Metabolic Syndrome, Testosterone, and Cardiovascular Mortality in Men

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

An audit of the measurement and reporting of male testosterone levels in UK clinical biochemistry laboratories

INTRODUCTION

A number of guidance documents have been published in recent years for the diagnosis and management of hypogonadism (HG). Laboratory practice has a major role in supporting guidelines with accurate and precise serum total testosterone (TT) methods and standardised pre- and post-analytical protocols. Our study investigated whether laboratory practice currently supports the management guidelines for HG.

METHODS

An internet-based questionnaire survey of senior laboratory biochemists (UK/Republic of Ireland) was conducted (April-May 2018). Questions reflected sampling, laboratory practice, reference ranges and reporting of results. The results were analysed in conjunction with data obtained from the UK National External Quality Assurance Service (UK NEQAS) on testosterone assay performance.

RESULTS

Analyses of 96 laboratory surveys returned the following: 74 laboratories stated that the optimal sampling time was communicated to users; 81 laboratories used immunoassays; 76 laboratories included reference ranges for adult men (31 had dual/multiple age-related intervals). Wide variability in lower/upper limits was evident in the common immunoassays; the majority of reference ranges were from manufacturers (50.0%) or historical (18.8%). Action limits based on TT levels were used by 64 laboratories, but 63 did not report a borderline range as suggested by the guidelines. Protocols for cascading tests based on TT were evident in 58 laboratories, with 50 laboratories offering estimated free testosterone; interpretative comments were provided by 67 laboratories, but no references were made to the management guidelines. Data from UK NEQAS demonstrated considerable variation in testosterone assay performance.

CONCLUSIONS

Our survey has highlighted inconsistencies that could lead to HG (and other conditions requiring measurement of TT) not being managed appropriately. The results from this survey and from UK NEQAS reinforce the requirement for action to be considered regarding the standardisation of testosterone assays and harmonisation of laboratory practice.

Cardiovascular Risks Associated with Gender and Aging

The aging and elderly population are particularly susceptible to cardiovascular disease. Age is an independent risk factor for cardiovascular disease (CVD) in adults, but these risks are compounded by additional factors, including frailty, obesity, and diabetes. These factors are known to complicate and enhance cardiac risk factors that are associated with the onset of advanced age. Sex is another potential risk factor in aging adults, given that older females are reported to be at a greater risk for CVD than age-matched men. However, in both men and women, the risks associated with CVD increase with age, and these correspond to an overall decline in sex hormones, primarily of estrogen and testosterone. Despite this, hormone replacement therapies are largely shown to not improve outcomes in older patients and may also increase the risks of cardiac events in older adults. This review discusses current findings regarding the impacts of age and gender on heart disease.

Testosterone and All-Cause Mortality in Older Men: The Role of Metabolic Syndrome

Previous studies have shown controversial results about the role of testosterone in all-cause mortality in elderly men. We hypothesized that metabolic syndrome (MetS) could partly explain this discrepancy. We therefore examined the association of all-cause mortality with total and bioavailable testosterone, taking into account the MetS. We used data from the Three-City Cohort (3C) study with 12-year follow-up. The 3C study included 3650 men aged >65 years in three French cities. Hormone was measured in a random subsample of 444 men, and MetS was determined as stated by the International Diabetes Federation criteria. We used inverse-probability-weighted Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs). Of 444 men included in the analysis, 106 (23.9%) had MetS at baseline, and 166 died over the follow-up. There was a significant interaction between testosterone level and MetS for all-cause mortality (P = 0.002 and P = 0.008 for total and bioavailable testosterone, respectively). Among men with MetS, a decrease in one standard deviation of testosterone was associated with higher mortality risk [HR 1.78 (95% CI 1.13 to 2.78) and HR 1.83 (95% CI 1.17 to 2.86) for total and bioavailable testosterone, respectively]. By contrast, there was no association of testosterone with mortality risk among men without MetS. Our results suggest that MetS modifies the association between testosterone and mortality in older men. If confirmed, these findings could contribute to improve risk stratification and better manage the health of older men.

Prevalence, Pathophysiology, and Management of Androgen Deficiency in Men with Metabolic Syndrome, Type 2 Diabetes Mellitus, or Both

The prevalence of type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) has increased in the United States over the past 40 years. These conditions, long linked with many cardiovascular complications, have recently been linked with androgen or testosterone deficiency in men. Several pathophysiologic hypotheses exist regarding this association, with the most widely reported a relationship to obesity and insulin resistance. Several randomized trials have confirmed that when testosterone replacement therapy is given to patients with T2DM, MetS, or both, metabolic parameters such as waist circumference, hemoglobin A1c , and systolic blood pressure are significantly reduced by up to 11 cm, 1.9%, and 23 mm Hg, respectively. This has not, however, resulted in improved cardiovascular outcomes, as evidenced in studies that found increased rates of cardiovascular events following testosterone replacement therapy. In this review, we summarize the relevant literature regarding the pathophysiology and management of androgen deficiency in men with T2DM, MetS, or both.

