Prevalence, incidence and risk factors of testosterone deficiency in a population-based cohort of men: results from the study of health in Pomerania

Positive association between serum bilirubin within the physiological range and serum testosterone levels

BACKGROUNDS

Research has demonstrated that elevated serum total bilirubin (STB) levels have a beneficial impact on various diseases, particularly metabolic syndrome. This study aims to investigate the association between STB levels and serum testosterone (STT) in order to determine if bilirubin plays a protective role in relation to testosterone deficiency (TD) risk.

METHODS

In this study, a total of 6,526 eligible male participants aged 20 years or older were analyzed, all of whom took part in the National Health and Nutrition Examination Survey (NHANES) conducted between 2011 and 2016. To investigate the relationship between STB and STT levels, we employed weighted multivariate regression models along with restricted cubic splines (RCS). Additionally, a subgroup analysis was conducted to explore the heterogeneity of this relationship across different subpopulations.

RESULTS

Among the participants, 1,832 individuals (28.07%) were identified as having testosterone deficiency (TD), defined as an STT level below 300 ng/dL. A significant positive correlation between STB and STT levels was observed in both crude and adjusted models (all P < 0.0001). The association between STB and STT levels was found to be statistically significant up to a threshold of 17.1 µmol/L, after which it became statistically insignificant(P for non-linearity = 0.0035). Weighted logistic regression analysis indicated that a 1 µmol/L increase in STB was associated with a 4% decrease in the likelihood of TD (odds ratio = 0.96, P < 0.0001). Subgroup analysis showed that the inverse relationship was limited to individuals aged 60 and over, non-smokers/drinkers, and obese individuals.

CONCLUSION

STB within the physiological range(17.1 µmol/L) was positively associated with STT in adult males. The potential protective role of bilirubin regarding testosterone levels merits further exploration.

The Association of Free Testosterone with Sarcopenic Obesity in Community-Dwelling Older Men: A Cross-Sectional Study

Background and Objectives: Sarcopenic obesity, a clinical condition coexisting with obesity and sarcopenia, is associated with a high risk of functional impairment, reduced quality of life, and increased mortality. A decline in age-related free testosterone (FT) levels has been reported to be associated with decreased muscle mass and muscle strength and increased fat mass. However, the association between low FT levels and risk of sarcopenic obesity has not been well studied. This study aimed to investigate the direct association between low FT levels and sarcopenic obesity. Materials and Methods: This cross-sectional study used data of 982 community-dwelling men aged 70-84 years from the Korean Frailty and Aging Cohort Study. Sarcopenia was defined according to the criteria of the Asian Group for Sarcopenia (AWGS) 2019. Obesity was defined as a body fat mass ≥28.3%. Participants who met both sarcopenia and obesity criteria were defined as having sarcopenic obesity. Low FT levels were defined as FT levels <17.35 pmol/L according to the Endocrine Society Clinical Practice Guidelines. Results: The prevalence of sarcopenia, obesity, and sarcopenic obesity was significantly higher in the low-FT group than in the normal-FT group. Low FT levels were significantly associated with a higher risk of obesity (odds ratio [OR], 2.09, 95% confidence interval [CI], 1.11-3.92), sarcopenia (2.57, 95% CI 1.08-6.10), and sarcopenic obesity (3.66, 95% CI 1.58-8.47) compared with the healthy control group. The risk of low appendicular skeletal muscle mass index (ASMI) (1.78, 95% CI 1.04-3.02) and high fat mass (1.92, 95% CI 1.12-3.31) was significantly higher in the low-FT group than in the normal-FT group. Conclusions: This study showed that low FT levels were associated with a higher risk of sarcopenic obesity. Low FT levels were mainly related to body composition parameters such as low ASMI and high fat mass.

Testosterone in COVID-19: An Adversary Bane or Comrade Boon

COVID-19 is a pandemic disease caused by severe acute respiratory coronavirus 2 (SARS-CoV-2), which leads to pulmonary manifestations like acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In addition, COVID-19 may cause extra-pulmonary manifestation such as testicular injury. Both high and low levels of testosterone could affect the severity of COVID-19. Herein, there is substantial controversy regarding the potential role of testosterone in SARS-CoV-2 infection and COVID-19 severity. Therefore, the present study aimed to review and elucidate the assorted view of preponderance regarding the beneficial and harmful effects of testosterone in COVID-19. A related literature search in PubMed, Scopus, Web of Science, Google Scholar, and Science Direct was done. All published articles related to the role of testosterone and COVID-19 were included in this mini-review. The beneficial effects of testosterone in COVID-19 are through inhibition of pro-inflammatory cytokines, augmentation of anti-inflammatory cytokines, modulation of the immune response, attenuation of oxidative stress, and endothelial dysfunction. However, its harmful effects in COVID-19 are due to augmentation of transmembrane protease serine 2 (TMPRSS2), which is essential for cleaving and activating SARS-CoV-2 spike protein during acute SARS-CoV-2 infection. Most published studies illustrated that low testosterone levels are linked to COVID-19 severity. A low testosterone level in COVID-19 is mainly due to testicular injury, the primary source of testosterone.

Why exercise has a crucial role in cancer prevention, risk reduction and improved outcomes

INTRODUCTION

Exercise is one of several factors known to lower the risk of developing cancer, as well as improve outcomes in patients already diagnosed. People who exercise after cancer have lower rates of cancer complications, treatment toxicities, relapse and improved survival. This review highlights the supportive data and biochemical processes, which explain these potential benefits.

SOURCES OF DATA

PubMed, Embase, Medline and Cochrane libraries were searched for papers which addressed the effects of exercise and physical activity on cancer for this review. The search terms used were physical activity, exercise and cancer up to February 2021. We also referred to the background research required for international exercise intervention study involving men with prostate cancer (INTERVAL-GAP4) and scrutinized references within the robust papers published on this subject to ensure we did not miss any clinically studies. One hundred and eighty eight papers were included.

AREAS OF AGREEMENT

Exercise programmes mitigate many of the complications and risks associated with cancer, particularly thromboembolism, fatigue, weight gain, arthralgia, cognitive impairment and depression.

AREAS OF CONTROVERSY

Molecular and biomarker changes, resulting from exercise, suggest that exercise elicits beneficial changes in insulin-related pathways, down-regulates inflammation and serum oestrogen levels, and enhances oxidative, immune and cellular repair pathways. Nonetheless, the evidence remains preliminary.

GROWING POINTS

The timing, intensity and challenges of prehabilitation, adjunct and rehabilitation exercise programmes are being increasingly understood but their implementation remains sporadic.

