Low serum testosterone, arterial stiffness and mortality in male haemodialysis patients

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.

Testosterone deficiency: a determinant of aortic stiffness in men

OBJECTIVE

Low testosterone levels and increased aortic stiffness are predictors of cardiovascular events. The influence of androgen level on the age- and blood pressure-related increase in aortic stiffness is unknown.

METHODS

From January 2007 to June 2011 we enrolled 455 consecutive men with no evidence of cardiovascular disease from a large cohort followed in our Department for arterial function studies. Their total testosterone (TT) levels were measured and carotid-femoral pulse wave velocity (PWVc-f) was measured as an index of aortic stiffness.

RESULTS

In multivariable analysis, PWVc-f values were inversely correlated to TT after adjustment for confounders (β = -0.365, P < 0.001). In younger age categories (<50 yrs and 50-59 yrs), patients with testosterone deficiency (TD) had higher blood pressure-adjusted PWVc-f (P < 0.001 and P = 0.005, respectively) compared to subjects with normal TT, indicating an "aging effect" of 10 years, whereas in older age categories such a difference was not observed. Furthermore, in men with a higher mean pressure (102-108 mmHg and >108 mmHg), patients with TD had higher age-adjusted PWVc-f (P < 0.001) compared to subjects with normal TT, indicating a synergistic unfavorable effect of testosterone deficiency and blood pressure on aortic stiffness.

CONCLUSIONS

TT levels are independently associated with aortic stiffening. The effect of low testosterone concentration on aortic stiffness is more prominent in young men and in subjects with higher blood pressure levels. These findings identify testosterone as a marker of arterial damage with special emphasis on young and hypertensive individuals and support its role as predictor of events.

Role of testosterone in the pathogenesis, progression, prognosis and comorbidity of men with chronic kidney disease

Testosterone deficiency and hypogonadism are common conditions in men with chronic kidney disease (CKD). A disturbed hypothalamic-pituitary-gonadal axis due to CKD is thought to contribute to androgen deficiency. Data from experimental studies support the hypothesis that exogenous administration of testosterone may induce the activation of the renin-angiotensin system (RAS), the production of endothelin and the regulation of anti- or/and proinflammatory cytokines involved in the pathogenesis of hypertension and kidney damage. On the other hand, low testosterone levels in male patients with CKD are paradoxically associated with a higher risk of morbidity and mortality, possibly explained by anemia, osteoporosis and cardiovascular disease. In this article, we present an overview of clinical and experimental studies of the impact of testosterone on the progression and prognosis of male patients with CKD; even today, this remains a controversial issue.

Association of serum total testosterone concentration with skeletal muscle mass in men under hemodialysis

PURPOSE

Although skeletal muscle wasting can occur in chronic kidney diseases, its relationship with the serum testosterone concentration remains uncertain. This study investigates the relationship between serum testosterone and skeletal muscle mass in men under hemodialysis (HD).

METHODS

Sixty men aged between 41 and 89 years undergoing HD for 15.0 ± 8.1 years were enrolled for this study. The muscle areas of the thigh (TMA) and abdomen (AMA) were measured by computed tomography (CT), and the association between these muscle areas and serum total testosterone was examined with adjustment of age and other nutritional variables.

RESULTS

The mean serum total testosterone in our HD patients (6.33 ± 2.90 ng/mL) was not lower than that of the Japanese general population, but showed a positive correlation with TMA (r = 0.39, p < 0.05), AMA (r = 0.52, p < 0.001), serum creatinine (r = 0.33, p < 0.05), and the creatinine generation rate (r = 0.26, p < 0.05). Serum total testosterone was inversely correlated with age (r = -0.32, p < 0.05), CRP (r = -0.31, p < 0.05), and IL-6 (r = -0.24, p < 0.05). A multiple-regression analysis showed both serum total testosterone and age to be an independent determinant of the muscle mass in these patients.

CONCLUSIONS

This study identified testosterone as a determinant of muscle mass in HD men.

