Declining gonadal function in elderly men

The burden of testosterone deficiency syndrome in adult men: economic and quality-of-life impact

INTRODUCTION

Testosterone deficiency syndrome (TDS) causes a wide range of symptoms that can lead to significant morbidity. Preliminary evidence has also linked TDS with premature mortality and with a number of comorbid diseases including diabetes and metabolic syndrome. Such associations can lead to substantial economic and quality-of-life implications, the magnitude of which remains largely unknown.

AIM

To review the economic and quality-of-life consequences of a largely untreated condition and to consider the likely health economic benefits of testosterone treatment.

METHODS

A systematic review of four main areas: epidemiological evidence of the magnitude of TDS, estimates of cost of illness, impact on quality-of-life, and cost-effectiveness of testosterone treatment.

MAIN OUTCOME MEASURE

Review of peer-reviewed literature.

RESULTS

The lack of clear universally accepted diagnostic criteria and the uncertainty surrounding the link between TDS and some of its consequences complicate the estimation of the burden of illness of TDS. Consequences of TDS that potentially lead to increased economic burden include depression, sexual dysfunction, mild cognitive impairment, osteoporosis, cardiovascular disease, and mortality. However, although good evidence exists demonstrating an association between TDS and sexual dysfunction and cognitive impairment, evidence is less strong for depression, the incidence of fractures and mortality, and highly controversial for cardiovascular disease. The consequences that are likely to impact on patients' quality of life include sexual function, energy levels, body composition, mood, and cognitive function.

CONCLUSION

Understanding the burden is only the first step decision makers need to take to decide whether to allocate scarce resources to treat the condition. To make informed decisions on when and who to treat information is also needed on the cost-effectiveness of available treatments. Such data would highlight the benefits of treatment of TDS to physicians, patients, and to society as a whole.

The role of hormones, cytokines and heat shock proteins during age-related muscle loss

Ageing is associated with a progressive decline of muscle mass, strength, and quality, a condition known as sarcopenia. Due to the progressive ageing of western populations, age-related sarcopenia is a major public health problem. Several possible mechanisms for age-related muscle atrophy have been described; however the precise contribution of each is unknown. Age-related muscle loss is thought to be a multi-factoral process composed of events such as physical activity, nutritional intake, oxidative stress, inflammatory insults and hormonal changes. There is a need for a greater understanding of the loss of muscle mass with age as this could have a dramatic impact on the elderly and critically ill if this research leads to maintenance or improvement in functional ability. This review aims to outline the process of skeletal muscle degeneration with ageing, normal and aberrant skeletal muscle regeneration, and to address recent research on the effects of gender and sex steroid hormones during the process of age-related muscle loss.

Osteoporosis in men

Osteoporosis has long been considered to be a disease of the aging female skeleton. As awareness of the pervasiveness of this disorder increases, it is clear that men are also at risk for this disorder. Recent epidemiological studies have confirmed that osteoporosis in men is an increasing health problem. This development not only has its roots in increased longevity but also in increased awareness of this problem in men. The purpose of this article is to review what is known about the factors in men that lead to acquisition, maintenance, and loss of bone, as well as new insights about the causes, pathogenesis, and treatment of osteoporosis in men.

Is there a relationship among age, international index of erectile function, international prostate symptom score, and aging males' symptoms score?

PURPOSE

To investigate the relationship among the International Index of Erectile Function (IIEF), International Prostate Symptom Score (IPSS), and Aging Males' Symptoms (AMS) scale scores in various age groups of males.

PATIENTS AND METHODS

A total of 307 male patients enrolled in the study. Mean age was 52.3 (range 21-77) years. Group 1 consisted of 51 (< or =39 years), Group 2 consisted of 160 (40-59 years), and Group 3 consisted of 96 (> or =60 years) patients. First five and 15th questions of the IIEF, IPSS, and AMS scale were replied by all the patients. The patients were assessed based on the IIEF for erectile dysfunction (ED), IPSS for lower urinary tract symptoms (LUTS), and AMS scale for Symptomatic Late-Onset Hypogonadism (SLOH).

RESULTS

ED, LUTS, and SLOH symptoms were detected in 236 (76.8%), 162 (52.8%), and 184 (59.9%) patients. Except for total AMS scores, IIEF and IPSS scores were significantly different among the groups (p (AMS) = 0.320, p (IIEF) = 0.000, p (IPSS) = 0.000). In the comparisons of the IIEF scores between the each group, significant differences were observed (p (Group1-Group2) = 0.000, p (Group1-Group3) = 0.000, p (Group2-Group3) = 0.000). Nevertheless, IPSS score was significantly lower in the patients with age < or =39 years than the other age groups (p = 0.000).

CONCLUSIONS

In the present study, ED ratio and LUTS severity significantly increased in older men. We did not find significant relationship between aging and SLOH symptoms. In the light of our results, LUTS seems to be an important risk factor on erectile function.

Endocrine disruptor vinclozolin induced epigenetic transgenerational adult-onset disease

The fetal basis of adult disease is poorly understood on a molecular level and cannot be solely attributed to genetic mutations or a single etiology. Embryonic exposure to environmental compounds has been shown to promote various disease states or lesions in the first generation (F1). The current study used the endocrine disruptor vinclozolin (antiandrogenic compound) in a transient embryonic exposure at the time of gonadal sex determination in rats. Adult animals from the F1 generation and all subsequent generations examined (F1-F4) developed a number of disease states or tissue abnormalities including prostate disease, kidney disease, immune system abnormalities, testis abnormalities, and tumor development (e.g. breast). In addition, a number of blood abnormalities developed including hypercholesterolemia. The incidence or prevalence of these transgenerational disease states was high and consistent across all generations (F1-F4) and, based on data from a previous study, appears to be due in part to epigenetic alterations in the male germ line. The observations demonstrate that an environmental compound, endocrine disruptor, can induce transgenerational disease states or abnormalities, and this suggests a potential epigenetic etiology and molecular basis of adult onset disease.

Testosterone and erectile physiology

The role of testosterone deficiency in sexual dysfunction is an important aspect of aging, because it affects such a large proportion of men over 50 years old. A number of age-related factors can cause sexual dysfunction (in particular erectile dysfunction) and testosterone deficiency, such as chronic illness and multiple medications, and the causative link between hypogonadism and erectile dysfunction is still debated. However, studies in castrated animals have proven that addition of testosterone, and its conversion to dihydrotestosterone, can restore erectile function. It appears that testosterone achieves this by peripheral mechanisms (endothelial dependent and independent) and central mechanisms. Testosterone replacement therapy is therefore effective for erectile dysfunction in men with hypogonadism, with success rates of 35-40%. Testosterone supplementation is also important in men who fail on phosphodiesterase type-5 inhibitors, because a minimum plasma concentration of testosterone is required for the successful restoration of erectile function with these agents. Testosterone gels are now the preferred formulation for testosterone supplementation and they can be highly beneficial in a proportion of men with erectile dysfunction.

