Effects of graded doses of testosterone on erythropoiesis in healthy young and older men

Steroidogenic enzyme expression in the human fetal liver and potential role in the endocrinology of pregnancy

The human feto-maternal unit produces large amounts of steroid hormones, particularly estrogens, during the second and third trimesters. The fetal adrenal gland and the placenta are considered the principal tissues driving steroid production but the fetal liver is likely to play an essential role in this process. This study was designed to measure transcript expression of proteins involved in steroid synthesis, metabolism, conjugation and signalling in the human fetal liver and to examine sex differences and effects of maternal smoking. Liver samples were taken from 55 normal fetuses from women undergoing second trimester elective termination. Levels of 23 mRNA transcripts encoding steroid synthesis/metabolic/conjugation enzymes and steroid receptors were measured by real-time PCR. The expression of representative proteins was confirmed by western blotting and immunohistochemistry. The human fetal livers expressed high levels of CYP19A1, SULT2A1, SULT1E1, HSD17B2, SRD5A3 and CYP3A7. Lower levels of SULT1A1, STS, UGT2B17, GPER, AKR1C3, UGT2B15, AR, CYP11A1, CYP21A2, HSD17B3, HSD17B1 and SRD5A1 were also detectable. The expression of ESR, ESR2, CYP17A1 and HSD3B transcripts was undetectable in most fetal livers, although HSD3B was shown to be present by western blotting. Sex differences were limited to SRD5A3 (lower in females) and UGT2B17 (higher in females). Maternal smoking increased the expression of CYP19A1, SULT2A1, UGT2B17, HSD17B2 and AKR1C3 and reduced the expression of SRD5A3 in the male fetal liver. This study shows that the human fetal liver is likely to have an extensive effect on circulating steroid levels in the human fetus and mother. The most important of these effects will be alterations to the species, conjugation and availability of estrogens in the fetus. Maternal smoking is likely to reduce circulating androgen bioactivity in male fetuses.

Is the haematopoietic effect of testosterone mediated by erythropoietin? The results of a clinical trial in older men

The stimulatory effects of testosterone on erythropoiesis are very well known, but the mechanisms underlying the erythropoietic action of testosterone are still poorly understood, although erythropoietin has long been considered a potential mediator. A total of 108 healthy men >65 years old with serum testosterone concentration <475 ng/dL were recruited by direct mailings to alumni of the University of Pennsylvania and Temple University, and randomized to receive a 60-cm(2) testosterone or placebo patch for 36 months. Ninety-six subjects completed the trial. We used information and stored serum specimens from this trial to test the hypothesis that increasing testosterone increases haemoglobin by stimulating erythropoietin production. We used information of 67 men, 43 in the testosterone group and 24 in the placebo group who had banked specimens available for assays of testosterone, haemoglobin and erythropoietin at baseline and after 36 months. The original randomized clinical study was primarily designed to verify the effects of testosterone on bone mineral density. The primary outcome of this report was to investigate whether or not transdermal testosterone increases haemoglobin by increasing erythropoietin levels. The mean age ± SD of the 67 subjects at baseline was 71.8 ± 4.9 years. Testosterone replacement therapy for 36 months, as compared with placebo, induced a significant increase in haemoglobin (0.86 ± 0.31 g/dL, p = 0.01), but no change in erythropoietin levels (-0.24 ± 2.16 mIU/mL, p = 0.91). Included time-varying measure of erythropoietin did not significantly account for the effect of testosterone on haemoglobin (Treatment-by-time: β = 0.93, SE = 0.33, p = 0.01). No serious adverse effect was observed. Transdermal testosterone treatment of older men for 36 months significantly increased haemoglobin, but not erythropoietin levels. The haematopoietic effect of testosterone does not appear to be mediated by stimulation of erythropoietin production.

The hypoxic testicle: physiology and pathophysiology

Mammalian spermatogenesis is a complex biological process occurring in the seminiferous tubules in the testis. This process represents a delicate balance between cell proliferation, differentiation, and apoptosis. In most mammals, the testicles are kept in the scrotum 2 to 7°C below body core temperature, and the spermatogenic process proceeds with a blood and oxygen supply that is fairly independent of changes in other vascular beds in the body. Despite this apparently well-controlled local environment, pathologies such as varicocele or testicular torsion and environmental exposure to low oxygen (hypoxia) can result in changes in blood flow, nutrients, and oxygen supply along with an increased local temperature that may induce adverse effects on Leydig cell function and spermatogenesis. These conditions may lead to male subfertility or infertility. Our literature analyses and our own results suggest that conditions such as germ cell apoptosis and DNA damage are common features in hypoxia and varicocele and testicular torsion. Furthermore, oxidative damage seems to be present in these conditions during the initiation stages of germ cell damage and apoptosis. Other mechanisms like membrane-bound metalloproteinases and phospholipase A2 activation could also be part of the pathophysiological consequences of testicular hypoxia.

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

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

Hormone replacement therapy and physical function in healthy older men. Time to talk hormones?

Improving physical function and mobility in a continuously expanding elderly population emerges as a high priority of medicine today. Muscle mass, strength/power, and maximal exercise capacity are major determinants of physical function, and all decline with aging. This contributes to the incidence of frailty and disability observed in older men. Furthermore, it facilitates the accumulation of body fat and development of insulin resistance. Muscle adaptation to exercise is strongly influenced by anabolic endocrine hormones and local load-sensitive autocrine/paracrine growth factors. GH, IGF-I, and testosterone (T) are directly involved in muscle adaptation to exercise because they promote muscle protein synthesis, whereas T and locally expressed IGF-I have been reported to activate muscle stem cells. Although exercise programs improve physical function, in the long-term most older men fail to comply. The GH/IGF-I axis and T levels decline markedly with aging, whereas accumulating evidence supports their indispensable role in maintaining physical function integrity. Several studies have reported that the administration of T improves lean body mass and maximal voluntary strength in healthy older men. On the other hand, most studies have shown that administration of GH alone failed to improve muscle strength despite amelioration of the detrimental somatic changes of aging. Both GH and T are anabolic agents that promote muscle protein synthesis and hypertrophy but work through separate mechanisms, and the combined administration of GH and T, albeit in only a few studies, has resulted in greater efficacy than either hormone alone. Although it is clear that this combined approach is effective, this review concludes that further studies are needed to assess the long-term efficacy and safety of combined hormone replacement therapy in older men before the medical rationale of prescribing hormone replacement therapy for combating the sarcopenia of aging can be established.

