Testosterone replacement in hypogonadal men: effects on obstructive sleep apnoea, respiratory drives, and sleep

Characterization of risk factors for obstructive sleep apnea and its association with absenteeism among nurses

PURPOSE

To characterize risk factors associated with obstructive sleep apnea (OSA) and its relationship with nurses' absenteeism.

METHODS

A cross-sectional study was conducted from 2018 to 2020 at a 1,000-bed academic hospital complex and biomedical research facility in Tehran, Iran. Participants were selected through consecutive sampling after obtaining ethical approval and informed consent. Data on demographics, medical conditions, occupational characteristics, and absenteeism were collected through face-to-face interviews. The STOP-Bang questionnaire was utilized to assess the probability of OSA. Statistical tests included the Mann-Whitney U, t-test, Chi-square, and multivariable regression.

RESULTS

In this study involving 304 nurses, the majority were female (81.3%), with an average age of 35. About 27 participants (8.9%) had a high probability of OSA, with male sex, older age, higher body mass index, neck circumference, and diastolic BP identified as the main determinants of OSA. Additionally, shift work and night shifts were associated with increased absenteeism, while sex showed no significant association with absenteeism rates among nurses.

CONCLUSION

Male sex, neck circumference (obesity), night shifts, and diastolic BP can predict OSA risk. However, unauthorized absence from work is not associated with a high risk for OSA (STOP-BANG ≥3) or the individual risk factors of OSA.

Pathophysiology Underlying Demographic and Obesity Determinants of Sleep Apnea Severity

Rationale: Sleep apnea is the manifestation of key endotypic traits, including greater pharyngeal collapsibility, reduced dilator muscle compensation, and elevated chemoreflex loop gain. Objectives: We investigated how endotypic traits vary with obesity, age, sex, and race/ethnicity to influence sleep apnea disease severity (apnea-hypopnea index [AHI]). Methods: Endotypic traits were estimated from polysomnography in a diverse community-based cohort study (Multi-Ethnic Study of Atherosclerosis, N = 1,971; age range, 54-93 yr). Regression models assessed associations between each exposure (continuous variables per 2 standard deviations [SDs]) and endotypic traits (per SD) or AHI (events/h), independent of other exposures. Generalizability was assessed in two independent cohorts. Results: Greater AHI was associated with obesity (+19 events/h per 11 kg/m2 [2 SD]), male sex (+13 events/h vs. female), older age (+7 events/h per 20 yr), and Chinese ancestry (+5 events/h vs. White, obesity adjusted). Obesity-related increase in AHI was best explained by elevated collapsibility (+0.40 SD) and greater loop gain (+0.38 SD; percentage mediated, 26% [95% confidence interval (CI), 20-32%]). Male-related increase in AHI was explained by elevated collapsibility (+0.86 SD) and reduced compensation (-0.40 SD; percentage mediated, 57% [95% CI, 50-66%]). Age-related AHI increase was explained by elevated collapsibility (+0.37 SD) and greater loop gain (+0.15 SD; percentage mediated, 48% [95% CI, 34-63%]). Increased AHI with Chinese ancestry was explained by collapsibility (+0.57 SD; percentage mediated, 87% [95% CI, 57-100]). Black race was associated with reduced collapsibility (-0.30 SD) and elevated loop gain (+0.29 SD). Similar patterns were observed in the other cohorts. Conclusions: Different subgroups exhibit different underlying pathophysiological pathways to sleep apnea, highlighting the variability in mechanisms that could be targeted for intervention.

A Scoping Review of Sleep Apnea: Where Do We Stand?

Obstructive sleep apnea (OSA), a condition in which there is a recurrent collapse of the upper airway while sleeping, is a widespread disease affecting 5% to 10% people worldwide. Despite several advances in the treatment modalities for OSA, morbidity and mortality remain a concern. Common symptoms include loud snoring, gasping for air during sleep, morning headache, insomnia, hypersomnia, attention deficits, and irritability. Obese individuals, male gender, older age (65+), family history, smoking, and alcohol consumption are well recognized risk factors of OSA. This condition holds the ability to increase inflammatory cytokines, cause metabolic dysfunction, and increase the sympathetic output, all of which exacerbate OSA due to their effect on the cardiovascular system. In this review, we discuss its brief history, risk factors, complications, treatment modalities, and the role of clinicians in curbing its risk.

A Narrative Review of Sex and Gender Differences in Sleep Disordered Breathing: Gaps and Opportunities

INTRODUCTION

Sleep disordered breathing (SDB) is a common condition, associated with multiple comorbidities including cardiovascular and metabolic disease. It has been previously established that SDB is more prevalent in men than women, shifting the literature's focus away from the latter population. As such, underdiagnosis, and thus undertreatment, of SDB in women exists.

METHODS

To establish the differences in prevalence, clinical presentation, and pathophysiology of SDB between the two sexes, a narrative review of the current literature was performed.

RESULTS

Rates of SDB are higher among men, likely driven by differences in symptom presentation between men and women, with women presenting with more "atypical" symptoms, and lack of sensitivity in SDB screening tools to detect SDB in women. In addition to the cardiovascular risks of SDB, women with SDB may have worse quality of life, higher prevalence of insomnia, and respiratory issues.