Emerging drugs for hypogonadism

Male hypogonadism is a common endocrine problem that affects men of all ages. Recently, there has been a surge in testosterone use among middle-aged and older men who in the past may have been considered to have borderline or even normal testosterone levels. This increasing use of testosterone therapy among men has paralleled the increasing improvements in the development of treatments for male hypogonadism that have been made over the past few decades. Current therapies using transdermal formulations and long-acting injectables such as testosterone undecanoate are quickly replacing the old injectable testosterone esters. In recent years, pharmaceutical sales and prescription data have readily shown a shift in the testosterone marketplace towards greater use of slightly more expensive treatments such as transdermal therapies, which are easier to administer and yield more physiological levels of testosterone. On the horizon are several new compounds in development, such as selective androgen receptor modulators (SARMS), 7alpha-methyl-19-nortestosterone, aromatase inhibitors, clomifene, dihydrotestosterone and human chorionic gonadotropin. Compounds such as SARMs are designed to selectively target androgen receptors in specific tissues (such as bone and muscles), in the hope of dispersing some of the side effects experienced on the prostate, which are presently associated with therapy of exogenous testosterone.

[LOH (late-onset hypogonadism) or the "aging male"]

Due to lacking evidence of the data about testosterone deficiency of the aging male or LOH (late-onset hypogonadism), this subject is still a challenge for urologists, endocrinologists, and dermatologists or andrologists. This challenge faces basic research as well as clinical investigations. We have to accept responsibility for solving this challenge to better understand and better treat our patients beyond the scope of current guidelines.

Management of the cardinal features of andropause

There are several problems facing aging men, especially sexual dysfunction, hypogonadism, and psychologic changes. This constellation of changes is sometimes referred to as "manopause" or "andropause." Unlike the dramatic changes in the hormonal milieu occurring during menopause in women, the age-related changes in reproductive hormones of men are subtle and occur gradually throughout the years of mature life. It has been estimated that circulating testosterone (T) declines longitudinally from age 19 at an average rate of 1% per year. The free or dialyzable fraction of serum T and the bioavailable (the sum of free fraction and loosely bound to albumin fraction) T decline more rapidly with age. Although the essential role of androgens in reproductive tissue development and emergence of secondary sex characteristics is well known, their role in adult sexual function seems to be primarily facultative. The effect of T on the central nervous system extends beyond sexual behavior. T has been shown to alter mood, memory, ability to concentrate, and the overall sense of vigor and well being that may interact with a host of other psychologic changes associated with aging. Disordered erectile function is not generally an endocrine problem but rather vascular, neurologic, and psychogenic in origin. It also may be the first sign of systemic vascular disease. The clinical management of andropause requires an individualized approach. In some men, the main problem may be psychologic, whereas in others, hypogonadism may play an important role. Many with erectile failure, suffer silently regardless of its etiology. In this review, we suggest some practical guidelines for the management of these conditions.

Serum testosterone levels and arterial blood pressure in the elderly

The aim of this study was to evaluate the relationship between serum testosterone levels and arterial blood pressure (BP) in the elderly. We studied 356 non-diabetic, non-smoking, non-obese men aged 60 to 80 years and untreated for hypertension. All subjects were evaluated in the morning after an overnight fast. Evaluation included measurements of the following: BP (by mercury sphygmomanometer, Korotkoff I and V), body weight, height and free testosterone (T) plasma levels (by radioimmunoassay). According to the BP values, the subjects were classified as normotensives (NT; n=112; SBP/DBP<140/90 mmHg), systolic and diastolic hypertensives (HT; n=127; SBP/DBP>140/90 mmHg), and isolated systolic hypertensives (ISH; n=117; SBP>140 mmHg and DBP<90 mmHg). T values decreased with increasing age in all 3 groups and was significantly lower in HT (-15%) and ISH men (-21%) than in NT men (p<0.05). In each group, the T levels showed a highly significant negative correlation with BMI (p<0.001). A significant negative correlation was also found between T levels and SBP in NT (r=-0.35, p<0.001), ISH (r=-0.67, p<0.001), and HT (r=-0.19, p<0.05) men, whereas a negative correlation with DBP was observed only in the NT men (r=-0.19, p<0.05). Adjusting for the BMI confirmed a significant difference in plasma T levels between ISH and NT men, but not between HT and NT men. Multiple regression analysis employing BP as a dependent variable confirmed a strong relationship between T levels and SBP in all 3 groups, whereas a significant relationship between T levels and DBP was found only in NT men. In conclusion, although further studies are needed to clarify the relationship between plasma T levels and BP, our findings suggest that in elderly men with ISH, the reduced plasma levels of testosterone might contribute to the increased arterial stiffness typical of these subjects.

Erectile dysfunction and andropause symptoms in infertile men

PURPOSE

We evaluated the prevalence of andropause symptoms and erectile dysfunction in our infertile population.

MATERIALS AND METHODS

A total of 302 consecutive men presenting for infertility evaluation and 60 consecutive men with proven fertility seeking vasectomy (controls) were administered the Androgen Deficiency in the Aging Male and Sexual Health Inventory for Men (SHIM) questionnaires. Information regarding other clinical parameters, including seminal parameters, was collected by review of patient charts.

RESULTS

Of the 302 infertile men screened, 38% reported significant andropause symptoms and 28% had abnormal SHIM scores. Of the subgroup of infertile men with nonobstructive azoospermia, 25% reported andropause symptoms and 27% had an abnormal SHIM score. In the fertile group 21% reported andropause symptoms and only 11% had an abnormal SHIM score. The prevalence of erectile dysfunction in infertile men was significantly higher than in the fertile controls (p = 0.007).

CONCLUSIONS

Andropause symptoms and erectile dysfunction are common among infertile men, affecting approximately 38% of this population. This finding suggests that the population of infertile men should be carefully screened to identify and treat those with erectile dysfunction.

The decline of androgen levels in elderly men and its clinical and therapeutic implications

Aging in men is accompanied by a progressive, but individually variable decline of serum testosterone production, more than 20% of healthy men over 60 yr of age presenting with serum levels below the range for young men. Albeit the clinical picture of aging in men is reminiscent of that of hypogonadism in young men and decreased testosterone production appears to play a role in part of these clinical changes in at least some elderly men, the clinical relevancy of the age-related decline in sex steroid levels in men has not been unequivocally established. In fact, minimal androgen requirements for elderly men remain poorly defined and are likely to vary between individuals. Consequently, borderline androgen deficiency cannot be reliably diagnosed in the elderly, and strict differentiation between "substitutive" and "pharmacological" androgen administration is not possible. To date, only a few hundred elderly men have received androgen therapy in the setting of a randomized, controlled study, and many of these men were not androgen deficient. Most consistent effects of treatment have been on body composition, but to date there is no evidence-based documentation of clinical benefits of androgen administration to elderly men with normal or moderately low serum testosterone in terms of diminished morbidity or of improved survival or quality of life. Until the long-term risk-benefit ratio for androgen administration to elderly is established in adequately powered trials of longer duration, androgen administration to elderly men should be reserved for the minority of elderly men who have both clear clinical symptoms of hypogonadism and frankly low serum testosterone levels.

