Low levels of estradiol are associated with vertebral fractures in older men, but not women: the Rancho Bernardo Study

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.

The Association Between Heavy Metals Exposure and Sex Hormones: a Systematic Review on Current Evidence

The general population is voluntarily or unintentionally exposed to heavy metals through ingestion of food, polluted water, or contact with soil, dust, or polluted air. A number of metals are considered as endocrine disruptors and can alter the level of reproductive hormones. This study aims to systematically review the epidemiological studies on the association between heavy metals exposure and sex hormones level. We conducted a systematic search from available databases, including PubMed, Clarivate Web of Science, Scopus, Google Scholar, and Cochrane Collaboration, until April 2021. The relevant studies were selected, and two reviewers conducted the quality assessment. Then, data were extracted based on the inclusion criteria. We identified nine articles related to the association between heavy metals exposure and sex hormones level. We summarized the relevant information. Due to the diversity of metals and the variety of sex hormones, the effect of exposure on hormones level was not clear; however in most studies, at least for one metal, a significant association (inverse or positive) was observed between metals exposure and hormones level. Heavy metals exposure may potentially alter sex hormone levels; however, further research is needed to evaluate the impact of this association.

The importance of association between sexsteroids deficiency, reduction of bone mineral density and falling risk in men with implications in medical rehabilitation

Introduction. Endocrino-metabolic rehabilitation represent one of the most complex sector in clinical medicine, regarding functional rehabilitation. Sex hormones deficiency plays an important role in the etiology of osteoporosis in men. At the same time, with age, the trophic role of androgens on muscle decreases and determines an increased frequency of falls. The objective of our study is to determine the association between sexsteroids deficiency, reduction of bone mineral density (BMD) and falling risk in men. Methods. Our retrospective cross-sectional study included 146 men aged between 65–85 years with low BMD (study group) and 121 men with normal BMD (control group). The measurement of Total testosterone (Tt), free testosterone (Tf) and estradiol (E2) serum levels was performed using the immunoassay or the immunoenzymatic methods. Femoral neck and lumbar spine BMD was determined using Dual-energy X-ray absorptiometry (DEXA). The risk of falls was assessed by Tandem Standing, Up & Go, Chair – Rising and walking speed tests. Results. We found a significantly association between Tf and E2 deficiency and low BMD (p=0.007). Also, in men with reduced BMD (study group) we observed significant lower levels of Tf (p<0.001) and E2 (p=0.003) compared to control group. E2 deficiency was associated significantly with low BMD and increased fall risk (p=0.001). At the same time the results highlighted significant lower levels of Tf in patients with BMD reduction and increased risk of falls (p=0.002). Tt deficiency was not associated with BMD reduction (p=0.088) or increased risk of falling (p=0.277). Conclusions. This research revealed a significant association between male sexsteroids deficiency, low BMD and increase of falling risk, with implications in rehabilitation program. The risk of ostoporosis and for falling in man can be estimated by determining serum Tf and E2 levels. Keywords: sexsteroids deficiency; bone mineral density; falling risk,

Hypogonadism, Type-2 Diabetes Mellitus, and Bone Health: A Narrative Review

One of the complications from chronic hyperglycemia and insulin resistance due to type 2 diabetes mellitus (T2DM) on the hypothalamic-pituitary-gonadal axis in men is the high prevalence of hypogonadotropic hypogonadism (HH). Both T2DM and hypogonadism are associated with impaired bone health and increased fracture risk but whether the combination results in even worse bone disease than either one alone is not well-studied. It is possible that having both conditions predisposes men to an even greater risk for fracture than either one alone. Given the common occurrence of HH or hypogonadism in general in T2DM, a significant number of men could be at risk. To date, there is very little information on the bone health men with both hypogonadism and T2DM. Insulin resistance, which is the primary defect in T2DM, is associated with low testosterone (T) levels in men and may play a role in the bidirectional relationship between these two conditions, which together may portend a worse outcome for bone. The present manuscript aims to review the available evidences on the effect of the combination of hypogonadism and T2DM on bone health and metabolic profile, highlights the possible metabolic role of the skeleton, and examines the pathways involved in the interplay between bone, insulin resistance, and gonadal steroids.