AREAS FOR DEVELOPING RESEARCH

More robust clinical trial data are needed to substantiate a causal effect of exercise on overall and cancer-specific survival. These studies are ongoing. Research evaluating the most cost-efficient ways of incorporating prehabilitation, adjunct and rehabilitation programmes into routine practice would be helpful to funding bodies and health care strategists.

Androgen Misuse and Abuse

Androgens are potent drugs requiring prescription for valid medical indications but are misused for invalid, unproven, or off-label reasons as well as being abused without prescription for illicit nonmedical application for performance or image enhancement. Following discovery and first clinical application of testosterone in the 1930s, commercialization of testosterone and synthetic androgens proliferated in the decades after World War II. It remains among the oldest marketed drugs in therapeutic use, yet after 8 decades of clinical use, the sole unequivocal indication for testosterone remains in replacement therapy for pathological hypogonadism, organic disorders of the male reproductive system. Nevertheless, wider claims assert unproven, unsafe, or implausible benefits for testosterone, mostly representing wishful thinking about rejuvenation. Over recent decades, this created an epidemic of testosterone misuse involving prescription as a revitalizing tonic for anti-aging, sexual dysfunction and/or obesity, where efficacy and safety remains unproven and doubtful. Androgen abuse originated during the Cold War as an epidemic of androgen doping among elite athletes for performance enhancement before the 1980s when it crossed over into the general community to become an endemic variant of drug abuse in sufficiently affluent communities that support an illicit drug industry geared to bodybuilding and aiming to create a hypermasculine body physique and image. This review focuses on the misuse of testosterone, defined as prescribing without valid clinical indications, and abuse of testosterone or synthetic androgens (androgen abuse), defined as the illicit use of androgens without prescription or valid indications, typically by athletes, bodybuilders and others for image-oriented, cosmetic, or occupational reasons.

Environmental and occupational exposures associated with male infertility

The upsurge in male infertility over the last two decades, possibly due to environmental exposure, has raised significant interest, particularly boosted by reports from fertility clinics, which showed that chronic diseases and hereditary or other medical conditions might only partially explain current incidence of male infertility. Both environmental and occupational settings may have a significant role in exposure to complex mixtures of endocrine disruptors (ED), which play a major role in fertility disorders. The aim of this review is to give an insight into the current knowledge on exposure settings which may be associated with male infertility. Our study relied on a systematic search of PubMed, Scopus, and Web of Science for articles published between January 2000 and September 2020. It showed that some well documented factors associated with male infertility include smoking, and physiological disturbances or chronic diseases such as obesity and diabetes, which in turn, may also reflect lifestyle choices and environmental exposures, especially to EDs such as phthalates, bisphenols, pesticides, and flame retardants. However, the number of studies on the aetiology of male infertility is still too low in comparison with the size of affected population. Occupational health follow-ups and medical surveillance do not collect any data on male infertility, even though ED chemicals are part of many technological processes.

Sociodemographic, lifestyle and medical influences on serum testosterone and sex hormone-binding globulin in men from UK Biobank

OBJECTIVE

Serum testosterone concentrations are affected by factors unrelated to hypothalamo-pituitary-testicular axis pathology. We evaluated the impact of sociodemographic, lifestyle and medical factors, on serum testosterone and sex hormone-binding globulin (SHBG) in men aged 40-69 years.

DESIGN

Cross-sectional analysis of 208,677 community-dwelling men from the UK Biobank.

MEASUREMENTS

We analysed associations of different factors with serum testosterone and SHBG (immunoassays) and calculated free testosterone (cFT), using smoothed centile plots, linear mixed models and effect size estimates.

RESULTS

Median (interquartile range) for serum testosterone was 11.6 (9.4-14.1) nmol/L, SHBG 36.9 (27.9-48.1) nmol/L and cFT 213 (178-255) pmol/L. Age and BMI were inversely associated with testosterone and cFT, while SHBG was associated with age and inversely with BMI (all P < .001). Living with a partner, (South) Asian ethnicity, never or previous smoker and some medical conditions were associated with lower testosterone. Poultry or fish eater, and higher physical activity were associated with higher testosterone (all P < .001). Testosterone was lowered by ~0.5 nmol/L across ages, ~1.5 nmol/L for BMI 30 vs 25 kg/m² , ~2 nmol/L for (South) Asian ethnicity, living with partner, college/university qualifications, low red meat eater, insufficient physical activity and 0.3-1.0 nmol/L with cardiovascular disease or diabetes. Different combinations of these factors varied serum testosterone by ~4 nmol/L, SHBG by ~30 nmol/L and cFT by ~60 pmol/L.

CONCLUSIONS

The identified modifiable risk factors support lifestyle-based interventions in men with low testosterone concentrations. Considering sociodemographic, lifestyle and medical factors facilitates more personalized interpretation of testosterone testing results with respect to existing reference ranges.

Andropause symptoms and sickness absence in Japanese male workers: a prospective study

OBJECTIVE

The purpose of the study was to investigate the association between andropause symptoms and sickness absence in Japanese male workers over 2 years.

METHODS

A baseline survey asking about andropause symptoms, along with blood sampling for testosterone level, was conducted in June 2009. A total of 418 men (mean age = 52.4 years, SD = 8.6) participated and were followed through 2011. Hazard ratios (HRs) and 95% confidence intervals (CIs) for sickness absence were calculated using Cox proportional hazard models.

RESULTS

During the follow-up period, 31 of 35 participants who took sickness absences had physical illnesses. A higher andropause symptom score was associated with an increased risk of sickness absence. Testosterone deficiency (<350 ng/dL) was not associated with sickness absence. Among the subscales of andropause symptoms, the somatic symptom score was positively associated with sickness absence, whereas testosterone deficiency combined with high sexual symptoms was not associated with sickness absence. Results were similar when limited to sickness absence because of physical illness. No significant interaction between andropause symptoms and testosterone deficiency was found.

CONCLUSIONS

Non-specific andropause symptoms unrelated to testosterone deficiency were positively associated with sickness absence.

Mobility and Biomechanical Functions in the Aging Male: Testosterone and the Locomotive Syndrome

In the current aging society, the occurrence of the locomotive syndrome, a condition in which the locomotive organs are impaired, is increasing. The locomotive system includes support (bones), mobility and impact absorption (joints and intervertebral disks), drive and control (muscles, nerves), and network (blood vessels). The impairment of any of those systems can lead to a major decrease in quality of life. In recent years, several studies on methods to improve and prevent conditions impairing the locomotive syndrome have been conducted. Almost in parallel with the structure supporting mobility and body functions, testosterone levels decrease with age. Testosterone is a hormone-regulating several pathways affecting each aspect of the locomotive syndrome. Testosterone is regulated by the pituitary gland triggering several processes in the body through genomic and non-genomic pathways, affecting muscles, bones, nerves, joints, intervertebral discs, and blood vessels. The purpose of this review is to investigate the role of testosterone in each of the systems involved in the locomotive syndrome.

