The relationship between sex hormones, sex hormone binding globulin and peripheral artery disease in older persons

Testosterone Replacement Therapy in Relation With Cardiovascular Disease in Cisgender Women and Transgender People

AIMS

This study aimed to investigate the association of testosterone replacement therapy (TTh) with risk of cardiovascular disease (CVD), and CVD-specific outcomes, in cisgender women and transgender population, and to determine whether this association varies by menopausal status.

METHODS

In 25 796 cisgender women and 1580 transgender people (≥30 years old) who were enrolled in the Optum's deidentified Clinformatics Data Mart Database (2007-2021), we identified 6288 pre- and postmenopausal cisgender women and 262 transgender people diagnosed with incident composite of CVD (coronary artery disease [CAD], congestive heart failure, stroke, and myocardial infarction). Prediagnostic prescription of TTh was ascertained for this analysis. Multivariable adjusted Cox proportional hazards models were used to examine the independent association of TTh with incident CVD.

RESULTS

We found a 24% increased risk of CVD (hazard ratio [HR] = 1.24; 95% CI, 1.15-1.34), 26% risk of CAD (HR = 1.26; 95% CI, 1.14-1.39), and a 29% risk of stroke (HR = 1.29; 95% CI, 1.14-1.45) after comparing cisgender women who used TTh with nonusers. Stratification by age group showed similar effects of TTh on CVD, CAD, and stroke. Among transgender people, TTh did not increase the risk of composite CVD, including by age stratification.

CONCLUSION

Use of TTh increased the risk of CVD, CAD, and stroke among cisgender women but not among transgender people. TTh is becoming more widely accepted in women, and it is the main medical treatment for transgender males. Therefore, use of TTh should be further investigated for the prevention of CVD.

Testosterone and Peripheral Arterial Disease

Testosterone levels in men begin declining in the early years of adulthood, with a 1-2% reduction/year. Low testosterone levels in men are associated with obesity, metabolic syndrome, diabetes mellitus, dyslipidaemia, hypertension and increased cardiovascular mortality. However, observational studies of testosterone levels in males and their relationship with peripheral arterial disease (PAD) have yielded mixed results; only some cohorts show a clear association with low free testosterone levels. This discrepancy may, in part, be due to methodological issues with estimating free testosterone but also to different effects of testosterone on the vessel wall and metabolism. While testosterone improves glycaemic control, has anti-obesity effects and induces vasodilation, it also stimulates platelet aggregation and increases the haematocrit. Androgen deprivation treatment for advanced prostate cancer may be associated with elevated cardiovascular risk, as is testosterone abuse for performance enhancement. On the other hand, judicious treatment of male hypogonadism or testosterone treatment of trans-men appears to be safe.

Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology

According to the free hormone hypothesis, biological activity of a certain hormone is best reflected by free rather than total hormone concentrations. A crucial element in this theory is the presence of binding proteins, which function as gatekeepers for steroid action. For testosterone, tissue exposure is governed by a delicate equilibrium between free and total testosterone which is determined through interaction with the binding proteins sex hormone-binding globulin and albumin. Ageing, genetics and various pathological conditions influence this equilibrium, hereby possibly modulating hormonal exposure to the target tissues. Despite ongoing controversy on the subject, strong evidence from recent in vitro, in vivo and human experiments emphasizes the relevance of free testosterone. Currently, however, clinical possibilities for free hormone diagnostics are limited. Direct immunoassays are inaccurate, while gold standard liquid chromatography with tandem mass spectrometry (LC-MS/MS) coupled equilibrium dialysis is not available for clinical routine. Calculation models for free testosterone, despite intrinsic limitations, provide a suitable alternative, of which the Vermeulen calculator is currently the preferred method. Calculated free testosterone is indeed associated with bone health, frailty and other clinical endpoints. Moreover, the added value of free testosterone in the clinical diagnosis of male hypogonadism is clearly evident. In suspected hypogonadal men in whom borderline low total testosterone and/or altered sex hormone-binding globulin levels are detected, the determination of free testosterone avoids under- and overdiagnosis, facilitating adequate prescription of hormonal replacement therapy. As such, free testosterone should be integrated as a standard biochemical parameter, on top of total testosterone, in the diagnostic workflow of male hypogonadism.