DISCUSSION

More research is needed to better define the unique pathophysiology and clinical presentation of SDB in women. In addition, an increased awareness among health care providers and the lay public of the SDB-specific sex and gender differences will serve to minimize disparities in identification and treatment of SDB in women.

Testosterone Supplementation Induces Age-Dependent Augmentation of the Hypoxic Ventilatory Response in Male Rats With Contributions From the Carotid Bodies

Excessive carotid body responsiveness to O₂ and/or CO₂/H⁺ stimuli contributes to respiratory instability and apneas during sleep. In hypogonadal men, testosterone supplementation may increase the risk of sleep-disordered breathing; however, the site of action is unknown. The present study tested the hypothesis that testosterone supplementation potentiates carotid body responsiveness to hypoxia in adult male rats. Because testosterone levels decline with age, we also determined whether these effects were age-dependent. In situ hybridization determined that androgen receptor mRNA was present in the carotid bodies and caudal nucleus of the solitary tract of adult (69 days old) and aging (193–206 days old) male rats. In urethane-anesthetized rats injected with testosterone propionate (2 mg/kg; i.p.), peak breathing frequency measured during hypoxia (FiO₂ = 0.12) was 11% greater vs. the vehicle treatment group. Interestingly, response intensity following testosterone treatment was positively correlated with animal age. Exposing ex vivo carotid body preparations from young and aging rats to testosterone (5 nM, free testosterone) 90–120 min prior to testing showed that the carotid sinus nerve firing rate during hypoxia (5% CO₂ + 95% N₂; 15 min) was augmented in both age groups as compared to vehicle (<0.001% DMSO). Ventilatory measurements performed using whole body plethysmography revealed that testosterone supplementation (2 mg/kg; i.p.) 2 h prior reduced apnea frequency during sleep. We conclude that in healthy rats, age-dependent potentiation of the carotid body’s response to hypoxia by acute testosterone supplementation does not favor the occurrence of apneas but rather appears to stabilize breathing during sleep.

Sex-Specific Effects of Stress on Respiratory Control: Plasticity, Adaptation, and Dysfunction

As our understanding of respiratory control evolves, we appreciate how the basic neurobiological principles of plasticity discovered in other systems shape the development and function of the respiratory control system. While breathing is a robust homeostatic function, there is growing evidence that stress disrupts respiratory control in ways that predispose to disease. Neonatal stress (in the form of maternal separation) affects "classical" respiratory control structures such as the peripheral O₂ sensors (carotid bodies) and the medulla (e.g., nucleus of the solitary tract). Furthermore, early life stress disrupts the paraventricular nucleus of the hypothalamus (PVH), a structure that has emerged as a primary determinant of the intensity of the ventilatory response to hypoxia. Although underestimated, the PVH's influence on respiratory function is a logical extension of the hypothalamic control of metabolic demand and supply. In this article, we review the functional and anatomical links between the stress neuroendocrine axis and the medullary network regulating breathing. We then present the persistent and sex-specific effects of neonatal stress on respiratory control in adult rats. The similarities between the respiratory phenotype of stressed rats and clinical manifestations of respiratory control disorders such as sleep-disordered breathing and panic attacks are remarkable. These observations are in line with the scientific consensus that the origins of adult disease are often found among developmental and biological disruptions occurring during early life. These observations bring a different perspective on the structural hierarchy of respiratory homeostasis and point to new directions in our understanding of the etiology of respiratory control disorders. © 2021 American Physiological Society. Compr Physiol 11:1-38, 2021.

Sex and Gender Differences in Lung Disease

Sex differences in the anatomy and physiology of the respiratory system have been widely reported. These intrinsic sex differences have also been shown to modulate the pathophysiology, incidence, morbidity, and mortality of several lung diseases across the life span. In this chapter, we describe the epidemiology of sex differences in respiratory diseases including neonatal lung disease (respiratory distress syndrome, bronchopulmonary dysplasia) and pediatric and adult disease (including asthma, cystic fibrosis, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, lung cancer, lymphangioleiomyomatosis, obstructive sleep apnea, pulmonary arterial hypertension, and respiratory viral infections such as respiratory syncytial virus, influenza, and SARS-CoV-2). We also discuss the current state of research on the mechanisms underlying the observed sex differences in lung disease susceptibility and severity and the importance of considering both sex and gender variables in research studies' design and analysis.

Obstructive Sleep Apnea and Testosterone Therapy

INTRODUCTION

There is persistent speculation that testosterone therapy (TTh) may induce worsening of obstructive sleep apnea (OSA). As both the incidence of OSA and the use of TTh grow more prevalent, it is important to review the current evidence that supports or refutes this relationship.

OBJECTIVES

To review the current literature regarding the relationship between TTh and OSA.

METHODS

A literature search was conducted to identify relevant studies. Search terms included "obstructive sleep apnea" and "testosterone replacement therapy." Titles and abstracts were reviewed for relevance. References from identified articles were searched and included, if appropriate.