Testosterone therapy: where do the latest guidelines agree and differ?

PURPOSE OF REVIEW

The incidence of testosterone deficiency and number of men on testosterone therapy (TTh) has increased significantly over the past 3 decades. This rise has been accompanied by controversies surrounding the indications and possible adverse effects of therapy. To better inform prescribing habits among providers, many major medical associations have devised guidelines regarding the diagnosis and management of testosterone deficiency. While these guidelines agree in many areas, there are some key differences that should be identified. This review will explore the similarities, differences, and rationale for these guidelines.

RECENT FINDINGS

Over the past 7 years, much attention has been devoted to the implications of TTh on cardiac health. All reviewed guidelines include dedicated sections discussing these implications and the society's position on prescribing testosterone considering recent findings, however, differ on specific contraindications to TTh and when to initiate therapy after a cardiovascular event. In addition, the American College of Physicians released its first guideline earlier this year which may impact prescribing habits among primary care physicians.

SUMMARY

The differences between testosterone deficiency guidelines may indicate gaps in our knowledge of testosterone deficiency and focuses of future research efforts. Prescribers should be aware of these differences and discuss all treatment options with their patients.

Enzyme immunoassay may be inadequate for measuring salivary testosterone in older men

Several correlations have been reported between men's testosterone (T) and other characteristics. Stalwart findings are a decline in T during the day, decline with obesity, and decline with advancing age. Here seven previously reported correlations are tested among older American men in the National Social Life, Health and Aging Project (NSHAP), their salivary T measured by enzyme immunoassays (EIA). Few significant correlations are found, with most tests producing weak or null results. These findings, overall, suggest that T does not "work" much among older men. However, a threat to this conclusion is raised by Welker et al. namely that EIA of salivary T may contain large errors, invalidating the tests. To check this possibility, these correlations from the literature were tested among older British men whose salivary T was measured by liquid chromatography-tandem mass spectroscopy (LC-MS/MS), a technique noted for its specificity. Not all could be tested, but the relationships of T with age, obesity, and health are significant among British men, indicating that T remains active in older men, and throwing doubt on the adequacy of EIA for measuring salivary T.

Mandibular-related bone metabolism in orchiectomized rats treated with sex hormones

OBJECTIVE

This study aimed to compare the impact of testosterone and estrogen replacement therapy on mandibular bone density and bone-related markers.

DESIGN

Forty male adult rats were randomly allocated to 4 experimental groups (n = 10/group): Sham (Control); Orchiectomy; Orchiectomy plus testosterone replacement; and orchiectomy plus estradiol replacement. Twenty-four days after orchiectomy, the hemi-mandibles were collected and processed for analysis of microhardness in cortical and trabecular bone, radiographic bone density and histomorphometric evaluation. Serum was collected for the analysis of calcium, phosphorus, alkaline phosphatase and magnesium.

RESULTS

The orchiectomy group had the lowest mandibular bone density (p < 0.01) and also their serum levels of alkaline phosphatase were higher than all other experimental groups (p < 0.001). Estradiol replacement significantly reduced microhardness when compared to orchiectomy in cortical bone (p < 0.05). Both testosterone and estrogen replacement reverted orchiectomy impact on this parameter (p < 0.01); and decreased alkaline phosphatase to levels comparable to the Sham-Control group. The effect of estrogen was more pronounced than testosterone, and a statistically significant difference was observed between Sham-Control and testosterone replacement (p < 0.05) but not between Sham-Control and estradiol replacement groups.

CONCLUSION

Our findings demonstrated that both estradiol and testosterone replacement therapies play a role in mandibular bone metabolism, but suggest different pathways.

The severity of hypogonadism symptoms and its risk factors among male employees of Tehran University of Medical Sciences

OBJECTIVES

The current study was conducted to examine the severity of hypogonadism symptoms and their risk factors among the male employees of Tehran University of Medical Sciences (TUMS).

METHODS

This cross-sectional study was conducted on 80 male employees aged 40-60 years, with hypogonadism, at TUMS. The participants were selected through census sampling. The data collection tools included the demographic questionnaire and the Aging Male Symptoms (AMS) questionnaire. The participants first completed the demographic questionnaire and then the AMS questionnaire. SPSS statistical software version 22 (Chicago, IL) was used to analyze the data, and one-way ANOVA tests, Pearson's correlation coefficient, and stepwise multivariate logistic regression were applied.

RESULTS

Based on our findings, the mean overall score of hypogonadism symptoms was 41.71 ± 9.20. Based on Pearson's correlation coefficient results, there was a statistically significant association between the severity of hypogonadism symptoms and age (p < .001). Furthermore, there were significant associations between the economic status, cigarette consumption and hours of sleep and the severity of hypogonadism symptoms (p < .001).

CONCLUSIONS

The current study's results showed that certain factors can affect hypogonadism in males. Thus, it is important to reduce the severity of hypogonadism symptoms and to modify the factors related to this phenomenon.

Age-Related Male Hypogonadism and Cognitive Impairment in the Elderly: Focus on the Effects of Testosterone Replacement Therapy on Cognition

BACKGROUND

Epidemiological data report that male hypogonadism may play a role in cognitive impairment in elderly. However, the effect of testosterone replacement therapy (TRT) on cognitive abilities in this cluster of patients has not been well established. Methods. PubMed/MEDLINE, Google Scholar, Cochrane Library, and Web of Science were searched by using free text words and medical subject headings terms related with "male hypogonadism", "late-onset hypogonadism", elderly, cognition, "mild cognitive impairment", memory, "testosterone replacement therapy" used in various combinations according to the specific clinical questions. Original articles, reviews, and randomized controlled trials written in English were selected. Results. A long-term TRT could improve specific cognitive functions, such as verbal and spatial memory, cognitive flexibility, and physical vitality. However, randomized controlled trials do not provide positive results, and in most of the cases TRT might not induce beneficial effects on cognitive function in elderly men. Discussion and conclusions. Since the lengthening of life expectancy, the prevalence rate of cognitive decline in elderly men is expected to increase remarkably over the next decade with considerable healthcare and economical concerns. Therefore, this remains a relevant clinical topic and further investigations are needed for clarifying the role of TRT especially in elderly men with hypogonadism.

Metabolic Effects of Testosterone Therapy in Men with Type 2 Diabetes and Metabolic Syndrome

INTRODUCTION

Up to 40% of men with type 2 diabetes (T2DM) and metabolic syndrome (MetS) have hypogonadotrophic hypogonadism (HH). Men with HH are at increased risk of cardiovascular (CV) and all-cause mortality, as well as of the development of incident T2DM.

