Differential effects of androgens and estrogens on bone turnover in normal men

Crosstalk Between the Neuroendocrine System and Bone Homeostasis

The homeostasis of bone microenvironment is the foundation of bone health and comprises 2 concerted events: bone formation by osteoblasts and bone resorption by osteoclasts. In the early 21st century, leptin, an adipocytes-derived hormone, was found to affect bone homeostasis through hypothalamic relay and the sympathetic nervous system, involving neurotransmitters like serotonin and norepinephrine. This discovery has provided a new perspective regarding the synergistic effects of endocrine and nervous systems on skeletal homeostasis. Since then, more studies have been conducted, gradually uncovering the complex neuroendocrine regulation underlying bone homeostasis. Intriguingly, bone is also considered as an endocrine organ that can produce regulatory factors that in turn exert effects on neuroendocrine activities. After decades of exploration into bone regulation mechanisms, separate bioactive factors have been extensively investigated, whereas few studies have systematically shown a global view of bone homeostasis regulation. Therefore, we summarized the previously studied regulatory patterns from the nervous system and endocrine system to bone. This review will provide readers with a panoramic view of the intimate relationship between the neuroendocrine system and bone, compensating for the current understanding of the regulation patterns of bone homeostasis, and probably developing new therapeutic strategies for its related disorders.

Male Osteoporosis and Frailty

It is estimated that 50% women and 20% of men over the age of 50 years will have an osteoporosis-related fracture in their remaining life. Although, Osteoporosis is generally thought to be a disease affecting females, more than a third of hip fractures occur in males due to reduced bone strength. Along with Osteoporosis, the other pathological process which occurs simultaneously is Sarcopenia. It is defined as age-related atrophy of skeletal muscle mass that reduces muscle strength, function, and quality of life. This chapter discusses the various aspects of the disease process in the males including its classification, clinical features, diagnosis and treatment.

Risk factor analysis for tibial tubercle avulsion fractures in children

PURPOSE

Tibial tubercle avulsion fractures (TTAFs) are rare in children, particularly bilateral TTAFs. This study aimed to elucidate the associating factors of TTAF, and compare the risk factor profiles of unilateral and bilateral injuries, thus provide clinical theoretical basis for reducing the occurrence of TTAFs.

METHODS

TTAF paediatric patients who were hospitalized between April 2017 and November 2022 were retrospectively analysed. Children who presented for physical examination during the same period were randomly selected, and were age- and sex-matched as controls. A subgroup analysis based on endocrine function was also performed. A risk factor analysis for bilateral TTAF was performed as well. Data were collected via medical records and a questionnaire. All variables were assessed for association with TTAF using univariate and multiple logistic regression analyses.

RESULTS

A total of 64 TTAF patients and controls were respectively included. Multivariate analysis demonstrated BMI (P = 0.000，OR = 3.172), glucose (P = 0.016，OR = 20.878), and calcium (P = 0.034，OR = 0.000) as independent associating factors of TTAF. Subgroup analysis showed significant differences in oestradiol (P = 0.014), progesterone (P = 0.006) and insulin levels (P = 0.005) between the TTAF and control groups. Bilateral TTAF was found to significantly associate with a history of knee joint pain (P = 0.026).

CONCLUSION

High BMI, hyperglycaemia, and low calcium levels were found as independent risk factors for TTAF in children. In addition, decreased oestradiol, elevated progesterone, and insulin resistance were identified as potential risk factors for TTAF. A history of knee pain may be suggestive of bilateral TTAF.

Pharmaceutical treatment of bone loss: From animal models and drug development to future treatment strategies

Animal models are fundamental to advance our knowledge of the underlying pathophysiology of bone loss and to study pharmaceutical countermeasures against it. The animal model of post-menopausal osteoporosis from ovariectomy is the most widely used preclinical approach to study skeletal deterioration. However, several other animal models exist, each with unique characteristics such as bone loss from disuse, lactation, glucocorticoid excess, or exposure to hypobaric hypoxia. The present review aimed to provide a comprehensive overview of these animal models to emphasize the importance and significance of investigating bone loss and pharmaceutical countermeasures from perspectives other than post-menopausal osteoporosis only. Hence, the pathophysiology and underlying cellular mechanisms involved in the various types of bone loss are different, and this might influence which prevention and treatment strategies are the most effective. In addition, the review sought to map the current landscape of pharmaceutical countermeasures against osteoporosis with an emphasis on how drug development has changed from being driven by clinical observations and enhancement or repurposing of existing drugs to today's use of targeted anti-bodies that are the result of advanced insights into the underlying molecular mechanisms of bone formation and resorption. Moreover, new treatment combinations or repurposing opportunities of already approved drugs with a focus on dabigatran, parathyroid hormone and abaloparatide, growth hormone, inhibitors of the activin signaling pathway, acetazolamide, zoledronate, and romosozumab are discussed. Despite the considerable progress in drug development, there is still a clear need to improve treatment strategies and develop new pharmaceuticals against various types of osteoporosis. The review also highlights that new treatment indications should be explored using multiple animal models of bone loss in order to ensure a broad representation of different types of skeletal deterioration instead of mainly focusing on primary osteoporosis from post-menopausal estrogen deficiency.

Bone health in ageing men

Osteoporosis does not only affect postmenopausal women, but also ageing men. The burden of disease is projected to increase with higher life expectancy both in females and males. Importantly, osteoporotic men remain more often undiagnosed and untreated compared to women. Sex steroid deficiency is associated with bone loss and increased fracture risk, and circulating sex steroid levels have been shown to be associated both with bone mineral density and fracture risk in elderly men. However, in contrast to postmenopausal osteoporosis, the contribution of relatively small decrease of circulating sex steroid concentrations in the ageing male to the development of osteoporosis and related fractures, is probably only minor. In this review we provide several clinical and preclinical arguments in favor of a 'bone threshold' for occurrence of hypogonadal osteoporosis, corresponding to a grade of sex steroid deficiency that in general will not occur in many elderly men. Testosterone replacement therapy has been shown to increase bone mineral density in men, however data in osteoporotic ageing males are scarce, and evidence on fracture risk reduction is lacking. We conclude that testosterone replacement therapy should not be used as a sole bone-specific treatment in osteoporotic elderly men.

Normal bone mineral density and bone microarchitecture in adult males with high and low risk of exercise addiction

Exercise addiction describes a pattern of excessive and obsessive exercise and is associated with hypoleptinemia and low testosterone that may have adverse skeletal effects. We used a validated questionnaire to identify males with high and low risk of exercise addiction. In a cross-sectional design, males (aged 21–49 years) with high (n = 20, exercise addictive) and low risk (n = 20, exercise controls) of exercise addiction had examinations of bone mass, bone microarchitecture, and estimated bone strength performed using dual-energy x-ray absorptiometry of the hip and spine and high-resolution peripheral quantitative computed tomography of the distal radius and tibia. Findings were compared between the groups and to a population-based sample of healthy men aged 20–80 years (n = 236). We found similar hip and spine bone mineral density in exercise addictive and controls. Cortical and trabecular bone microarchitecture and estimated bone strength in radius and tibia did not differ significantly between the groups. Multiple regression analyses adjusting for age, body weight, free testosterone, and hours of weekly training did not alter findings. Also, bone indices from both groups were within 95% prediction bands derived from the population-based sample for the vast majority of indices. Neither group had no associations between circulating leptin or free testosterone and bone outcomes. In conclusion, in a study on younger males, we found no associations between high risk of exercise addiction and various indices of bone mass and bone quality indicative of altered skeletal health.

Relation of Testosterone, Dihydrotestosterone, and Estradiol With Changes in Outcomes Measures in the Testosterone Trials

CONTEXT

Many effects of testosterone are mediated through dihydrotestosterone (DHT) and estradiol.

OBJECTIVE

To determine the relative contributions of each hormone to the observed effects of testosterone treatment in older men with hypogonadism.

METHODS

Using data from the Testosterone Trials, we assessed the association of changes in total testosterone, estradiol, and DHT levels over 12 months of testosterone treatment with hemoglobin, high-density lipoprotein (HDL) cholesterol, volumetric bone mineral density (vBMD) of lumbar spine, sexual desire, and prostate-specific antigen (PSA). We used random forests to model the associations of predicted mean changes in outcomes with change in each hormone at low, mean, or high change in the other 2 hormones. Stepwise regression models were run to confirm the findings of random forests.