RESULTS

The association between TTh and OSA was initially described in a 1978 case report of an individual with worsened nighttime apneas during testosterone administration, a trend seen again in subsequent small case series. In the 1990s, a large retrospective analysis and the first randomized controlled trial on the subject revealed no increased incidence of OSA in individuals on TTh. A randomized controlled trial conducted in 2012 provided a possible explanation to the previously reported discrepancies, describing a time-limited effect, wherein measures of OSA were elevated at seven weeks but were not significantly different at 18 weeks after initiation of TTh. A recent cohort study demonstrated an incidence of OSA in individuals on TTh of 16.5% compared with 12.7% in controls. TTh is thought to affect OSA in several ways. Theories that the anabolic effects of testosterone may decrease airway patency or that testosterone alters sleep architecture have been largely disproven. More likely, testosterone plays a role in altering neural response pathways to hypoxemia.

CONCLUSIONS

TTh likely plays a small role in exacerbating or inducing changes in OSA that may be time limited in nature. Clinicians may choose to exercise caution in prescribing TTh to individuals suffering from severe OSA. Payne K, Lipshultz LI, Hotaling JM, et al. Obstructive Sleep Apnea and Testosterone Therapy. J Sex Med 2021;9:296-303.

Sex differences in breathing

Breathing is a vital behavior that ensures both the adequate supply of oxygen and the elimination of CO₂, and it is influenced by many factors. Despite that most of the studies in respiratory physiology rely heavily on male subjects, there is much evidence to suggest that sex is an important factor in the respiratory control system, including the susceptibility for some diseases. These different respiratory responses in males and females may be related to the actions of sex hormones, especially in adulthood. These hormones affect neuromodulatory systems that influence the central medullary rhythm/pontine pattern generator and integrator, sensory inputs to the integrator and motor output to the respiratory muscles. In this article, we will first review the sex dependence on the prevalence of some respiratory-related diseases. Then, we will discuss the role of sex and gonadal hormones in respiratory control under resting conditions and during respiratory challenges, such as hypoxia and hypercapnia, and whether hormonal fluctuations during the estrous/menstrual cycle affect breathing control. We will then discuss the role of the locus coeruleus, a sexually dimorphic CO₂/pH-chemosensitive nucleus, on breathing regulation in males and females. Next, we will highlight the studies that exist regarding sex differences in respiratory control during development. Finally, the few existing studies regarding the influence of sex on breathing control in non-mammalian vertebrates will be discussed.

[Obstructive sleep apnea syndrome and age-related hypohonadism]

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a common disease that causes a different spectrum of life processes violations in the continuum of 'sleep-wakefulness'. OSAS in combination with age-specific hypogonadism as a systemic pathology requires certain interdisciplinary approaches involving both the correction of the obstruction, and testosterone therapy in men with hypogonadism.

AIM

Assessment of the effect of combined use of CPAP (Continuous Positive Airway Pressure) and testosterone replacement therapy (transdermal form - Androgel) on indicators of polysomnography monitoring (PSG) with simultaneous study of erectile function and testosterone secretion.

MATERIAL AND METHODS

26 men with OSAS and andropause (mean age - 46,1±8,4 years, BMI - 35,2±4,6 kg/m2) were examined. All patients were divided into 2 groups: men with therapy CPAP (n=14); men with combination therapy CPAP and Androgel (50 mg 1 times a day) (n=12). CPAP was carried out by automatic apparatus: Prisma 20A ('Weinemann', Germany) and iSleep 20i ('Breas', Sweden). Duration of therapy in both groups was 2 months.

RESULTS

There were no statistically significant differences in the baseline characteristics of the physical examination, the level of total testosterone, PSG and nocturnal penile patterns in both groups of patients. After combination therapy (CPAP and Androgel) in men found the increase of total testosterone levels by 2 times (p<0,05) and improvement in indicators of altered nocturnal penile erection episodes (Tup, Tmax, Tm/R, Tup/R, the total number of NPT (p<0,05)) compared with similar parameters in men with only on CPAP-therapy was found. Indicators of the objective status were improved, although there were no changes in PSG characteristics in both groups.

CONCLUSION

The results of this study indicate greater efficiency of the combined method of treatment (CPAP+Androgel) in patients with OSAS and andropause.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Testosterone replacement therapy: For whom, when and how?

The finding of low circulating testosterone level in men is relatively frequent. The symptoms of hypogonadism are very frequent in the aging men. However, the diagnosis of hypogonadism is often neglected and the opportunity to replace low testosterone in older men is highly debated. The aim of this narrative review is to summarize the steps necessary to formulate a proper diagnosis and to guide toward an individualized treatment. While universally recognized the need to treat the young adults with known causes of pituitary or testicular failure, there are controversies on the cost-benefit of treating testosterone deficiency in older men. Discrepancies among the several available guidelines do not help to clarify the scenario, however, the recent larger clinical trials have shed some light on the fact that testosterone treatment carries some benefit, that is not free from risks. We provide an updated review of the diagnostic hallmarks, the several treatment modalities, with their advantages and disadvantages, and how to individualize and monitor treatment in order to maximize the benefits and minimize the risks. The treatment of male hypogonadism can no longer be downgraded and must become part of the cultural baggage of the endocrinologist.

Obstructive Sleep Apnea and Testosterone Deficiency

Obstructive sleep apnea (OSA) is a common disorder characterized by intermittent hypoxia and sleep fragmentation. OSA in middle-aged men is often associated with decreased testosterone secretion, together with obesity and aging. Although OSA treatment does not reliably increase testosterone levels in most studies, OSA treatment with testosterone replacement therapy (TRT) may not only improve hypogonadism, but can also alleviate erectile/sexual dysfunction. However, because TRT may exacerbate OSA in some patients, patients should be asked about OSA symptoms before and after starting TRT. Furthermore, TRT should probably be avoided in patients with severe untreated OSA.