Testosterone and metabolic syndrome

Controversies surround the usefulness of identifying patients with the metabolic syndrome (MetS). Many of the components are accepted risk factors for cardiovascular disease (CVD). Although the MetS as defined includes many men with insulin resistance, insulin resistance is not universal. The low total testosterone (TT) and sex hormone binding globulin (SHBG) levels in these men are best explained by the hyperinsulinism and increased inflammatory cytokines that accompany obesity and increased waist circumference. It is informative that low SHBG levels predict future development of the MetS. Evidence is strong relating low TT levels to CVD in men with and without the MetS; however, the relationship may not be causal. The recommendations of the International Diabetes Federation for managing the MetS include cardiovascular risk assessment, lifestyle changes in diet, exercise, weight reduction and treatment of individual components of the MetS. Unfortunately, it is uncommon to see patients with the MetS lose and maintain a 10% weight loss. Recent reports showing testosterone treatment induced dramatic changes in weight, waist circumference, insulin sensitivity, hemoglobin A1c levels and improvements in each of the components of the MetS are intriguing. While some observational studies have reported that testosterone replacement therapy increases cardiovascular events, the Food and Drug Administration in the United States has reviewed these reports and found them to be seriously flawed. Large, randomized, placebo-controlled trials are needed to provide more definitive data regarding the efficacy and safety of this treatment in middle and older men with the MetS and low TT levels.

The Association of Reproductive Hormone Levels and All-Cause, Cancer, and Cardiovascular Disease Mortality in Men

CONTEXT

Testosterone (T) levels have been associated with mortality, but controversy exists.

OBJECTIVE

Our objective was to investigate associations between serum levels of total T, SHBG, free T, estradiol, LH and FSH, and subsequent mortality with up to 30 years of follow-up.

DESIGN

This was a prospective cohort study consisting of men participating in four independent population-based surveys (MONICA I-III and Inter99) from 1982 to 2001 and followed until December 2012 with complete registry follow-up.

SETTING AND PARTICIPANTS

A total of 5350 randomly selected men from the general population aged 30, 40, 50, 60, or 70 years at baseline participated.

MAIN OUTCOMES AND MEASURES

All-cause mortality, cardiovascular disease (CVD) mortality, and cancer mortality were the main outcomes.

RESULTS

A total of 1533 men died during the follow-up period; 428 from CVD and 480 from cancer. Cox proportional hazard models revealed that men in highest LH quartile had an increased all-cause mortality compared to lowest quartile (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.14-1.53). Likewise, increased quartiles of LH/T and estradiol increased the risk of all-cause mortality (HR, 1.23; 95% CI, 1.06-1.43; HR, 1.23; 95% CI 1.06-1.43). No association to T levels was found. Higher LH levels were associated with increased cancer mortality (HR, 1.42; 95% CI, 1.10-1.84) independently of smoking status. Lower CVD mortality was seen for men with T in the highest quartile compared to lowest (HR, 0.72; 95% CI, 0.53-0.98). Furthermore, negative trends were seen for SHBG and free T in relation to CVD mortality, however insignificant.

CONCLUSION

The observed positive association of LH and LH/T, but not T, with all-cause mortality suggests that a compensated impaired Leydig cell function may be a risk factor for death by all causes in men. Our findings underpin the clinical importance of including LH measurement in the diagnostic work-up of male patients seeking help for possible androgen insufficiency.

Association of metabolic syndrome with testosterone and inflammation in men

OBJECTIVE

There is limited data on the assessment of relationship between sex hormones, metabolic syndrome (MS) and inflammation. Therefore, our objective was to examine the relationship between metabolic syndrome, testosterone and inflammation.

PATIENTS AND METHODS

It was a cross-sectional study which included 309 subjects in the age range of 30-70years. Blood was analyzed for plasma glucose, serum lipids, total testosterone (TT) and high-sensitivity C-reactive protein (hs-CRP).

RESULTS

There were 153 patients with metabolic syndrome and 156 without MS according to modified NCEP guidelines. Age, BMI, obesity, dyslipidaemia, smoking (OR=2.35, CI=1.35-4.09), LDL-Ch, low TT (OR=0.76, CI=0.38-1.52) and elevated hs-CRP (OR=1.56, CI=0.87-2.80) were significant independent predictors of MS (all P<0.05).