Is There Room for SERMs or SARMs as Alternative Therapies for Adult Male Hypogonadism?

Hypogonadotropic hypogonadism (HH) can be sustained by organic or functional alterations of the hypothalamic-pituitary-testicular axis. Functional HH is related to systemic alterations, such as obesity or chronic inflammatory diseases, but could contribute to a negative course of the illness. For such situation, according to results obtained in infertile women, the administration of selective estrogen receptor modulators (SERMs) has been proposed in males too, with positive results on both metabolic and sexual function. This class of medications increases gonadotropin levels via antagonism to the estrogenic receptor; similar biological effects are also exerted by aromatase inhibitors (AIs), despite different mechanism of action. After a brief review of trials regarding SERMs and AIs use in male HH, we describe the structure and function of the androgen receptor (AR) as a basis for clinical research about compounds able to bind to AR, in order to obtain specific effects (SARMs). The tissue selectivity and different metabolic fate in comparison to testosterone can potentiate anabolic versus androgenic effects; therefore, they might be a valid alternative to testosterone replacement therapy avoiding the negative effects of testosterone (i.e., on prostate, liver, and hematopoiesis). Trials are still at an early phase of investigation and, at the moment, the application seems to be more useful for chronic disease with catabolic status while the validation as replacement for hypogonadism requires further studies.

Bone and body composition response to testosterone therapy vary according to polymorphisms in the CYP19A1 gene

PURPOSE

To evaluate the influence of single nucleotide polymorphisms (SNPs) of CYP19A1 on the response and susceptibility to side effects from testosterone therapy. This is a prospective, single-arm study of men with low-morning serum testosterone (<10.68 nmol/l) administered testosterone cypionate 200 mg intramuscularly every 2 weeks for 18 months.

METHODS

We measured areal bone mineral density (aBMD) and body composition by dual energy X-ray absorptiometry, tibial volumetric BMD and geometry by peripheral quantitative computer tomography, bone turnover markers by enzyme-linked immunosorbent assay, testosterone, and estradiol by liquid-chromatography/mass-spectroscopy, genotyping by microarray, CYP19A1 expression by quantitative polymerase chain reaction, hematocrit and prostate-specific antigen (PSA).

RESULTS

We enrolled 105 men (40-74-years-old). SNPs rs1062033 and rs700518 were associated with significant differences in outcomes at 18 months. The GG genotype in rs1062033 had significant increase in whole body aBMD, but had significant decrease in tibial bone size compared to the CG and CC genotypes. Body composition analysis showed that the CC genotype of rs1062033, and the AA genotype of rs700518, had significant increase in total lean and appendicular lean mass compared to CG and GG, and AG and GG, respectively. The GG genotype of rs700518 had significant increase in PSA (GG = 105.8 ± 23.3% vs. AG + AA = 53.4 ± 11.3%, p = 0.046) while hematocrit changes were comparable among genotypes. CYP19A1 expression was highest in GG genotype in both SNPs.

CONCLUSIONS

For the first time, we demonstrated that CYP19A1 SNPs influence response to testosterone therapy in hypogonadal men, highlighting the importance of genetic profiling in therapeutics even for common clinical conditions.

