Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts male aging study

[Testosterone deficiency and the problem of normal values]

If a testosterone deficiency is demonstrated, the exact cause of the endocrine hypogonadism should be determined by appropriate endocrinological, imaging and other andrological diagnostic techniques, as such a deficiency can be the result of various illnesses. At present there are no satisfactory evidence based, generally accepted norms for testosterone levels recognised for the aging male. Laboratory analysis of testosterone must be carried out taking into consideration the physiological variability using methods validated in house, with strict internal and external quality control. For the diagnosis of reduced testosterone levels, satisfactorily established own normal values for the technique used are recommended.

Endocrine Aspects of Sexual Dysfunction in Men

INTRODUCTION

Endocrine disorders of sex steroid hormones may adversely affect men's sexual function. Aim. To provide expert opinions/recommendations concerning state-of-the-art knowledge for the pathophysiology, diagnosis and treatment of endocrinologic sexual medicine disorders.

METHODS

An International Consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 17 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge in the respective sexual medicine topic represent the opinion of experts from five continents developed in a scientific and debate process. Concerning the Endocrine committee, there were eight experts from seven countries.

MAIN OUTCOME MEASURE

Expert opinions/recommendations are based on grading of evidence-based medical literature, extensive internal committee discussion over 2 years, public presentation and deliberation.

RESULTS

Hypogonadism is a clinical and biochemical syndrome characterized by a deficiency in serum androgen levels which may decrease sexual interest, quality of erections and quality of life. Biochemical investigations include testosterone and either bioavailable or calculated free testosterone; prolactin should be considered when hypogonadism has been documented. If clinically indicated, androgen therapy should maintain testosterone within the physiological range avoiding supraphysiologic values. Digital rectal examination and determination of serum prostate specific antigen values are mandatory prior to therapy and regularly thereafter. Androgen therapy is usually long-term requiring regular follow-up, frequent monitoring of blood levels and beneficial and adverse therapeutic responses.

CONCLUSIONS

Safe and effective treatments for endocrinologic sexual medicine disorders examined by prospective, placebo-controlled, multi-institutional clinical trials are needed.

Recombinant human chorionic gonadotropin but not dihydrotestosterone alone stimulates osteoblastic collagen synthesis in older men with partial age-related androgen deficiency

Several randomized trials of androgen supplementation in older men have been undertaken. However, the relative contributions of testosterone (T) and estrogens on bone metabolism in aging men are controversial. Within the setting of two double-blind, placebo-controlled studies, we evaluated the effect of dihydrotestosterone (DHT) and recombinant human chorionic gonadotropin (rhCG) on bone turnover in healthy, community-dwelling older men with partial androgen deficiency (total T < or = 15 nmol/liter). In the first study, 35 men (age 68.3 +/- 6.8 yr; baseline T, 13.9 +/- 3.3 nmol/liter) were randomized to receive either daily transdermal DHT (n = 17) or placebo for 3 months. In the second study, 40 men (age 67.4 +/- 5.4 yr; baseline T, 11.4 +/- 2.2 nmol/liter) were randomized to receive either rhCG s.c. (n = 20), two injections weekly, or placebo for 3 months. The following parameters were measured before, monthly during, and 1 month after treatment: serum T, estradiol (E2), and LH; markers of bone formation, serum amino-terminal propeptide of type I procollagen (S-PINP) and osteocalcin; markers of bone resorption, serum carboxyterminal cross-linked telopeptide of type I collagen and urinary deoxypyridinoline. Compared with placebo, treatment with DHT significantly increased serum DHT and suppressed LH and T levels, whereas E2 concentrations and markers of bone turnover did not change. In contrast, rhCG therapy significantly increased both T and E2, with the increases in E2 being supraphysiological. At the same time, rhCG significantly increased S-PINP concentrations with peak levels after 1 month (Delta40%; P = 0.02 compared with placebo). In contrast, serum osteocalcin and carboxyterminal cross-linked telopeptide of type I collagen and urinary deoxypyridinoline levels did not change. The change in S-PINP levels correlated with the change in E2 levels (r = 0.59; P = 0.02) but not with a change in T. We conclude that in older men with partial age-related androgen deficiency, rhCG treatment stimulates osteoblastic collagen formation proportionally to increased E2 concentrations but does not alter markers of mature osteoblastic function or bone resorption. In contrast, treatment with a pure, nonaromatizable androgen (DHT) has no effect on bone turnover despite a 20-fold increase in serum levels. Bone resorption was not accelerated during unchanged (DHT) or increased (rhCG) E2 levels, suggesting that minimal E2 levels are needed to maintain stable resorption, although direct androgen receptor-mediated effects cannot be excluded. If androgen supplementation is required for aging men, aromatizable androgens with sufficient endogenous estrogenic activity may have the most beneficial effects on bone.