Telomere length versus hormonal and bone mineral status in healthy elderly men

Telomeres, the termini of linear chromosomes, exert a key role in the process of cellular ageing. Progressive telomere shortening is implicated in senescence in vitro and ample evidence exists to support the hypothesis that telomere length is correlated with chronological age and ageing phenotypes in vivo. In this study, we assessed whether mean telomere length of peripheral blood leukocytes predicts age-associated bone loss and/or is related to sex steroid status in an elderly healthy male population (71-86 years). Out of this population, we selected 110 samples for telomere restriction fragment (TRF) length analysis. Fasting blood was analysed for testosterone, estradiol, sex hormone binding globulin and biochemical markers of bone turnover. Also, the bioavailable fractions of sex steroids were calculated. Bone mineral density was measured at baseline and longitudinal follow-up was available for 84 men. We found that mean TRF length was inversely correlated with age (r=-0.19; P=0.049). Although no correlations were found with sex steroids or BMD at baseline, age corrected mean TRF length was associated with longitudinal bone loss for different distal forearm sites (P<0.05). Further studies are required to confirm our results, yet in this study, the predictive value of telomere length for bone loss appears to be substantial, hence underscoring the role of telomere length as a biomarker of ageing phenotypes.

Relationship between serum sex steroids and Aging Male Symptoms score and International Index of Erectile Function

OBJECTIVES

To determine the relationship between the total and subscale scores of the Aging Male Symptoms (AMS) and International Index of Erectile Function (IIEF) questionnaires, age, and serum sex steroids levels.

METHODS

A total of 348 patients enrolled in the study answered the AMS and IIEF questionnaires. Hormonal analysis, including total testosterone, free testosterone (FT), estradiol (E2), and dehydroepiandrosterone-sulphate (DHEA-S) measurement, were performed. The patients with a total AMS score of 29 were considered to have aging male symptoms and the patients with an IIEF score of less than 26 were considered to have sexual dysfunction.

RESULTS

Although DHEA-S levels were significantly lower and E2 levels were greater in the men with aging male symptoms according to the AMS, the DHEA-S and FT levels were significantly lower in the men with sexual dysfunction, as determined by the IIEF score. Serum DHEA-S and FT levels and age correlated significantly with the IIEF scores. The total AMS score correlated significantly only with age. Although serum total testosterone, FT, and DHEA-S levels correlated significantly with the andrologic symptoms of AMS, the serum E2 levels correlated with psychological symptoms of AMS.

CONCLUSIONS

Although aging male symptoms and the effects of hormonal changes on these symptoms have been controversial, DHEA-S and E2 might play some important roles in the symptoms of aging men.

Influence of physiological androgen levels on wound healing and immune status in men

Aging in men is associated with a progressive decline in the production of several hormones, including androgens. The extent to which an age-dependent decline in androgen levels lead to health problems or can affect quality of life remains under debate. Clinical results on replacement therapy do not yet provide a definitive clue on the benefit/risk balance. A sexual dimorphism of the immune system is well established, and the differences between female and male immune responses under normal, as well as pathological, conditions are generally attributed to the influence of estrogens, progestins, and androgens. The suppressive effects of male sex hormones on immune functions have been observed in a wide variety of disease processes and appear to be testosterone-mediated. Endogenous testosterone inhibits skin wound healing response in males and is associated with an enhanced inflammatory response. Although there are no known gender-related differences in permeability barrier function in adults, estrogens accelerates--whereas testosterone retards--barrier development in fetal skin, and male fetuses demonstrate slower barrier development than female littermates.

Sex Steroid Level, Androgen Receptor Polymorphism, and Depressive Symptoms in Healthy Elderly Men

OBJECTIVES

To determine the prevalence of depression in a cohort of elderly men as assessed using a 30-item Geriatric Depression Scale (GDS) score and to describe the association between this score and sex steroids, androgen receptor (AR) polymorphism, and general health status.

DESIGN

Observational study on the relationship between sex steroid status and health-related parameters.

SETTING

Community-based.

PARTICIPANTS

Ambulatory men (n=236 in 1997, n=192 in 2000) aged 70 and older at inclusion in 1996, interviewed in 1997 and 2000.

MEASUREMENTS

Serum levels of testosterone, estradiol, sex hormone binding globulin (SHBG), dehydroepiandrosterone-sulfate (DHEAS), cortisol, and the AR gene cytosine, adenine, guanine (CAG)-repeat length polymorphism were determined. Free testosterone and free estradiol were calculated. Questionnaires included GDS, 36-item Short Form, and Rapid Disability Rating Scale-2.

RESULTS

Median age was 75.3 years (interquartile range=73.5-78.5). A GDS score of 11 or greater was found in 30 (12.7%) men. Age and GDS score were significantly interrelated (P<.01), as were all health-assessment scores. GDS scores were not related to (free) testosterone or AR polymorphism in 1997 or 2000. In 1997 only (n=236), higher GDS scores were related to higher estradiol, free estradiol, and DHEAS levels.

CONCLUSION

The data did not support a role for testosterone in depression in elderly community-based men as assessed using the GDS.

Prevalence and incidence of androgen deficiency in middle-aged and older men: estimates from the Massachusetts Male Aging Study

Little is known about the descriptive epidemiology of androgen deficiency. In this study, we sought to address this issue by providing estimates of the crude and age-specific prevalence and incidence rates of androgen deficiency in a randomly sampled population-based cohort of middle-aged and older men. Data on androgen deficiency (defined using both signs/symptoms plus total and calculated free testosterone) were available for n = 1691 (baseline) and n = 1087 (follow-up) men from the Massachusetts Male Aging Study. Crude and age-specific prevalence and incidence rates were calculated. Based on these estimates, projections for the number of cases of androgen deficiency in the 40- to 69-yr-old U.S. male population were computed. Estimates of the crude prevalence of androgen deficiency at baseline and follow-up were 6.0 and 12.3%, respectively. Prevalence increased significantly with age. From baseline age-specific prevalence data, it is estimated that there are approximately 2.4 million 40- to 69-yr-old U.S. males with androgen deficiency. The crude incidence rate of androgen deficiency was 12.3 per 1,000 person-years, and the rate increased significantly (P < 0.0001) with age. Based on these incidence data, we can expect approximately 481,000 new cases of androgen deficiency per year in U.S. men 40-69 yr old.

Testosterone replacement therapy: current trends and future directions

Male hypogonadism is characterized by abnormally low serum testosterone levels associated with typical symptoms, including mood disturbance, sexual dysfunction, decreased muscle mass and strength, and decreased bone mineral density. By restoring serum testosterone levels to the normal range using testosterone replacement therapy, many of these symptoms can be relieved. For many years, injectable testosterone esters or surgically implanted testosterone pellets have been the preferred treatment for male hypogonadism. Recently, newer treatment modalities have been introduced, including transdermal patches and gels. The development of a mucoadhesive sustained-release buccal tablet is the latest innovation, which will provide patients with an additional option. The availability of new treatment modalities has helped to renew interest in the management of male hypogonadism, highlighting the need to address a number of important but previously neglected questions in testosterone replacement therapy. These include the risks and benefits of treatment in different patient populations (e.g. the elderly) and the need for evidence-based diagnosis and treatment monitoring guidelines. While some recommendations have been developed in individual countries, up-to-date, internationally accepted evidence-based guidelines that take into account national differences in clinical practice and healthcare delivery would optimize patient care universally.