AIM

To review the current literature on the metabolic effects of testosterone therapy (TTh) in men with T2DM and MetS.

METHODS

We searched MEDLINE, Embase, and Cochrane Reviews for articles on T2DM, HH, testosterone deficiency, and CV and all-cause mortality published between May 2005 and July 2018, yielding 1817 articles, including 54 clinical trials and 32 randomized controlled trials (RCTs).

MAIN OUTCOME MEASURES

The main outcomes were glycemic control, insulin resistance, lipid profile, and metabolic markers associated with increased CV risk.

RESULTS

RCTs of TTh suggest significant benefits for sexual function, quality of life, glycemic control, insulin sensitivity, anemia, bone density, and fat and lean muscle mass that might be expected to translate into reduced long-term morbidity and mortality. Several longitudinal and observational studies suggest long-term sustained improvements in metabolic parameters and a trend toward reduced CV and all-cause mortality, especially in men at increased CV risk, such as those with T2DM and MetS. The greatest benefit is seen in those men treated with TTh to target levels and for longer durations.

CONCLUSION

Meta-analyses of RCTs, rather than providing clarification, may have further confused the issue by including underpowered studies of inadequate duration, multiple therapy regimens, some obsolete or withdrawn, and built-in bias in terms of studies included or excluded from analysis. Hackett G. Metabolic Effects of Testosterone Therapy in Men with Type 2 Diabetes and Metabolic Syndrome. Sex Med Rev 2019;7:476-490.

Metabolic Disorders and Male Hypogonadotropic Hypogonadism

Several studies highlight that testosterone deficiency is associated with, and predicts, an increased risk of developing metabolic disorders, and, on the other hand, is highly prevalent in obesity, metabolic syndrome and type-2 diabetes mellitus. Models of gonadotropin releasing hormone deficiency, and androgen deprivation therapy in patients with prostate cancer, suggest that hypogonadotropic hypogonadism might contribute to the onset or worsening of metabolic conditions, by increasing visceral adiposity and insulin resistance. Nevertheless, in functional hypogonadism, as well as in late onset hypogonadism, the relationship between hypogonadotropic hypogonadism and metabolic disorders is bidirectional, and a vicious circle between the two components has been documented. The mechanisms underlying the crosstalk between testosterone deficiency and metabolic disorders include increased visceral adipose tissue and insulin resistance, leading to development of metabolic disorders, which in turn contribute to a further reduction of testosterone levels. The decrease in testosterone levels might be determined by insulin resistance-mediated and, possibly, pro-inflammatory cytokine-mediated decrease of sex hormone binding globulin, resulting in a temporary increased free testosterone available for aromatization to estradiol in visceral adipose tissue, followed by a subsequent decrease in free testosterone levels, due to the excess of visceral adipose tissue and aromatization; by a direct inhibitory effect of increased leptin levels on Leydig cells; and by a reduced gonadotropin secretion induced by estradiol, inflammatory mediators, leptin resistance, and insulin resistance, with the ultimate determination of a substantial hypogonadotropic hypogonadism. The majority of studies focusing on the effects of testosterone replacement therapy on metabolic profile reported a beneficial effect of testosterone on body weight, waist circumference, body mass index, body composition, cholesterol levels, and glycemic control. Consistently, several interventional studies demonstrated that correction of metabolic disorders, in particular with compounds displaying a greater impact on body weight and insulin resistance, improved testosterone levels. The aim of the current review is to provide a comprehensive overview on the relationship between hypogonadotropic hypogonadism and metabolism, by clarifying the independent role of testosterone deficiency in the pathogenesis of metabolic disorders, and by describing the relative role of testosterone deficiency and metabolic impairment, in the context of the bidirectional relationship between hypogonadism and metabolic diseases documented in functional hypogonadotropic hypogonadism. These aspects will be assessed by describing metabolic profile in men with hypogonadotropic hypogonadism, and androgenic status in men with metabolic disorders; afterwards, the reciprocal effects of testosterone replacement therapy and corrective interventions on metabolic derangements will be reported.

The association between serum testosterone and insulin resistance: a longitudinal study

The objective of this study was to investigate whether there is a bidirectional association between testosterone concentrations and insulin resistance, in a prospective population study. A random population sample of 1400 men, aged 30-74, was examined in 2002-2005 in southwestern Sweden and followed up in 2012-2014 (N = 657). After excluding subjects without information on sex hormones and insulin resistance, 1282 men were included in the baseline study. Fasting measurements of plasma glucose, insulin and hormones were performed. Insulin resistance was defined using HOMA-Ir. Mean age at baseline was 47.3 ± 11.4 years. From the follow-up survey 546 men were included, mean age 57.7 ± 11.6 years. Low concentrations of total testosterone at baseline were significantly associated with high logHOMA-Ir at follow-up in a multivariable model including age, waist-hip ratio, physical activity, alcohol intake, smoking, LDL, CRP, hypertension, diabetes and logHOMA-Ir at baseline as covariates (β = -0.096, P = 0.006). Similar results were observed for bioavailable testosterone. Men within the lowest quartile of total testosterone at baseline had significantly higher logHOMA-Ir at follow-up than other quartiles (Q1 vs Q2 P = 0.008, Q1 vs Q3 P = 0.001, Q1 vs Q4 P = 0.052). Multivariable analysis of the impact of insulin resistance at baseline on testosterone levels at follow-up revealed no significant associations regarding testosterone concentrations (β = -0.003, P = 0.928) or bioavailable testosterone (β = -0.006, P = 0.873), when adjusting for baseline concentrations of total testosterone, age, waist-hip-ratio, LDL, CRP, physical activity, alcohol intake, smoking, hypertension and diabetes. Low testosterone concentrations at baseline predicted higher insulin resistance at follow-up, but high insulin resistance at baseline could not predict low testosterone at follow-up.

Type 2 Diabetes and Testosterone Therapy

A third of men with type 2 diabetes (T2DM) have hypogonadotrophic hypogonadism (HH) and associated increased risk of cardiovascular and all-cause mortality. Men with HH are at increased risk of developing incident T2DM. We conducted MEDLINE, EMBASE, and COCHRANE reviews on T2DM, HH, testosterone deficiency, cardiovascular and all-cause mortality from May 2005 to October 2017, yielding 1,714 articles, 52 clinical trials and 32 randomized controlled trials (RCT). Studies with testosterone therapy suggest significant benefits in sexual function, quality of life, glycaemic control, anaemia, bone density, fat, and lean muscle mass. Meta-analyses of RCT, rather than providing clarification, have further confused the issue by including under-powered studies of inadequate duration, multiple regimes, some discontinued, and inbuilt bias in terms of studies included or excluded from analysis.