Neonatal maternal separation opposes the facilitatory effect of castration on the respiratory response to hypercapnia of the adult male rat: Evidence for the involvement of the medial amygdala

Respiratory manifestations of panic disorder (PD) include a greater respiratory instability and enhanced responsiveness to CO₂ compared to normal individuals. Although the prevalence of PD is approximately three times greater in women compared to men, the origins of this sexual dimorphism remain poorly understood. Similar to PD patients, adult female rats previously subjected to neonatal maternal separation (NMS) show an increase in their ventilatory response to CO₂ . Because this effect of NMS is not observed in males, we hypothesised that testosterone prevents NMS-induced hyper-responsiveness to CO₂ . Pups subjected to NMS were placed in an incubator for 3 h d^-1 from postnatal days 3-12. Control pups remained undisturbed. At adulthood (8-10 weeks of age), rats were then subjected either to sham surgery or castration. Fourteen days later, breathing was measured at rest (room air) and during acute exposure to hypercapnia (5 and 10% CO₂ for 10 minutes each) using plethysmography. To gain insight into the mechanisms involved, c-fos expression was used as an indicator of neuronal activation. Brains were collected following air or CO₂ exposure for quantification of c-fos positive cells by immunohistochemistry in selected regions, including the paraventricular nucleus of the hypothalamus, the dorsomedial hypothalamus and the amygdalar complex. Castration produced a 100% increase of hyperventilatory response to 10% CO₂ in control rats. Unexpectedly, castration had no effect on the hyperventilatory response of NMS rats. The intensity of the hypercapnic response was inversely correlated with c-fos expression in the medial amygdala. We conclude that testosterone prevents the hyper-responsiveness to CO₂ , whereas NMS attenuates sensitivity to hormone withdrawal. We propose that an inhibitory influence from the medial amygdala contributes to this effect.

Sex differences in sleep disordered breathing in adults

The prevalence of sleep disordered breathing is greater in men compared to women. This disparity could be due to sex differences in the diagnosis and presentation of sleep apnea, and the pathophysiological mechanisms that instigate this disorder. Women tend to report more non-typical symptoms of sleep apnea compared to men, and the presentation of apneic events are more prevalent in rapid compared to non-rapid eye movement sleep. In addition, there is evidence of sex differences in upper airway structure and mechanics and in neural mechanisms that impact on the control of breathing. The purpose of this review is to summarize the literature that addresses sex differences in sleep-disordered breathing, and to discuss the influence that upper airway mechanics, chemoreflex properties, and sex hormones have in modulating breathing during sleep in men and women.

Testosterone Deficiency and Sleep Apnea

Obstructive sleep apnea (OSA) is a common condition among middle-aged men and is often associated with reduced testosterone (T) levels. OSA can contribute to fatigue and sexual dysfunction in men. There is suggestion that T supplementation alters ventilatory responses, possibly through effects on central chemoreceptors. Traditionally, it has been recommended that T replacement therapy (TRT) be avoided in the presence of untreated severe sleep apnea. With OSA treatment, however, TRT may not only improve hypogonadism, but may also alleviate erectile/sexual dysfunction.

Obesity may be the common pathway for sleep-disordered breathing in women with polycystic ovary syndrome

OBJECTIVE

Polycystic ovary syndrome (PCOS) is one of the most common endocrinological disorders in women of reproductive age, and is characterized by hyperandrogenism. It is associated with long-term metabolic dysfunctions including sleep-disordered breathing (SDB). We hypothesized that the increased prevalence of SDB in PCOS results from raised testosterone levels.

METHODS

This was a prospective, cross-sectional, case-control study in which 50 case patients with untreated PCOS and 100 control subjects were included. All the case patients and control subjects went through a detailed clinical, biochemical, and hormonal evaluation. Overnight polysomnography was performed in all case patients and the snorers (16 of 100) in the control group.

RESULTS

SDB was seen in 66% of the case patients and in 4% of control group with (odds ratio [OR] = 46.5, 95% confidence interval [CI] = 14.6-148.4; p <0.001). After adjustment for body mass index (BMI) and waist circumference (WC), the difference was not significant (p = 0.993 and p = 0.931, respectively). The SDB patients with PCOS showed significantly higher respiratory distress index (RDI) values than SDB patients in the control group (22.5 ± 21.5 vs 9.0 ± 5.6, p = 0.01). On the Epworth Sleepiness Scale the PCOS case patients reported feeling more sleepy than did the control subjects (12.5 ± 3.2 vs 9.32 ± 1.7, p <0.001). Free testosterone levels were also significantly higher in the PCOS group than in the control subjects (2.95 ± 3.44 vs 1.5 ± 1.0, p <0.001). There was a significant correlation between free testosterone level and RDI values (r = 0.377; p = 0.007), WC (r = 0.315; p = 0.026), and BMI (r = 0.398; p = 0.004). A significant correlation of WC (r = 0.551; p <0.001) and BMI (r = 0.572; p <0.001) was observed with RDI.