CONCLUSIONS

The low testosterone and high hs-CRP levels are independent predictors of metabolic syndrome.

Diabetes severity, metabolic syndrome, and the risk of erectile dysfunction

INTRODUCTION

Erectile dysfunction (ED) is more common in men with type 2 diabetes mellitus (T2DM), obesity, and/or the metabolic syndrome (MetS).

AIM

The aim of this study is to investigate the associations among proxy measures of diabetic severity and the presence of MetS with ED in a nationally representative U.S. data sample.

METHODS

We performed a cross-sectional analysis of adult participants in the 2001-2004 National Health and Nutrition Examination Survey.

MAIN OUTCOME MEASURES

ED was ascertained by self-report. T2DM severity was defined by calculated measures of glycemic control and insulin resistance (IR). IR was estimated using fasting plasma insulin (FPI) levels and the homeostasis model assessment of IR (HOMA-IR) definition. We classified glycemic control using hemoglobin-A1c (HbA1c) and fasting plasma glucose (FPG) levels. MetS was defined by the American Heart Association and National Heart, Lung, and Blood Institute criteria. Logistic regression models, adjusted for sociodemographics, risk factors, and comorbidities, were fitted for each measure of T2DM severity, MetS, and the presence of ED.

RESULTS

Proxy measures of glycemic control and IR were associated with ED. Participants with FPG between 100-126 mg/dL (5.6-7 mmol/L) and ≥ 126 mg/dL (>7 mmol/L) had higher odds of ED, odds ratio (OR) 1.22 (confidence interval or CI, 0.83-1.80), and OR 2.68 (CI, 1.48-4.86), respectively. Participants with HbA1c 5.7-6.4% (38.8-46.4 mmol/mol) and ≥ 6.5% (47.5 mmol/mol) had higher odds of ED (OR 1.73 [CI, 1.08-2.76] and 3.70 [CI, 2.19-6.27], respectively). When FPI and HOMA-IR were evaluated by tertiles, there was a graded relation among participants in the top tertile. In multivariable models, a strong association remained between HbA1c and ED (OR 3.19 [CI,1.13-9.01]). MetS was associated with >2.5-fold increased odds of self reported ED (OR 2.55 [CI, 1.85-3.52]).

CONCLUSIONS

Poor glycemic control, impaired insulin sensitivity, and the MetS are associated with a heightened risk of ED.

The Relationship between Testosterone Deficiency and Men's Health

Testosterone is important in the physiology of various organs and tissues. The serum testosterone concentration gradually declines as one of the processes of aging. Thus, the concept of late-onset hypogonadism has gained increasing attention in the last few years. Reported symptoms of late-onset hypogonadism are easily recognized and include diminished sexual desire and erectile quality, particularly in nocturnal erections, changes in mood with concomitant decreases in intellectual activity and spatial orientation, fatigue, depression and anger, a decrease in lean body mass with associated decreases in muscle volume and strength, a decrease in body hair and skin alterations, and decreased bone mineral density resulting in osteoporosis. Among these various symptoms, sexual dysfunction has been the most common and necessary to treat in the field of urology. It is well known that a low serum testosterone level is associated with erectile dysfunction and hypoactive sexual libido and that testosterone replacement treatment can improve these symptoms in patients with hypogonadism. Recently, in addition to sexual dysfunction, a close relationship between metabolic syndrome, characterized by central obesity, insulin resistance, dyslipidemia, and hypertension, and late-onset hypogonadism has been highlighted by several epidemiologic studies. Several randomized control trials have shown that testosterone replacement treatment significantly decreases insulin resistance in addition to its advantage for obesity. Furthermore, metabolic syndrome is one of the major risk factors for cardiovascular disease, and a low serum testosterone level is closely related to the development of atherosclerosis. Presently, it is speculated that a low serum testosterone level may increase the risk for cardiovascular disease. Thus, testosterone is a key molecule in men's health, especially that of elderly men.

Androgen therapy in men with testosterone deficiency: can testosterone reduce the risk of cardiovascular disease?

