/T ratio with body composition among men ages 30 to 79 in the Boston Area Community Health/Bone Survey. Total, trunk, and appendicular lean and fat mass were measured by dual-energy x-ray absorptiometry at baseline, and weight and waist/hip circumference were measured at baseline and follow-up. Partial Pearson correlation coefficients were used to estimate the linear relationship between each body composition measure and log-transformed hormone variable.

RESULTS

In cross-sectional analyses of 821 men, T, calculated free T, and SHBG were inversely correlated with fat mass, weight, body mass index, waist/hip circumference, and waist-to-hip ratio, with multivariable-adjusted correlations ranging from -0.13 to -0.37. Calculated free E2 was positively correlated with percentage total (r = .13) and trunk (r = .15) fat mass, and E2/T was positively correlated with all measures examined (r = .13-.40). There were no significant multivariable-adjusted longitudinal associations between baseline hormone levels and change in weight, body mass index, waist/hip circumference, or waist-to-hip ratio after an average follow-up of 4.8 years.

CONCLUSIONS

We observed significant cross-sectional associations between hormone levels, including E2, T, and E2/T, and body composition measures in men. Longitudinal analyses showing no influence of baseline hormone levels on change in anthropometric measures imply that body composition affects hormone levels and not the reverse.

Reproductive aging in men

Aging in men is associated with a decrease in serum testosterone levels due to attrition in testicular Leydig cells and slowing of the hypothalamic GnRH pulse generator. The practicing endocrinologist is frequently consulted for consideration of testosterone therapy in older men with late-onset hypogonadism (LOH), a condition that many clinicians fail to distinguish from organic hypogonadism. Recent data using syndromic definition show that only 2% of 40-80-year-old men have LOH. Co-morbidities and obesity strongly contribute to LOH, suggesting that testosterone is a biomarker of health. Hence, prevention and treatment of these co-morbidities might attenuate age-related decline in androgen levels.

Testosterone therapy and cardiovascular events among men: a systematic review and meta-analysis of placebo-controlled randomized trials

BACKGROUND

Testosterone therapy is increasingly promoted. No randomized placebo-controlled trial has been implemented to assess the effect of testosterone therapy on cardiovascular events, although very high levels of androgens are thought to promote cardiovascular disease.

METHODS

A systematic review and meta-analysis was conducted of placebo-controlled randomized trials of testosterone therapy among men lasting 12+ weeks reporting cardiovascular-related events. We searched PubMed through the end of 2012 using "("testosterone" or "androgen") and trial and ("random*")" with the selection limited to studies of men in English, supplemented by a bibliographic search of the World Health Organization trial registry. Two reviewers independently searched, selected and assessed study quality with differences resolved by consensus. Two statisticians independently abstracted and analyzed data, using random or fixed effects models, as appropriate, with inverse variance weighting.

RESULTS

Of 1,882 studies identified 27 trials were eligible including 2,994, mainly older, men who experienced 180 cardiovascular-related events. Testosterone therapy increased the risk of a cardiovascular-related event (odds ratio (OR) 1.54, 95% confidence interval (CI) 1.09 to 2.18). The effect of testosterone therapy varied with source of funding (P-value for interaction 0.03), but not with baseline testosterone level (P-value for interaction 0.70). In trials not funded by the pharmaceutical industry the risk of a cardiovascular-related event on testosterone therapy was greater (OR 2.06, 95% CI 1.34 to 3.17) than in pharmaceutical industry funded trials (OR 0.89, 95% CI 0.50 to 1.60).

CONCLUSIONS

The effects of testosterone on cardiovascular-related events varied with source of funding. Nevertheless, overall and particularly in trials not funded by the pharmaceutical industry, exogenous testosterone increased the risk of cardiovascular-related events, with corresponding implications for the use of testosterone therapy.

Simultaneous determination of endogenous steroid hormones in human and animal plasma and serum by liquid or gas chromatography coupled to tandem mass spectrometry

Analytical methodologies based on liquid or gas chromatography coupled to tandem mass spectrometry for the simultaneous determination of two or more endogenous steroid hormones in human and animal plasma and serum has received increased attention the last few years. Especially in the clinical setting steroid profiling is of major importance in disease diagnostics. This paper discusses recent findings in such multi-steroid hormone procedures published from 2001 to 2012. The aim was to elucidate possible relationships between chosen analytical technique and the obtained analyte sensitivity for endogenous steroid hormones. By evaluating the success, at which the currently applied techniques have been utilized, more general knowledge on the field is provided. Furthermore the evaluation provides directions in which future studies may be interesting to conduct.

Ageing and Brugada syndrome: considerations and recommendations

Brugada syndrome is an inherited disease associated with an increased risk of lethal ventricular arrhythmias. Such arrhythmias stem from innate disruptions in cardiac electrophysiology. Typically, such arrhythmias occur in the third or fourth decade of life. However, Brugada syndrome may also affect geriatric patients. In this paper, we focus on the ageing patient with Brugada syndrome, and specifically, on the interaction between Brugada syndrome and the more usually acquired clinical problems that may occur with increasing age, such as the use of cardiovascular and non-cardiovascular drugs, or the need for surgery. Such common conditions may also disrupt cardiac electrophysiology, thereby conferring added risk for Brugada syndrome patients. We present some considerations and recommendations that may serve as guidance to address these complexities.