CONCLUSION

Testosterone-induced obesity is probably the common pathway for the development of SDB in PCOS.

Testosterone Deficiency and Sleep Apnea

Obstructive sleep apnea (OSA) is a common condition among middle-aged men and is often associated with reduced testosterone (T) levels. OSA can contribute to fatigue and sexual dysfunction in men. There is suggestion that T supplementation alters ventilatory responses, possibly through effects on central chemoreceptors. Traditionally, it has been recommended that T replacement therapy (TRT) be avoided in the presence of untreated severe sleep apnea. With OSA treatment, however, TRT may not only improve hypogonadism, but may also alleviate erectile/sexual dysfunction.

Sex differences in sleep: impact of biological sex and sex steroids

Men and women sleep differently. While much is known about the mechanisms that drive sleep, the reason for these sex differences in sleep behaviour is unknown and understudied. Historically, women and female animals are underrepresented in studies of sleep and its disorders. Nevertheless, there is a growing recognition of sex disparities in sleep and rhythm disorders. Women typically report poorer quality and more disrupted sleep across various stages of life. Findings from clinical and basic research studies strongly implicate a role for sex steroids in sleep modulation. Understanding how neuroendocrine mediators and sex differences influence sleep is central to advancing our understanding of sleep-related disorders. The investigation into sex differences and sex steroid modulation of sleep is in its infancy. Identifying the mechanisms underlying sex and gender differences in sleep will provide valuable insights leading to tailored therapeutics that benefit each sex. The goal of this review is to discuss our current understanding of how biological sex and sex steroids influence sleep behaviour from both the clinical and pre-clinical perspective.

Outcomes of androgen replacement therapy in adult male hypogonadism: recommendations from the Italian society of endocrinology

OBJECTIVE

We developed clinical practice guidelines to assess the individual risk-benefit profile of androgen replacement therapy in adult male hypogonadism (HG), defined by the presence of specific signs and symptoms and serum testosterone (T) below 12 nmol/L.

PARTICIPANTS

The task force consisted of eight clinicians experienced in treating HG, selected by the Italian Society of Endocrinology (SIE). The authors received no corporate funding or remuneration.

CONSENSUS PROCESS

Consensus was guided by a systematic review of controlled trials conducted on men with a mean T < 12 nmol/L and by interactive discussions. The guidelines were reviewed and sequentially approved by the SIE Guidelines Commission and Executive Committee.

CONCLUSIONS

We recommend T supplementation (TS) for adult men with severely reduced T levels (T < 8 nmol/L) to improve body composition and sexual function. We suggest that TS be offered to subjects with T < 12 nmol/L to improve glycaemic control, lipid profile, sexual function, bone mineral density, muscle mass and depressive symptoms, once major contraindications have been ruled out. We suggest that lifestyle changes and other available interventions (e.g. for erectile dysfunction) be suggested prior to TS. We suggest that TS should be combined with currently available treatments for individuals at high risk for complications, such as those with osteoporosis and/or metabolic disorders. We recommend against using TS to improve cardiac outcome and limited mobility. We recommend against using TS in men with prostate cancer, unstable cardiovascular conditions or elevated haematocrit. The task force places a high value on the timely treatment of younger and middle-aged subjects to prevent the long-term consequences of hypoandrogenism.

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.

Male hypogonadism

Male hypogonadism is a clinical syndrome that results from failure to produce physiological concentrations of testosterone, normal amounts of sperm, or both. Hypogonadism may arise from testicular disease (primary hypogonadism) or dysfunction of the hypothalamic-pituitary unit (secondary hypogonadism). Clinical presentations vary dependent on the time of onset of androgen deficiency, whether the defect is in testosterone production or spermatogenesis, associated genetic factors, or history of androgen therapy. The clinical diagnosis of hypogonadism is made on the basis of signs and symptoms consistent with androgen deficiency and low morning testosterone concentrations in serum on multiple occasions. Several testosterone-replacement therapies are approved for treatment and should be selected according to the patient's preference, cost, availability, and formulation-specific properties. Contraindications to testosterone-replacement therapy include prostate and breast cancers, uncontrolled congestive heart failure, severe lower-urinary-tract symptoms, and erythrocytosis. Treatment should be monitored for benefits and adverse effects.

Testosterone and estradiol are not affected in male and female patients with obstructive sleep apnea treated with continuous positive airway pressure

BACKGROUND

Continuous positive airway pressure (CPAP) improves symptoms in patients with obstructive sleep apnea syndrome (OSAS). It is currently unclear, whether CPAP also alters endocrine parameters such as sex hormone levels. In a previous study, we have found no changes in sex hormones in patients with OSAS after one night with CPAP.

AIM

The aim of this study was to prove long-term effects of CPAP on sex hormone concentrations in patients with OSAS.

METHODS

Twenty-two women and 67 men with severe OSAS (respiratory distress index > 30/h) were enrolled in the study. Fasting blood venous samples were taken before CPAP therapy and after 1 and 6 months of CPAP treatment. Testosterone and estradiol were measured in all samples using commercially available ELISA kits.

RESULTS

No effects of long-term CPAP treatment were found on testosterone or estradiol levels in OSAS patients of either gender.