Testosterone a key factor in gender related metabolic syndrome

Metabolic syndrome (MetS) is highly correlated with cardiovascular diseases. Although an excess of body fat is a determinant factor for MetS development, a reduced level of testosterone plays a fundamental role in its regulation. Low testosterone level is highly related to insulin resistance, visceral obesity and MetS. We have searched in Pubmed clinical trial with the password: testosterone and insulin resistance, and testosterone and MetS. We found 19 studies on the correlation between testosterone level with insulin resistance and 18 on the effect of testosterone therapy on MetS. A high correlation between low testosterone and insulin resistance has been found in men, but not in women. Testosterone administration in hypogonadal men improved MetS and reduced the mortality risk. Androgen and oestrogen receptors are expressed in adipocytes, muscle and liver tissue, and their activation is necessary to improve metabolic control. Normalization of testosterone level should be the primary treatment in men, along with caloric restriction and physical exercise. These findings come mainly from correlative data, and there remains a need for randomized trials to strengthen this evidence. This review will consider the effects of testosterone on the regulation and development of MetS in men and women.

Testosterone level and risk of type 2 diabetes in men: a systematic review and meta-analysis

BACKGROUND

Type 2 diabetes is a risk factor for testosterone deficiency and impaired sex steroid status. Some studies also investigated the association of testosterone level with diabetes risk in men, but reported controversial findings. To clarify this issue, we conducted a systematic review and meta-analysis.

METHODS

PubMed, EMBASE and Web of Science were searched for eligible cohort or nested case-control studies published up to August 15, 2017. Meta-analysis was used to calculate the pooled relative risk (RR) of type 2 diabetes associated with higher testosterone level.

RESULTS

Thirteen cohort or nested case-control studies with 16,709 participants were included. Meta-analysis showed that higher total testosterone level could significantly decrease the risk of type 2 diabetes in men (RR = 0.65; 95% CI 0.50-0.84; P = 0.001), and higher free testosterone level could also decrease the risk of type 2 diabetes in men (RR = 0.94; 95% CI 0.90-0.99; P = 0.014). After excluding two studies that did not calculate RRs by quartiles of testosterone levels, both higher total testosterone and free testosterone levels could decrease the risk of type 2 diabetes in men, and the pooled RRs were 0.62 (95% CI 0.51-0.76; P < 0.001) and 0.77 (95% CI 0.61-0.98; P = 0.03), respectively.

CONCLUSION

This meta-analysis suggests that higher testosterone level can significantly decrease the risk of type 2 diabetes in men. Therefore, combined with previous researches, the findings above suggest a reverse-causality scenario in the relation between testosterone deficiency and risk of type 2 diabetes in men.

Causal relationship between obesity and serum testosterone status in men: A bi-directional mendelian randomization analysis

CONTEXT

Obesity in men is associated with low serum testosterone and both are associated with several diseases and increased mortality.

OBJECTIVES

Examine the direction and causality of the relationship between body mass index (BMI) and serum testosterone.

DESIGN

Bi-directional Mendelian randomization (MR) analysis on prospective cohorts.

SETTING

Five cohorts from Denmark, Germany and Sweden (Inter99, SHIP, SHIP Trend, GOOD and MrOS Sweden).

PARTICIPANTS

7446 Caucasian men, genotyped for 97 BMI-associated SNPs and three testosterone-associated SNPs.

MAIN OUTCOME MEASURES

BMI and serum testosterone adjusted for age, smoking, time of blood sampling and site.

RESULTS

1 SD genetically instrumented increase in BMI was associated with a 0.25 SD decrease in serum testosterone (IV ratio: -0.25, 95% CI: -0.42--0.09, p = 2.8*10-3). For a body weight reduction altering the BMI from 30 to 25 kg/m2, the effect would equal a 13% increase in serum testosterone. No association was seen for genetically instrumented testosterone with BMI, a finding that was confirmed using large-scale data from the GIANT consortium (n = 104349).

CONCLUSIONS

Our results suggest that there is a causal effect of BMI on serum testosterone in men. Population level interventions to reduce BMI are expected to increase serum testosterone in men.

Exercise-induced biochemical changes and their potential influence on cancer: a scientific review

AIM

To review and discuss the available international literature regarding the indirect and direct biochemical mechanisms that occur after exercise, which could positively, or negatively, influence oncogenic pathways.

METHODS

The PubMed, MEDLINE, Embase and Cochrane libraries were searched for papers up to July 2016 addressing biochemical changes after exercise with a particular reference to cancer. The three authors independently assessed their appropriateness for inclusion in this review based on their scientific quality and relevance.

RESULTS

168 papers were selected and categorised into indirect and direct biochemical pathways. The indirect effects included changes in vitamin D, weight reduction, sunlight exposure and improved mood. The direct effects included insulin-like growth factor, epigenetic effects on gene expression and DNA repair, vasoactive intestinal peptide, oxidative stress and antioxidant pathways, heat shock proteins, testosterone, irisin, immunity, chronic inflammation and prostaglandins, energy metabolism and insulin resistance.

SUMMARY

Exercise is one of several lifestyle factors known to lower the risk of developing cancer and is associated with lower relapse rates and better survival. This review highlights the numerous biochemical processes, which explain these potential anticancer benefits.

Testosterone deficiency in adults and corresponding treatment patterns across the globe

The global prevalence of testosterone deficiency (TD) ranges from 10–40%. The actual diagnosis of TD is controversial, as a wide range of total testosterone (TT) thresholds are used for diagnosis (200–400 ng/dL), and physicians differ in their emphasis placed on clinical symptoms. There are also significant global differences in the prescription patterns of testosterone replacement therapy (TRT). In the United States, prescription of TRT is significantly higher than the rest of the world, increasing 3-fold over the last 10 years and more so in eugonadal men. The majority of treating physicians emphasizes clinical symptomology of TD over laboratory values, and up to one-fourth of their patients do not even have serum testosterone levels. There are significant inter-physician differences in willingness to prescribe TRT in the setting of prostate cancer. Data is scarce on testosterone prescribing patterns in Africa, Asia, and the Middle East. More literature is needed to better characterize how physicians from different regions diagnose TD.

Clinical correlates of sex hormones in women: The study of health in Pomerania

BACKGROUND

Despite associations of sex hormones in women with increased cardiometabolic risk and mortality, the clinical correlates of altered sex hormone concentrations in women are less clearly understood. We investigated a broad range of clinical correlates of sex hormones in women from a large population-based sample.