Testosterone as potential effective therapy in treatment of obesity in men with testosterone deficiency: a review

OBJECTIVE

Obesity negatively affects human health. Limiting food intake, while producing some weight loss, results in reduction of lean body mass. Combined with moderate exercise it produces significant weight loss, maintains lean body mass and improves insulin sensitivity, but appears difficult to adhere to. Bariatric surgery is clinically effective for severely obese individuals compared with non-surgical interventions, but has limitations. Clinical and pre-clinical studies have implicated a role for testosterone (T) in the patho-physiology of obesity.

EVIDENCE ACQUISITION AND SYNTHESIS

A literature search in PubMed on the role of T in counteracting obesity and its complications.

RESULTS

Obesity per se impairs testicular T biosynthesis. Furthermore, lower-than-normal T levels increase accumulation of fat depots, particularly abdominal (visceral) fat. This fat distribution is associated with development of metabolic syndrome (MetS) and its sequels, namely type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). T treatment reverses fat accumulation with significant improvement in lean body mass, insulin sensitivity and biochemical profiles of cardiovascular risk. The contribution of T to combating obesity in hypogonadal men remains largely unknown to medical professionals managing patients with obesity and metabolic syndrome. Many physicians associate T treatment in men with risks for prostate malignancy and CVD. These beliefs are not supported by recent insights.

CONCLUSION

While overall treatment of obesity is unsuccessful, T treatment of hypogonadal men may be effective, also because it improves mood, energy, reduces fatigue and may motivate men to adhere to diet and exercise regimens designed to combat obesity.

Hematological changes during androgen deprivation therapy

Androgen deprivation therapy (ADT) has been associated with a plethora of adverse effects, consistent with the androgen dependency of multiple reproductive and somatic tissues. One such tissue is the hemopoietic system, and one of the most predictable consequences of ADT is the development of anemia. Although anemia caused by ADT is rarely severe, ADT is often given to frail, elderly men with increased susceptibility to anemia due to multiple other causes. ADT-associated anemia may contribute to fatigue and reduced quality of life (QoL) in such men, although this requires further study. While anemia is an independent risk factor of mortality in men with prostate cancer, it is not known whether treatment of ADT-associated anemia alters clinically important outcomes, or whether treatment affects mortality. Awareness of the phenomenon of ADT-induced anemia should avoid unnecessary work-up in mild cases of normocytic normochromic anemia. However, assessment and treatment of more severe anemia may be required. This should be determined on an individual basis. In contrast to the well-described actions of ADT on erythropoiesis, its effect on other hemopoietic lineages has been less well elucidated. While preclinical studies have found roles for androgens in maturation and differentiated function of neutrophils, lymphocytes and platelets, the implications of these findings for men with prostate cancer receiving ADT require further studies.

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.

Low testosterone in ageing men: a modifiable risk factor for frailty?

There is substantial interest in the role of testosterone (T) in male ageing. Studies suggest that low T may be a risk factor for frailty, the vulnerable health status that occurs at advanced ages. However, T deficiency is relatively rare in ageing men and, importantly, is linked to modifiable risk factors including body weight and concurrent illnesses. These observations shift the focus away from hormone replacement and towards potential preventative strategies to help maintain T levels in ageing men. Furthermore, the effects of T on physical function remain inconsistent, and studies examining the safety of T treatment in ageing males raise concerns. Further research may usefully focus on novel pro-anabolic pharmaceutical agents, which together with other interventions will allow for optimal management of frailty.

High serum zinc and serum testosterone levels were associated with excessive erythrocytosis in men at high altitudes

Chronic mountain sickness (CMS), a lack of adaptation to altitude characterized by excessive erythrocytosis (EE), is a health problem associated with life at high altitude. The erythropoietic process is regulated by both erythropoietin and testosterone. Zinc (Zn) is known to be related with testosterone and hemoglobin levels; meanwhile, nitric oxide was also associated with adaptation to high altitude. The aim of this study was to determine the relationship of hemoglobin and CMS score with serum levels of zinc, total testosterone (TT), calculated free testosterone (cFT), bioavailable testosterone (BAT), hemoglobin, and nitric oxide in men at high altitude with or without EE. Men residing in Lima (150 m) and Cerro de Pasco (4,340 m), Peru, were divided into three groups: (1) low altitude, (2) high altitude without EE (hemoglobin < 21 g/dl), and (3) high altitude with EE (hemoglobin ≥ 21 g/dl). Adjusted multivariable regression models showed that serum testosterone (total or free) and Zn levels were independently correlated with increased hemoglobin levels. Similarly, hemoglobin was positively related with signs/symptoms of CMS; however, both increased the serum Zn and the nitric oxide levels correlated with reduced risk for signs/symptoms of CMS. In conclusion, higher serum testosterone levels and Zn levels were associated with EE, and low scores of signs/symptoms of CMS were associated with higher Zn and nitric oxide levels.

Onset of effects of testosterone treatment and time span until maximum effects are achieved

OBJECTIVE

Testosterone has a spectrum of effects on the male organism. This review attempts to determine, from published studies, the time-course of the effects induced by testosterone replacement therapy from their first manifestation until maximum effects are attained.

DESIGN

Literature data on testosterone replacement.