Male reproductive function in relation with thyroid alterations

Despite the high prevalence of thyroid diseases in the general population, the impact of the latter on male reproductive function has been the subject of only a few well-controlled clinical studies. Hyperthyroidism appears to cause alterations in the sex steroid hormone metabolism as well as in spermatogenesis and fertility. Sperm motility is mainly affected. These abnormalities reverse after restoration of euthyroidism. The effects of hypothyroidism on male reproduction appear to be more subtle than those of hyperthyroidism and reversible. Severe juvenile hypothyroidism may be associated with precocious puberty. Hypothyroidism in adults is associated with disturbances in the sex steroid hormone metabolism as well as infertility, although available data concerning the latter are scarce. Radioiodine ((131)I) treatment for dfferentiated thyroid cancer may cause transient impairment of testicular function Gonadal damage may be cumulative in those requiring multiple administrations and sperm banking should be considered in such patients.

Partial androgen deficiency in aging type 2 diabetic men and its relationship to glycemic control

Aging in the male is associated with both a higher incidence of type 2 diabetes and hypogonadism. However, little information is available about the complex of symptoms and hormonal changes related to partial androgen deficiency in aging (called andropause) in type 2 diabetic men. Here, for the first time, we used a combination of clinical and hormonal criteria to define andropause and to analyze the relationships between the androgen environment and glucose metabolism in 55 type 2 diabetic men (63.6 +/- 7.9 years, mean +/- SD). Low plasma levels of total testosterone (< or =3.4 ng/mL) and free testosterone (< or =11 pg/mL) were found in 20% and 54.5%, respectively, of the diabetic men. The fraction of diabetic men with subnormal levels of total testosterone increased with aging: 14.2% (50 to 59 years), 17.4% (60 to 69 years) and 36% (> 70 years). The corresponding figures for subnormal values of free testosterone were 38%, 69.6%, and 54.5%, respectively. In the whole group of type 2 diabetic men, no significant linear correlations between total or free testosterone with fasting plasma glucose, insulin, C-peptide, or fructosamine values could be established. Total testosterone was positively correlated with glycosylated haemoglobin (HbA(1c)) levels (r =.322, P =.01). Although fasting plasma glucose was marginally higher in aging type 2 diabetic patients with andropause than in those without andropause (162 +/- 6.9 v 139 +/- 8.9, mean +/- SEM, P =.05), there were no differences between both subgroups for plasma fasting insulin, C-peptide, fructosamine, or HbA(1c) levels. Replacement therapy (150 mg intramuscular [IM] of enanthate of testosterone every 14 days for 6 months) was applied in 10 type 2 diabetic men with clinical features of andropause associated with subnormal concentrations of serum testosterone. The treatment induced significant increases in total plasma testosterone (baseline: 3.9 +/- 0.3; at 6 months: 7.1 +/- 0.9 ng/mL, mean +/- SEM, P =.003) and free testosterone (baseline: 9.3 +/- 0.6; at 6 months 17.6 +/- 2.4 pg/mL, P =.003), but had a neutral effect on overall glycemic control. These data show a high prevalence of andropause in aging type 2 diabetic men and suggest that the endogenous androgen environment, as well as correction of the partial androgen deficiency, do not have a meaningful effect on glycemic control.

Androgen Replacement Therapy

The major goal of androgen substitution is to replace testosterone at levels as close to physiological levels as is possible. For some androgen-dependent functions testosterone is a pro-hormone, peripherally converted to 5alpha-dihydrotestosterone (DHT) and 17beta-estradiol (E2), of which the levels preferably should be within normal physiological ranges. Furthermore, androgens should have a good safety profile without adverse effects on the prostate, serum lipids, liver or respiratory function, and they must be convenient to use and patient-friendly, with a relative independence from medical services. Natural testosterone is viewed as the best androgen for substitution in hypogonadal men. The reason behind the selection is that testosterone can be converted to DHT and E2, thus developing the full spectrum of testosterone activities in long-term substitution. The mainstays of testosterone substitution are parenteral testosterone esters (testosterone enantate and testosterone cipionate) administered every 2-3 weeks. A major disadvantage is the strongly fluctuating levels of plasma testosterone, which are not in the physiological range at least 50% of the time. Also, the generated plasma E2 is usually supraphysiological. A major improvement is parenteral testosterone undecanoate producing normal plasma levels of testosterone for 12 weeks, with normal plasma levels of DHT and E2 also. Subcutaneous testosterone implants provide the patient, depending on the dose of implants, with normal plasma testosterone for 3-6 months. However, their use is not widespread. Oral testosterone undecanoate dissolved in castor oil bypasses the liver via its lymphatic absorption. At a dosage of 80 mg twice daily, plasma testosterone levels are largely in the normal range, but plasma DHT tends to be elevated. For two decades transdermal testosterone preparations have been available and have an attractive pharmacokinetic profile. Scrotal testosterone patches generate supraphysiological plasma DHT levels, which is not the case with the nonscrotal testosterone patches. Transdermal testosterone gel produces fewer skin irritations than the patches and offers greater flexibility in dosage. Oromucosal testosterone preparations have recently become available. Testosterone replacement is usually of long duration and so patient compliance is of utmost importance. Therefore, the patient must be involved in the selection of type of testosterone preparation. Administration of testosterone to young individuals has almost no adverse effects. With increasing age the risk of adverse effects on the prostate, the cardiovascular system and erythropoiesis increases. Consequently, short-acting testosterone preparations are better suited for aging androgen-deficient men.

Endocrine alterations in the aging male

The recent increase in the elderly population, current health trends and awareness of age-related changes in the male endocrine system, have led to discussions about the role of the hormonal changes in the aging process in males. Better prevention and treatment of suboptimal health status and age-related diseases in aging men are based on an improved understanding of aging, particularly of the significance of age-associated hormonal changes. The aims of this study were 1) to evaluate the age dependence of the serum concentrations of the following important hormonal parameters in adult males using the IMMULITE 1 automated assay system (DPC, Los Angeles): testosterone, dehydro-epiandrosterone sulfate (DHEAS), estradiol (E2), sex hormone binding globulin (SHBG), lutropin (LH), follitropin (FSH), cortisol, prolactin, thyroid stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) and the growth hormone-dependent parameters insulin-like growth factor (IGF-I) and IGF-binding protein-3 (IGFBP-3) and 2) to derive the following parameters: calculated free testosterone (cFT), ratio of calculated free testosterone to total testosterone (% cFT) and free androgen index (FAI). We found a significant decrease between the 21-30-year age group and the > 70-year age group for total testosterone (-42.4%), FAI (-65.5%), cFT (-60.0%), % cFT (-30.0%), DHEAS (-71.9%), E2 (-35.4%), TSH (-23.6%), IGF-I (-40.3%) and IGFBP-3 (-26.5%). Since the decreases in the FAI and cFT were greater than that of total testosterone and because these derived parameters reflect the biologically active fraction of testosterone, FAI and cFT are better markers for androgen deficiency in males. In contrast, a significant increase with age was observed for SHBG (+61.2%), LH (+40.0%), FSH (+98.3%) and cortisol (+54.2%). No significant alterations with age were observed for prolactin, fT3 and fT4. The study demonstrates that determining complete profiles of the androgenic, gonadotropic, adrenocortical, thyroid, pituitary and growth hormone/IGF endocrine axes in middle-aged and elderly men may be helpful in obtaining a correct clinical diagnosis for various hormonal disorders.