RESULT

Predicted increases in hemoglobin and sexual desire were greater with larger increases in estradiol and were larger with high change in DHT compared with low change in DHT. Greater increases in estradiol were associated with larger decreases in HDL cholesterol; this association did not vary according to changes in DHT or testosterone. Change in vBMD was most robustly associated with change in estradiol and was greater with high change in testosterone and DHT. There was no consistent relation between change in PSA and change in any hormone.

CONCLUSION

Change in estradiol level was the best predictor not only of the change in vBMD and sexual desire but also of the changes in hemoglobin and HDL cholesterol. Consideration of testosterone, estradiol, and DHT together offers a superior prediction of treatment response in older hypogonadal men than testosterone alone.

Role of sex steroids hormones in the regulation of bone metabolism in men: Evidence from clinical studies

Sex steroids regulate bone metabolism in young men during growth and consolidation. Their deficit during growth compromises longitudinal and radial growth of bones and has a negative impact on body height, bone width, peak areal bone mineral density (aBMD) and bone microarchitecture. In older men, the deficit of sex steroid hormones (mainly 17β-oestradiol) contributes to high bone turnover rate, low aBMD, poor bone microarchitecture, low estimated bone strength, accelerated bone loss and rapid decline of bone microarchitecture. The role of 17β-oestradiol is confirmed by the case of men with congenital oestrogen receptor deficit and with congenital aromatase deficiency. 17β-oestradiol inhibits bone resoption, whereas both hormones regulate bone formation. However, the associations are weak. Prospective data on the utility of blood 17β-oestradiol or testosterone for fracture risk assessment are inconsistent. Men with hypogonadism have decreased aBMD and poor bone microarchitecture. In men with hypogonadism, testosterone replacement therapy increases aBMD and improves bone microarchitecture. In men with prostate cancer, androgen deprivation therapy (gonadoliberin analogues) induces rapid bone loss and severe deterioration of bone microarchitecture.

Cancer Treatment–Induced Bone Loss and Role of Denosumab in Nonmetastatic Prostate Cancer: A Narrative Review

Bone loss is an important complication of prostate cancer and its associated treatments, especially androgen-deprivation therapy (ADT). There is a 5 to 10 times increased loss of bone mineral density (BMD) in men receiving ADT with yearly 4 to 13% BMD loss. The risk of fracture increases yearly by 5 to 8% with ADT. ADT associated bone loss of 10 to 15% of BMD doubles the risk of fractures. Hence, BMD evaluation through dual-energy X-ray absorptiometry and evaluation of individual fracture risk assessed before initiating ADT. The use of vitamin D, calcium, bisphosphonates, and denosumab has shown improved bone health in men with prostate cancer receiving ADT. Denosumab 60 mg is approved to increase bone mass in men at high risk for fractures receiving ADT for nonmetastatic prostate cancer. Denosumab has shown improvement of 5.6% BMD at 2 years in nonmetastatic prostate cancer patients, with significant improvements seen at the total hip, femoral neck, and distal third of the radius. Denosumab has shown a 62% decreased incidence of new vertebral fractures at 36 months. Furthermore, denosumab delays the onset of bone metastases in high-risk nonmetastatic prostate cancer patients. Denosumab can be preferred over other bone modifying agents owing to several advantages, such as subcutaneous administration and no requirement of hospitalization, no dose modifications in renal impairment and less incidence of acute phase anaphylactic reactions. We review the available evidence of denosumab for managing bone loss in nonmetastatic prostate cancer patients. The relevant articles used in this narrative review were obtained through general search on google and PubMed using the key terms “non-metastatic prostate cancer,” “denosumab,” “bone loss,” “bone mineral density,” “fracture,” “CTIBL,” and “chemotherapy induced bone loss.”

Increased Bone Mineral Density in Male Patients With Idiopathic Hypogonadotropic Hypogonadism Who Undergo Sex Hormone Therapy: Findings From Cross-Sectional and Longitudinal Studies

OBJECTIVE

This retrospective observational study assessed the long-term impact of pulsatile gonadotropin-releasing hormone, combined gonadotropin, or testosterone replacement therapy on total hip, femoral, and lumbar bone mineral density (BMD) and Z-scores in adult men with idiopathic hypogonadotropic hypogonadism (IHH).

METHODS

In the cross-sectional study, 69 patients were allocated to untreated (n = 42) and treated (n = 27) groups. The untreated group included IHH patients without hormone therapy history, while the treated group included age- and body mass index-matched patients who had received hormone therapy for at least 5 years. The longitudinal study included 53 IHH patients, and their hip and lumbar BMDs were measured several times during hormone therapy. We then evaluated the changes in their BMD.

RESULTS

Our cross-sectional study showed that the treated group had a significantly higher BMD and Z-score for total hip, femoral neck, and lumbar spine (P < 0.001 for all) than the untreated group, and the average bone mass even reached the age-matched normal range. The prevalence of low BMD was 80.95% and 11.11% in untreated and treated groups, respectively. In the longitudinal study (N = 53), the total hip, femoral neck, and lumbar spine BMD gradually increased during treatment. The lumbar spine showed a greater increment in BMD compared with the total hip and femoral neck (P < 0.05).

CONCLUSION

Sex hormone therapy improved hip and lumbar spine BMD and Z-scores in patients with IHH. The lumbar spine showed a greater improvement in BMD compared with the total hip and femoral neck.

Osteocalcin and its forms respond similarly to exercise in males and females

INTRODUCTION

Acute exercise increases osteocalcin (OC), a marker of bone turnover, and in particular the undercarboxylated form (ucOC). Males and females differ in baseline levels of total OC and it is thought the hormonal milieu may be driving these differences. Males and females adapt differently to the same exercise intervention, however it is unclear whether the exercise effects on OC are also sex-specific. We tested whether the responses of OC and its forms to acute High Intensity Interval Exercise (HIIE) and High Intensity Interval Training (HIIT) differed between males and females. Secondly, we examined whether sex hormones vary with OC forms within sexes to understand if these are driving factor in any potential sex differences.

METHODS

Total OC (tOC), undercarboxylated OC (ucOC), and carboxylated OC (cOC) were measured in serum of 96 healthy participants from the Gene SMART cohort (74 males and 22 females) at rest, immediately after, and 3 h after a single bout of HIIE, and at rest, 48 h after completing a four week HIIT intervention. Baseline testosterone and estradiol were also measured for a subset of the cohort (Males = 38, Females = 20). Linear mixed models were used to a) uncover the sex-specific effects of acute exercise and short-term training on OC forms and b) to examine whether the sex hormones were associated with OC levels.

RESULTS

At baseline, males had higher levels of tOC, cOC, and ucOC than females (q < 0.01). In both sexes tOC, and ucOC increased to the same extent after acute HIIE. At baseline, in males only, higher testosterone was associated with higher ucOC (β = 3.37; q < 0.046). Finally, tOC and ucOC did not change following 4 weeks of HIIT.

CONCLUSION/DISCUSSION

While there were no long-term changes in OC and its forms. tOC and ucOC were transiently enhanced after a bout of HIIE similarly in both sexes. This may be important in metabolic signalling in skeletal muscle and bone suggesting that regular exercise is needed to maintain these benefits. Overall, these data suggest that the sex differences in exercise adaptations do not extend to the bone turnover marker, OC.

Dimethandrolone Undecanoate, a Novel, Nonaromatizable Androgen, Increases P1NP in Healthy Men Over 28 Days

CONTEXT

Dimethandrolone undecanoate (DMAU) is being developed as a male contraceptive. Daily oral administration of DMAU, a potent androgen that is not aromatized, markedly suppresses serum testosterone (T) and estradiol (E2) in healthy men. E2 deficiency can increase bone resorption in men.

OBJECTIVE

This work aimed to assess changes in bone turnover markers with DMAU administration in a 28-day study.

DESIGN

A randomized, double-blind, placebo-controlled study was conducted.

SETTING

This study took place at 2 academic medical centers.