RESULTS

Effects on sexual interest appear after 3 weeks plateauing at 6 weeks, with no further increments expected beyond. Changes in erections/ejaculations may require up to 6 months. Effects on quality of life manifest within 3-4 weeks, but maximum benefits take longer. Effects on depressive mood become detectable after 3-6 weeks with a maximum after 18-30 weeks. Effects on erythropoiesis are evident at 3 months, peaking at 9-12 months. Prostate-specific antigen and volume rise, marginally, plateauing at 12 months; further increase should be related to aging rather than therapy. Effects on lipids appear after 4 weeks, maximal after 6-12 months. Insulin sensitivity may improve within few days, but effects on glycemic control become evident only after 3-12 months. Changes in fat mass, lean body mass, and muscle strength occur within 12-16 weeks, stabilize at 6-12 months, but can marginally continue over years. Effects on inflammation occur within 3-12 weeks. Effects on bone are detectable already after 6 months while continuing at least for 3 years.

CONCLUSION

The time-course of the spectrum of effects of testosterone shows considerable variation, probably related to pharmacodynamics of the testosterone preparation. Genomic and non-genomic effects, androgen receptor polymorphism and intracellular steroid metabolism further contribute to such diversity.

Clinical significance of anaemia associated with prolactin-secreting pituitary tumours in men

BACKGROUND

An association between prolactin-secreting pituitary adenomas and anaemia in male patients has been recently reported. Our aim has been to evaluate the prevalence of anaemia in men with prolactinomas and to assess the relationships between haemoglobin concentrations and pituitary function at diagnosis in these patients.

METHODS

In a retrospective analysis, 26 male patients with prolactinomas (22 macroprolactinomas and 4 microprolactinomas) were studied. Blood haemoglobin concentration, haematocrit value and baseline hormonal levels were collected at the time of prolactinoma diagnosis. The presence or absence of partial or total hypopituitarism was also evaluated at diagnosis. Logistic regression analysis was used to assess the presence of anaemia as a function of serum hormone concentrations and pituitary dysfunction.

RESULTS

  Patient bearing macroprolactinomas showed significant lower haemoglobin concentrations than those found in patients with microprolactinomas (13.5 ± 1.2 g/dl vs. 15.1 ± 0.9 g/dl, p < 0.05). Anaemia (haemoglobin < 13 g/dl) was present in nine (34.6%) patients, all of them with macroprolactinomas. The degree of anaemia was mild (haemoglobin > 11 g/dl) in all patients. No correlation between haemoglobin and serum prolactin was found. Haemoglobin concentration was significantly lower in men with hypogonadism (n = 14) than in eugonadal men. Haemoglobin value was also significantly lower in patients with total hypopituitarism in comparison with patients with partial hypopituitarism (12.4 ± 1.0 g/dl, n = 7 vs. 14.0 ± 1.2 g/dl, n = 13, p = 0.007). The number of affected pituitary axes was found to be related with the presence of anaemia. Logistic regression analysis showed that anaemia was related with FT4 (OR 0.23; 95% CI 0.06-0.81, p = 0.02), cortisol (OR 0.81; 95% CI 0.68-0.96, p= 0.02) and the presence of hypopituitarism (OR 20.0; 95% CI 1.68-238.63, p = 0.02).

CONCLUSIONS

  Anaemia was found in about a third of men with prolactinomas. Our results also suggest that the presence of anaemia in these patients seems to be associated with panhypopituitarism.

Male hormonal contraception: potential risks and benefits

An effective, safe, reversible, and acceptable method of contraception is an important component of reproductive health and provides the opportunity of shared responsibility for family planning for both partners. Female hormonal contraceptives have been proven to be safe, reversible, available and widely acceptable by different populations. In contrast, male hormonal contraception, despite significant progress showing contraceptive efficacy comparable to female hormonal methods during last three decades, has not yet led to an approved product. Safety of a pharmaceutical product is an appropriate concern but the majority of male hormonal contraceptive clinical trials have not reported significant short term safety concerns. While the absence of serious adverse effects is encouraging, the studies have been designed for efficacy endpoints not long term safety. In this review we summarize potential risks and benefits of putative male hormonal contraceptives on reproductive and non-reproductive organs. While the review covers what we believe will be the likely class of drugs used for male hormonal contraception a true assessment of long term risks and benefits cannot be achieved without an available product.

Late-onset hypogonadism

Late-onset hypogonadism is a clinical and biological syndrome associated with advancing age and characterized by typical symptoms and a deficiency in serum testosterone levels. It is a common condition but often underdiagnosed and undertreated. The main symptoms of hypogonadism are reduced libido/erectile dysfunction, reduced muscle mass and strength, increased adiposity, osteoporosis/low bone mass, depressed mood, and fatigue. Testosterone replacement therapy is only warranted in the presence of both clinical symptoms suggesting hormone deficiency and decreased hormone levels. It improves libido and sexual function, bone density, muscle mass, body composition, mood, erythropoiesis, cognition, quality of life, and cardiovascular disease.

Threshold haemoglobin levels and the prognosis of stable coronary disease: two new cohorts and a systematic review and meta-analysis

BACKGROUND

Low haemoglobin concentration has been associated with adverse prognosis in patients with angina and myocardial infarction (MI), but the strength and shape of the association and the presence of any threshold has not been precisely evaluated.

METHODS AND FINDINGS

A retrospective cohort study was carried out using the UK General Practice Research Database. 20,131 people with a new diagnosis of stable angina and no previous acute coronary syndrome, and 14,171 people with first MI who survived for at least 7 days were followed up for a mean of 3.2 years. Using semi-parametric Cox regression and multiple adjustment, there was evidence of threshold haemoglobin values below which mortality increased in a graded continuous fashion. For men with MI, the threshold value was 13.5 g/dl (95% confidence interval [CI] 13.2-13.9); the 29.5% of patients with haemoglobin below this threshold had an associated hazard ratio for mortality of 2.00 (95% CI 1.76-2.29) compared to those with haemoglobin values in the lowest risk range. Women tended to have lower threshold haemoglobin values (e.g, for MI 12.8 g/dl; 95% CI 12.1-13.5) but the shape and strength of association did not differ between the genders, nor between patients with angina and MI. We did a systematic review and meta-analysis that identified ten previously published studies, reporting a total of only 1,127 endpoints, but none evaluated thresholds of risk.