Changes in fertility and hormone replacement therapy in kidney disease

Infertility is common among men and women with CKD and fertility is usually restored with successful kidney transplantation. There are many causes of infertility in those on dialysis, including sexual dysfunction and impaired spermatogenesis and ovulation resulting from an altered hormonal milieu. There is little information about infertility in CKD, but it is clear that ESRD results in low rates of pregnancy in women. Early reports of increased pregnancy rates in women on nocturnal hemodialysis suggest that this modality may improve the abnormal reproductive hormonal milieu of ESRD; small studies of men on dialysis also suggest this. Just as the specific causes of infertility in men and women with CKD/ESRD are unknown, we also lack information about the appropriateness of hormone replacement in these patients. This paper reviews these linked issues, pointing out the lack of data upon which to base clinical decision-making about these quality-of-life issues in our CKD/ESRD patients.

Plasma total testosterone and incident cardiovascular events in hypertensive patients

BACKGROUND

Androgen deficiency confers an independent risk for cardiovascular events and total mortality. Hypertension, a major contributory factor to the development of cardiovascular disease, has also been associated with increased prevalence of low testosterone. We investigated whether low androgen concentration predicts incident major adverse cardiovascular events (MACE) in middle-aged nondiabetic hypertensive patients without clinical atherosclerosis.

METHODS

MACE in relation to total testosterone (TT) were analyzed with proportional hazards models in 228 male patients (mean age 56 years).

RESULTS

During a mean follow-up of 44 months, 19 of 228 participants (8.3%) experienced a MACE. Compared to patients who did not experience MACE, hypertensive subjects who developed MACE had lower TT concentration (3.9±0.7ng/ml vs. 4.6±1.5ng/ml, P < 0.01) and a higher prevalence of hypogonadism (36% vs. 16%, P < 0.05). Subjects in the lowest TT tertile (<4.0ng/ml) had a statistically significant higher risk of MACE compared to those in the highest tertile (>4.9ng/ml) in multivariate Cox models adjusted for age, systolic blood pressure, and risk factors (all P < 0.05). A TT plasma level of 5.04ng/ml was associated with a negative predictive value (ability to "rule out" MACE) of 97.2%. Addition of TT to standard risk factors model yielded a net reclassification improvement of 38.8 % (P < 0.05).

CONCLUSIONS

Our results show that low plasma testosterone is associated with increased risk for a MACE in hypertensive patients. Low endogenous androgen concentration improves risk prediction when added to standard risk factors and may represent a valuable biomarker of prediction of cardiovascular disease risk in these patients.

Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry Candidate Reference Method for Total Testosterone in Human Serum

BACKGROUND

We developed and evaluated a candidate reference measurement procedure (RMP) to standardize testosterone measurements, provide highly accurate and precise value assignments for the CDC Hormone Standardization Program, and ensure accurate and comparable results across testing systems and laboratories.

METHODS

After 2 liquid/liquid extractions of serum with a combination of ethyl acetate and hexane, we quantified testosterone by isotope-dilution liquid chromatography–tandem mass spectrometry with electrospray ionization in the positive ion mode monitoring 289→97 m/z (testosterone) and 292→112 m/z (3C13 testosterone). We used calibrator bracketing and gravimetric measurements to give higher specificity and accuracy to serum value assignments. The candidate RMP was evaluated for accuracy by use of NIST-certified reference material SRM971 and validated by split-sample comparison to established RMPs. We evaluated intraassay and interassay imprecision, measurement uncertainty, potential interferences, and matrix effects.

RESULTS

A weighted Deming regression comparison of the candidate RMP to established RMPs showed agreement with no statistical difference (slope 0.99, 95% CI 0.98–1.00, intercept 0.54, 95% CI −1.24 to 2.32) and a bias of ≤0.3% for NIST SRM971. The candidate RMP gave maximum intraassay, interassay, and total percent CVs of 1.5%, 1.4%, and 1.7% across the concentrations of testosterone typically found in healthy men and women. We tested structural analogs of testosterone and 125 serum samples and found no interferences with the measurement.

CONCLUSIONS

This RMP for testosterone can serve as a higher-order standard for measurement traceability and can be used to provide an accuracy base to which routine methods can be compared in the CDC Hormone Standardization Program.

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.

Impaired aortic elastic properties in patients with adult-onset hypogonadism

BACKGROUND

Recent studies have shown a strong relationship between testosterone levels and vasomotor actions. The aim of this study is to compare the elastic properties of the aorta in male patients with hypogonadism and eugonadal healthy control subjects.