Bioavailable estradiol and an aromatase gene polymorphism are determinants of bone mineral density changes in men over 70 years of age

The question of whether and to what extent the sex steroid deficiency in elderly men contributes to the pathogenesis of bone loss has not been fully explored. The aim of the present study was to assess the association of serum bioavailable (Bio) estradiol (E(2)) with the evolution of bone mineral density (BMD) in 214 community-dwelling men aged 71-86 yr as well as the possible modulation of estrogen effects by a tetranucleotide (TTTA)(n)-repeat polymorphism of the CYP19 gene, which encodes the aromatase enzyme that converts androgens into estrogens. BMD was measured at yearly intervals over a period of 4 yr using dual x-ray absorptiometry. Fasting blood was analyzed at baseline for testosterone (T), E(2), and SHBG; the respective bioavailable fractions, BioT and BioE(2), were calculated. Serum BioE(2) was associated with baseline BMD at different assessed skeletal sites, with correlation coefficients ranging between 0.23 and 0.37 (P < 0.001). Estimated annual percentage change of BMD (%BMD) was -0.39% [95% confidence index (CI), -0.56, -0.22] at the total hip, -0.04% (95% CI, -0.29, 0.21) at the femoral neck, and -0.37% (95% CI, -0.45, -0.29) at the total distal forearm. Higher circulating BioE(2) levels were associated with less bone loss at the forearm and the hip (P < 0.05). The CYP19 gene (TTTA)(n)-repeat length (determined by fragment analysis) was not associated with baseline BMD in the total group of elderly men. However, a significant association was observed between the CYP19 genotype and BMD change at the distal forearm; the highest bone loss was observed in subjects homozygotic for the shortest observed allele length of (TTTA)(7)-repeats (P < 0.02). The CYP19 (TTTA)(n)-repeat length was not associated with either baseline BioE(2) or the BioT/BioE(2) ratio. In multiple linear regression models, the CYP19 genotype and serum BioE(2) were determinants of %BMD change at the forearm (P < 0.05). No significant contribution of BioT to %BMD change was evident. As to fracture risk, the allele containing the shortest (TTTA)(n)-repeat length was more represented not only in elderly men with a positive personal fracture history (Pearson's chi(2) test = 4.03; df = 1; P = 0.05) but also in study subjects with a positive fracture history in their first-degree relatives (Pearson's chi(2) test = 6.48; df = 1; P = 0.01). In conclusion, the results of this prospective observational study support the view that BioE(2) is a determinant of bone density changes in elderly men and, furthermore, provide an indication that the aromatase enzyme may exert a direct modulatory action on bone metabolism at the tissue level in elderly men.

Androgen deficiency in the aging male: benefits and risks of androgen supplementation

There is now convincing evidence that in a subset of aging men, increasing with age, plasma testosterone levels fall below a critical level resulting in hypogonadism. This state of testosterone deficiency has an impact on bone, muscle and brain function and is maybe a factor in the accumulation of visceral fat which again has a significant impact on the cardiovascular risk profile. From the above it follows that androgen replacement to selected men with proven androgen deficiency will have beneficial effects. There is, however a concern that androgen administration to aging men may be harmful in view of effects on prostate disease. Benign prostate hyperplasia (BPH) and prostate cancer are typically diseases of the aging male, steeply increasing with age. But epidemiological studies provide no clues that the levels of circulating androgen are correlated with or predict prostate disease. Similarly, androgen replacement studies in men do not suggest that these men suffer in a higher degree from prostate disease than control subjects. It seems a defensible practice to treat aging men with androgens if and when they are testosterone-deficient, but long-term studies including sufficient numbers of men are needed.

Andropause: an androgen deficiency state in the ageing male

An age-related decline in circulating testosterone levels has been shown to occur in the adult male population starting as early as middle age and continuing on into old age. This decline in testosterone has been associated with a number of changes in body composition and sexual performance in the male that are directly attributable to an androgen deficiency state, which can be restored by the use of testosterone replacement therapy. The term 'andropause' has been used to describe this gradual drop in testosterone in the ageing male and is characterised by different endocrine, somatic and psychic changes that become more pronounced as the male gets older. For some males, the adjustment of circulating testosterone levels with replacement therapy to levels seen in young men can improve physical performance, induce a sense of well-being and restore the androgen-dependent sex drive that declines with ageing.

Effects of exogenous testosterone on testicular luteinizing hormone and follicle-stimulating hormone receptors during aging

During aging, the male Japanese quail exhibits a loss of fertility, increased morphological abnormalities in the testes, and a higher incidence of Sertoli cell tumors. Although there is a coincident loss of reproductive behavior, plasma androgen levels remain high until testicular regression occurs in association with senescence. The purpose of this study was to compare mean specific binding of chicken luteinizing hormone (LH) and follicle-stimulating hormone (FSH) as a measure of testicular receptors during identified stages during aging. Males were categorized according to age (young = 9 months, middle aged = 24 months, or old = 36+ months) and sexual behavior (active or inactive). Testicular samples were collected immediately after perfusion with 4% paraformaldehyde from the following groups: young active (n = 8), young photoregressed (n = 5), young photoregressed plus testosterone implant (n = 4), middle-aged active (n = 8), middle-aged inactive (n = 4), old inactive (n = 5), and old inactive plus testosterone implant (n = 6). A crude plasma membrane fraction was prepared from the testes of each bird and an aliquot deriving from 10 mg of testicular tissue was used for binding assay. Specific binding of labeled LH or FSH was expressed as percentage of total radioactive hormone. Results showed significant (P < 0.05) age-related decreases in both FSH and LH receptor numbers. The highest FSH binding was found in young and middle-aged active males, with low binding in old inactive males. Testicular LH binding decreased during aging, with a sharp decrease in middle-aged males, which was similar to old males. Testosterone implants weakly stimulated FSH and LH binding in old males. Both LH and FSH binding decreased in photoregressed young males. However, testosterone implants stimulated increased LH binding, but did not affect FSH binding in young photoregressed males. These results provide evidence for separate regulation of testicular LH and FSH receptors, with testosterone stimulation of LH receptor, but not FSH receptor number in young males. However, during aging there appears to be a loss of this response, potentially because of the reduced efficacy of testosterone stimulation, thereby implying a diminished capacity for response with aging.

Osteoporosis in men: pathophysiology, evaluation, and therapy

Osteoporosis is a serious health problem for men. An advance in our understanding of the pathophysiology and treatment of this disorder has resulted in the possibility of a gender-specific approach to screening, diagnosis, and treatment. Here we review the data on osteoporosis in men, discuss controversies regarding whom to screen, whom to treat, and how to treat. Recent treatment data as they relate to men are reviewed, and a clinical treatment algorithm is presented.

Age and sex steroid-related changes in glucocorticoid sensitivity of pro-inflammatory cytokine production after psychosocial stress

Aging is associated with an increased susceptibility to infections and chronic inflammatory diseases. This might be caused by dysregulations of the endocrine system with increased activity of the hypothalamus-pituitary-adrenal (HPA) axis and decreased levels of sex steroids. Therefore, we investigated the stress-response of the HPA axis and glucocorticoid (GC) sensitivity of pro-inflammatory cytokine production in elderly men, compared to testosterone-treated elderly men and young controls. Stress-induced increases in cortisol did not differ significantly between experimental groups (F=2.10; p>0.10), but GC sensitivity increased significantly in young controls and testosterone-treated elderly men, while a decrease was found in untreated elderly men (F=5.28; p<0.01). We conclude that the increase in GC sensitivity after stress serves to protect the individual from detrimental increases of pro-inflammatory cytokines, a mechanism that is disturbed in elderly men and partly restored by testosterone treatment.