Estrogen Deficiency Aggravates Fluoride-Induced Liver Damage and Lipid Metabolism Disorder in Rats

Estrogen exerts essential role in liver metabolism, and its deficiency is frequently accompanied by a series of metabolic disorder diseases. To investigate the role of estrogen deficiency in fluorine ions (F^-) induced liver injury, the ovariectomy (OVX) rat models were performed by surgically removing the ovaries, and the rats from OVX and non-OVX models were exposed to differential dose of F^- (0, 25, 50 and 100 mg/L) in drinking water for 90 days. The liver morphological structure was evaluated by hematoxylin-eosin staining. Proliferation ability of hepatocytes was evaluated by 5-bromo-2-deoxyuridine (BrdU) assay. And distribution of lipid droplets in liver tissue was observed via oil red O staining. In addition, the liver function and lipid metabolism parameters in serum were detected by commercial kits. Results showed that F^- induced hepatocytes morphological damage and inhibited the proliferation ability of hepatocytes; estrogen deficiency exacerbated these changes. The deposition of lipid droplets in the liver tissue was multiplicative with increased F^- dose, especially after estrogen deficiency. In addition, F^- exposure increased (P < 0.05 or P < 0.01) serum aminotransferase (ALT), aminotransferase (AST), alkaline phosphatase (ALP), and γ-glutamyl transpeptidase (γ-GT) activities and total bilirubin (T-bil) level; meanwhile, serum triglyceride (TG) and cholesterol (TC) levels were also elevated (P < 0.05 or P < 0.01). F^--induced liver function and lipid metabolism indexes were further increased (P < 0.05 or P < 0.01) in the state of estrogen deficiency. In conclusion, estrogen deficiency aggravated F^--induced liver damage and lipid metabolism disorder.

In-hospital mortality in patients with acute limb ischemia over a 12-year period in the Brazilian public health-care system

Background

Arterial diseases represent a severe public health problem in the 21st century. Although men have a higher overall prevalence, reports have suggested that women may exhibit atypical manifestations, be asymptomatic, and have hormonal peculiarities, resulting in worse outcomes and severe emergencies, such as acute limb ischemia (ALI).

Objectives

To analyze the morbidity and mortality profile of ALI emergencies in Brazil between 2008 and 2019.

Methods

An ecological study was carried out with secondary data from SIH/SUS, using ICD-10 code I.74 The proportions of emergency hospital admissions and in-hospital mortality rates (HMR) by gender, ethnicity, and age were extracted from the overall figures. P<0.05 was considered significant.

Results

From 2008 to 2019, there were 195,567 urgent hospitalizations due to ALI in Brazil, 111,145 (56.8%) of which were of men. Women had a higher HMR (112:1,000 hospitalizations) than men (85:1,000 hospitalizations) (p<0.05), and a higher chance of death (OR=1.36; p<0.05). Furthermore, mean survival was significantly higher among men (8,483/year versus 6,254/year; p<0.05). Stratified by ethnicity, women who self-identified as white (OR=1.44; p<0.05), black (OR=1.33; p<0.05), and brown (RR=1.25; p <0.05) had greater chances of death than men in the same ethnicity categories. Moreover, women over the age of 50 years had a higher chance of death, with a progressive increment in risk as age increased.

Conclusions

There was a trend to worse prognosis in ALI emergencies associated with women, especially in older groups. The literature shows that the reasons for these differences are still poorly investigated and more robust studies of this relevant disease in the area of vascular surgery are encouraged.

Aging and sex hormones in males

Several large cohort studies have disclosed the trajectories of sex steroids changes overtime in men and their clinical significance. In men the slow, physiological decline of serum testosterone (T) with advancing age overlaps with the clinical condition of overt, pathological hypogonadism. In addition, the increasing number of comorbidities, together with the high prevalence of chronic diseases, all further contribute to the decrease of serum T concentrations in the aging male. For all these reasons both the diagnosis of late-onset hypogonadism (LOH) in men and the decision about starting or not T replacement treatment remain challenging. At present, the biochemical finding of T deficiency alone is not sufficient for diagnosing hypogonadism in older men. Coupling hypogonadal symptoms with documented low serum T represents the best strategy to refine the diagnosis of hypogonadism in older men and to avoid unnecessary treatments.