METHOD

A total of 22 male with hypogonadism (mean age: 35.2 ± 9.5 years, mean disease duration: 5.3 ± 1.8 years) and 25 age-, sex- and weight-matched eugonadal healthy subjects (mean age: 34.5 ± 8.2 years) were enrolled in the study. Aortic stiffness (β) index, aortic strain (AoS) and aortic distensibility (AoD) were calculated from the aortic diameters measured by transthoracic echocardiography and blood pressure obtained by sphygmomanometer.

RESULTS

The routinely performed echocardiographic parameters were similar between patient and control groups. There were significant differences between the control and patient groups in β index (1.75 ± 0.44 vs 2.68 ± 1.72, p < 0.001), AoS (18.52 ± 6.44 vs 12.35 ± 3.88%, p < 0.001) and AoD (7.56 ± 2.86 vs 3.96 ± 1.24, 10(-6) cm(2)/dyn, p < 0.001). There were statistically significant positive correlations between the serum total testosterone level and AoD (r = 0.539, p < 0.001) and AoS (r = 0.372, p = 0.036); moreover, there was a negative correlation between the serum total testosterone level and β index (r = - 0.462, p = 0.001). In multivariate analysis, serum total testosterone level was significantly related with AoD, AoS and β index (respectively, RR = 2.88, p = 0.004; RR = 3.45, p = 0.001; RR = 2.64, p = 0.01).

CONCLUSION

The study results showed that aortic elasticity was impaired in patients with hypogonadism. We also have demonstrated a statistically significant correlation between aortic elastic properties and the serum total testosterone level.

The vulnerable man: impact of testosterone deficiency on the uraemic phenotype

Testosterone deficiency or hypogonadism is a common finding in men undergoing dialysis, to a great extent a consequence of the failing kidney per se. Testosterone restoration in hypogonadism is common practice among endocrinologists. However, there is currently little awareness of this condition among both uremic patients and nephrologists, and in many cases, testosterone deficiency remains unscreened and untreated. This review article summarizes our current understanding of the role of testosterone deficiency at the crossroad of cardiometabolic complications of patients with chronic kidney disease. Pathways discussed include, among others, the plausible role of testosterone deficiency in the development of anaemia and ESA hyporesponsiveness, muscle catabolism, endothelial dysfunction, cognitive dysfunction, decreased libido, cardiovascular disease and mortality. As there are limited sources to guide decision-making, we also review existing testosterone replacement therapy studies in the context of CKD as well as considerations for side and adverse effects. This review makes a case for consideration of screening and better management of hypogonadism in men undergoing dialysis.

Prolactin levels, endothelial dysfunction, and the risk of cardiovascular events and mortality in patients with CKD

BACKGROUND AND OBJECTIVES

Both prolactin clearance and production are altered in CKD. In nonrenal populations, emerging evidence suggests that prolactin participates in the atherosclerotic process. Given the elevated cardiovascular risk of CKD, this study examined links between prolactinemia, vascular derangements, and outcomes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This observational study was conducted in two cohorts: one with 457 nondialyzed CKD patients (mean age 52±12 years; 229 men) with measurements of flow-mediated dilation (FMD) and carotid intima-media thickness and one with 173 hemodialysis patients (65±12 years; 111 men) with measurements of pulse wave velocity (PWV). Patients were followed for cardiovascular events (n=146, nondialyzed cohort) or death (n=79, hemodialysis cohort).

RESULTS

Prolactin levels increased along with reduced kidney function. Prolactin significantly and independently contributed to explain the variance of both FMD (in nondialyzed patients) and PWV (in hemodialysis patients), but not intima-media thickness. In Cox analyses, the risk of cardiovascular events in nondialyzed patients increased by 27% (hazard ratio [HR], 1.27; 95% confidence interval [95% CI], 1.17-1.38) for each 10 ng/ml increment of prolactin. Similarly, the risk for all-cause and cardiovascular mortality in hemodialysis patients increased by 12% (HR, 1.12; 95% CI, 1.06-1.17) and 15% (HR, 1.15; 95% CI, 1.08-1.21), respectively. This was true after multivariate adjustment for confounders and after adjustment within the purported causal pathway (FMD or PWV).

CONCLUSIONS

Prolactin levels directly associated with endothelial dysfunction/stiffness and with increased risk of cardiovascular events and mortality in two independent cohorts of CKD patients.