METHODS

Data from 2560 women from two cohorts of the Study of Health in Pomerania were used. Stepwise multivariable regression models were implemented to investigate a broad range of behavioral, socio-demographic, and cardiometabolic clinical correlates related to total testosterone (TT), free testosterone (fT), androstenedione (ASD), dehydroepiandrosterone-sulfate (DHEAS), estrone (E1), estradiol (E2), and sex hormone-binding globulin (SHBG).

RESULTS

Waist circumference and BMI (β-coefficient: -0.03; 95% CI: -0.04; 0.03) were inversely related to SHBG, and BMI was positively related to TT (β-coefficient: 0.005; 95% CI: 0.001; 0.009), fT, E1, and E2. Smoking was positively related to TT (β-coefficient: 0.04; 95% CI: 0.01; 0.06), ASD, and fT. Systolic blood pressure (TT: β-coefficient: 0.002; 95% CI: 0.001; 0.003), hypertension (TT: β-coefficient: 0.05; 95% CI: 0.003; 0.11), low-density lipoprotein (LDL) cholesterol (TT: β-coefficient: 0.02; 95% CI: 0.01; 0.05), and total cholesterol (TT: β-coefficient: -0.03; 95% CI: 0.01; 0.05) were positively related to TT and ASD. Finally, type 2 diabetes mellitus (T2DM), and metabolic syndrome (MetS) were positively related to fT, but inversely related to SHBG.

CONCLUSIONS

Our population-based study, with sex hormone concentrations measured by liquid chromatography tandem mass spectrometry, revealed associations between clinical correlates including waist circumference, smoking, cohabitation, systolic blood pressure, cholesterol, and MetS with sex hormones. Thus, sex hormones and SHBG may play a role in the cardiovascular risk profile of women.

Trenbolone Improves Cardiometabolic Risk Factors and Myocardial Tolerance to Ischemia-Reperfusion in Male Rats With Testosterone-Deficient Metabolic Syndrome

The increasing prevalence of obesity adds another dimension to the pathophysiology of testosterone (TEST) deficiency (TD) and potentially impairs the therapeutic efficacy of classical TEST replacement therapy. We investigated the therapeutic effects of selective androgen receptor modulation with trenbolone (TREN) in a model of TD with the metabolic syndrome (MetS). Male Wistar rats (n=50) were fed either a control standard rat chow (CTRL) or a high-fat/high-sucrose (HF/HS) diet. After 8 weeks of feeding, rats underwent sham surgery or an orchiectomy (ORX). Alzet miniosmotic pumps containing either vehicle, 2-mg/kg·d TEST or 2-mg/kg·d TREN were implanted in HF/HS+ORX rats. Body composition, fat distribution, lipid profile, and insulin sensitivity were assessed. Infarct size was quantified to assess myocardial damage after in vivo ischaemia reperfusion, before cardiac and prostate histology was performed. The HF/HS+ORX animals had increased sc and visceral adiposity; circulating triglycerides, cholesterol, and insulin; and myocardial damage, with low circulating TEST compared with CTRLs. Both TEST and TREN protected HF/HS+ORX animals against sc fat accumulation, hypercholesterolaemia, and myocardial damage. However, only TREN protected against visceral fat accumulation, hypertriglyceridaemia, and hyperinsulinaemia and reduced myocardial damage relative to CTRLs. TEST caused widespread cardiac fibrosis and prostate hyperplasia, which were less pronounced with TREN. We propose that TEST replacement therapy may have contraindications for males with TD and obesity-related MetS. TREN treatment may be more effective in restoring androgen status and reducing cardiovascular risk in males with TD and MetS.

Estimating age-specific trends in circulating testosterone and sex hormone-binding globulin in males and females across the lifespan

BACKGROUND

Age-specific trends of serum testosterone and sex hormone-binding globulin across the full lifespan have not been reported.

METHODS

We deduced age-specific trends in serum testosterone and sex hormone-binding globulin in males and females between ages 10 and 90 from a large sample of consecutive results from a single large pathology laboratory. Coded results of 110,712 consecutive blood samples requesting serum testosterone over seven years (2007-2013) comprising blood testosterone, sex hormone-binding globulin and calculated free testosterone together with gender and age were analysed create smoothed age-specific centiles (2.5%, 5%, 25%, 50%, 75%, 95%, 97.5%) for males and females.

RESULTS

These identified the pubertal increases in serum testosterone in males peaking at 20 years of age and remaining stable thereafter until the eighth decade. In females, circulating testosterone peaked in late adolescence and declined gradually over the next two decades but remained stable across menopause and beyond. After early childhood, serum sex hormone-binding globulin declines to a nadir in males at the age of 20 years and remains stable till the sixth decade with a gradual, progressive rise thereafter. In females, the sex hormone-binding globulin nadir is reached earlier with levels rising gradually and progressively with age thereafter and accelerating after the age of 70 years. Females also exhibit a second sex hormone-binding globulin peak during reproductive ages reflected only in upper centiles due to effects of pregnancy and oral contraceptive use in a significant minority of females.

CONCLUSIONS

This large sample of clinical data provides a comprehensive profile of androgen status across the lifespan from early adolescence to late old age.

Impact of Diet-Induced Obesity and Testosterone Deficiency on the Cardiovascular System: A Novel Rodent Model Representative of Males with Testosterone-Deficient Metabolic Syndrome (TDMetS)

INTRODUCTION

Current models of obesity utilise normogonadic animals and neglect the strong relationships between obesity-associated metabolic syndrome (MetS) and male testosterone deficiency (TD). The joint presentation of these conditions has complex implications for the cardiovascular system that are not well understood. We have characterised and investigated three models in male rats: one of diet-induced obesity with the MetS; a second using orchiectomised rats mimicking TD; and a third combining MetS with TD which we propose is representative of males with testosterone deficiency and the metabolic syndrome (TDMetS).

METHODS

Male Wistar rats (n = 24) were randomly assigned to two groups and provided ad libitum access to normal rat chow (CTRL) or a high fat/high sugar/low protein "obesogenic" diet (OGD) for 28 weeks (n = 12/group). These groups were further sub-divided into sham-operated or orchiectomised (ORX) animals to mimic hypogonadism, with and without diet-induced obesity (n = 6/group). Serum lipids, glucose, insulin and sex hormone concentrations were determined. Body composition, cardiovascular structure and function; and myocardial tolerance to ischemia-reperfusion were assessed.

RESULTS

OGD-fed animals had 72% greater fat mass; 2.4-fold greater serum cholesterol; 2.3-fold greater serum triglycerides and 3-fold greater fasting glucose (indicative of diabetes mellitus) compared to CTRLs (all p<0.05). The ORX animals had reduced serum testosterone and left ventricle mass (p<0.05). In addition to the combined differences observed in each of the isolated models, the OGD, ORX and OGD+ORX models each had greater CK-MB levels following in vivo cardiac ischemia-reperfusion insult compared to CTRLs (p<0.05).