CONCLUSIONS

The results are in line with previous smaller studies. However, our study is larger and longer than previously published studies. In addition, this is the first study analyzing the effects of CPAP on testosterone and estradiol and in both genders. Positive effects of CPAP on sexual functions reported in other studies might, thus, be mediated by other than endocrine effects.

Gonadal steroid modulation of sleep and wakefulness in male and female rats is sexually differentiated and neonatally organized by steroid exposure

The paucity of clinical and preclinical studies investigating sex differences in sleep has resulted in mixed findings as to the exact nature of these differences. Although gonadal steroids are known to modulate sleep in females, less is known about males. Moreover, little evidence exists concerning the origin of these sex differences in sleep behavior. Thus, the goal of this study was to directly compare the sensitivity of sleep behavior in male and female Sprague Dawley rats to changes in the gonadal steroid milieu and to test whether the sex differences in sleep are the result of brain sexual differentiation or differences in circulating gonadal steroids. Here we report the magnitude of change in sleep behavior induced by either estradiol (E2) or testosterone (T) was greater in females compared with males, suggesting that sleep behavior in females is more sensitive to the suppressive effects of gonadal steroids. Furthermore, we demonstrated that the organizational effects of early gonadal steroid exposure result in male-like responsivity to gonadal steroids and directly alter the activity of the ventrolateral preoptic area (VLPO), an established sleep-promoting nucleus, in adult masculinized females. Moreover, the nonaromatizable androgen dihydrotestosterone did not suppress sleep in either males or females, suggesting that the T-mediated effect in females was due to the aromatization of T into E2. Together our data suggest that, like sex behavior, sex differences in sleep follow the classical organizational/activational effects of gonadal steroids.

Metabolism, temperature, and ventilation

In mammals and birds, all oxygen used (VO2) must pass through the lungs; hence, some degree of coupling between VO2 and pulmonary ventilation (VE) is highly predictable. Nevertheless, VE is also involved with CO2 elimination, a task that is often in conflict with the convection of O2. In hot or cold conditions, the relationship between VE and VO2 includes the participation of the respiratory apparatus to the control of body temperature and water balance. Some compromise among these tasks is achieved through changes in breathing pattern, uncoupling changes in alveolar ventilation from VE. This article examines primarily the relationship between VE and VO2 under thermal stimuli. In the process, it considers how the relationship is influenced by hypoxia, hypercapnia or changes in metabolic level. The shuffling of tasks in emergency situations illustrates that the constraints on VE-VO2 for the protection of blood gases have ample room for flexibility. However, when other priorities do not interfere with the primary goal of gas exchange, VE follows metabolic rate quite closely. The fact that arterial CO2 remains stable when metabolism is changed by the most diverse circumstances (moderate exercise, cold, cold and exercise combined, variations in body size, caloric intake, age, time of the day, hormones, drugs, etc.) makes it unlikely that VE and metabolism are controlled in parallel by the condition responsible for the metabolic change. Rather, some observations support the view that the gaseous component of metabolic rate, probably CO2, may provide the link between the metabolic level and VE.

Orexin: a potential role in the process of obstructive sleep apnea

Obstructive sleep apnea (OSA) is a complicated disease with an unrecognized mechanism. Obesity, sex, age, and smoking have been found to be independent correlates of OSA. Orexin (also named hypocretin) mainly secreted by lateral hypothalamus neurons has a wide array of biological functions like regulating sleep, energy levels and breathing. Several clinical studies found ties between orexin and OSA. Because of the close correlation between orexin and obesity, sex, age and smoking (which are the key risk factors for OSA patients), we hypothesize that orexin may play a key role in the pathogenesis of OSA.

Short-term effects of continuous positive airway pressure on sex hormones in men and women with sleep apnoea syndrome

Patients with sleep apnoea syndrome (SAS) suffer from symptoms of hypogonadism. Besides surgical interventions, in some cases, the standard care of SAS for most patients is continuous positive airway pressure (CPAP). Studies focusing on the long-term effects of CPAP on testosterone levels revealed conflicting results. None of the studies included female patients with SAS. The aim of our study was to analyse and compare sex hormone levels in saliva before and after a night without and with CPAP in women and men with SAS. The results were negative. One night with CPAP did not affect the dynamics of sex hormones, neither in men nor in women. Future studies should focus on long-term effects of CPAP in both genders.

The effects of testosterone on ventilatory responses in men with obstructive sleep apnea: a randomised, placebo-controlled trial

We recently showed that testosterone therapy worsens sleep-disordered breathing at 6-7 weeks, but not after 18 weeks, in men with obstructive sleep apnea. Changes in ventilatory chemoreflexes may be responsible. The effect of testosterone on ventilatory chemoreflexes in men with obstructive sleep apnea has not been systematically studied before. Twenty-one obese men with obstructive sleep apnea, a subgroup of our recent report, were randomised in an 18-week, randomised, double-blind, placebo-controlled, parallel group trial to three intramuscular injections (0, 6, 12 weeks) of either 1000 mg testosterone undecanoate (n = 10) or placebo (n = 11). Awake ventilatory chemoreflex testing was performed before (week 0), during (week 6) and at the end of treatment (week 18) to determine the ventilatory carbon dioxide recruitment threshold and chemosensitivity. Sleep and breathing was assessed by overnight polysomnography at 0, 7 and 18 weeks. Serum hormones levels were measured at every visit. A significant increase in blood testosterone levels (5.65 nmol L(-1) , 0.51-10.8 nmol L(-1) , P = 0.03) and lean muscle mass (2.36 kg, 0.8-3.9 kg, P = 0.007) between the two groups was observed as expected. No significant differences were seen in ventilatory chemoreflexes between the two groups at 6 weeks or at 18 weeks. However, positive correlations were observed between changes in serum testosterone and hyperoxic ventilatory recruitment threshold (r = 0.55, P = 0.03), and between changes in hyperoxic ventilatory recruitment threshold and time spent with oxygen saturations during sleep <90% (r = 0.57, P = 0.03) at 6-7 weeks, but not at 18 weeks. Time-dependent alterations in ventilatory recruitment threshold may therefore mediate the time-dependent changes in sleep breathing observed with testosterone.