CONCLUSIONS

There is an association between low haemoglobin concentration and increased mortality. A large proportion of patients with coronary disease have haemoglobin concentrations below the thresholds of risk defined here. Intervention trials would clarify whether increasing the haemoglobin concentration reduces mortality.

Male late-onset hypogonadism: pathogenesis, diagnosis and treatment

Some aging men develop a condition of suppressed serum testosterone levels, which is associated with diffuse sexual, physical and psychological symptoms. Several terms are used for this syndrome, but late-onset hypogonadism (LOH) is preferred. The diagnosis of LOH is often uncertain because symptoms (occurring in 20-40% of men) and low circulating testosterone (found in 20% of men >70 years of age) seldom occur together. The strict diagnostic criteria for LOH include reproducibly low serum testosterone levels and sexual symptoms, including erectile dysfunction and reduced frequency of sexual thoughts and morning erections. Using these diagnostic criteria, only 2% of 40-80-year-old men have LOH. Obesity and impaired general health (including diabetes mellitus, cardiovascular and chronic obstructive pulmonary disease, and frailty) are more common reasons for low testosterone than advanced age per se. It seems logical, therefore, to begin by treating these conditions before testosterone replacement therapy is initiated. Even then, testosterone should only be used if there are no contraindications, such as unstable cardiac disease, serious prostate symptoms and high hemoglobin level. The long-term benefit of testosterone replacement therapy is uncertain, and the experimental nature of the treatment, and its associated risks, must be fully explained to the patient before treatment begins.

Gonadal status and physical performance in older men

OBJECTIVE

To test the relationship between gonadal status and objective measures and determinants of physical performance in older men and their determinants.

METHODS

The study included 455 ≥ 65 year older men of InCHIANTI study, Italy, with complete data on testosterone levels, hand grip strength, cross-sectional muscle area (CSMA), short physical performance battery (SPPB). Linear models were used to test the relationship between gonadal status and determinants of physical performance.

RESULTS

Three different groups of older men were created: (1) severely hypogonadal (N=23), total testosterone levels ≤ 230 ng /dl; (2) moderately hypogonadal (N=88), total testosterone >230 and < 350 ng/dl) and (3) eugonadal (N=344), testosterone levels ≥ 350 ng/dl. With increased severity of hypogonadal status, participants were significantly older while their BMI was substantially similar. In the age and BMI adjusted analysis, there was a significant difference in haemoglobin levels, hand grip strength and SPPB score (p for trend < 0.001) among three groups, with severely hypogonadal men having lower values of haemoglobin, muscle strength and physical performance. We found no association between testosterone group assignment and calf muscle mass and 4 m walking speed. In the multivariate analysis grip strength (p for trend = 0.004) and haemoglobin (p for trend < 0.0001) but not SPPB and other determinants of physical performance were significantly different between the three groups.

CONCLUSIONS

In older men, gonadal status is independently associated with some determinants (haemoglobin and muscle strength) of physical performance.

A safety study of administration of parenteral testosterone undecanoate to elderly men over minimally 24 months

This study investigated the safety of administration of long-acting parenteral testosterone undecanoate (TU) to 122 hypogonadal, mainly elderly men, aged 59.6 ± 8.0 years (range 18-83 years old), with baseline testosterone levels between 5.8 and 12.1 nmol l(-1) (mean ± SD = 9.3 ± 1.7). Patients were followed for 24 months. Plasma testosterone rose from 9.3 ± 1.7 to 14.9 ± 4.5 nmol l(-1) (P< 0.01) at 3 months, then stabilised at 19.2 ± 4.6 nmol l(-1) after 6 months. International Prostate Symptoms Scores and Residual Bladder Volumes decreased significantly (P <0.01) over the study period. Prostate volume and prostate-specific antigen levels fluctuated over the study period but had not increased significantly after 24 month. Haemoglobin concentrations increased significantly (P < 0.001) over the 24 months while the haematocrit increased significantly (P < 0.001) during the first 15 months and then levelled off. Statistical analysis with expressing values as means ± SD masks excesses above reference values of individual patients. These excesses were noted in low numbers, were permanently present in some but not in other individuals, and did not increase in number over the 24 month study period. Over 24 months treatment with TU appeared acceptably safe, but longer and larger scale studies are needed.

Clinical review: Why is androgen replacement in males controversial?

CONTEXT

Symptoms and signs consistent with androgen deficiency and low testosterone levels are recognized frequently in clinical practice. Recent population-based epidemiological studies indicate that low testosterone levels in men are associated with increased morbidity and mortality. The clinician must be able to counsel patients to help them determine whether testosterone replacement therapy is appropriate for them.

EVIDENCE ACQUISITION

The authors have conducted a literature search in PubMed, and we have reviewed references in the multiple systematic reviews and meta-analyses that have been published on this topic.

EVIDENCE SYNTHESIS

We have attempted to provide the reader with an appreciation of the evidence that can be used to support the diagnosis of androgen deficiency, the efficacy of treatment, the potential risks of treatment, the therapeutic options, and the recommendations for monitoring treatment.