Lack of influence of the androgen receptor gene CAG-repeat polymorphism on sex steroid status and bone metabolism in elderly men

OBJECTIVE

Population means for serum testosterone (T) levels in healthy men decrease with ageing but there is considerable interindividual variability of serum T in elderly men. Ultimate androgen action is mediated through the androgen receptor. Subtle differences in androgen sensitivity might contribute to serum T variability through the T negative feedback regulation. The androgen receptor gene (AR) contains in exon 1 a polymorphic trinucleotide CAG-repeat, whose length modulates androgen receptor action. The aims of the study were to assess the potential contribution of the AR CAG-repeat polymorphism in the interindividual variability of serum T and in the determination of bone metabolism in ambulatory elderly men.

DESIGN AND PATIENTS

We used cross-sectional baseline data of a longitudinal study investigating the process of ageing, in particular the changes in hormonal status and bone metabolism, in a cohort of 273 community-dwelling healthy men, between age 71 and 86 years.

MEASUREMENTS

AR CAG-repeat length was determined by automated DNA sequencing of exon 1 of the AR gene. Serum T, sex hormone binding globulin, LH and oestradiol were measured by specific immunoassays. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. Bone turnover was assessed by measurement of serum bone-specific alkaline phosphatase, serum osteocalcin, serum C-terminal type I procollagen peptide, serum and urinary C-terminal telopeptides of type I collagen and urinary deoxypyridinoline levels, with use of immunoassays.

RESULTS

No significant association was found between the AR CAG-repeat length and either total or free T, LH or the androgen sensitivity index (LHxT). BMD measurements at the hip and the forearm were not associated with AR CAG-repeat length and there was no association of this AR polymorphism with any of the biochemical markers of bone turnover. Results were not different after adjustments for age and body mass index.

CONCLUSIONS

The findings of the present study do not support the view that in community-dwelling, healthy elderly men the androgen receptor gene CAG-repeat polymorphism has a substantial impact on interindividual variability of serum testosterone levels or on the determination of bone turnover and bone mineral density.

Inverse association between bone turnover rate and bone mineral density in community-dwelling men >70 years of age: no major role of sex steroid status

Bone loss is accelerated in elderly men. Little is known about the pathophysiology of senile bone loss or about the role played by relative sex steroid deficiency in the determination of bone turnover in elderly men. In a population-based sample of 283 healthy, ambulatory men, aged 71-86 years, we sought to determine whether lower bone mineral density (BMD; using dual-energy X ray absorptiometry at the hip and the forearm) is associated with higher bone turnover, and we assessed the impact of sex steroid status on bone turnover. Indices of bone formation, serum osteocalcin (s-Oc), and bone-specific alkaline phosphatase (s-bAP) and indices of bone resorption, serum and urinary telopeptide of type I collagen (s-CTx and u-CTx), and urinary free deoxypyridinoline (u-Dpd) were intercorrelated (r = 0.29-0.76, p < 0.001). Bone turnover indices were negatively associated with BMD (r = -0.17 to -0.34, p < 0.01). In univariate analyses, there was a trend toward weak negative associations of bone turnover markers with serum free testosterone (FT), significant only for s-Oc and s-CTx (r = -0.16 and -0.14, p < 0.01), and with serum free estradiol (FE(2)), significant only for u-CTx and s-CTx (r = -0.18 and -0.19; p < 0.01). The lower quartile for FE(2) was associated with higher values of u-CTx (p = 0.003) and s-CTx (p < 0.001). However, in multivariate models, for the individual markers of bone turnover a negative association between estradiol (E(2)) or FE(2) and s-CTx was the only remaining (marginally) significant association (p < 0.05) for the relationship between sex steroids and any of the bone turnover indices assessed. In community-dwelling men age >70 years, bone turnover rate, as determined by biochemical markers, is a significant negative determinant of prevalent BMD. However, the findings do not support the view that relative differences in sex steroid status, as observed among healthy elderly men, have a major impact on bone turnover.

Age-related increase in mitochondrial superoxide generation in the testosterone-producing cells of Brown Norway rat testes: relationship to reduced steroidogenic function?

Aging in Brown Norway rats is accompanied by the reduced production of testosterone by the Leydig cells, the testicular cells responsible for synthesizing and secreting this essential steroid. As yet, the mechanism by which Leydig cell steroidogenesis is reduced is unknown. Herein we assess the production of mitochondrial reactive oxygen species by intact Leydig cells isolated from the testes of young and old rats. To this end, Leydig cells were incubated with lucigenin (bis-N-methylacridinium nitrate), a probe that enters cells, localizes to mitochondria, and yields a significant chemiluminescent response following its reaction with intramitochondrial superoxide. Leydig cells from old rats elicited significantly greater lucigenin-derived chemiluminescence (LDCL) than those from young rats. Electron microscopic stereological analysis revealed that the absolute volume of mitochondria in the old cells was reduced from that in the young. These results, taken together, suggest that there are age-related changes in the production of reactive oxygen species by the mitochondria of Leydig cells, with those of old Leydig cells producing significantly greater levels than those of young Leydig cells. The results are consistent with the proposal that mitochondrial-derived reactive oxygen may play a role in the irreversible decline in the ability of old Leydig cells to produce testosterone.

Continuously proliferative stem germ cells partially repopulate the aged, atrophic rat testis after gonadotropin-releasing hormone agonist therapy

Aging in the male human is accompanied by testicular atrophy, although relatively little is known about the mechanisms underlying germ cell loss. Testicular atrophy in the aged Brown Norway rat, an animal model for studies of aging in the human, has been attributed to a loss of spermatogonial stem cells. However, examination of testicular cross-sections from 27-mo-old Brown Norway rats indicated that approximately 14% of type A spermatogonia were stem cells. Furthermore, using bromodeoxyuridine labeling, we found that approximately 47% of these stem cells were actively dividing, with a cell cycle time of approximately 12.6 days. Both serum and testicular interstitial fluid testosterone levels were depressed in the aged rat. Therapy with the GnRH agonist, leuprolide, which has been empirically shown to reverse testicular atrophy in other models of germ cell loss, also partially restored spermatogenesis in the aged Brown Norway rat. The extent of testicular atrophy varied considerably, not only within the control and leuprolide-treatment groups but also between the left and right testes of the same animals. No significant difference was found between the mean percentage of populated tubules in 31-mo-old control animals (16.2 +/- 28%, mean +/- SD) and 31-mo-old leuprolide-treated animals (20.9 +/- 19.8%), but categorical comparisons showed that significantly fewer leuprolide-treated animals and testes contained < or = 1% populated tubules, indicating that GnRH agonist therapy stimulates differentiation of type A spermatogonia. An increase in the ratio of soluble to membrane stem cell factor mRNA levels was present in aged rats and partially reversed following leuprolide therapy.

Regular moderate intensity physical activity and blood concentrations of endogenous anabolic hormones and thyroid hormones in aging men

BACKGROUND

Physical activity has been reported to affect endocrine function in elderly men.

OBJECTIVE

To establish an association between regular moderate physical activity and endogenous anabolic hormone levels in healthy aging men.