PARTICIPANTS

Healthy men, age 18 to50 years (n = 81), participated.

INTERVENTION

Men received 0, 100, 200, or 400 mg of oral DMAU for 28 days. Serum C-terminal telopeptide of type I collagen (CTX; bone resorption marker) and procollagen type I amino-terminal propeptide (P1NP; bone formation marker) were measured on days 1 and 28.

MAIN OUTCOME MEASURES

Changes in bone turnover markers and serum hormones over the treatment period were measured.

RESULTS

On day 28, median serum T and E2 were markedly suppressed in all treatment groups vs placebo (P < .001 for both). Percentage change (%) in serum P1NP significantly differed across treatment groups (P = .007): Serum P1NP significantly increased in the 200 mg (5%, interquartile range [IQR] -7% to 27%) and 400 mg (22%, IQR -1% to 40%) groups relative to placebo (-8%, IQR -20% to 0%). Change (%) in serum CTX did not differ between groups (P = .09).

CONCLUSIONS

DMAU administration for 28 days to healthy men leads to marked suppression of serum T and E2, yet increases P1NP, a serum marker of bone formation. Longer-term studies of the potent androgen DMAU are warranted to determine its impact on bone health in men.

Autophagy: A Promising Target for Age-related Osteoporosis

Autophagy is a process the primary role of which is to clear up damaged cellular components such as long-lived proteins and organelles, thus participating in the conservation of different cells. Osteoporosis associated with aging is characterized by consistent changes in bone metabolism with suppression of bone formation as well as increased bone resorption. In advanced age, not only bone mass but also bone strength decrease in both sexes, resulting in an increased incidence of fractures. Clinical and animal experiments reveal that age-related bone loss is associated with many factors such as accumulation of autophagy, increased levels of reactive oxygen species, sex hormone deficiency, and high levels of endogenous glucocorticoids. Available basic and clinical studies indicate that age-associated factors can regulate autophagy. Those factors play important roles in bone remodeling and contribute to decreased bone mass and bone strength with aging. In this review, we summarize the mechanisms involved in bone metabolism related to aging and autophagy, supplying a theory for therapeutic targets to rescue bone mass and bone strength in older people.

Parturitions, menopause and other physiological stressors are recorded in dental cementum microstructure

The life history pattern of recent humans is uniquely derived in many of its aspects including an extended post-reproductive lifespan combined with short interbirth intervals. A number of theories have been proposed to explain the evolution of this unusual pattern. However most have been difficult to test due to the fragmentary nature of the hominin fossil record and the lack of methods capable of inferring such later life history events. In search of a method we tested the hypothesis that the physiologically impactful events of parturition and menopause are recorded in dental cementum microstructure. We performed histomorphological analyses of 47 teeth from 15 individuals with known life history events and were able to detect reproductive events and menopause in all females. Furthermore, we found that other stressful events such as systemic illnesses and incarceration are also detectable. Finally, through the development of a novel analytical method we were able to time all such events with high accuracy (R-squared = 0.92).

Circulatory pattern of cytokines, adipokines and bone markers in postmenopausal women with low BMD

Objective: In addition to some well-characterized bone turnover markers (BTMs), cytokines and adipokines have also been suggested to be linked to osteoporosis seen in menopause. However, there is much controversy on the possible association between these markers and bone mineral density (BMD). This study was aimed at measuring circulatory levels of selected cytokines, adipokines and BTMs in postmenopausal women with normal and low BMD. Methods: The study population included 71 post-menopausal women, of whom 25 had normal BMD, 31 had osteopenia and 13 had osteoporosis. Circulatory levels of selected pro-resorptive (TNF-α, IL-1β, IL-6, IL-8, IL-12, IL-17), anti-resorptive (IFN-γ, IL-4, IL-10, IL-13, TGF-β) and five adipokine markers (adiponectin, adipsin, lipocalin-2/NGAL, PAI-1 and resistin) were measured using the Multiplex system and read on the Magpix ELISA platform. Further, two bone turnover markers (PINP, CTX) as well as estradiol levels were assayed from the same samples. Results: While circulatory levels of cytokines were comparable between groups, women with low BMD had statistically significantly higher median circulatory levels of adipokines as compared to those with normal BMD. Further, while levels of CTX were not different between the two groups; PINP, PINP/CTX ratio and estradiol levels were significantly lower in women with low BMD. Levels of adiponectin, PINP, PINP/CTX ratio and estradiol correlated significantly with BMD of the hip and spine. Conclusion: The associations between various markers and BMD are complex and multivariate. Our data provide insights into the possible use of circulatory levels of cytokines, adipokines and bone turnover markers on the pathogenesis of postmenopausal osteoporosis because of the well-documented effects of these molecules on bone tissue and their relevance to osteoporosis.

PC-3-Derived Exosomes Inhibit Osteoclast Differentiation by Downregulating miR-214 and Blocking NF-κB Signaling Pathway

Prostate cancer is a serious disease that can invade bone tissues. These bone metastases can greatly decrease a patient's quality of life, pose a financial burden, and even result in death. In recent years, tumor cell-secreted microvesicles have been identified and proposed to be a key factor in cell interaction. However, the impact of cancer-derived exosomes on bone cells remains unclear. Herein, we isolated exosomes from prostate cancer cell line PC-3 and investigated their effects on human osteoclast differentiation by tartrate-resistant acid phosphatase (TRAP) staining. The potential mechanism was evaluated by qRT-PCR, western blotting, and microRNA transfection experiments. The results showed that PC-3-derived exosomes dramatically inhibited osteoclast differentiation. Marker genes of mature osteoclasts, including CTSK, NFATc1, ACP5, and miR-214, were all downregulated in the presence of PC-3 exosomes. Furthermore, transfection experiments showed that miR-214 downregulation severely impaired osteoclast differentiation, whereas overexpression of miR-214 promoted differentiation. Furthermore, we demonstrated that PC-3-derived exosomes block the NF-κB signaling pathway. Our study suggested that PC-3-derived exosomes inhibit osteoclast differentiation by downregulating miR-214 and blocking the NF-κB signaling pathway. Therefore, elevating miR-214 levels in the bone metastatic site may attenuate the invasion of prostate cancer.

Effect of Androgen-Deprivation Therapy on Bone Mineral Density in Patients with Prostate Cancer: A Systematic Review and Meta-Analysis

We aimed to evaluate the change in bone mineral density (BMD) in patients with prostate cancer (PCa) receiving androgen deprivation therapy (ADT) compared to those with PCa or other urologic conditions not receiving ADT. Literature searches were conducted throughout October 2018. The eligibility of each study was assessed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using the Participant, Intervention, Comparator, Outcome, and Study design method. The outcomes analyzed were the mean difference (MD) of percent changes in BMD of lumbar spine, femur neck, and total hip. Five prospective cohort studies with a total of 533 patients were included in the present study. Statistically significant decreases of BMD change relative to the control group were observed in the ADT treatment group in the lumbar spine (MD −3.60, 95% CI −6.72 to −0.47, P = 0.02), femoral neck (MD −3.11, 95% CI −4.73 to −1.48, P = 0.0002), and total hip (MD −1.59, 95% CI −2.99 to −0.19, P = 0.03). There is a significant relationship between ADT and BMD reduction in patients with PCa. Regular BMD testing and the optimal treatment for BMD loss should, therefore, be considered in patients with PCa undergoing ADT.