CONCLUSIONS

We think that published clinical experience justifies testosterone replacement therapy in males who have not initiated puberty by age 14 and in males with low testosterone levels due to classical diseases of the hypothalamic-pituitary-gonadal axis. The benefit:risk ratio is less certain in older men and in those with chronic diseases associated with low testosterone levels. The decision to treat in this setting is much more controversial because there are few large clinical trials that have demonstrated efficacy and no large clinical trials that have determined potential risks of increasing the incidence of clinical prostate cancers or cardiovascular events. We provide a critical review of the evidence that supports treatment and potential risks and ways to reduce the risks if the physician and patient elect testosterone replacement.

Effect of a prolonged altitude expedition on glucose tolerance and abdominal fatness

In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action.

Testosterone suppresses hepcidin in men: a potential mechanism for testosterone-induced erythrocytosis

CONTEXT

The mechanisms by which testosterone increases hemoglobin and hematocrit are unknown.

OBJECTIVE

The aim was to test the hypothesis that testosterone-induced increase in hematocrit is associated with suppression of the iron regulatory peptide hepcidin.

PARTICIPANTS

Healthy younger men (ages 19-35 yr; n = 53) and older men (ages 59-75 yr; n = 56) were studied.

METHODS

Weekly doses of testosterone enanthate (25, 50, 125, 300, and 600 mg) were administered over 20 wk, whereas endogenous testosterone was suppressed by monthly GnRH agonist administration. Blood and serum parameters from each individual were measured at wk 0, 1, 2, 4, 8, and 20. Longitudinal analyses were performed to examine the relationship between hepcidin, hemoglobin, hematocrit, and testosterone while controlling for potential confounders.

RESULTS

High levels of testosterone markedly suppressed serum hepcidin within 1 wk. Hepcidin suppression in response to testosterone administration was dose-dependent in older men and more pronounced than in young men, and this corresponded to a greater rise in hemoglobin in older men. Serum hepcidin levels at 4 and 8 wk were predictive of change in hematocrit from baseline to peak levels.

CONCLUSION

Testosterone administration is associated with suppression of serum hepcidin. Greater increases in hematocrit in older men during testosterone therapy are related to greater suppression of hepcidin.

Low free testosterone predicts frailty in older men: the health in men study

CONTEXT

The prevalence of frailty increases, whereas testosterone decreases, as men age. Low testosterone may be a risk factor for development of this syndrome.

OBJECTIVE

Our objective was to determine whether testosterone levels are associated with frailty.

DESIGN

We conducted a prospective cohort study.

SETTING AND PARTICIPANTS

Between 2001 and 2004, frailty was assessed in 3616 community-dwelling men aged 70-88 yr. Frailty was reassessed in 1586 men aged 76-93 yr in 2008-2009.

MAIN OUTCOME MEASURES

Frailty was assessed with the FRAIL scale, comprising five domains: fatigue, difficulty climbing a flight of stairs, difficulty walking more than 100 m, more than five illnesses present, or weight loss greater than 5%. Testosterone, SHBG, and LH were assayed at baseline. Free testosterone was calculated using mass action equations.

RESULTS

At baseline, 15.2% of men (n = 548) were frail (at least three deficits), increasing to 23.0% (n = 364) at follow-up. At baseline, each 1 sd decrease in total or free testosterone level was associated with increased odds of frailty [odds ratio (OR) = 1.23; 95% confidence interval (CI) = 1.11-1.38, and OR = 1.29; 95% CI = 1.15-1.44 for total and free testosterone, respectively]. Lower LH was associated with reduced odds of frailty (OR = 0.88; 95% CI = 0.81-0.95). Adjustments were made for age, body mass index, smoking, diabetes, social support, and other covariates. At follow-up, only lower free testosterone levels (OR = 1.22; 95% CI = 1.05-1.42) predicted frailty.

CONCLUSIONS

Lower free testosterone was independently associated with frailty at baseline and follow-up. Randomized trials should explore whether testosterone therapy can prevent the development of frailty.

Tissue selectivity and potential clinical applications of trenbolone (17beta-hydroxyestra-4,9,11-trien-3-one): A potent anabolic steroid with reduced androgenic and estrogenic activity

Recently, the development of selective androgen receptor modulators (SARMs) has been suggested as a means of combating the deleterious catabolic effects of hypogonadism, especially in skeletal muscle and bone, without inducing the undesirable androgenic effects (e.g., prostate enlargement and polycythemia) associated with testosterone administration. 17beta-Hydroxyestra-4,9,11-trien-3-one (trenbolone; 17beta-TBOH), a synthetic analog of testosterone, may be capable of inducing SARM-like effects as it binds to androgen receptors (ARs) with approximately three times the affinity of testosterone and has been shown to augment skeletal muscle mass and bone growth and reduce adiposity in a variety of mammalian species. In addition to its direct actions through ARs, 17beta-TBOH may also exert anabolic effects by altering the action of endogenous growth factors or inhibiting the action of glucocorticoids. Compared to testosterone, 17beta-TBOH appears to induce less growth in androgen-sensitive organs which highly express the 5alpha reductase enzyme (e.g., prostate tissue and accessory sex organs). The reduced androgenic effects result from the fact that 17beta-TBOH is metabolized to less potent androgens in vivo; while testosterone undergoes tissue-specific biotransformation to more potent steroids, dihydrotestosterone and 17beta-estradiol, via the 5alpha-reductase and aromatase enzymes, respectively. Thus the metabolism of 17beta-TBOH provides a basis for future research evaluating its safety and efficacy as a means of combating muscle and bone wasting conditions, obesity, and/or androgen insensitivity syndromes in humans, similar to that of other SARMs which are currently in development.

Androgens, angiogenesis and cardiovascular regeneration

PURPOSE OF REVIEW

Striking sex differences exist not only in the incidence of cardiovascular disease, but also in the clinical outcomes. Although cardiovascular events occur earlier in men, in women, it appears they have poorer short-term and long-term outcomes following these events compared to men. Thus, intrinsic sex differences may exist not only in atherogenesis, but also with respect to cardiovascular adaptation/repair in response to ischemia and/or infarction. Angiogenesis, the growth of new blood vessels, is essential for organ development and is critical to cardiovascular repair/regeneration. Although the effect of estrogen on angiogenesis has been studied extensively, the role of androgens has remained largely unexplored.