CONCLUSION

Our findings provide evidence to support that the MetS and TD independently impair myocardial tolerance to ischemia-reperfusion. The combined OGD+ORX phenotype described in this study is a novel animal model with associated cardiovascular risk factors and complex myocardial pathology which may be representative of male patients presenting with TDMetS.

The complex and multifactorial relationship between testosterone deficiency (TD), obesity and vascular disease

Testosterone deficiency (TD) is a well-established and recognized medical condition that contributes to several co-morbidities, including metabolic syndrome, visceral obesity and cardiovascular disease (CVD). More importantly, obesity is thought to contribute to TD. This complex bidirectional interplay between TD and obesity promotes a vicious cycle, which further contributes to the adverse effects of TD and obesity and may increase the risk of CVD. Testosterone (T) therapy for men with TD has been shown to be safe and effective in ameliorating the components of the metabolic syndrome (Met S) and in contributiong to increased lean body mass and reduced fat mass and therefore contributes to weight loss. We believe that appropriate T therapy in obese men with TD is a novel medical approach to manage obesity in men with TD. Indeed, other measures of lifestyle and behavioral changes can be used to augment but not fully replace this effective therapeutic approach. It should be noted that concerns regarding the safety of T therapy remain widely unsubstantiated and considerable evidence exists supporting the benefits of T therapy. Thus, it is paramount that clinicians managing obese men with TD be made aware of this novel approach to treatment of obesity. In this review, we discuss the relationship between TD and obesity and highlight the contemporary advancement in management of obesity with pharmacological and surgical approaches, as well as utilization of T therapy and how this intervention may evolve as a novel approach to treatment of obesity in men with TD .

Testosterone deficiency, insulin-resistant obesity and cognitive function

Testosterone is an androgenic steroid hormone, which plays an important role in the regulation of male reproduction and behaviors, as well as in the maintenance of insulin sensitivity. Several studies showed that testosterone exerted beneficial effects in brain function, including preventing neuronal cell death, balancing brain oxidative stress and antioxidant activity, improving synaptic plasticity and involving cognitive formation. Although previous studies showed that testosterone deficiency is positively correlated with cognitive impairment and insulin-resistant obesity, several studies demonstrated contradictory findings. Thus, this review comprehensively summarizes the current evidence from in vitro, in vivo and clinical studies of the relationship between testosterone deficiency and insulin-resistant obesity as well as the correlation between either insulin-resistant obesity or testosterone deficiency and cognitive impairment. Controversial reports and the mechanistic insights regarding the roles of testosterone in insulin-resistant obesity and cognitive function are also presented and discussed.

Genetic and environmental influence on the association between testosterone, sex hormone-binding globulin and body composition in Korean men

OBJECTIVES

This study aimed to evaluate an association between testosterone, sex hormone-binding globulin and body composition as well as the influence of genetic and environmental factors on the association.

DESIGN

A cross-sectional study.

SETTING

Community-based study.

PARTICIPANTS

One thousand and eighty-three Korean men including 144 pairs of monozygotic twins.

MAIN OUTCOME MEASURE

Levels of serum total testosterone (TT) and sex hormone-binding globulin (SHBG) were measured by chemiluminescence immunoassay, and free testosterone (cFT) was calculated using Vermeulen's method. Detailed body composition was measured using dual-energy X-ray absorptiometry. We performed linear mixed regression analysis with consideration of familial correlations and covariates.

RESULTS

Each 1-SD increase in age-adjusted levels of TT, cFT and SHBG was associated with lower levels of adiposity measures and absolute measures of lean body mass. On the other hand, percentage total lean mass increased with increasing levels of TT, cFT and SHBG (P < 0·05). Bivariate variance-component analyses revealed that most body composition measures had a significant inverse unique environmental correlation with both TT and SHBG, and a significant genetic correlation with TT. A co-twin control study in monozygotic twins showed that within-pair differences in adiposity measures were inversely associated with within-pair differences in the levels of TT and SHBG, while within-pair differences in lean mass were inversely associated with within-pair differences in the levels of TT.

CONCLUSIONS

The significant associations of body composition with testosterone and SHBG were influenced by both genetic and environmental factors. Further efforts to elucidate related genes and modifiable environmental factors are needed.

Prediction of prevalent but not incident non-alcoholic fatty liver disease by levels of serum testosterone

BACKGROUND AND AIMS

The association between testosterone level and development of non-alcoholic fatty liver disease (NAFLD) is not well known. We examined the relationship of total testosterone level with development and regression of NAFLD.

METHODS

Among the men who had undergone repeated liver ultrasonography in 2 years or more at a health promotion center, subjects with available serum testosterone level at baseline were included in the study. Alcohol consumers (> 20 g/day) were excluded from the study.

RESULTS

Among the 1944 men, 44.3% of subjects were diagnosed with NAFLD. Higher level of testosterone significantly lowered the prevalence of fatty liver (odds ratios per SD increase, 0.686 and 0.795 at baseline and follow-up, respectively). During the median 4.2 years follow-up, 22.4% of subjects in the normal group developed fatty liver, and 21.0% of subjects in the NAFLD group recovered at the follow-up. In longitudinal analyses, higher level of testosterone was significantly associated with the development or regression of fatty liver, before adjustment for obesity and metabolic parameters. However, in the full-adjusted model, testosterone level did not influence the development or regression of fatty liver.

CONCLUSIONS

Although testosterone level was significantly low in the subjects with NAFLD in cross-sectional analyses, baseline testosterone level did not independently influence the development or regression of fatty liver at the median 4.2 years follow-up. Obesity and metabolic parameters may play key roles in the link between testosterone level and NAFLD.

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.

Testosterone level in men with type 2 diabetes mellitus and related metabolic effects: A review of current evidence

A significant proportion of patients with type 2 diabetes mellitus have a low testosterone level relative to reference ranges based on healthy young men. Only a small number of these patients suffer from classical hypogonadism as a result of recognizable hypothalamic-pituitary-gonadal axis pathology. The cut-off value of the serum testosterone level in men without obvious hypothalamic-pituitary-gonadal axis pathology is controversial. It is unclear to what extent a low serum testosterone level causally leads to type 2 diabetes and/or the metabolic syndrome. From a theoretical standpoint, there can be complex interactions among the hypothalamic-pituitary-gonadal axis, body composition and insulin resistance, which can be further influenced by intrinsic and extrinsic factors to give rise to metabolic syndrome, glucose intolerance, and low-grade inflammation to increase the risk of cardiovascular disease. Although a low serum testosterone level frequently coexists with cardiometabolic risk factors and might serve as a biomarker, more studies are required to clarify the causal, mediating or modifying roles of low serum testosterone level in the development of adverse clinical outcomes. Currently, there are insufficient randomized clinical trial data to evaluate the effects of testosterone replacement therapy on meaningful clinical outcomes. The risk-to-benefit ratio of testosterone therapy in high-risk subjects, such as those with type 2 diabetes, also requires elucidation. The present article aims to review the current evidence on low serum testosterone levels in patients with type 2 diabetes, and its implications on cardiovascular risk factors, metabolic syndrome and adverse clinical outcomes.