Androgen receptor SUMOylation regulates bone mass in male mice

The crucial effects of androgens on the male skeleton are at least partly mediated via the androgen receptor (AR). In addition to hormone binding, the AR activity is regulated by post-translational modifications, including SUMOylation. SUMOylation is a reversible modification in which Small Ubiquitin-related MOdifier proteins (SUMOs) are attached to the AR and thereby regulate the activity of the AR and change its interactions with other proteins. To elucidate the importance of SUMOylation of AR for male bone metabolism, we used a mouse model devoid of the two AR SUMOylation sites (AR^SUM-; K381R and K500R are substituted). Six-month-old male AR^SUM- mice displayed significantly reduced trabecular bone volume fraction in the distal metaphyseal region of femur compared with wild type (WT) mice (BV/TV, -19.1 ± 4.9%, P < 0.05). The number of osteoblasts per bone perimeter was substantially reduced (-60.5 ± 7.2%, P < 0.001) while no significant effect was observed on the number of osteoclasts in the trabecular bone of male AR^SUM- mice. Dynamic histomorphometric analysis of trabecular bone revealed a reduced bone formation rate (-32.6 ± 7.4%, P < 0.05) as a result of reduced mineralizing surface per bone surface in AR^SUM- mice compared with WT mice (-24.3 ± 3.6%, P < 0.001). Furthermore, cortical bone thickness in the diaphyseal region of femur was reduced in male AR^SUM- mice compared with WT mice (-7.3 ± 2.0%, P < 0.05). In conclusion, mice devoid of AR SUMOylation have reduced trabecular bone mass as a result of reduced bone formation. We propose that therapies enhancing AR SUMOylation might result in bone-specific anabolic effects with minimal adverse effects in other tissues.

The androgen receptor is required for maintenance of bone mass in adult male mice

Previous studies evaluating the role of the androgen receptor (AR) for bone mass have used mouse models with global or tissue-specific lifelong inactivation of the AR. However, these mouse models have the AR inactivated already early in life and the relative roles of the AR during development, sexual maturation and in adult mice cannot be evaluated separately. The aim of the present study was to determine the specific roles of the AR in bone during sexual maturation and in adult mice. The AR was conditionally ablated at four (pre-pubertal) or ten (post-pubertal) weeks of age in male mice using tamoxifen-inducible Cre-mediated recombination. Both the pre-pubertal and the post-pubertal AR inactivation were efficient demonstrated by substantially lower AR mRNA levels in seminal vesicle, bone and white adipose tissue as well as markedly reduced weights of reproductive tissues when comparing inducible ARKO mice and control mice at 14 weeks of age. Total body BMD, as analyzed by DXA, as well as tibia diaphyseal cortical bone thickness and proximal metaphyseal trabecular bone volume fraction, as analyzed by μCT, were significantly reduced by both pre-pubertal and post-pubertal AR inactivation. These bone effects were associated with an increased bone turnover, indicating a high bone turnover osteoporosis. Pre-pubertal but not post-pubertal AR inactivation resulted in substantially increased fat mass. In conclusion, the AR is required for maintenance of both trabecular and cortical bone in adult male mice while AR expression during puberty is crucial for normal fat mass homeostasis in adult male mice.

Daidzein upregulates anti-aging protein Klotho and NaPi 2a cotransporter in a rat model of the andropause

In a rat model of the andropause we aimed to examine the influence of daidzein, soy isoflavone, on the structure and function of parathyroid glands (PTG) and the expression levels of some of the crucial regulators of Ca²⁺ and Pi homeostasis in the kidney, and to compare these effects with the effects of estradiol, serving as a positive control. Middle-aged (16-month-old) male Wistar rats were divided into the following groups: sham-operated (SO), orchidectomized (Orx), orchidectomized and estradiol-treated (Orx+E; 0.625mg/kg b.w./day, s.c.) as well as orchidectomized and daidzein-treated (Orx+D; 30mg/kg b.w./day, s.c.) group. Every treated group had a corresponding control group. PTH serum concentration was decreased in Orx+E and Orx+D groups by 10% and 21% (p<0.05) respectively, in comparison with the Orx. PTG volume was decreased in Orx+E group by 16% (p<0.05), when compared to the Orx. In Orx+E group expression of NaPi 2a was lower (p<0.05), while NaPi 2a abundance in Orx+D animals was increased (p<0.05), when compared to Orx. Expression of PTH1R was increased (p<0.05) in Orx+E group, while in Orx+D animals the same parameter was decreased (p<0.05), in comparison with Orx. Klotho expression was elevated (p<0.05) in Orx+D rats, in regard to Orx. Orx+D induced reduction in Ca²⁺/creatinine and Pi/creatinine ratio in urine by 32% and 16% (p<0.05) respectively, in comparison with Orx. In conclusion, presented results indicate the more coherent beneficial effects of daidzein compared to estradiol, on disturbed Ca²⁺ and Pi homeostasis, and presumably on bone health, in the aging male rats.

Impact of occupational cadmium exposure on bone in sewage workers

Cadmium (Cd) is one of the environmental risk factors for bone loss. The present study included 40 sewage workers occupationally exposed to Cd. Forty nonexposed men were included as a control group. Current smokers represented 65% and 47.5% of the exposed and control groups, respectively. The study aimed to investigate the hazard of occupational Cd exposure on bone health. This was achieved through measuring serum and urinary Cd, and calcium (Ca), in addition to serum osteoprotegerin (OPG) and estrogen receptor-α gene. Results showed significant elevation in serum Cd, OPG, and urinary Ca levels in the exposed compared to the controls. Bony aches and joint pain were more prevalent among the exposed workers. Serum and urinary Cd increased in exposed smokers relative to control smokers. Also, serum OPG levels showed significant rise among exposed smoker and nonsmoker compared to control smoker and nonsmoker groups. Serum Cd level increased significantly in PP and pp genotypes in exposed workers compared to controls, while elevated levels of serum OPG was observed in PP and Pp genotypes in exposed workers relative to controls. Urinary Cd exhibited significant rise in both PP and pp genotypes in exposed workers, while Ca excretion was elevated in pp genotype only. The study reflected an association of genetic predisposition and Cd exposure in progression of osteoporosis. Further research is needed to explain the mechanisms of Cd impact on bone. The role of smoking is important and hence smoking cessation programs are essential for sewage workers.

Yield of diagnostic tests in unexplained renal hypophosphatemia: a case series

BACKGROUND

Isolated renal hypophosphatemia may be inherited or acquired. An increasing number of patients with unexplained renal hypophosphatemia is being referred to our clinics, but the optimal diagnostic work-up is not known. Therefore, the aim of this study was to assess the diagnostic yield in these patients.

METHODS

We retrospectively evaluated all patients who were referred because of unexplained isolated renal hypophosphatemia to two academic tertiary referral centers in The Netherlands in the period of 2013-2017.

RESULTS

We evaluated 17 patients. In five female patients renal hypophosphatemia could be attributed to the use of oral contraceptives. The other 12 patients had a median age of 48 years (10 males). There were no other signs of tubulopathy and none of the patients used drugs known to be associated with hypophosphatemia. FGF23 levels were above normal (> 125 RU/ml) in 2/12 patients. Genetic testing, performed in all patients, did not identify a mutation in genes known to be associated with renal phosphate wasting. A scan with a radiolabeled somatostatin analogue was performed in 8 patients. In one patient, with an FGF23 level of 110 RU/ml, an increased uptake of the somatostatin analog was observed due to tumor induced osteomalacia (TIO).

CONCLUSIONS

Oral contraceptive use is an important but under-recognized cause of renal hypophosphatemia. The cause of isolated renal hypophosphatemia remained unexplained in the majority of other patients despite extensive and expensive additional investigations. The pre-test probability for tumor-induced osteomalacia or inherited renal hypophosphatemia in a patient with aspecific complaints and a normal FGF23 level is low. Further research is needed to investigate which patients should be screened for TIO. At present we suggest to perform somatostatin scans only in patients with severe complaints, elevated FGF23 levels, or progressive disease.

Hormonal and bone parameters in pubertal girls

Here we analyzed associations between muscles mass, total bone mineral content (BMC), lumbar spine bone density (BMD L1-L4) and serum or urine hormones in healthy peripubertal girls. Total BMC and areal BMD L1-L4, muscle mass and fat were measured by dual-energy X-ray absorptiometry (DXA). Muscle force (N) was estimated by a dynamometer. Circulating estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), 25-hydroxy vitamin D, parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1), leptin, osteocalcin, bone isoenzyme of alkaline phosphatase (bALP) and total calcium and phosphorus were quantified as the nocturnal melatonin and serotonin urinary excretion. Partial correlations adjusted for height, Tanner score and physical activity confirmed positive relationships between BMC or BMD L1-L4 (Z-score) and lean mass or fat. Furthermore, positive relationship was observed between BMC or BMD L1-L4 (Z-score) and serum leptin. After adjustment for Tanner score and physical activity, positive associations were observed between lean mass and IGF-1, leptin levels or muscle force. We proved positive relationships between bone mass and serum leptin in peripubertal girls.