Effect of testosterone treatment on bone remodelling markers and mineral density in obese dieting men in a randomized clinical trial

To assess the effect of testosterone treatment on bone remodelling and density in dieting obese men, 100 obese men aged 53 years (interquartile range 47-60) with a total testosterone level <12 nmol/L receiving 10 weeks of a very low energy diet (VLED) followed by 46 weeks of weight maintenance were randomly assigned at baseline to 56 weeks of intramuscular testosterone undecanoate (n = 49, cases) or matching placebo (n = 51, controls). Pre-specified outcomes were between-group differences (mean adjusted difference, MAD) in serum c-telopeptide (CTx), N-terminal propeptide of type 1 procollagen (P1NP) and bone mineral density (BMD). At trial end, CTx was significantly reduced in men receiving testosterone compared to placebo, MAD -66 ng/L (95% CI -113, -18), p = 0.018, and this was apparent already after the 10 week VLED phase, MAD -63 ng/L (95% CI -108, -18), p = 0.018. P1NP was marginally increased after VLED, MAD +4.2 ug/L (95% CI -0.01, +8.4), p = 0.05 but lower at study end, MAD -5.6 ug/L (95% CI -10.1, -1.1), p = 0.03. No significant changes in sclerostin, lumbar spine BMD or femoral BMD were seen. We conclude that in obese men with low testosterone levels undergoing weight loss, bone remodelling markers are modulated in a way that may have favourable effects on bone mass.

Analysis of correlation between estradiol and fracture of femur neck

Osteoporosis is a major public health challenge all over the world. Estrogen hormone was cited amongst other hormones to be an efficient hormone for the production and maintenance of bone density. This study was designed with the purpose of evaluating and analyzing the estradiol effect on fractures of femur neck in the Iranian society. This study evaluated men over 50 years of age suffering with mild trauma (falling off the same level height or lower) and with a fracture on their femur neck. Also, their serum level of estradiol was measured with an ELISA method. Using this procedure, the patients were assigned into groups with either normal estradiol serum level (10pg/ml and higher) or with lower than normal level (lower than 10 pg/ml). A control group including 50-year-old and older men without hip fracture, or its history, was chosen to access their estradiol serum level. Data collected from these two groups were statistically compared. A total of 120 patients were evaluated (60 in the control and 60 in the test group). The mean age of patients in the control and test groups were 67.9±10.22 and 69.5±8.84 years, respectively (p=0.376). Smoker patients’ percentages in the control and test groups were 35% and 31.7%, respectively (p=0.699). On the basis of the serum estradiol level, patients’ percentages with low estradiol level in control and test groups were 10% and 16.7%, respectively (p=0.283). The only significant factor in predicting serum estradiol level was smoking. In conclusion, in this study it was observed that fractures of the femoral neck following a mild trauma were not correlated to low level of serum estradiol.

Hypogonadal Men with Higher Body Mass Index have Higher Bone Density and Better Bone Quality but Reduced Muscle Density

Although hypogonadism is a risk factor for bone loss and fractures, the different etiopathophysiology and hormonal profile of classical and obesity-induced hypogonadism may lead to differences in musculoskeletal profile. This is a cross-sectional study of hypogonadal men between 40 and 74 years old. Our outcomes include: areal bone mineral density (aBMD) and body composition by dual-energy X-ray absorptiometry; volumetric BMD (vBMD) and soft tissue composition of the tibia by peripheral quantitative computed tomography. Fracture risk assessment tool (FRAX) scores were evaluated. Testosterone, estradiol, luteinizing hormone, follicle stimulating hormone, sex hormone-binding globulin, C-telopeptide, osteocalcin, and sclerostin were measured. We divided the population into subgroups of BMI: group 1: BMI < 30; group 2: BMI ≥30 to <35 and group 3: BMI ≥ 35 kg/m². One-hundred five men were enrolled. Spine and hip aBMD, and total and trabecular vBMD at the 4% tibia significantly increased with increasing BMI. Cortical thickness (330.7 ± 53.2, 343.3 ± 35.4, and 358.7 ± 38.2 mm, p = 0.04; groups 1, 2 and 3, respectively) and cortical area (5.3 ± 0.7, 5.5 ± 0.6, and 5.7 ± 0.6 mm, p = 0.01; groups 1, 2 and 3, respectively) at 38% tibia increased with increasing BMI. While absolute lean mass increased with increasing BMI, % lean mass and muscle density (70.2 ± 5.0, 71.3 ± 6.4, and 67.1 ± 5.1 mg/cm³; groups 1, 2 and 3, respectively) were lowest in group 3. Although severely obese hypogondal men have better BMD and bone quality, they have reduced muscle density, the significance of which remains to be determined.