RECENT FINDINGS

Multiple lines of evidence now suggest an important role for androgens in cardiovascular repair and regeneration. Studies suggest that androgens stimulate angiogenesis via vascular endothelial growth factor-related mechanisms and by the stimulation of erythropoietin production. Furthermore, endothelial progenitor cells, important in angiogenesis, appear to be hormonally regulated and an important target of androgen action.

SUMMARY

Given the age-related decline in androgens, the findings discussed here have implications for therapeutic angiogenesis and androgen replacement therapies in aging and hypogonadal men.

Genetic variation in androgen disposition: implications in clinical medicine including testosterone abuse

BACKGROUND

Testosterone replacement therapy in hypogonadal men has been used for > 60 years. The use of testosterone substitution is continuously growing and is given to aging men to improve the quality of life. Because testosterone use is associated with muscle strength enhancing effects, it has become a popular drug to abuse. Doping with anabolic steroids, such as testosterone, is a severe challenge to the vision, moral and ethics in sports and has also become a significant and increasing problem in society.

OBJECTIVE

The primary aim of this review is to summarize and discuss the contribution of genetic components to inter-individual variation in androgen disposition.

CONCLUSION

Genetic variation has a large impact on androgen disposition. This variation is of the utmost importance for the interpretation of doping test results and may modulate the effects of testosterone replacement therapy and testosterone doping.

Reference intervals for serum testosterone, SHBG, LH and FSH in males from the NORIP project

Reference intervals were calculated for male testosterone, SHBG, FSH and LH in serum from 599 individuals in the NORIP study. At 30 years of age, reference limits were calculated to 10.4-32.6 nmol/L testosterone, 13.5-57.4 nmol/L SHBG, 1.93-9.7 IU/L LH and 1.5-10.3 IU/L FSH, at 50 years, 9.3-31.3 nmol/L (testosterone), 18.4-75.6 nmol/L (SHBG), 2.01-10.4 IU/L (LH) and 2.04-12.4 IU/L (FSH), and at 70 years 8.6 to 30.7 nmol/L (testosterone), 27.8-101 nmol/L (SHBG), 2.22-11.2 IU/L (LH) and 2.71-14.2 IU/L (FSH). All age-+related changes were statistically significant. Reference intervals were also calculated for indices derived from testosterone, SHBG and albumin. Free androgen index, simply the ratio between testosterone and SHBG, returned results differing from the other elaborate indices, and the study thus favors use of a more elaborate index such as calculated free testosterone (CFT).

Androgens and male aging: Current evidence of safety and efficacy

Many signs of aging, such as sexual dysfunction, visceral obesity, impaired bone and muscle strength, bear a close resemblance to features of hypogonadism in younger men. The statistical decline of serum testosterone in aging men is solidly documented. It has been presumed that the above features of aging are related to the concurrent decline of androgens, and that correction of the lower-than-normal circulating levels of testosterone will lead to improvement of symptoms of aging. But in essence, the pivotal question whether the age-related decline of testosterone must be viewed as hypogonadism, in the best case reversed by testosterone treatment, has not been definitively resolved. Studies in elderly men with lower-than-normal testosterone report improvement of features of the metabolic syndrome, bone mineral density, of mood and of sexual functioning. But as yet there is no definitive proof of the beneficial effects of restoring testosterone levels to normal in elderly men on clinical parameters. Few of these studies meet as yet rigorous standards of scientific enquiry: double-blind, placebo-controlled design of the study. The above applies also to the assessment of safety of testosterone administration to elderly men. There is so far no convincing evidence that testosterone is a main factor in the development of prostate cancer in elderly men and guidelines for monitoring the development of prostate disease have been developed. It is of note that there are presently no long-term safety data with regard to the prostate. Polycythemia is another potential complication of testosterone treatment. It is dose dependent and can be managed with dose adjustment.

Testosterone and the aging male: to treat or not to treat?

It is well-established that total testosterone (TT) in men decreases with age and that bioavailable testosterone (bio-T) falls to an even greater extent. The clinical relevance of declining androgens in the aging male and use of testosterone replacement therapy (TRT) in this situation is controversial. Most studies have been short term and there are no large randomized placebo-controlled trials. Testosterone has many physiological actions in: muscles, bones, hematopoietic system, brain, reproductive and sexual organs, adipose tissue. Within these areas it stimulates: muscle growth and maintenance, bone development while inhibiting bone resorption, the production of red blood cells to increase hemoglobin, libido, enhanced mood and cognition, erectile function and lipolysis. Anabolic deficits in aging men can induce: frailty, sarcopenia, poor muscle quality, muscle weakness, hypertrophy of adipose tissue and impaired neurotransmission. The aging male with reduced testosterone availability may present with a wide variety of symptoms which in addition to frailty and weakness include: fatigue, decreased energy, decreased motivation, cognitive impairment, decreased self-confidence, depression, irritability, osteoporotic pain and the lethargy of anemia. In addition, testosterone deficiency is also associated with type-2 diabetes, the metabolic syndrome, coronary artery disease, stroke and transient ischemic attacks, and cardiovascular disease in general. Furthermore, there are early studies to suggest that TRT in men with low testosterone levels may improve metabolic status by: lowering blood sugar and HbA1C in men with type-2 diabetes, reducing abdominal girth, ameliorating features of the metabolic syndrome, all of which may be protective of the cardiovascular system. The major safety issue is prostate cancer but there is no evidence that supports the idea that testosterone causes the development of a de novo cancer. So on balance in a man with symptoms of hygonadism and low or lowish levels of testosterone with no evidence of prostate cancer such as a normal PSA a therapeutic (4-6 months) trial of TRT is justified. Treatment and monitoring of this duration will determine whether the patient is responsive.