Dihydrotestosterone, a robust promoter of osteoblastic proliferation and differentiation: understanding of time-mannered and dose-dependent control of bone forming cells

Objective(s):

The present study was aimed to evaluate the time-mannered and dose-dependent effects of 5α-dihydrotestosterone (5α-DHT) on the proliferation and differentiation of bone forming cells using MC3T3-E1 cells.

Materials and Methods:

Cell proliferation was analyzed using MTS and phase contrast microscopic assays. Osteogenic differentiation was assessed through a series of in vitro experiments including crystal violet staining, alkaline phosphatase (ALP) activity, and Van Gieson (VG) staining. Taken together, the efficiency of bone mineralization was examined by using alizarin red s (ARS) staining, Von Kossa staining, scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analysis.

Results:

The resulting data revealed that 5α-DHT exhibits promising potential particularly at a dose of 0.1 ng/ml, in promoting the growth of MC3T3-E1 cells compared to the control group (CN). Moreover, a significantly higher ALP activity was evident in the experimental group treated with 5α-DHT compared to the CN group at various time intervals. MC3T3-E1 cells treated with 5α-DHT also expressed a remarkably higher collagen deposition and mineralization (calcium and phosphate contents) compared to the CN group at various time intervals.

Conclusion:

Conclusively, we suggest that 5α-DHT exhibits outstanding potential of promoting proliferation and differentiation in osteoblasts which could be the in vitro basis for the efficacy of 5α-DHT in the treatment of androgen-deficient male osteoporosis.

Network meta-analysis of the efficacy and adverse effects of several treatments for advanced/metastatic prostate cancer

This network meta-analysis was conducted to compare the efficacy and adverse effects of several treatments for advanced/metastatic prostate cancer (PC). The PubMed and Cochrane Library databases were searched for randomized controlled trials of treatments for advanced/metastatic PC. Eighteen studies covering 6,340 patients were included in this analysis. The calculated were odds ratios, 95% confidence intervals, and the surface under the cumulative ranking (SUCRA) curve. Pairwise meta-analysis showed that overall survival rates achieved with radiotherapy or endocrine therapy were lower than obtained with radiotherapy + endocrine therapy. The endocrine therapy includes estrogen therapy, luteinizing hormone-releasing hormone agonist (LHRH-A), anti-androgen therapy (ADT), ADT + LHRH-A and estrogen therapy + LHRH-A, and its SUCRA values indicated that for overall response rate, estrogen therapy + LHRH-A ranked the highest (92.6%); for overall survival rate, ADT ranked the highest (75.2%); for anemia, estrogen therapy ranked the highest (88.2%); and for diarrhea and hot flushes, ADT ranked the highest (diarrhea, 87.4%; hot flushes, 89.3%). Cluster analysis on the endocrine therapy showed that ADT + LHRH-A achieved the highest overall survival and overall response rates in the treatment of advanced/metastatic PC. Estrogen therapy and ADT had the lowest incidences of diarrhea and anemia. Thus, combined radiotherapy + endocrine therapy had higher overall survival rate, and among the endocrine therapy, in terms of overall response rate and overall survival rate, ADT + LHRH-A may be a better regimen in the treatment of advanced or metastatic PC.

Cathepsin K Inhibitors for Osteoporosis: Biology, Potential Clinical Utility, and Lessons Learned

Cathepsin K is a cysteine protease member of the cathepsin lysosomal protease family. Although cathepsin K is highly expressed in osteoclasts, lower levels of cathepsin K are also found in a variety of other tissues. Secretion of cathepsin K from the osteoclast into the sealed osteoclast-bone cell interface results in efficient degradation of type I collagen. The absence of cathepsin K activity in humans results in pycnodysostosis, characterized by increased bone mineral density and fractures. Pharmacologic cathepsin K inhibition leads to continuous increases in bone mineral density for ≤5 years of treatment and improves bone strength at the spine and hip. Compared with other antiresorptive agents, cathepsin K inhibition is nearly equally efficacious for reducing biochemical markers of bone resorption but comparatively less active for reducing bone formation markers. Despite multiple efforts to develop cathepsin K inhibitors, potential concerns related to off-target effects of the inhibitors against other cathepsins and cathepsin K inhibition at nonbone sites, including skin and perhaps cardiovascular and cerebrovascular sites, prolonged the regulatory approval process. A large multinational randomized, double-blind phase III study of odanacatib in postmenopausal women with osteoporosis was recently completed. Although that study demonstrated clinically relevant reductions in fractures at multiple sites, odanacatib was ultimately withdrawn from the regulatory approval process after it was found to be associated with an increased risk of cerebrovascular accidents. Nonetheless, the underlying biology and clinical effects of cathepsin K inhibition remain of considerable interest and could guide future therapeutic approaches for osteoporosis.

Osteoporosis in men

Osteoporotic fractures are the leading cause of morbidity and mortality among aging men. 30% of all hip fractures occur in men, and mortality resulting from not only the hip fracture, but also the spine and other major osteoporotic fractures, is significantly higher in men than in women. As in women, hypogonadism is the best documented risk factor for developing osteoporosis in men. In older men, testosterone levels are negatively correlated with the risk of fractures, and it seems that this age-related testosterone deficiency should not be considered as one of the many causes of secondary osteoporosis, rather one of the major and most important mechanisms of senile osteoporosis. Acute hypogonadism induced by ablation treatment for prostate cancer (surgical or pharmacological castration, antiandrogen therapy) is associated with an extremely high risk of fracture. Other documented causes of bone loss in men are cigarette smoking and alcohol abuse, and a number of diseases that require corticosteroid treatment. Pharmacotherapy of osteoporosis should be recommended to all men with a diagnosed osteoporotic fracture and all men with a high 10-year absolute fracture risk (FRAX^TM). Not all drugs registered for the treatment of postmenopausal osteoporosis have been registered for the treatment of osteoporosis in men, and others have not been the subject of long-term and costly clinical trials required for such registration. The risk reduction of new fractures was documented only for treatment with zoledronic acid. Risedronate, strontium ranelate, teriparatide, and denosumab in men increase in bone mineral density comparable to that seen in postmenopausal women.

Effect of Testosterone Treatment on Volumetric Bone Density and Strength in Older Men With Low Testosterone: A Controlled Clinical Trial

IMPORTANCE

As men age, they experience decreased serum testosterone concentrations, decreased bone mineral density (BMD), and increased risk of fracture.

OBJECTIVE

To determine whether testosterone treatment of older men with low testosterone increases volumetric BMD (vBMD) and estimated bone strength.

DESIGN, SETTING, AND PARTICIPANTS

Placebo-controlled, double-blind trial with treatment allocation by minimization at 9 US academic medical centers of men 65 years or older with 2 testosterone concentrations averaging less than 275 ng/L participating in the Testosterone Trials from December 2011 to June 2014. The analysis was a modified intent-to-treat comparison of treatment groups by multivariable linear regression adjusted for balancing factors as required by minimization.

INTERVENTIONS

Testosterone gel, adjusted to maintain the testosterone level within the normal range for young men, or placebo gel for 1 year.

MAIN OUTCOMES AND MEASURES

Spine and hip vBMD was determined by quantitative computed tomography at baseline and 12 months. Bone strength was estimated by finite element analysis of quantitative computed tomography data. Areal BMD was assessed by dual energy x-ray absorptiometry at baseline and 12 months.

RESULTS

There were 211 participants (mean [SD] age, 72.3 [5.9] years; 86% white; mean [SD] body mass index, 31.2 [3.4]). Testosterone treatment was associated with significantly greater increases than placebo in mean spine trabecular vBMD (7.5%; 95% CI, 4.8% to 10.3% vs 0.8%; 95% CI, -1.9% to 3.4%; treatment effect, 6.8%; 95% CI, 4.8%-8.7%; P < .001), spine peripheral vBMD, hip trabecular and peripheral vBMD, and mean estimated strength of spine trabecular bone (10.8%; 95% CI, 7.4% to 14.3% vs 2.4%; 95% CI, -1.0% to 5.7%; treatment effect, 8.5%; 95% CI, 6.0%-10.9%; P < .001), spine peripheral bone, and hip trabecular and peripheral bone. The estimated strength increases were greater in trabecular than peripheral bone and greater in the spine than hip. Testosterone treatment increased spine areal BMD but less than vBMD.