Testosterone and weight loss: the evidence

PURPOSE OF REVIEW

The purpose of this article is to examine the contemporary data linking testosterone therapy in overweight and obese men with testosterone deficiency to increased lean body mass, decreased fat mass, improvement in overall body composition and sustained weight loss. This is of paramount importance because testosterone therapy in obese men with testosterone deficiency represents a novel and a timely therapeutic strategy for managing obesity in men with testosterone deficiency.

RECENT FINDINGS

Long-term testosterone therapy in men with testosterone deficiency produces significant and sustained weight loss, marked reduction in waist circumference and BMI and improvement in body composition. Further, testosterone therapy ameliorates components of the metabolic syndrome. The aforementioned improvements are attributed to improved mitochondrial function, increased energy utilization, increased motivation and vigor resulting in improved cardio-metabolic function and enhanced physical activity.

SUMMARY

The implication of testosterone therapy in management of obesity in men with testosterone deficiency is of paramount clinical significance, as it produces sustained weight loss without recidivism. On the contrary, alternative therapeutic approaches other than bariatric surgery failed to produce significant and sustained outcome and exhibit a high rate of recidivism. These findings represent strong foundations for testosterone therapy in obese men with testosterone deficiency and should spur clinical research for better understanding of usefulness of testosterone therapy in treatment of underlying pathophysiological conditions of obesity.

[Testosterone deficiency - an underestimated risk for men? Prevalence of hypogonadism]

BACKGROUND

Testosterone deficiency represents a significant health risk factor for men but the importance has so far been underestimated. Besides physiological and age-related reduction, acquired testosterone deficiency may also occur. Testosterone deficiency is a possible result of commonly occurring diseases or is itself the basis for development of different diseases. The scope of the present investigation was measurement of serum testosterone levels in different age groups.

MATERIALS AND METHODS

Serum testosterone levels were determined in samples from 5,735 healthy men at the LADR laboratory MVZ Dr. Kramer & colleagues, Geesthacht under routine conditions. The frequency of testosterone deficiency was calculated in different age groups and compared using SPSS 19.0 software.

RESULTS

Pathologically low testosterone levels (< 2.5 ng/ml) were found in 15.2 % of subjects while 37.4 % had a testosterone level lower than 3.5 ng/ml. Decreased testosterone levels were not associated with age. In addition the proportion of men with decreased serum testosterone levels was comparable in all age groups. The average serum testosterone level decreased slightly in all age groups during the period before midday.

CONCLUSIONS

The data reveal high rates of testosterone deficiency in men independent of patient age. As decreased serum testosterone levels may be the consequence of several diseases and can be causally involved in the pathogenesis of further diseases, it is strongly recommended that serum testosterone measurement should be included in the diagnostic arsenal especially when symptoms, such as loss of libido, erectile dysfunction, lack of concentration, depression, lethargy, irritability and sleep disturbance are present.

Systematic Literature Review of the Epidemiology of Nongenetic Forms of Hypogonadism in Adult Males

This study summarizes the literature on the prevalence, incidence, and proportion of patients receiving treatment for male hypogonadism and a systematic literature search was performed for articles published in the last 20 years. Of the 97 studies identified, 96 examined the prevalence, 2 examined the incidence, and 4 examined the proportion of males with hypogonadism patients receiving treatment. Based on studies conducted in Europe and USA, the prevalence of hypogonadism in the general population ranged from 2.1% to 12.8% of middle-aged to older men, with an estimated incidence of 12 new cases per 1,000 person-years. Prevalence was higher among patients with comorbid conditions, such as type 2 diabetes mellitus and obesity. Approximately 10–12% of men with hypogonadism were receiving testosterone treatment. This literature review suggests that there is potentially a significant burden of hypogonadism in the general population. Burden seems to increase with age and in the presence of certain disease conditions. Data suggests that many hypogonadal men who may benefit from testosterone replacement are not receiving treatment. This may be the result of underdiagnosis of the disease, lack of awareness by patients or physicians, irregularities surrounding the diagnostic criteria, and deficiency of long-term safety studies.

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.

An update on male hypogonadism therapy

INTRODUCTION

Men who have symptoms associated with persistently low serum total testosterone level should be assessed for testosterone replacement therapy.

AREAS COVERED

Acute and chronic illnesses are associated with low serum testosterone and these should be recognized and treated. Once the diagnosis of male hypogonadism is made, the benefits of testosterone treatment usually outweigh the risks. Without contraindications, the patient should be offered testosterone replacement therapy. The options of testosterone delivery systems (injections, transdermal patches/gels, buccal tablets, capsules and implants) have increased in the last decade. Testosterone improves symptoms and signs of hypogonadism such as sexual function and energy, increases bone density and lean mass and decreases visceral adiposity. In men who desire fertility and who have secondary hypogonadism, testosterone can be withdrawn and the patients can be placed on gonadotropins. New modified designer androgens and selective androgen receptor modulators have been in preclinical and clinical trials for some time. None of these have been assessed for the treatment of male hypogonadism.

EXPERT OPINION

Despite the lack of prospective long-term data from randomized, controlled clinical trials of testosterone treatment on prostate health and cardiovascular disease risk, the available evidence suggests that testosterone therapy should be offered to symptomatic hypogonadal men.

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.

Physical activity - an important preanalytical variable

The concentration of several biochemical and hematological biomarkers is strongly influenced by a number of preanalytical variables. Several lines of evidence attest that short, middle, and long-term exercise, as well as the relative intensity of physical effort (from mild to strenuous), may influence a broad array of laboratory variables. The amount of extracellular release and clearance from blood of most of these biomarkers is markedly influenced by the biological characteristics of the molecule(s), level of training, type, intensity and duration of exercise, and time of recovery after training. It is hence noteworthy that test results that fall outside the conventional reference ranges in athletes not only may reflect the presence of a given disease, but may frequently mirror an adaptation to regular training or changes that have occurred during and/or following strenuous exercise, and which should be clearly acknowledged to prevent misinterpretation of laboratory data. The aim of this narrative review is to provide an update about the most significant changes of some biochemical and hematological biomarkers in response to physical exercise, for appropriate interpretation of these changes in the context of physically active subjects.