Minireview: Nuclear receptors, hematopoiesis, and stem cells

Nuclear receptors (NRs) regulate a panoply of biological processes, including the function and development of cells within the hematopoietic and immune system, such as erythrocytes, monocytes, and lymphocytes. Significantly less is known regarding the function of NRs in regulating the fate of hematopoietic stem cells (HSCs), the self-renewing, pluripotent cells that give rise to the entirety of the blood and immune systems throughout the lifetime of an individual. Several recent studies suggest, either directly or indirectly, a role for members of the NR family in regulating the differentiation and self-renewal of HSCs, embryonic stem cells, and induced pluripotent stem cells. Herein, we review in detail the function of specific NRs in controlling HSC and other stem cell fate and propose a framework through which these observations can be translated into therapeutic amplification of HSCs for clinical purposes.

Position stand on androgen and human growth hormone use

Hoffman, JR, Kraemer, WJ, Bhasin, S, Storer, T, Ratamess, NA, Haff, GG, Willoughby, DS, and Rogol, AD. Position stand on Androgen and human growth hormone use. J Strength Cond Res 23(5): S1-S59, 2009-Perceived yet often misunderstood demands of a sport, overt benefits of anabolic drugs, and the inability to be offered any effective alternatives has fueled anabolic drug abuse despite any consequences. Motivational interactions with many situational demands including the desire for improved body image, sport performance, physical function, and body size influence and fuel such negative decisions. Positive countermeasures to deter the abuse of anabolic drugs are complex and yet unclear. Furthermore, anabolic drugs work and the optimized training and nutritional programs needed to cut into the magnitude of improvement mediated by drug abuse require more work, dedication, and preparation on the part of both athletes and coaches alike. Few shortcuts are available to the athlete who desires to train naturally. Historically, the NSCA has placed an emphasis on education to help athletes, coaches, and strength and conditioning professionals become more knowledgeable, highly skilled, and technically trained in their approach to exercise program design and implementation. Optimizing nutritional strategies are a vital interface to help cope with exercise and sport demands (). In addition, research-based supplements will also have to be acknowledged as a strategic set of tools (e.g., protein supplements before and after resistance exercise workout) that can be used in conjunction with optimized nutrition to allow more effective adaptation and recovery from exercise. Resistance exercise is the most effective anabolic form of exercise, and over the past 20 years, the research base for resistance exercise has just started to develop to a significant volume of work to help in the decision-making process in program design (). The interface with nutritional strategies has been less studied, yet may yield even greater benefits to the individual athlete in their attempt to train naturally. Nevertheless, these are the 2 domains that require the most attention when trying to optimize the physical adaptations to exercise training without drug use.Recent surveys indicate that the prevalence of androgen use among adolescents has decreased over the past 10-15 years (). The decrease in androgen use among these students may be attributed to several factors related to education and viable alternatives (i.e., sport supplements) to substitute for illegal drug use. Although success has been achieved in using peer pressure to educate high school athletes on behaviors designed to reduce the intent to use androgens (), it has not had the far-reaching effect desired. It would appear that using the people who have the greatest influence on adolescents (coaches and teachers) be the primary focus of the educational program. It becomes imperative that coaches provide realistic training goals for their athletes and understand the difference between normal physiological adaptation to training or that is pharmaceutically enhanced. Only through a stringent coaching certification program will academic institutions be ensured that coaches that they hire will have the minimal knowledge to provide support to their athletes in helping them make the correct choices regarding sport supplements and performance-enhancing drugs.The NSCA rejects the use of androgens and hGH or any performance-enhancing drugs on the basis of ethics, the ideals of fair play in competition, and concerns for the athlete's health. The NSCA has based this position stand on a critical analysis of the scientific literature evaluating the effects of androgens and human growth hormone on human physiology and performance. The use of anabolic drugs to enhance athletic performance has become a major concern for professional sport organizations, sport governing bodies, and the federal government. It is the belief of the NSCA that through education and research we can mitigate the abuse of androgens and hGH by athletes. Due to the diversity of testosterone-related drugs and molecules, the term androgens is believed to be a more appropriate term for anabolic steroids.

Effect of long-acting testosterone treatment on functional exercise capacity, skeletal muscle performance, insulin resistance, and baroreflex sensitivity in elderly patients with chronic heart failure a double-blind, placebo-controlled, randomized study

OBJECTIVES

This study investigated the effect of a 12-week long-acting testosterone administration on maximal exercise capacity, ventilatory efficiency, muscle strength, insulin resistance, and baroreflex sensitivity (BRS) in elderly patients with chronic heart failure (CHF).

BACKGROUND

CHF is characterized by a metabolic shift favoring catabolism and impairment in skeletal muscle bulk and function that could be involved in the pathophysiology of heart failure.

METHODS

Seventy elderly patients with stable CHF-median age 70 years, ejection fraction 31.8 +/- 7%-were randomly assigned to receive testosterone (n = 35, intramuscular injection every 6 weeks) or placebo (n = 35), both on top of optimal medical therapy. At baseline and at the end of the study, all patients underwent echocardiogram, cardiopulmonary exercise test, 6-min walk test (6MWT), quadriceps maximal voluntary contraction (MVC), and isokinetic strength (peak torque) and BRS assessment (sequences technique).

RESULTS

Baseline peak oxygen consumption (VO(2)) and quadriceps isometric strength showed a direct relation with serum testosterone concentration. Peak VO(2) significantly improved in testosterone but was unchanged in placebo. Insulin sensitivity was significantly improved in testosterone. The MVC and peak torque significantly increased in testosterone but not in placebo. The BRS significantly improved in testosterone but not in placebo. Increase in testosterone levels was significantly related to improvement in peak VO(2) and MVC. There were no significant changes in left ventricular function either in testosterone or placebo.