CONCLUSIONS AND RELEVANCE

Testosterone treatment for 1 year of older men with low testosterone significantly increased vBMD and estimated bone strength, more in trabecular than peripheral bone and more in the spine than hip. A larger, longer trial could determine whether this treatment also reduces fracture risk.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00799617.

Male Hypogonadism and Osteoporosis: The Effects, Clinical Consequences, and Treatment of Testosterone Deficiency in Bone Health

It is well recognized that bone loss accelerates in hypogonadal states, with female menopause being the classic example of sex hormones affecting the regulation of bone metabolism. Underrepresented is our knowledge of the clinical and metabolic consequences of overt male hypogonadism, as well as the more subtle age-related decline in testosterone on bone quality. While menopause and estrogen deficiency are well-known risk factors for osteoporosis in women, the effects of age-related testosterone decline in men on bone health are less well known. Much of our knowledge comes from observational studies and retrospective analysis on small groups of men with variable causes of primary or secondary hypogonadism and mild to overt testosterone deficiencies. This review aims to present the current knowledge of the consequences of adult male hypogonadism on bone metabolism. The direct and indirect effects of testosterone on bone cells will be explored as well as the important differences in male osteoporosis and assessment as compared to that in females. The clinical consequence of both primary and secondary hypogonadism, as well as testosterone decline in older males, on bone density and fracture risk in men will be summarized. Finally, the therapeutic options and their efficacy in male osteoporosis and hypogonadism will be discussed.

Eurycoma longifolia as a potential alternative to testosterone for the treatment of osteoporosis: Exploring time-mannered proliferative, differentiative and morphogenic modulation in osteoblasts

ETHNOPHARMACOLOGICAL RELEVANCE

Eurycoma longifolia (EL) has been well-studied traditionally as a chief ingredient of many polyherbal formulations for the management of male osteoporosis. It has also been well-recognised to protect against bone calcium loss in orchidectomised rats.

AIM OF THE STUDY

To evaluate the effects of EL on the time-mannered sequential proliferative, differentiative, and morphogenic modulation in osteoblasts compared with testosterone.

MATERIALS AND METHODS

Cell proliferation was analysed using MTS assay and phase contrast microscopy. Osteogenic differentiation of MC3T3-E1 cells was assessed through a series of characteristic assays which include crystal violet staining, alkaline phosphatase (ALP) activity and Van Gieson staining. Taken together, the bone mineralization of extra cellular matrix (ECM) was estimated using alizarin red s (ARS) staining, von kossa staining, scanning electron microscopic (SEM) and energy dispersive x-ray (EDX) analysis.

RESULTS

The cell proliferation data clearly revealed the efficiency of EL particularly at a dose of 25µg/mL, in improving the growth of MC3T3-E1 cells compared with the untreated cells. Data also showed the prominence of EL in significantly promoting ALP activity throughout the entire duration of treatment compared with the testosterone-treated cells. The osteogenic differentiation potential of EL was further explored by analysing mineralization data which revealed that the calcified nodule formation (calcium deposition) and phosphate deposition was more pronounced in cells treated with 25µg/mL concentration of EL at various time points compared with the untreated and testosterone treated cells. The scanning electron microscopic (SEM) analysis also revealed highest globular masses of mineral deposits (identified as white colour crystals) in the ECM of cultured cells treated with 25µg/mL concentration of EL.

CONCLUSION

Compared to testosterone, greater potential of EL in promoting the proliferation and osteogenic differentiation of MC3T3-E1 cells provides an in vitro basis for the prevention of male osteoporosis. Thus, we anticipate that EL can be considered as an alternative approach to testosterone replacement therapy (TRT) for the treatment of male osteoporosis.

Vertebral Volumetric Bone Density and Strength Are Impaired in Women With Low-Weight and Atypical Anorexia Nervosa

CONTEXT

Areal bone mineral density (BMD) is lower, particularly at the spine, in low-weight women with anorexia nervosa (AN). However, little is known about vertebral integral volumetric BMD (Int.vBMD) or vertebral strength across the AN weight spectrum, including "atypical" AN [body mass index (BMI) ≥18.5 kg/m2].

OBJECTIVE

To investigate Int.vBMD and vertebral strength, and their determinants, across the AN weight spectrum.

DESIGN

Cross-sectional observational study.

SETTING

Clinical research center.

PARTICIPANTS

153 women (age 18 to 45): 64 with low-weight AN (BMI <18.5 kg/m2; 58% amenorrheic), 44 with atypical AN (18.5≤BMI<23 kg/m2; 30% amenorrheic), 45 eumenorrheic controls (19.2≤BMI<25 kg/m2).

MEASURES

Int.vBMD and cross-sectional area (CSA) by quantitative computed tomography of L4; estimated vertebral strength (derived from Int.vBMD and CSA).

RESULTS

Int.vBMD and estimated vertebral strength were lowest in low-weight AN, intermediate in atypical AN, and highest in controls. CSA did not differ between groups; thus, vertebral strength (calculated using Int.vBMD and CSA) was driven by Int.vBMD. In AN, Int.vBMD and vertebral strength were associated positively with current BMI and nadir lifetime BMI (independent of current BMI). Int.vBMD and vertebral strength were lower in AN with current amenorrhea and longer lifetime amenorrhea duration. Among amenorrheic AN, Int.vBMD and vertebral strength were associated positively with testosterone.

CONCLUSIONS

Int.vBMD and estimated vertebral strength (driven by Int.vBMD) are impaired across the AN weight spectrum and are associated with low BMI and endocrine dysfunction, both current and previous. Women with atypical AN experience diminished vertebral strength, partially due to prior low-weight and/or amenorrhea. Lack of current low-weight or amenorrhea in atypical AN does not preclude compromise of vertebral strength.

Estrogens and Androgens in Skeletal Physiology and Pathophysiology

Estrogens and androgens influence the growth and maintenance of the mammalian skeleton and are responsible for its sexual dimorphism. Estrogen deficiency at menopause or loss of both estrogens and androgens in elderly men contribute to the development of osteoporosis, one of the most common and impactful metabolic diseases of old age. In the last 20 years, basic and clinical research advances, genetic insights from humans and rodents, and newer imaging technologies have changed considerably the landscape of our understanding of bone biology as well as the relationship between sex steroids and the physiology and pathophysiology of bone metabolism. Together with the appreciation of the side effects of estrogen-related therapies on breast cancer and cardiovascular diseases, these advances have also drastically altered the treatment of osteoporosis. In this article, we provide a comprehensive review of the molecular and cellular mechanisms of action of estrogens and androgens on bone, their influences on skeletal homeostasis during growth and adulthood, the pathogenetic mechanisms of the adverse effects of their deficiency on the female and male skeleton, as well as the role of natural and synthetic estrogenic or androgenic compounds in the pharmacotherapy of osteoporosis. We highlight latest advances on the crosstalk between hormonal and mechanical signals, the relevance of the antioxidant properties of estrogens and androgens, the difference of their cellular targets in different bone envelopes, the role of estrogen deficiency in male osteoporosis, and the contribution of estrogen or androgen deficiency to the monomorphic effects of aging on skeletal involution.

Testosterone therapy and prostate cancer

The use of exogenous testosterone to treat hypogonadism in the men with a history of prostate cancer (CaP) remains controversial due to fears of cancer recurrence or progression. Due to the detrimental impact of hypogonadism on patient quality of life, recent work has examined the safety of testosterone therapy (TTh) in men with a history of CaP. In this review, we evaluate the literature with regards to the safety of TTh in men with a history of CaP. TTh results in improvements in quality of life with little evidence of biochemical recurrence or progression in men with a history of CaP, or de novo cancer in unaffected men. An insufficient amount of evidence is currently available to truly demonstrate the safe use of TTh in men with low risk CaP. In men with high-risk cancer, more limited data suggest that TTh may be safe, but these findings remain inconclusive. Despite the historic avoidance of TTh in men with a history of CaP, the existing body of evidence largely supports the safe and effective use of testosterone in these men, although additional study is needed before unequivocal safety can be demonstrated.