Oestradiol levels and superoxide dismutase activity in age-related cataract: a case-control study

BACKGROUND

It has been suggested that the higher prevalence of cataract in women is caused by a withdrawal effect of oestrogen at menopause. In vitro studies have demonstrated protection of serum oestradiol (E2) against oxidative stress through upregulation of antioxidant enzymes, including superoxide dismutase (SOD). The purpose of the present study was to investigate E2 levels and SOD erythrocyte activity in patients with age-related cataract.

METHODS

The studied subjects consisted of 103 patients with age-related cataract and 22 controls. Cataracts were classified as nuclear, cortical, or posterior subcapsular. Blood samples were collected and data on smoking, hormonal use, diabetes and age at menarche/menopause was obtained for all individuals. Serum oestradiol analyses were performed with radioimmunoassay (RIA) and SOD activity was measured in erythrocyte lysates.

RESULTS

A negative correlation between age and E2 concentration was seen in a linear regression analysis. No correlation was seen between SOD activity and age or gender and no correlation between E2 levels and SOD activity was found using multiple linear regression. The mean level of E2 for all male subjects was 50.1 ± 16.3 pmol/L, significantly higher compared to 13.8 ± 11.8 pmol/L for postmenopausal women.

CONCLUSION

The present study does not support a role for E2-induced effects on SOD in cataract formation. The findings of higher E2 levels in men than in postmenopausal women may suggest that decreased oestrogen at menopause is partially responsible for the gender-related difference in cataract prevalence. However, the latter can only be verified through prospective randomized trials using hormonal replacement therapy.

Sex hormones, sex hormone binding globulin, and vertebral fractures in older men

The association between sex hormones and sex hormone binding globin (SHBG) with vertebral fractures in men is not well studied. In these analyses, we determined whether sex hormones and SHBG were associated with greater likelihood of vertebral fractures in a prospective cohort study of community dwelling older men. We included data from participants in MrOS who had been randomly selected for hormone measurement (N=1463, including 1054 with follow-up data 4.6years later). Major outcomes included prevalent vertebral fracture (semi-quantitative grade≥2, N=140, 9.6%) and new or worsening vertebral fracture (change in SQ grade≥1, N=55, 5.2%). Odds ratios per SD decrease in sex hormones and per SD increase in SHBG were estimated with logistic regression adjusted for potentially confounding factors, including age, bone mineral density, and other sex hormones. Higher SHBG was associated with a greater likelihood of prevalent vertebral fractures (OR: 1.38 per SD increase, 95% CI: 1.11, 1.72). Total estradiol analyzed as a continuous variable was not associated with prevalent vertebral fractures (OR per SD decrease: 0.86, 95% CI: 0.68 to 1.10). Men with total estradiol values ≤17pg/ml had a borderline higher likelihood of prevalent fracture than men with higher values (OR: 1.46, 95% CI: 0.99, 2.16). There was no association between total testosterone and prevalent fracture. In longitudinal analyses, SHBG (OR: 1.42 per SD increase, 95% CI: 1.03, 1.95) was associated with new or worsening vertebral fracture, but there was no association with total estradiol or total testosterone. In conclusion, higher SHBG (but not testosterone or estradiol) is an independent risk factor for vertebral fractures in older men.