Sex differences in vascular physiology and pathophysiology: estrogen and androgen signaling in health and disease

Sex differences between women and men are often overlooked and underappreciated when studying the cardiovascular system. It has been long assumed that men and women are physiologically similar, and this notion has resulted in women being clinically evaluated and treated for cardiovascular pathophysiological complications as men. Currently, there is increased recognition of fundamental sex differences in cardiovascular function, anatomy, cell signaling, and pathophysiology. The National Institutes of Health have enacted guidelines expressly to gain knowledge about ways the sexes differ in both normal function and diseases at the various research levels (molecular, cellular, tissue, and organ system). Greater understanding of these sex differences will be used to steer future directions in the biomedical sciences and translational and clinical research. This review describes sex-based differences in the physiology and pathophysiology of the vasculature, with a special emphasis on sex steroid receptor (estrogen and androgen receptor) signaling and their potential impact on vascular function in health and diseases (e.g., atherosclerosis, hypertension, peripheral artery disease, abdominal aortic aneurysms, cerebral aneurysms, and stroke).

Biology of frailty: Modulation of ageing genes and its importance to prevent age-associated loss of function

Frailty is associated with loss of functional reserve as well as with the prediction of adverse events in the old population. The traditional criteria of frailty are based on five physical determinations described in the Cardiovascular Health Study. We propose that biological and genetic markers of frailty should be used to increase the predictive capacity of the established clinical indeces. In recent times, research for biological markers of frailty has gained impetus. Finding a biological markers with diagnostic and prognostic capacity would be a major milestone to identify frailty risk, and also pre-frailty status. In the first section of the manuscript, we review the available biomarkers that help to monitor and prevent the evolution and the efficacy of interventions to delay the onset of frailty and to prevent its progression to incapacity. We also discuss the contribution of genetics to frailty. There are scientific bases that support that genetics influences frailty, although environmental factors probably will have the highest contribution. We review the known SNPs of the genes associated with frailty and classify them, taking into account the pathway in which they are involved. We also highlight the importance of longevity genes and their possible relation with frailty, citing centenarians who reach a very old age as an example of successful ageing. Finally, the reversibility of frailty is discussed. It can potentially be treated with nutritional or pharmacological interventions. However, physical exercise seems to be the most effective strategy to treat and prevent frailty. The last section of the manuscript is devoted to explaining the recommendations on the appropriate design of an exercise protocol to maximize its beneficial effects in a population of frail individuals.

Testosterone in women--the clinical significance

Testosterone is an essential hormone for women, with physiological actions mediated directly or via aromatisation to oestradiol throughout the body. Despite the crucial role of testosterone and the high circulating concentrations of this hormone relative to oestradiol in women, studies of its action and the effects of testosterone deficiency and replacement in women are scarce. The primary indication for the prescription of testosterone for women is loss of sexual desire, which causes affected women substantial concern. That no formulation has been approved for this purpose has not impeded the widespread use of testosterone by women--either off-label or as compounded therapy. Observational studies indicate that testosterone has favourable cardiovascular effects measured by surrogate outcomes; however, associations between endogenous testosterone and the risk of cardiovascular disease and total mortality, particularly in older women, are yet to be established. Adverse cardiovascular effects have not been seen in studies of transdermal testosterone therapy in women. Clinical trials suggest that exogenous testosterone enhances cognitive performance and improves musculoskeletal health in postmenopausal women. Unmet needs include the availability of approved testosterone formulations for women and studies to elucidate the contribution of testosterone to cardiovascular, cognitive, and musculoskeletal health and the risk of cancer.