A concise review of testosterone and bone health

Osteoporosis is a condition causing significant morbidity and mortality in the elderly population worldwide. Age-related testosterone deficiency is the most important factor of bone loss in elderly men. Androgen can influence bone health by binding to androgen receptors directly or to estrogen receptors (ERs) indirectly via aromatization to estrogen. This review summarized the direct and indirect effects of androgens on bone derived from in vitro, in vivo, and human studies. Cellular studies showed that androgen stimulated the proliferation of preosteoblasts and differentiation of osteoblasts. The converted estrogen suppressed osteoclast formation and resorption activity by blocking the receptor activator of nuclear factor k-B ligand pathway. In animal studies, activation of androgen and ERα, but not ERβ, was shown to be important in acquisition and maintenance of bone mass. Human epidemiological studies demonstrated a significant relationship between estrogen and testosterone in bone mineral density and fracture risk, but the relative significance between the two remained debatable. Human experimental studies showed that estrogen was needed in suppressing bone resorption, but both androgen and estrogen were indispensable for bone formation. As a conclusion, maintaining optimal level of androgen is essential in preventing osteoporosis and its complications in elderly men.

Effects of Testosterone and Estradiol Deficiency on Vasomotor Symptoms in Hypogonadal Men

CONTEXT

The hormonal basis of vasomotor symptoms (VMS) in hypogonadal men is incompletely understood.

OBJECTIVE

To determine the contributions of testosterone and estradiol deficiency to VMS in hypogonadal men.

DESIGN

Two randomized trials were conducted sequentially between September 2004 and April 2011. Controls were recruited separately.

SETTING

A single-site academic medical center.

PARTICIPANTS

Healthy men ages 20-50, with normal serum testosterone levels.

INTERVENTION

Cohort 1 (n = 198, 81% completion) received goserelin acetate every 4 weeks to suppress gonadal steroids and were randomized to placebo or 1.25, 2.5, 5, or 10 g of testosterone gel daily for 16 weeks. Cohort 2 (n = 202, 78% completion) received the same regimen as cohort 1 plus anastrozole to block aromatization of testosterone. Controls (n = 37, 89% completion) received placebos for goserelin acetate and testosterone.

MAIN OUTCOME MEASURES

Incidence of visits with VMS. This was a preplanned secondary analysis.

RESULTS

VMS were reported at 26% of visits in cohort 1, and 35% of visits in cohort 2 (P = .02), demonstrating an effect of estradiol deficiency. When adjacent estradiol level groups in cohort 1 were compared, the largest difference in VMS incidence was observed between the 5-9.9 and 10-14.9 pg/mL groups (38% vs 16%, P < .001). In cohort 2, the 10-g testosterone group differed significantly from placebo (16% vs 43%, P = .048) after adjustment for small differences in estradiol levels, indicating that high testosterone levels may suppress VMS.

CONCLUSIONS

Estradiol deficiency is the key mediator of VMS in hypogonadal men. At high levels, testosterone may have a suppressive effect.

Enclomiphene citrate for the treatment of secondary male hypogonadism

INTRODUCTION

Hypogonadism is a growing concern in an aging male population. Historically treated using exogenous testosterone, concerns about possible adverse effects of testosterone have led physicians to seek alternative treatment approaches.

AREAS COVERED

Enclomiphene citrate is the trans isomer of clomiphene citrate, a non-steroidal estrogen receptor antagonist that is FDA-approved for the treatment of ovarian dysfunction in women. Clomiphene citrate has also been used off-label for many years to treat secondary male hypogonadism, particularly in the setting of male infertility. Here we review the literature examining the efficacy and safety of enclomiphene citrate in the setting of androgen deficiency.

EXPERT OPINION

Initial results support the conclusion that enclomiphene citrate increases serum testosterone levels by raising luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels, without negatively impacting semen parameters. The ability to treat testosterone deficiency in men while maintaining fertility supports a role for enclomiphene citrate in the treatment of men in whom testosterone therapy is not a suitable option.

Testosterone and Adult Male Bone: Actions Independent of 5α-Reductase and Aromatase

Androgens and estrogens influence skeletal development and maintenance in males. However, the relative contributions of the circulating sex steroid hormones that originate from testicular/adrenal secretion versus those produced locally in bone via intracrine action require further elucidation. Our novel hypothesis is that testosterone exerts direct protective effects on the adult male skeleton independently of the actions of 5α-reductase or aromatase.

Analysis of the relationship between the blood concentration of several metals, macro- and micronutrients and endocrine disorders associated with male aging

Beyond 30 years of age, men experience a decline in the production of testosterone, yet only a few develop late-onset hypogonadism. This study was designed to determine the relationship between blood concentrations of metals, macro- and micronutrients and age-related testosterone deficiency and associated hormonal changes in aging men. The research involved 313 men aged 50-75 years. We used ELISA to determine the concentrations of total testosterone (TT), free testosterone (FT), estradiol (E2), dehydroepiandrosterone sulfate (DHEAS) and sex hormone-binding globulin (SHBG). We calculated free androgen index (FAI). With the use of emission spectrometry in inductively coupled argon plasma, we determined the whole-blood concentrations of lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As) and tungsten (W), as well as serum concentrations of magnesium (Mg), iron (Fe), calcium (Ca), copper (Cu), zinc (Zn), selenium (Se), chromium (Cr), manganese (Mn) and molybdenum (Mo). The study showed no relationship between TT and FT and the concentrations of metals. Men with TT deficiency had significantly lower concentrations of Mg and Fe and increased Mn. Men with FT deficiency had higher W and Cr levels and lower Fe. Assessing the correlation between the concentrations of hormones, SHBG and FAI, and the concentration of metals and macro- and microelements in the blood of the men, we found positive correlations between the concentrations of TT-Mg, TT-Fe, TT-Mo, FT-Fe, E2-As, SHBG-Mn, FAI-W, FAI-As, FAI-Zn and FAI-Ca, and negative correlations between the concentrations of TT-Mn, FT-Cd, FT-Cr, E2-Hg, E2-Cr, SHBG-W, SHBG-As, SHBG-Zn, SHBG-Ca, FAI-Pb and FAI-Mn. Positive correlations between As and E2 and between As and FAI may suggest a lack of association between this metal and hypogonadism in people not exposed to excess As levels. Our research indicates a positive relationship between the concentrations of Mg, Fe and Zn and endocrine system in aging men, in contrast to Mn and Cr. Toxic metals (Cd, Pb) seemed to negatively affect the level of bioavailable testosterone. In persons not exposed to As, As does not contribute late-onset hypogonadism. Heavy metals (Pb, Cd, Hg and W) may contribute to a lower concentration of DHEAS. The role of W in men with LOH was found to be ambiguous, as on the one hand its concentration was higher in men with FT deficiency, and on the other hand it positively correlated with FAI, which in turn indirectly indicates testosterone availability. Copper and selenium do not seem to play any significant role in the occurrence of TT deficiency in aging men.

Increased risk of osteoporosis in patients with erectile dysfunction: A nationwide population-based cohort study

In this study, we aimed to investigate the risk of osteoporosis in patients with erectile dysfunction (ED) by analyzing data from the Taiwan National Health Insurance Research Database (NHIRD). From the Taiwan NHIRD, we analyzed data on 4460 patients aged ≥40 years diagnosed with ED between 1996 and 2010. In total, 17,480 age-matched patients without ED in a 1:4 ratio were randomly selected as the non-ED group. The relationship between ED and the risk of osteoporosis was estimated using Cox proportional hazard regression models. During the follow-up period, 264 patients with ED (5.92%) and 651 patients without ED (3.65%) developed osteoporosis. The overall incidence of osteoporosis was 3.04-fold higher in the ED group than in the non-ED group (9.74 vs 2.47 per 1000 person-years) after controlling for covariates. Compared with patients without ED, patients with psychogenic and organic ED were 3.19- and 3.03-fold more likely to develop osteoporosis. Our results indicate that patients with a history of ED, particularly younger men, had a high risk of osteoporosis. Patients with ED should be examined for bone mineral density, and men with osteoporosis should be evaluated for ED.