Abrupt decrease in serum testosterone levels after an oral glucose load in men: implications for screening for hypogonadism

OBJECTIVE

This study examines the physiological impact of a glucose load on serum testosterone (T) levels in men with varying glucose tolerance (GT).

DESIGN

Cross-sectional study.

PATIENTS AND METHODS

74 men (19-74 years, mean 51·4 ± 1·4 years) underwent a standard 75-g oral glucose tolerance test with blood sampling at 0, 30, 60, 90 and 120 min. Fasting serum glucose, insulin, total T (and calculated free T), LH, SHBG, leptin and cortisol were measured.

RESULTS

57% of the men had normal GT, 30% had impaired GT and 13% had newly diagnosed type 2 diabetes. Glucose ingestion was associated with a 25% decrease in mean T levels (delta = -4·2 ± 0·3 nm, P < 0·0001). T levels remained suppressed at 120 min compared with baseline (13·7 ± 0·6 vs 16·5 ± 0·7 nm, P < 0·0001) and did not differ across GT or BMI. Of the 66 men with normal T levels at baseline, 10 (15%) had levels that decreased to the hypogonadal range (<9·7 nm) at one or more time points. SHBG, LH and cortisol levels were unchanged. Leptin levels decreased from baseline at all time points (P < 0·0001).

CONCLUSIONS

Glucose ingestion induces a significant reduction in total and free T levels in men, which is similar across the spectrum of glucose tolerance. This decrease in T appears to be because of a direct testicular defect, but the absence of compensatory changes in LH suggests an additional central component. Men found to have low nonfasting T levels should be re-evaluated in the fasting state.

Low testosterone concentrations in men contribute to the gender gap in cardiovascular morbidity and mortality

BACKGROUND

Across the industrialized world, men experience an earlier onset of cardiovascular disease (CVD) and a life expectancy 5 to 10 years shorter than women. Low total testosterone (TT) concentrations in men have been suggested as a novel CVD risk factor, but its contribution to this gender gap is less well studied.

METHODS

We used data of 4152 individuals (2113 women and 2039 men) aged 20 to 79 years from the longitudinal population-based cohort Study of Health in Pomerania, Germany. Multivariable Poisson and Cox proportional hazard regression models were used to investigate the risk of incident cardiovascular morbidity (5-year examination follow-up), as well as all-cause and CVD mortality (10-year follow-up) between men and women. Additionally, the added risk attributable to low TT in men (<10th percentile) was assessed.

RESULTS

Compared with women, men were uniformly at higher risk of incident cardiovascular morbidity, including overweight, hypertension, dyslipidemia, metabolic syndrome, and type 2 diabetes mellitus. Men were also at increased all-cause mortality (hazard ratio = 2.05; 95% CI, 1.61-2.60) and 10-year CVD risk compared with women. In subgroup analyses, men with low TT showed the highest 10-year CVD and mortality risk compared with both men with higher TT and women. TT was also negatively associated with cardiovascular risk as defined by the Framingham risk score (P < 0.001), after multivariable adjustment.

CONCLUSIONS

Analyzing a large population-based sample, we observed that men have a generally higher risk of incident cardiovascular morbidity and mortality. Furthermore, men with low TT concentrations were identified as high-risk individuals with regard to 10-year CVD and mortality risk.

Mendelian randomization suggests non-causal associations of testosterone with cardiometabolic risk factors and mortality

Prospective studies showed that low serum testosterone concentrations are associated with various cardiometabolic risk factors and mortality. However, the causal nature of these associations is controversial. We studied 1 882 men aged 20-79 years with serum testosterone concentrations and genotyping data from the longitudinal population-based Study of Health in Pomerania. Testosterone concentrations were cross-sectionally associated with cardiometabolic risk factors, including anthropometric, lipid, blood pressure and glycaemic parameters; and prospectively with all-cause mortality (277 deaths, 14.7%) during the 10-year follow-up. To overcome problems of residual confounding, reverse causation, or regression dilution bias in the investigated testosterone-outcome associations, we used two-stage least square regression models with previously identified polymorphisms at the SHBG gene (rs12150660) and X chromosome (rs5934505) as multiple genetic instruments in an instrumental variable (IV) approach, also known as Mendelian randomization. In standard regression analyses, testosterone was robustly associated with a wide range of cardiometabolic risk factors. In subsequent IV analyses, no such significant associations were observed. Similarly, prospective analyses showed a consistent association of low testosterone concentrations with increased all-cause mortality risk, which was not apparent in subsequent IV analyses. The present Mendelian randomization analyses did not detect any evidence for causal associations of testosterone concentrations with cardiometabolic risk factors and mortality, suggesting that previously reported associations might largely result from residual confounding or reverse causation. Although testosterone assessment might improve risk prediction, implementation of testosterone replacement therapy requires further evidence of a direct effect on cardiometabolic outcomes from double-blinded randomized controlled trials and large-scale Mendelian randomization meta-analyses.