The biomarker sex hormone-binding globulin - from established applications to emerging trends in clinical medicine

Sex hormone-binding globulin (SHBG) is a serum glycoprotein exhibiting the unique feature of binding sex steroids with high affinity and specificity. Its serum levels are regulated not only by androgens and estrogens but also by thyroid hormones and other metabolic factors. Several disease conditions are accompanied by altered SHBG levels such as hyper- and hypoandrogenism, thyroid disorders, pituitary diseases, liver disorders, and breast as well as prostate cancer. Additionally, several drugs and alcohol consumption influence serum concentrations of SHBG. In some cases, altered SHBG levels are a specific result of the underlying pathology. In others, they merely constitute an epiphenomenon, which still might offer the possibility of using serum measurements of SHBG as surrogate marker. This review article portrays the different disorders associated with altered SHBG levels and discusses the usefulness of SHBG as disease biomarker from a clinicians as well as from an endocrinological researchers point of view.

Association of sex hormones with carotid artery distensibility in men and postmenopausal women: multi-ethnic study of atherosclerosis

The decline in carotid distensibility with age is steeper in women than in men, however, the correlates of this sex difference are not known. We examined the association of bioavailable testosterone, estradiol, dehydroepiandrosterone, and sex hormone-binding globulin, in 2783 postmenopausal women and 2987 men aged 45 to 84 years at the Multi-Ethnic Study of Atherosclerosis baseline examination. Carotid artery lumen diameters by ultrasound and brachial artery blood pressures were measured at systole and diastole. Regression models to determine the association of carotid distensibility coefficient and lumen diameter with sex-specific quartiles of sex hormones were adjusted for age, race, height, weight, diabetes mellitus, current smoking, antihypertensive medication use, total and high-density lipoprotein cholesterol levels, and hormone replacement therapy in women. A higher DC indicates a more distensible vessel. In women, higher dehydroepiandrosterone (P=0.008) and lower sex hormone-binding globulin (P=0.039) were associated with lower distensibility; higher dehydroepiandrosterone and lower estradiol were associated with smaller carotid diameters. In men, higher Bio-T (P=0.009) and lower estradiol (P=0.007) were associated with greater distensibility and also with smaller diameters (P=0.012 and 0.002, respectively). An androgenic internal milieu is associated with lesser carotid distensibility and diameter remodeling in women, but the opposite is true for men. Higher levels of estradiol are associated with smaller carotid diameters in both the sexes. Future longitudinal and experimental studies are needed to reveal the mechanism and clinical consequences of these associations.

Evidence for low androgenicity among Indian (South Asian) men

There are increasing data indicating profound ethnic differences in the levels of virilization of males. It is well understood that the intensity of testosterone-mediated effects is modulated by sex hormone binding globulin (SHBG) and the CAG repeat lengths in the androgen receptor (AR) gene. We determined the serum testosterone, estradiol and SHBG levels and average CAG repeat lengths among a group of healthy older Indian men living in Connecticut, USA and compared these parameters with those of a reference group of white Caucasian men. We also compared various parameters that represent the end-manifestations of testosterone activity - serum prostate-specific antigen (PSA) levels, lean body mass, skeletal mineralization and visceral fat. Our data suggest that men from the Indian subcontinent are smaller, manifest lower levels of circulating free testosterone, lower mean PSA levels and lean body mass, but are comparable to white Caucasian men in terms of SHBG, estradiol, levels of visceral fat and CAG repeat length. These data suggest that Indian men manifest a lower level of virilization compared to white Caucasian males and that this might be due to lower mean circulating testosterone levels rather than higher AR CAG repeat length or SHBG.

The Effect of Testosterone on Cardiovascular Disease

Cardiovascular disease is the leading cause of death in the United States. Testosterone is the principal male sex hormone and plays an important role in men’s health and well-being. Historically, testosterone was believed to adversely affect cardiovascular function. However, contemporary literature has refuted this traditional thinking; testosterone has been suggested to have a protective effect on cardiovascular function through its effects on the vascular system. Data from modern research indicate that hypogonadism is closely related to the development of various cardiovascular risk factors, including hyperlipidemia and insulin resistance. Several studies have demonstrated beneficial effects of testosterone supplementation therapy on reversing symptoms of hypogonadism and improving cardiovascular disease risk profiles. In this review, we perform a critical analysis on the association between testosterone and cardiovascular disease.