11: Androgen deficiency and replacement therapy in men

Androgen deficiency is a clinical diagnosis confirmed by hormone assays. Among younger men, androgen deficiency is usually due to underlying hypothalamopituitary or testicular disorders. Androgen replacement therapy should be started after proof of androgen deficiency and should continue lifelong with monitoring. Men presenting with erectile dysfunction should be evaluated for androgen deficiency, but it is an uncommon cause; if overt androgen deficiency is confirmed, an underlying disorder needs further specialist investigation. In the absence of characteristic underlying testicular or pituitary disorders, new diagnosis of androgen deficiency in older men is difficult because of the non-specific symptoms and the decline in blood testosterone levels seen in healthy ageing and chronic medical disorders. There remains no convincing evidence that androgen therapy is either effective treatment or safe for older men unless they have frank androgen deficiency.

Effects of aromatase inhibition in elderly men with low or borderline-low serum testosterone levels

As men age, serum testosterone levels decrease, a factor that may contribute to some aspects of age-related physiological deterioration. Although androgen replacement has been shown to have beneficial effects in frankly hypogonadal men, its use in elderly men with borderline hypogonadism is controversial. Furthermore, current testosterone replacement methods have important limitations. We investigated the ability of the orally administered aromatase inhibitor, anastrozole, to increase endogenous testosterone production in 37 elderly men (aged 62-74 yr) with screening serum testosterone levels less than 350 ng/dl. Subjects were randomized in a double-blind fashion to the following 12-wk oral regimens: group 1: anastrozole 1 mg daily (n = 12); group 2: anastrozole 1 mg twice weekly (n = 11); and group 3: placebo daily (n = 14). Hormone levels, quality of life (MOS Short-Form Health Survey), sexual function (International Index of Erectile Function), benign prostate hyperplasia severity (American Urological Association Symptom Index Score), prostate-specific antigen, and measures of safety were compared among groups. Mean +/- SD bioavailable testosterone increased from 99 +/- 31 to 207 +/- 65 ng/dl in group 1 and from 115 +/- 37 to 178 +/- 55 ng/dl in group 2 (P < 0.001 vs. placebo for both groups and P = 0.054 group 1 vs. group 2). Total testosterone levels increased from 343 +/- 61 to 572 +/- 139 ng/dl in group 1 and from 397 +/- 106 to 520 +/- 91 ng/dl in group 2 (P < 0.001 vs. placebo for both groups and P = 0.012 group 1 vs. group 2). Serum estradiol levels decreased from 26 +/- 8 to 17 +/- 6 pg/ml in group 1 and from 27 +/- 8 to 17 +/- 5 pg/ml in group 2 (P < 0.001 vs. placebo for both groups and P = NS group 1 vs. group 2). Serum LH levels increased from 5.1 +/- 4.8 to 7.9 +/- 6.5 U/liter and from 4.1 +/- 1.6 to 7.2 +/- 2.8 U/liter in groups 1 and 2, respectively (P = 0.007 group 1 vs. placebo, P = 0.003 group 2 vs. placebo, and P = NS group 1 vs. group 2). Scores for hematocrit, MOS Short-Form Health Survey, International Index of Erectile Function, and American Urological Association Symptom Index Score did not change. Serum prostate-specific antigen levels increased in group 2 only (1.7 +/- 1.0 to 2.2 +/- 1.5 ng/ml, P = 0.031, compared with placebo). These data demonstrate that aromatase inhibition increases serum bioavailable and total testosterone levels to the youthful normal range in older men with mild hypogonadism. Serum estradiol levels decrease modestly but remain within the normal male range. The physiological consequences of these changes remain to be determined.

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.