One's sex, sleep, and posttraumatic stress disorder

Women are approximately twice as likely as men to develop posttraumatic stress disorder (PTSD) after trauma exposure. Mechanisms underlying this difference are not well understood. Although sleep is recognized to have a critical role in PTSD and physical and psychological health more generally, research into the role of sleep in PTSD sex differences has been only recent. In this article, we review both animal and human studies relevant to sex differences in sleep and PTSD with an emphasis on the roles of sex hormones. Sleep impairment including insomnia, trauma-related nightmares, and rapid-eye-movement (REM) sleep fragmentation has been observed in individuals with chronic and developing PTSD, suggesting that sleep impairment is a characteristic of PTSD and a risk factor for its development. Preliminary findings suggested sex specific patterns of sleep alterations in developing and established PTSD. Sleep maintenance impairment in the aftermath of trauma was observed in women who subsequently developed PTSD, and greater REM sleep fragmentation soon after trauma was associated with developing PTSD in both sexes. In chronic PTSD, reduced deep sleep has been found only in men, and impaired sleep initiation and maintenance with PTSD have been found in both sexes. A limited number of studies with small samples have shown that sex hormones and their fluctuations over the menstrual cycle influenced sleep as well as fear extinction, a process hypothesized to be critical to the pathogenesis of PTSD. To further elucidate the possible relationship between the sex specific patterns of PTSD-related sleep alterations and the sexually dimorphic risk for PTSD, future studies with larger samples should comprehensively examine effects of sex hormones and the menstrual cycle on sleep responses to trauma and the risk/resilience for PTSD utilizing various methodologies including fear conditioning and extinction paradigms and animal models.

Hypogonadism in the aging male diagnosis, potential benefits, and risks of testosterone replacement therapy

Hypogonadism in older men is a syndrome characterized by low serum testosterone levels and clinical symptoms often seen in hypogonadal men of younger age. These symptoms include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men with a significant percentage of men over 60 years of age having serum testosterone levels below the lower limits of young male adults. There are a variety of testosterone formulations available for treatment of hypogonadism. Data from many small studies indicate that testosterone therapy offers several potential benefits to older hypogonadal men. A large multicenter NIH supported double blind, placebo controlled study is ongoing, and this study should greatly enhance the information available on efficacy and side effects of treatment. While safety data is available across many age groups, there are still unresolved concerns associated with testosterone therapy. We have reviewed the diagnostic methods as well as benefits and risks of testosterone replacement therapy for hypogonadism in aging men.

Updates on the relation of weight excess and reproductive function in men: sleep apnea as a new area of interest

Obesity has a negative effect on male reproductive function. It is associated with low testosterone levels and alteration in gonadotropin secretion. Male obesity has been linked to reduced male fertility. Data regarding the relation of obesity to sperm parameters are conflicting in terms of the nature and magnitude of the effect. New areas of interest are emerging that can help explain the variation in study results, such as genetic polymorphism and sleep apnea. Sleep disorders have been linked to altered testosterone production and hypogonadism in men. It was also correlated to erectile dysfunction. The relation of sleep disorders to male fertility and sperm parameters remains to be investigated. Men with hypogonadism and infertility should be screened for sleep apnea. Treatment of obesity and sleep apnea improves testosterone levels and erectile function.

Diagnosis and treatment of sexual dysfunctions in late-onset hypogonadism

Testosterone is the principal androgen in the human male. The decline of testosterone with aging was recognized to be associated with a number of symptoms and signs that reduce the quality of life and that may even have severe, debilitating consequences. Clinically, late-onset hypogonadism (LOH) is diagnosed by use of biochemical and clinical measures. Despite published guidelines and recommendations, however, uncertainty surrounds the profile of clinical symptoms as well as the biochemical threshold of diagnosis. Clinicians should be aware of these shortcomings while adhering to the guidelines. Current treatment methods are centered on restoring testosterone to mid to lower levels of young men with natural testosterone replacements. Although recent studies have highlighted possible additional benefits involving improvement of systemic disorders, the goal of treatment is to improve sexual function, while observing for adverse effects in the prostate. Overall, the problem of LOH in debilitating the quality of life and well-being is real, and by following proper guidelines with attentiveness to the results of treatment trials, testosterone replacement therapy presents a safe and effective treatment option.