Lower plasma testosterone or dihydrotestosterone, but not estradiol, is associated with symptoms of intermittent claudication in older men

OBJECTIVE

In men, testosterone (T) levels decline with age, and lower T predicts all-cause and cardiovascular mortality. However, the associations of T and its metabolites, dihydrotestosterone (DHT) and estradiol (E2), with symptomatic peripheral arterial disease remain unclear. We assessed associations of T, DHT and E2 with lower limb intermittent claudication in older men.

DESIGN

Cross-sectional study.

PARTICIPANTS

Community-dwelling men aged 70-89 years resident in Perth, Western Australia.

MEASUREMENTS

Intermittent claudication was ascertained by the Edinburgh Claudication Questionnaire. Early morning, plasma T, DHT and E2 were assayed using liquid chromatography-tandem mass spectrometry.

RESULTS

There were 268 men with intermittent claudication and 2435 without claudication or any leg pain. Men with nonspecific leg pain (n = 986) were excluded. After adjusting for age, smoking, BMI, waist/hip ratio, hypertension, dyslipidaemia, diabetes, creatinine and prevalent cardiovascular disease (CVD), higher T was associated with reduced risk of having claudication (per 1 SD increase, odds ratio [OR] = 0·80, 95% confidence interval [CI] = 0·69-0·94, P = 0·006; quartiles, Q4/Q1, OR = 0·54, 95% CI = 0·36-0·81). Higher DHT was associated with reduced risk of having claudication (per 1 SD increase, OR = 0·86, 95% CI = 0·73-1·00, P = 0·048; Q4/Q1, OR = 0·64, 95% CI = 0·43-0·95). E2 was not associated with claudication (per 1 SD increase, OR = 0·96, 95% CI = 0·83-1·11, P = 0·565; Q4/Q1, OR = 0·88, 95% CI = 0·60-1·29).

CONCLUSIONS

Lower T or DHT levels, but not E2, are associated with symptoms of intermittent claudication in older men. Reduced exposure to androgens may represent a causal factor or biomarker for symptomatic peripheral arterial disease. Further studies are needed to examine underlying mechanisms and evaluate therapeutic options in ageing men.

SHBG and endothelial function in older subjects

BACKGROUND

Endothelial dysfunction is predictor of cardiovascular diseases that have different prevalence in men and women before menopause. Sex hormones and sex hormone binding globulin (SHBG), novel risk factors for diabetes and cardiovascular diseases even in older individuals, might explain this difference. However, the relationship between these hormones and endothelial function has never been addressed in the elderly.

METHODS AND RESULTS

430 men and,424 women 70 years older of Prospective Study of the Vasculature in Uppsala Seniors study, with complete data on SHBG, testosterone(T), estradiol(E2), endothelium-independent vasodilation (EIDV), endothelium-dependent vasodilation(EDV), flow-mediated vasodilation (FMD) and the pulse wave analysis (reflection index, RI) were evaluated. Multivariate regression analysis adjusted for confounders was used to assess the relationship between T, E2, SHBG and endothelial function. In men we found a positive relationship between SHBG and EDV (β ± SE 3.60 ± 0.83, p<0.0001), EIDV (2.42 ± 0.58, p<0.0001) but not with FMD. The relationship between SHBG and EDV and EIDV was maintained after adjustment for sex (1.64 ± 0.47, p<0.001 and 1.79 ± 0.35, p<0.0006, respectively). After adjustment for confounders, the relationship between SHBG and EDV and EIDV was still statistically significant (2.63 ± 0.90 and 1.86 ± 0.63, p = 0.004 for both). In women SHBG and EIDV were positively associated (1.58 ± 0.46; p = 0.0007), and this relationship was independent of sex (1.79 ± 0.35; p<0.001). No significant interaction SHBG * SEX was found for EIDV (p = 0.72). In a combined analysis in two sexes, SHBG and EIDV were positively associated (1.13 ± 0.45; p = 0.01). SHBG was not associated with EDV, FMD and RI. No significant relationship was found between T or E2 and EDV, EIDV, FMD or RI in both sexes.

CONCLUSIONS

In older men SHBG, but not T and E2, is positively and independently associated with EDV in resistance arteries. In both sexes, SHBG was positively and independently associated with EIDV.