Hepatitis C virus coinfection as a risk factor for osteoporosis and fracture

PURPOSE OF REVIEW

With increased survival of HIV-infected patients, osteoporotic fractures have developed as a major cause of morbidity in these patients, and chronic hepatitis C virus (HCV) coinfection has emerged as a significant contributor to this increased fracture risk. The present article reviews the epidemiologic and clinical evidence for osteoporosis and increased fracture risk among HIV/HCV coinfected patients, and potential mechanisms for these outcomes with HCV coinfection.

RECENT FINDINGS

Epidemiologic studies suggest that HIV/HCV coinfected patients exhibit a three-fold increased fracture incidence compared with uninfected controls, and 1.2-2.4-fold increased fracture risk compared with HIV monoinfected patients. Recent reports suggest that chronic HCV coinfection is independently associated with reduced bone mineral density in HIV, but that it is not associated with significantly increased bone turnover. The deleterious impact of chronic HCV on BMD and fracture risk occurs even in the absence of advanced liver fibrosis or cirrhosis. New tools to assess bone quality, including the trabecular bone score, high-resolution peripheral quantitative computed tomography, and in-vivo microindentation, may help improve understanding of the mechanisms of HCV-associated skeletal fragility. The impact of approved antiosteoporosis medications and direct-acting antivirals for the treatment of chronic HCV infection on patients' bone health remain to be studied.

SUMMARY

Chronic HCV infection is an independent risk factor for osteoporosis and fractures among HIV-infected patients, even before the development of cirrhosis. The underlying mechanisms are being unraveled, but major questions persist regarding the optimal evaluation and management of bone health in HIV/HCV coinfected patients.

Battle of the sex steroids in the male skeleton: and the winner is

Male osteoporosis is a multifactorial disease, although it is often in part related to hypogonadism. While testosterone replacement therapy has been shown to improve bone mineral density, studies have also linked bone loss and higher fracture risk in men to low estrogen levels. In this issue of the JCI, Finkelstein and colleagues report the results of a clinical study in a cohort of healthy adult men aimed at further discerning the specific roles of androgen and estrogen deficiency in bone loss. The results of their study support previous findings that estrogen deficiency has a dramatic effect on bone homeostasis in men. Future studies to corroborate and expand on these findings have potential to influence the clinical management of male osteoporosis.

Gonadal steroid-dependent effects on bone turnover and bone mineral density in men

BACKGROUND

Severe gonadal steroid deficiency induces bone loss in adult men; however, the specific roles of androgen and estrogen deficiency in hypogonadal bone loss are unclear. Additionally, the threshold levels of testosterone and estradiol that initiate bone loss are uncertain.

METHODS

One hundred ninety-eight healthy men, ages 20-50, received goserelin acetate, which suppresses endogenous gonadal steroid production, and were randomized to treatment with 0, 1.25, 2.5, 5, or 10 grams of testosterone gel daily for 16 weeks. An additional cohort of 202 men was randomized to receive these treatments plus anastrozole, which suppresses conversion of androgens to estrogens. Thirty-seven men served as controls and received placebos for goserelin and testosterone. Changes in bone turnover markers, bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA), and BMD by quantitative computed tomography (QCT) were assessed in all men. Bone microarchitecture was assessed in 100 men.

RESULTS

As testosterone dosage decreased, the percent change in C-telopeptide increased. These increases were considerably greater when aromatization of testosterone to estradiol was also suppressed, suggesting effects of both testosterone and estradiol deficiency. Decreases in DXA BMD were observed when aromatization was suppressed but were modest in most groups. QCT spine BMD fell substantially in all testosterone-dose groups in which aromatization was also suppressed, and this decline was independent of testosterone dose. Estradiol deficiency disrupted cortical microarchitecture at peripheral sites. Estradiol levels above 10 pg/ml and testosterone levels above 200 ng/dl were generally sufficient to prevent increases in bone resorption and decreases in BMD in men.

CONCLUSIONS

Estrogens primarily regulate bone homeostasis in adult men, and testosterone and estradiol levels must decline substantially to impact the skeleton.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00114114.

FUNDING

AbbVie Inc., AstraZeneca Pharmaceuticals LP, NIH.

Mechanisms of bone disease in HIV and hepatitis C virus: impact of bone turnover, tenofovir exposure, sex steroids and severity of liver disease

OBJECTIVE

Both HIV and hepatitis C virus (HCV) infections are associated with higher osteoporotic fracture risk. Increased bone turnover, liver fibrosis, tenofovir (TDF) use or hormonal imbalances are possible underlying mechanisms.

DESIGN

This prospective, cross-sectional study assessed 298 male volunteers with either virologically suppressed HIV or untreated HCV mono-infections, HIV/HCV co-infection and noninfected controls.

METHODOLOGY

Study participants underwent bone mineral density (BMD) by dual-energy x-ray absorptiometry and measurement of bone turnover markers [BTM: C-telopeptide (CTX) and osteocalcin (OC)], insulin-like growth factor-1 (IGF-1), the sex steroids testosterone (T) and estradiol (E2), and the aspartate aminotransferase-to-platelet ratio index (APRI). Impact of HIV and HCV status on BMD was evaluated in multivariate models adjusting for APRI score, BTM, TDF exposure, IGF-1, and sex steroids.

RESULTS

HIV and HCV status independently predicted lower BMD, controlling for age, race, BMI, and smoking (P = 0.017 and P = 0.010, respectively), whereas APRI did not (P = 0.84). HIV was associated with increased bone resorption (CTX: P < 0.001) and formation (OC: P = 0.014), whereas HCV infection was not associated with CTX (P = 0.30) or OC (P = 0.36). TDF exposure was associated with lower BMD (P < 0.01). IGF-1 was significantly decreased in HCV and increased in HIV. Tumor necrosis factor-α (P = 0.98), IGF-1 (P = 0.80), bioavailable T (P = 0.45) and E2 (P = 0.27) were not associated with BMD and did not attenuate the impact of HIV or HCV on BMD.

CONCLUSION

HIV and TDF exposure decrease BMD through increased bone turnover, although the lower BMD in HCV is not explained by a high turnover state. Neither virus' effect on BMD is likely mediated through increased inflammation, liver fibrosis, IGF-1, or sex steroids.

Blood Cadmium Is Associated with Osteoporosis in Obese Males but Not in Non-Obese Males: The Korea National Health and Nutrition Examination Survey 2008-2011

Osteoporosis in males is becoming an important health concern in an aging society. The aim of this study was to investigate the associations between cadmium exposure and osteoporosis by considering the effect of obesity in aged males using a representative sample of the Korean population. Using the fourth and fifth Korea National Health and Nutrition Examination Survey data, 1089 males over 50 years of age were analyzed. The blood cadmium concentration was measured. The bone mineral density in the total hip, femur neck, and lumbar spine was measured using dual-energy X-ray absorptiometry. T-scores to determine the presence of osteoporosis were calculated using a Korean reference. Subjects were stratified into two groups according to obesity status (body mass index <25 kg/m² and ≥25 kg/m²). In comparison with obese subjects with blood cadmium <1.00 μg/L, those with blood cadmium >1.50 μg/L had odds ratios of 4.57 (95% confidence interval [CI] 1.49–14.01) and 5.71 (95% CI 1.99–16.38) at the femur neck and any site, respectively, after adjusting for potential confounders such as age, serum creatinine, vitamin D deficiency, smoking, alcohol drinking, and physical activity level. However, this association was not significant in non-obese males. In conclusion, the effect of cadmium on osteoporosis was different by obesity status in aged males.

Management of endocrine disease: Secondary osteoporosis: pathophysiology and management

Osteoporosis is a skeletal disorder characterized by decreased mass and compromised bone strength predisposing to an increased risk of fractures. Although idiopathic osteoporosis is the most common form of osteoporosis, secondary factors may contribute to the bone loss and increased fracture risk in patients presenting with fragility fractures or osteoporosis. Several medical conditions and medications significantly increase the risk for bone loss and skeletal fragility. This review focuses on some of the common causes of osteoporosis, addressing the underlying mechanisms, diagnostic approach and treatment of low bone mass in the presence of these conditions.