The challenges of testosterone deficiency. Uncovering the problem, evaluating the role of therapy

In addition to its relatively uncommon congenital causes, testosterone deficiency in men occurs in a diverse range of clinical conditions. Even healthy men are now known to begin experiencing progressive yet subtle declines in testosterone secretion after age 30. Diagnosis can be challenging, and testosterone replacement therapy does not alleviate all symptoms in all men. Nevertheless, some men can get relief with intramuscular long-acting testosterone esters, transdermal testosterone patches, or transdermal testosterone gel.

Increased risk of falls and increased bone resorption in elderly men with partial androgen deficiency: the MINOS study

The goal of this study was to identify the clinical and biological patterns of hypogonadism in a cohort of 1040 elderly men. Residual androgenic activity was estimated by total testosterone as well as the apparent free testosterone concentration (AFTC) and free testosterone index (FTI) calculated on the basis of concentrations of SHBG and total testosterone using appropriate formulae. The lower limit of the normal range defined by 2 SD below the mean in 150 healthy, nonobese, and nonsmoking men, aged 19-40 yr, was calculated for total testosterone (9.26 nmol/liter), AFTC (146 pmol/liter), and FTI (0.14 nmol/nmol). The prevalence of hypogonadism increased with ageing. Hypogonadal men were older and heavier (due to a higher fat body mass) and had lower concentrations of 17 beta-estradiol and androstenedione than men with normal androgenic activity. Men with decreased AFTC had a slightly lower bone mineral density (BMD) at certain sites. Men with decreased FTI had lower appendicular skeletal muscle mass and relative skeletal muscle index. For all three measures of androgenic activity, hypogonadal men had increased levels of the markers of bone resorption. In the multiple regression models including both 17 beta-estradiol and testosterone (total, AFTC, or FTI), 17 beta-estradiol was the only significant determinant of BMD. In the multiple regression models including 17 beta-estradiol and AFTC or FTI, only testosterone was a significant determinant of the variability in bone formation markers, whereas both 17 beta-estradiol and testosterone were significant determinants of the variability of the markers of bone resorption. Hypogonadism was associated with an increase in the risk of falls, an impairment of static and dynamic balance, as well as the inability to stand up from a chair and to perform the tandem walk. Decreased AFTC (<146 pmol/liter) discriminated best men with functional disabilities (odds ratio, 1.54-7.95; P < 0.05-0.0001). Hypogonadal elderly men had increased bone resorption that was not adequately matched by an increase in bone formation, lower muscle strength, impaired static and dynamic balance, a higher risk of falls, and, in men with low AFTC, a slightly lower BMD. Low AFTC seems to have the best discriminative power for densitometric, biochemical, and functional parameters, followed by FTI, whereas total testosterone was the least discriminative. In multiple regression models, 17 beta-estradiol was the strongest determinant of BMD, and AFTC and FTI were significant determinants of the variability in bone formation markers, whereas both 17 beta-estradiol and testosterone determined the variability in bone resorption markers.

The ageing male and erectile dysfunction

Erectile dysfunction is common in the ageing man and reliable therapies are needed. The pathophysiology of erectile dysfunction in this group mainly includes chronic ischaemia, which triggers the deterioration of cavernosal smooth muscle and the development of corporeal fibrosis. Assessing the ageing man with erectile dysfunction who seeks medical treatment should comprise a thorough medical and sexual history, a systemic and focused physical examination and selected blood tests. Oral drug therapy represents a safe and effective option for most ageing men.

Hypogonadism and diabetes

Clinicians have been aware of the increased prevalence of low testosterone levels in patients with type II diabetes for several years, but how these two conditions are associated is difficult to determine. Older age and obesity may be factors, as both are associated with type II diabetes and both decrease testosterone levels. Sex hormone-binding globulin (SHBG), the major serum carrier protein for testosterone, also may have an impact. SHBG levels fall with obesity and increase with aging. Some studies indicate lower SHBG levels in type II diabetes. Most of the differences in testosterone levels between diabetic and nondiabetic patients may be due to reduced SHBG, rather than reduced testosterone production. However, free testosterone levels fall with increasing age and obesity, rendering many type II diabetic patients testosterone deficient. Testosterone replacement may improve insulin sensitivity in hypogonadal, overweight men with type II diabetes by altering body composition, but studies are conflicting.