Testosterone restores respiratory long term facilitation in old male rats by an aromatase-dependent mechanism

Steroidal sex hormones play an important role in the neural control of breathing. Previous studies in our laboratory have shown that gonadectomy in young male rats (3 months) eliminates a form of respiratory plasticity induced by intermittent hypoxia, known as long term facilitation (LTF). Testosterone replenishment restores LTF in gonadectomized male rats, and this is dependent on the conversion of testosterone to oestradiol by aromatase. By middle age (12 months), male rats no longer exhibit LTF of hypoglossal motor output; phrenic LTF is significantly reduced, and this persists into old age. We tested the hypothesis that LTF can be restored in old male rats by administration of testosterone. Intact Fischer 344 rats (>20 months) were implanted with Silastic tubing containing testosterone (T), T plus an aromatase inhibitor (T+ADT), or 5α-dihydrotestosterone (DHT), a form of testosterone not converted to oestradiol. One week post-surgery, LTF of hypoglossal and phrenic motor output was measured. By comparison with control rats, hypoglossal LTF was increased in testosterone-treated rats, with levels approaching that of normal young rats. LTF was not restored in T+ADT or DHT-treated rats. Aromatase levels in hypoglossal and phrenic nuclei did not change with age. As serum testosterone levels did not decline with age, local bioavailability of testosterone in old rats may be a limiting factor in the expression of this form of respiratory plasticity. Our findings suggest that testosterone supplementation could potentially be used to enhance upper airway control in the elderly.

Late-life onset hypogonadism: a review

Increased longevity and population aging will increase the number of men with late-onset hypogonadism, a common condition that is often under diagnosed and under treated. The indication of testosterone replacement therapy (TRT) treatment requires the presence of low testosterone level and symptoms and signs of hypogonadism. Although there is a lack of large-scale, long-term studies assessing the benefits and risks of TRT in men with hypogonadism, reports indicate that TRT may produce a wide range of benefits that include improvement in libido and sexual function, bone density, muscle mass, body composition, mood, erythropoiesis, cognition, quality of life, and cardiovascular disease. Perhaps the most controversial area is the issue of risk, especially the possible stimulation of prostate cancer by testosterone, even though there is no evidence to support this risk. Other possible risks include worsening symptoms of benign prostatic hypertrophy, liver toxicity, hyperviscosity, erythrocytosis, worsening untreated sleep apnea, or severe heart failure. Despite this controversy, testosterone supplementation in the United States has increased substantially in the past several years. The physician should discuss with the patient the potential benefits and risks of TRT. This review discusses the benefits and risks of TRT.

Endocrine aspects of obstructive sleep apnea

CONTEXT

Some endocrine and metabolic disorders are associated with a high frequency of obstructive sleep apnea (OSA), and treatment of the underlying endocrine disorder can improve and occasionally cure OSA. On the other hand, epidemiological and interventional studies suggest that OSA increases the cardiovascular risk, and a link between OSA and glucose metabolism has been suggested, via reduced sleep duration and/or quality.

EVIDENCE ACQUISITION

We reviewed the medical literature for key articles through June 2009.

EVIDENCE SYNTHESIS

Some endocrine and metabolic conditions (obesity, acromegaly, hypothyroidism, polycystic ovary disease, etc.) can be associated with OSA. The pathophysiological mechanisms of OSA in these cases are reviewed. In rare instances, OSA may be improved or even cured by treatment of underlying endocrine disorders: this is the case of hypothyroidism and acromegaly, situations in which OSA is mainly related to upper airways narrowing due to reversible thickening of the pharyngeal walls. However, when irreversible skeletal defects and/or obesity are present, OSA may persist despite treatment of endocrine disorders and may thus require complementary therapy. This is also frequently the case in patients with obesity, even after substantial weight reduction.

CONCLUSIONS

Given the potential neurocognitive consequences and increased cardiovascular risk associated with OSA, specific therapy such as continuous positive airway pressure is recommended if OSA persists despite effective treatment of its potential endocrine and metabolic causes. "Apropos of sleep, that sinister adventure of all our nights, we might say that men go to bed daily with an audacity that would be incomprehensible if we did not know that it is the result of ignorance of the danger." Charles Baudelaire, in "Fusées, IX"

Neuroendocrine alterations in obese patients with sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a serious, prevalent condition that has significant morbidity and mortality when untreated. It is strongly associated with obesity and is characterized by changes in the serum levels or secretory patterns of several hormones. Obese patients with OSAS show a reduction of both spontaneous and stimulated growth hormone (GH) secretion coupled to reduced insulin-like growth factor-I (IGF-I) concentrations and impaired peripheral sensitivity to GH. Hypoxemia and chronic sleep fragmentation could affect the sleep-entrained prolactin (PRL) rhythm. A disrupted Hypothalamus-Pituitary-Adrenal (HPA) axis activity has been described in OSAS. Some derangement in Thyroid-Stimulating Hormone (TSH) secretion has been demonstrated by some authors, whereas a normal thyroid activity has been described by others. Changes of gonadal axis are common in patients with OSAS, who frequently show a hypogonadotropic hypogonadism. Altogether, hormonal abnormalities may be considered as adaptive changes which indicate how a local upper airway dysfunction induces systemic consequences. The understanding of the complex interactions between hormones and OSAS may allow a multi-disciplinary approach to obese patients with this disturbance and lead to an effective management that improves quality of life and prevents associated morbidity or death.