PARTICIPANTS

Twenty four middle-aged (57.4+/-4.7 years) and 24 elderly (68.3+/-2.6 years) physically active men who in the past 10 years had been regularly bicycling during leisure time were compared with 24 middle-aged (57.9+/-4.0 years) and 24 elderly (67.2+/-1.7 years) sedentary men. Groups did not differ for body composition.

MEASUREMENTS

Serum dehydroepiandrosterone sulfate (DHEAS), insulin-like growth factor-I (IGF-1), free testosterone (FT), and thyroid hormone levels were assessed.

RESULTS

In general, elderly men had lower IGF-1 (P<0.001), DHEAS (P=0.013), and triodothyronine levels (P<0.001) than their middle-aged counterparts. Independently of age, however, physically active men had on average higher IGF-1 (P=0.031), DHEAS (P=0.001), and triodothyronine serum levels (P<0.001) than sedentary men. FT and thyroid stimulating hormone (TSH) serum concentrations did not differ across age groups, but physically active men had lower TSH values than sedentary men (P=0.021).

CONCLUSIONS

Our results suggest that, in aging men, regular moderate physical activity is associated with higher levels of IGF-1 and DHEAS levels and with thyroid function alterations.

Aging and the neuroendocrine regulation of reproduction and body weight

Aging in men is associated with a decline in trophic factors such as testosterone (T), alterations in body composition and impaired energy and body weight regulation. We performed studies to investigate the mechanisms underlying age-related changes in the neuroendocrine control of testis function, body composition, food intake and body weight in the Brown Norway (BN) rat. We found that similar to aging men, male BN rats demonstrate both primary and secondary testicular failure with aging without confounding age-related tumors, hormonal changes and systemic illnesses. With aging, these animals have blunted circadian variations in luteinizing hormone (LH) and T, and decreased hypothalamic gonadotropin-releasing hormone (GnRH) synthetic capacity with preserved pituitary gonadotropin responses to GnRH. We found that aging male BN rats have increased peripheral and visceral adiposity associated with increased insulin and leptin levels, and decreased relative lean body mass and muscle mass. We found that these rats exhibit reduced food intake and body weight gain associated with decreased hypothalamic neuropeptide Y (NPY) gene expression in the arcuate nucleus (ARC), both during ad-libitum feeding and after a 72-h fast. Recently, we found that old male BN rats treated chronically with troglitazone, an insulin sensitizer, lowered high insulin and leptin levels, decreased body fat, and corrected the blunted food intake and body weight gain response to fasting without affecting basal ARC NPY gene expression. These findings suggested that hyperinsulinemia and/or hyperleptinemia associated with aging may contribute to the age-related impairment in energy and weight regulation. Our studies suggest that the aging male BN rat is an excellent model to investigate the mechanisms underlying the age-associated changes in the neuroendocrine control of body composition, energy intake and body weight.

Age-related changes of serum sex hormones, insulin-like growth factor-1 and sex-hormone binding globulin levels in men: cross-sectional data from a healthy male cohort

The age-dependent decline of the gonadal and somatotopic axis has been causally linked to frailty in the elderly by their effects on muscle mass and bone mineral density. However, for healthy men data on serum oestrogens and androgens, as well as IGF-1, as a common outcome measure covering the whole adult age range are scarce. We therefore studied healthy, nonobese male subjects between 20 and 80 years of age to asses their morning concentrations of total (T), free (FT), bioavailable testosterone (bT), oestradiol (E2), bioavailable oestradiol (bE2), oestrone (E1), sex-hormone binding globulin (SHBG), and insulin-like growth factor 1 (IGF-1). Five hundred and seventy-two male healthy volunteers with a BMI < 30 kg/m2 recruited from regular blood donors and senior sports clubs participated in the study. Serum samples were obtained during morning hours and T, FT, E2, E1, SHBG, albumin and IGF-1 were measured by radio-immunoassay systems. In addition, bT and bE2 were calculated. A potential relationship between sex hormones and IGF-1 was tested by multiple regression analysis including age and BMI. Ageing was negatively related to serum levels of sex steroids and IGF-1 (both P < 0.0001) with a mean decrease (youngest vs. oldest) of 51% for T, 64% for FT, 78% for bT, 32% for E2, 62% for bE2, 29% for E1 and 51% for IGF-1 starting in early adulthood whereas SHBG increased after the 5th decade of life (ANOVA P < 0.001). The decline of sex hormones and IGF-1 remained relatively unchanged after adjustment for BMI. Multiple regression analysis revealed an age-and BMI- independent association between oestradiol and IGF-1. In contrast to the female situation sex hormones in healthy, nonobese men decline continuously with age. This process has already started in the third decade, and is paralleled by a decline of IGF-1 serum levels leading to a substantial proportion of elderly men with markedly lowered serum levels of bioavailable sex hormones and IGF-1 compared to the young adult male range. With the recent demonstration of beneficial effects of androgen replacement therapy in healthy males on general well being, muscle mass and bone mineral density the present data may underline the importance of more detailed studies on the biological significance of hormonal changes in men with age.

Sarcopenia: current concepts

Sarcopenia, the loss of muscle mass and strength with age, is becoming recognized as a major cause of disability and morbidity in the elderly population. Sarcopenia is part of normal aging and does not require a disease to occur, although muscle wasting is accelerated by chronic diseases. Sarcopenia is thought to have multiple causes, although the relative importance of each is not clear. Neurological, metabolic, hormonal, nutritional, and physical-activity-related changes with age are likely to contribute to the loss of muscle mass. In this review, we discuss current concepts of the pathogenesis, treatment, and prevention of sarcopenia.

Background for studies on the treatment of male osteoporosis: state of the art

Male osteoporosis represents an important, although long underestimated, public health problem. Both in men and in women aging is accompanied by continuous bone loss and by an exponential increase in the incidence of osteoporotic fracture, with a female to male incidence ratio of about 2 to 3 to 1 in the elderly for hip and vertebral fractures. Morbidity after osteoporotic fractures appears to be more serious and mortality more common in men than in women. To date, no single treatment has been proved to be effective and safe in published prospective studies. The present report, based on a systematic search of the literature on male osteoporosis, summarises the state of the art on the clinical consequences of male osteoporosis and its risk factors, in relation to the present state of knowledge about female osteoporosis. This constitutes the background for the design of rational clinical development strategies for therapeutic interventions in male osteoporosis. From this review of the literature it is apparent that notwithstanding the existing sex differences in pathophysiology of osteoporosis and the difference in age-specific incidence of osteoporotic fractures, there are also important similarities between osteoporosis in women and men. The higher incidence of fracture in women than in men results from quantitative differences in risk factors rather than from different risk factors. Even though there are sex differences in bone geometry, incidence of fracture seems to be similar in men and women for a same absolute areal bone mineral density. However, the lack of data on the changes in fracture rates in men resulting from pharmacological intervention, leading to changes in bone mineral density or bone turnover, remains the main limitation for extrapolation of established treatment outcomes from women to men.

Serum inhibin B levels in community-dwelling elderly men

BACKGROUND AND OBJECTIVE

Ageing in men is accompanied by a decline of Leydig cell function, with a 50% decrease of the population means for serum free testosterone between age 25 and 75 years. Information on Sertoli cell function and spermatogenesis in the elderly is scarce. Studies on seminal parameters in ageing men have suggested that spermatogenesis may be fairly well maintained in the elderly, but they included mostly selected subjects and only few men over 60 years. More systematic studies are lacking. The aim of the present study was to assess serum inhibin B levels in elderly men as an index of global Sertoli cell function and spermatogenic activity.