CONCLUSIONS

These results suggest that long-acting testosterone therapy improves exercise capacity, muscle strength, glucose metabolism, and BRS in men with moderately severe CHF. Testosterone benefits seem to be mediated by metabolic and peripheral effects.

Androgens and erythropoiesis: past and present

Association between androgens and erythropoiesis has been known for more than seven decades. Androgens stimulate hematopoietic system by various mechanisms. These include stimulation of erythropoietin release, increasing bone marrow activity and iron incorporation into the red cells. Before the discovery of recombinant erythropoietin (rhEpo), androgens were used in the treatment of anemia associated with renal disease, bone marrow suppression, and hypopituitarism. Anabolism is an additional advantage of androgen therapy. Furthermore, in light of recent reports regarding adverse effects of rhEpo, the role of androgen therapy in various types of anemias should be readdressed. Polycythemia remains a known side effect of androgen therapy. In this review, we will briefly discuss the initial animal and human studies which demonstrated the role of androgens in the treatment of anemia, their mechanism of action, a detailed account of the efficacy of androgens in the treatment of various anemias, the erythropoietic side effects of androgens and finally, the relationship between hematocrit levels and cardiovascular disease.

High serum testosterone levels are associated with excessive erythrocytosis of chronic mountain sickness in men

Chronic mountain sickness (CMS) is characterized by excessive erythrocytosis (EE) secondary to hypoventilation. Erythropoietin (Epo) and testosterone regulate erythrocyte production. Low thyroid hormone levels are also associated to hypoventilation. Hence, these hormones can play a role in etiopathogeny of EE. The purpose of this study was to elucidate the effect of sexual and thyroid hormones and Epo in residents from Lima (150 m) and Cerro de Pasco (4,340 m), Peru, and the response to human chorionic gonadotrophin stimulation (hCG). Three groups, one at low altitude and two at high altitude [1 with hemoglobin values >16-21 g/dl and the second with Hb >or=21 g/dl (EE)], were studied. hCG was administered intramuscularly in a single dose (1,000 IU), and blood samples were obtained at 0, 6, 12, 24, 48, and 72 h after injection. High-altitude natives present similar levels of gonadotropins and thyroid hormones but lower dehydroepiandrosterone sulphate (DHEAS) levels (P < 0.01) and greater Epo (P < 0.01), 17alpha-hydroxyprogesterone (P < 0.01), and testosterone levels (P < 0.01) than those at 150 m. Serum testosterone levels (524.13 +/- 55.91 microg/dl vs. 328.14 +/- 53.23 ng/dl, means +/- SE; P < 0.05) and testosterone/DHEAS ratios are higher (7.98 +/- 1.1 vs. 3.65 +/- 1.1; P < 0.01) and DHEAS levels lower in the EE group (83.85 +/- 14.60 microg/dl vs. 148.95 +/- 19.11 ug/dl; P < 0.05), whereas Epo was not further affected. Testosterone levels were highest and DHEAS levels lowest in the EE group at all times after hCG stimulation. In conclusion, high androgen activity could be involved in the etiopathogeny of CMS. This evidence provides an opportunity to develop new therapeutic strategies.

Testosterone action on erythropoiesis does not require its aromatization to estrogen: Insights from the testosterone and estrogen treatment of two aromatase-deficient men

Androgens act on erythropoiesis, but the relative role of testosterone (T) and estradiol (E(2)) on erythropoietic parameters in men is a poorly investigated issue. In order to evaluate separately the effects on erythropoiesis of high-dose T administration alone and of physiological dose of E(2) administration alone two adult men with aromatase deficiency were assessed before and during each treatment. Blood cell count, hemoglobin (Hb), hematocrit (Hct), erythrocyte mean cell volume (MCV), erythrocyte mean corpuscular hemoglobin (MCH), erythrocyte mean corpuscular hemoglobin concentration (MCHC), serum ferritin, iron and total iron-binding capacity (TIBC), serum erythropoietin, serum total testosterone and estradiol were evaluated. Hb, Hct and red cell count rose during testosterone treatment, consistently with the increase in circulating testosterone, but failed to increase during estradiol treatment. A decrease in Hb, Hct and red cell count was recorded in one of the two subjects during estradiol treatment, with a concomitant decrease in serum testosterone. Circulating T alone is capable of and sufficient to influence erythropoiesis, especially at supraphysiological dosage, while circulating E(2) have not the same effect on erythropoietic parameters, suggesting the hypothesis that the erythropoietic changes induced by androgens are not mediated via its aromatization to estrogens.

Serum testosterone levels correlate with haemoglobin in middle-aged and older men

BACKGROUND

Lower testosterone levels are associated with anaemia in older men and women. The relation between testosterone and haemoglobin (Hb) in younger and middle-aged men is less well defined. The aim of the study was to examine the association between testosterone and Hb levels in men spanning middle to older ages.

METHODS

A cross-sectional analysis of 492 men aged 30.7-94.5 years from the Busselton Health Survey, Western Australia, was carried out. Haemoglobin (Hb), early-morning serum total testosterone and sex hormone-binding globulin (SHBG) were measured. Free testosterone was calculated using mass action equations.

RESULTS

Haemoglobin correlated to total and free testosterone concentrations (r= 0.13, P= 0.003 and r= 0.20, P < 0.001, respectively). Hb and SHBG were inversely correlated (r=-0.14, P= 0.001). Hb increased across lowest to highest quartiles of total testosterone (P= 0.02) and free testosterone (P < 0.001), but not SHBG. After adjusting for age, waist circumference, smoking status, alcohol consumption, renal function and ferritin, total testosterone was associated with Hb (beta= 0.037, P= 0.003) as was free testosterone (beta= 2.32, P < 0.001), whereas SHBG was not associated.

CONCLUSION

Testosterone concentration modulates Hb levels in community-dwelling men across a wide age range. Further studies are needed to clarify implications of this association between testosterone and Hb in men.