Declining testicular function in aging men

Age-related decline in male sex hormones, particularly testosterone, is referred to as andropause. Like menopause, andropause is associated with physical and emotional changes that may be alleviated by hormone replacement therapy. Hypogonadism in aging men, as defined by a low free testosterone index, is due to declining testosterone production and increased sex hormone-binding globulin levels. About 30% of men in their 60s and more than 80% of men over 80 y may have a low free testosterone index. Diagnosis of hypogonadism is based on clinical symptoms (eg, decreased muscle mass, fractures, loss of libido) and laboratory determinations of serum testosterone-usually total testosterone levels. Measuring bioavailable testosterone, or free testosterone, is expensive and time-consuming, but may more accurately detect hypogonadism. Testosterone replacement therapy is generally safe in aging men and may improve libido, cognition, bone mineral density, body mass composition, and serum lipoproteins. Although contraindicated in men with prostate or breast cancer, testosterone replacement therapy in aging men warrants examination. Any of the available testosterone formulations can be used, but injectable forms have certain advantages, including excellent dose adjustability, lack of skin irritation, and low cost.

Testosterone replacement therapy in male hypogonadism

In human males 6-7 mg of testosterone are secreted by the testes in a circadian rhythm with a nocturnal rise in testosterone followed by a decline during the day. Testosterone is necessary to induce and maintain secondary sexual characteristics, lean muscle mass, bone density and for normal sexual behaviour and cognitive function in men. Replacement therapy has been shown to be beneficial in men with overt hypogonadism. Natural testosterone should be used and not modified molecules. Testosterone is currently available in oral, intramuscular, subcutaneous and transdermal preparations. Recent advances in testosterone replacement therapy include testosterone gels which provide flexibility in dosing and minimal skin irritation resulting in good compliance, and the development of longer acting intramuscular preparations which result in more stable testosterone levels with longer injection intervals. All patients receiving testosterone should be carefully monitored for changes in hematocrit, liver function, lipid parameters and prostate specific antigen (PSA).This article reviews the current experience with the use of various forms of testosterone for the treatment of male hypogonadism.

Effect of growth hormone (GH) and/or testosterone replacement on the prostate in GH-deficient adult patients

The prostate is a target organ of the GH and IGF-I axis because prostate hypertrophy is found in acromegaly, reduced prostate size is found in GH deficiency (GHD) patients, and additionally, IGF-I is reported to be a positive predictor factor of prostate cancer. To investigate whether GH replacement therapy in adult patients with GHD has adverse effects on the prostate, we studied the effect of 12-month GH or GH plus testosterone replacement on prostate pathophysiology in 24 adult patients with GHD (11 euandrogenemic and 13 hypoandrogenemic), compared with 24 age-matched healthy controls. At study entry, GHD patients had lower prostate volume than controls (19.4 +/- 1.7 vs. 24.9 +/- 1.7 ml; P = 0.03). After 12 months of treatment, all hypoandrogenemic patients achieved normal testosterone levels, and prostate volume increased in the patients to the same level as controls (25.0 +/- 1.9 ml). The percentage increase in prostate volume was greater in hypoandrogenemic patients receiving both GH and testosterone replacement (51 +/- 11%) than in those receiving GH replacement alone (15 +/- 3%; P < 0.0009). At baseline, prostate volume was similar in GHD patients below or above 60 yr of age (16.8 +/- 1.3 vs. 23 +/- 3.6 ml; P = 0.08), whereas after treatment it was higher in the latter patients (21.8 +/- 1.2 vs. 29.5 +/- 3.9 ml; P = 0.04). Prostate-specific antigen (PSA) and free PSA did not change, whereas PSA density was significantly reduced after treatment in hypoandrogenemic patients; there was also no change in calcifications, cysts, or nodules. In conclusion, GH replacement restores prostate size to normal in both young and elderly patients, with no increase in prostate abnormalities. Because the simultaneous treatment with GH and testosterone induces an increase of prostate size by 50% of baseline on average, care is suggested in elderly patients with prostate hyperplasia to avoid any risk of prostate symptoms. In these cases, GH replacement might be performed sequentially to reduce the hypertrophic effect of combining GH and testosterone.