SUBJECTS AND MEASUREMENTS

Specific immunoassays were used to determine serum levels of inhibin B, gonadotrophins, testosterone and oestradiol in blood obtained between 0800 and 1000 h. from 189 ambulatory, community-dwelling elderly men (age: 70-85 years) and, for comparison, from 51 middle-aged (35-54 years) and 50 young (< 35 years) controls.

RESULTS

All age groups combined, serum inhibin B was only weakly negatively correlated to age (Spearman correlation coefficient: - 0.17; P < 0.01) and more strongly to serum FSH (- 0. 52; P < 0.001). In a multiple regression analysis serum FSH, but not age or serum free testosterone, emerged as an independent determinant of serum inhibin B levels. An age-related decline of median inhibin B levels in the study population was essentially limited to the younger age groups, with stable levels between age 35 and 79 years, and only a modest further decrease thereafter. There was a progressive age-related increase of serum FSH across age groups with, consequently, a marked decrease of the serum inhibin B : FSH ratio. The prevalence of men presenting with low serum inhibin B (below 10th percentile for inhibin B levels in men < 35 years), indicative of deficient Sertoli cell function and spermatogenesis, increased most strikingly between men < 35 years and those 35-54 years, which contrasts with the more progressive increase at an older age of the prevalence of low serum (free) testosterone.

CONCLUSION

Global testicular Sertoli cell function and spermatogenic activity, as assessed indirectly through serum inhibin B levels, appear to be well maintained in ambulatory elderly men, albeit there are age-related alterations at the level of the Sertoli cells as indicated by a progressive increase of testicular drive by pituitary FSH.

Serum leptin levels in healthy ageing men: are decreased serum testosterone and increased adiposity in elderly men the consequence of leptin deficiency?

OBJECTIVE

The limited information on serum leptin levels in elderly men suggests the occurrence of an age-related decrease, with disruption of the relationship between fat mass and leptin levels. A relative leptin deficiency might thus be implicated in the increase of fat mass and decrease of serum testosterone levels in elderly men. Therefore, we have reevaluated the age-related changes in serum leptin levels and their relationship with adiposity and androgen levels in a large group of community dwelling men.

SUBJECTS AND MEASUREMENTS

Serum leptin and androgen levels were measured in 271 healthy, ambulatory elderly men (median age 74 years), as well as in 61 middle-aged (median 43 years) and 40 young (median 25.5 years) controls. Adiposity was assessed by anthropometrical measurements (body mass index; BMI) and by estimation of fat mass by the bio-impedance method.

RESULTS

Serum leptin levels, whether or not adjusted for BMI, were found to increase with age, the values tending to level off after the age of 45 years, and were strongly correlated to BMI (r = 0.77) and fat mass assessed by the bio-impedance method (r = 0.81). Linear regression analysis showed a similar slope for the relationship between BMI and serum leptin in the three age groups. Multiple linear regression analysis indicated BMI, age and serum insulin, but not serum testosterone, as significant independent correlates of serum leptin. Serum (free) testosterone levels were negatively correlated with age and serum leptin, also after partialization for BMI: rank correlation coefficients vs. age and serum leptin, respectively, were - 0.20 (P < 0.001) and - 0.16 (P < 0.01) for total testosterone and - 0.60 (P < 0.001) and - 0.23 (P < 0.001) for free testosterone. Dehydroepiandrosterone sulphate (DHEAS) and leptin levels emerged as significant independent correlates in a multiple linear regression model for total serum testosterone; BMI and serum insulin became highly significant correlates in the same model when leptin was omitted from the independent variables.

CONCLUSION

Ageing in men is accompanied by a rise of serum leptin levels with a maintained strong association between serum leptin and adiposity in elderly men. Testosterone does not appear to be a major determinant of serum leptin in healthy men, while leptin does emerge as a negative correlate of serum testosterone. Increased fat mass and decreased testosterone production in elderly men cannot be attributed to a relative leptin deficiency.

Significance of skeletal muscle properties on fitness, long-term physical training and serum lipids

The percentage of slow-twitch (ST) fibers in a person's skeletal muscle, e.g. muscle fiber composition (ST-%), may have a significant impact on physical activity, fitness level, serum high density lipoprotein cholesterol (HDL-C) concentration, and ultimately, on the risk of coronary heart disease (CHD). We studied the effect of a 12 month home-based exercise training program on skeletal muscle metabolic activity, serum lipids, and hormones in 12 healthy middle-aged men (sedentary men) with a low level of fitness and leisure-time physical activity (LTPA). Their parameters and changes in them were compared with 12 men of the same age with defined CHD and with two groups (15 each) of physically active men, who had either a high ST-% (high-ST-men) or a low ST-% (low-ST-men). In the sedentary men, CHD-patients and low-ST-men, the mean ST-% (42, 44, and 49%, respectively) was similar but was significantly higher in the high-ST-men (73%). The sedentary men whose LTPA mean was 34 and 19% of the mean of low-ST-men (mean of 2137 kcal/week) and high-ST-men (mean of 3845 kcal/week), respectively, increased their LTPA from a mean of 728-1526 kcal/week (P < 0.01). After training, we found an increase in serum HDL-C by 21%, (P < 0.01) and apo A-I by 36% (P < 0.01), and a decrease in serum LDL-C by 8%. The cholesterol/HDL-C ratio decreased by 17(% (P < 0.01) and the LDL-C/HDL-C ratio decreased by 22% (P < 0.01). Skeletal muscle lipoprotein lipase (LPL) activity increased by 65% (P < 0.001). Moreover, the increase in LPL as well as in HDL-C concentration tended to be more pronounced the higher the level was before training. The oxidative enzyme activity of alpha-ketoglutarate dehydrogenase (KGDH) in skeletal muscle and the activity of carnitine palmitoyltransferase (CPT) in lipid metabolism increased, whereas glycolytic phosphofructokinase (PFK) did not change but the PFK to CPT ratio decreased, which was reflected as a decrease of lactate accumulation during exercise. Increase in CPT activity correlated significantly (r(s) = 0.81, P < 0.01) with the increase in HDL-C concentration. In all men (n = 54), the CPT activity correlated negatively with serum triglyceride concentration (r(s) = -0.34, P < 0.05) but positively with serum HDL-C concentration and ST-% (r(s) = 0.34, P < 0.05 and r(s) = 0.47, P < 0.01, respectively). In all healthy men, (n = 42) LTPA correlated with both Vo2max, and ST-% (r(s) = 0.76, P < 0.001 and r(s) = 0.54, P < 0.001, respectively) and with serum HDL-C and apo A-I concentrations (r(s) = 0.35, P < 0.05 and r(s) = 0.54, P < 0.001, respectively). Serum sex hormones did not show significant associations with serum lipids, but in sedentary men, serum total and free testosterone as well as the ratio of free testosterone to free estradiol decreased significantly after training. These findings confirm the pronounced effects of a home-based exercise training program on CHD risk factors and they underline the importance of considering skeletal muscle properties when studying serum lipids and lipoproteins and their modifications in the field of health-related fitness and physical activity.