Obesity, hypertension, insulin resistance (IR), dyslipidaemia, impaired coagulation profile and chronic inflammation characterize cardiovascular risk factors in men. Adipose tissue is an active endocrine organ producing substances that suppress testosterone (T) production and visceral fat plays a key role in this process. Low T leads to further accumulation of fat mass, thus perpetuating a vicious circle. In this review, we discuss reduced levels of T and increased cardiovascular disease (CVD) risk factors by focusing on evidence derived from three different approaches. (i) epidemiological/ observational studies (without intervention); (ii) androgen deprivation therapy (ADT) studies (standard treatment in advanced prostate cancer); and (iii) T replacement therapy (TRT) in men with T deficiency (TD). In epidemiological studies, low T is associated with obesity, inflammation, atherosclerosis and the progression of atherosclerosis. Longitudinal epidemiological studies showed that low T is associated with an increased cardiovascular mortality. ADT brings about unfavourable changes in body composition, IR and dyslipidaemia. Increases in fibrinogen, plasminogen activator inhibitor 1 and C-reactive protein have also been observed. TRT in men with TD has consistently shown a decrease in fat mass and simultaneous increase in lean mass. T is a vasodilator and in long-term studies, it was shown to reduce blood pressure. There is increasing evidence that T treatment improves insulin sensitivity and lipid profiles. T may possess anti-inflammatory and anti-coagulatory properties and therefore TRT contributes to reduction of carotid intima media thickness. We suggest that T may have the potential to decrease CVD risk in men with androgen deficiency.

The 20-year public health impact and direct cost of testosterone deficiency in U.S. men

INTRODUCTION

Testosterone deficiency (TD) imposes a substantial public health burden in the U.S. We modeled the costs associated with TD-related sequelae including cardiovascular disease (CVD), diabetes mellitus (DM), and osteoporosis-related fractures (ORFs).

AIM

To quantify the incremental cost burden imposed by TD's cardiometabolic sequelae.

METHOD

Incidence, prevalence, and mortality of these conditions were collected for men ages 45-74 from six national databases and large cross-sectional studies. Relative risk (RR) rates were determined for these sequelae in patients with T < 300 ng/dL. The prevalence of TD was determined for this cohort of men.

MAIN OUTCOME MEASURES

Adjusted incidence and prevalence were determined. Annual costs for the three TD-related sequelae were inflated at a real rate of 3% for 20 years.

RESULTS

Actual and adjusted (normalized for T deficiency) rates of CVD, DM, and ORFs in U.S. men aged 45-74 assuming a TD prevalence of 13.4% were calculated. We determined that, over a 20-year period, T deficiency is projected to be involved in the development of approximately 1.3 million new cases of CVD, 1.1 million new cases of DM, and over 600,000 ORFs. In year 1, the attributed cost burden of these diseases was approximately $8.4 billion. Over the entire 20-year period, T deficiency may be directly responsible for approximately $190-$525 billion in inflation-adjusted U.S. health care expenditures.

CONCLUSION

TD may be a significant contributor to adverse public health. Further study is needed to definitively describe the whether TD is a modifiable risk factor for CVD, DM, and ORFs. This may represent an opportunity for nationwide public health initiatives aimed at preventive care.

The direct and indirect costs among U.S. privately insured employees with hypogonadism

INTRODUCTION

While previous studies have noted that hypogonadism (HG) may pose a significant economic and quality-of-life burden, no studies have evaluated the impact of HG on healthcare utilization and costs in the United States.

AIM

Compare direct (health care) and indirect (disability leave or medical absence) costs between privately insured U.S. employees with HG and controls without HG.

METHODS

The study sample included 4,269 male employees, ages 35-64, with ≥ 2 HG diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification: 257.2x) or ≥ 1 HG diagnosis and ≥ 1 claim for testosterone therapy, 1/1/2005-3/31/2009, identified from a large, private insurance administrative database that includes medical, prescription drug, and disability claims data. The index date was the most recent HG diagnosis that had continuous eligibility for at least 1 year before (baseline period) and 1 year after (study period). Employees with HG were matched 1:1 on age, region, salaried vs. nonsalaried employment status, and index year to controls without HG.

MAIN OUTCOME MEASURES

Descriptive analyses compared demographic characteristics, comorbidities, resource utilization, direct and indirect costs inflated to USD 2009. Multivariate analyses adjusting for baseline characteristics were used to estimate risk-adjusted costs.

RESULTS

HG employees and controls had a mean age of 51 years. HG employees compared with controls had higher baseline comorbidity rates, including hyperlipidemia (50.2% vs. 25.3%), hypertension (37.7% vs. 21.1%), back/neck pain (32.0% vs. 15.7%), and human immunodeficiency virus/acquired immunodeficiency syndrome (7.1% vs. 0.3%) (all P < 0.0001). HG employees had higher mean study period direct ($10,914 vs. $3,823) and indirect costs ($3,204 vs. $1,450); HG-related direct costs were $832 (all P < 0.0001). Risk-adjusted direct ($9,291 vs. $5,248) and indirect ($2,729 vs. $1,840) costs were also higher for HG employees (all P < 0.0001).

CONCLUSIONS

Employees with HG had higher comorbidity rates and costs compared with controls. Given the low HG-related costs, a primary driver of costs among HG patients appears to be their comorbidity burden.