High Serum SHBG Predicts Incident Vertebral Fractures in Elderly Men

Previous prospective cohort studies have shown that serum levels of sex steroids and sex hormone-binding globulin (SHBG) associate with nonvertebral fracture risk in men. The predictive value of sex hormones and SHBG for vertebral fracture risk specifically is, however, less studied. Elderly men (aged ≥ 65 years) from Sweden and Hong Kong participating in the Osteoporotic Fractures in Men (MrOS) study had baseline estradiol and testosterone analyzed by gas chromatography-mass spectrometry (GC-MS) and SHBG by immunoradiometric assay (IRMA). Incident clinical vertebral fractures (n = 242 cases) were evaluated in 4324 men during an average follow-up of 9.1 years. In a subsample of these men (n = 2256), spine X-rays were obtained at baseline and after an average follow-up of 4.3 years to identify incident radiographic vertebral fractures (n = 157 cases). The likelihood of incident clinical and radiographic vertebral fractures was estimated by Cox proportional hazards models and logistic regression models, respectively. Neither serum estradiol (hazard ratio [HR] per SD increase = 0.93, 95% confidence interval [CI] 0.80-1.08) nor testosterone (1.05, 0.91-1.21) predicted incident clinical vertebral fractures in age-adjusted models in the combined data set. High serum SHBG, however, associated with increased clinical vertebral fracture risk (1.24, 1.12-1.37). This association remained significant after further adjustment for FRAX with or without bone mineral density (BMD). SHBG also associated with increased incident radiographic vertebral fracture risk (combined data set; odds ratio [OR] per SD increase = 1.23, 95% CI 1.05-1.44). This association remained significant after adjustment for FRAX with or without BMD. In conclusion, high SHBG predicts incident clinical and radiographic vertebral fractures in elderly men and adds moderate information beyond FRAX with BMD for vertebral fracture risk prediction.

High aromatase activity in hypogonadal men is associated with higher spine bone mineral density, increased truncal fat and reduced lean mass

OBJECTIVE

Because the aromatase enzyme catalyzes the conversion of testosterone to estradiol (E2), the activity of this enzyme could be important in the musculoskeletal health of men with low testosterone. The objective of the present study is to determine the influence of aromatase activity on the bone mineral density (BMD) and body composition of patients with hypogonadism.

DESIGN

Cross-sectional study.

METHODS

The baseline data of 90 patients between 40 and 74 years old who participated in a genetic study of response to testosterone therapy in men with low testosterone (i.e., <300 ng/dl) were analyzed. BMD and body composition were measured by dual-energy X-ray absorptiometry. Serum testosterone was measured by automated immunoassay, E2 was measured by ultrasensitive enzyme immunoassay, and sex hormone-binding globulin was measured by enzyme immunoassay.

RESULTS

Men in the highest tertile of E2 to testosterone ratio (E2:T) had the highest spine BMD (P ≤ 0.037), highest truncal fat (P=0.046), and lowest truncal lean body mass (P=0.045). A similar pattern was observed in the upper extremities; that is, fat mass significantly increased (P=0.047), whereas lean mass significantly decreased (P=0.034) with increasing E2:T tertiles.

CONCLUSION

The present findings suggest that in men with hypogonadism, aromatase activity could be an important determinant of musculoskeletal health. Men with high aromatase activity are able to maintain a higher BMD despite low circulating testosterone, but they have lower lean and higher truncal fat mass as compared to those with lower aromatase activity.

The endocrine role of estrogens on human male skeleton

Before the characterization of human and animal models of estrogen deficiency, estrogen action was confined in the context of the female bone. These interesting models uncovered a wide spectrum of unexpected estrogen actions on bone in males, allowing the formulation of an estrogen-centric theory useful to explain how sex steroids act on bone in men. Most of the principal physiological events that take place in the developing and mature male bone are now considered to be under the control of estrogen. Estrogen determines the acceleration of bone elongation at puberty, epiphyseal closure, harmonic skeletal proportions, the achievement of peak bone mass, and the maintenance of bone mass. Furthermore, it seems to crosstalk with androgen even in the determination of bone size, a more androgen-dependent phenomenon. At puberty, epiphyseal closure and growth arrest occur when a critical number of estrogens is reached. The same mechanism based on a critical threshold of serum estradiol seems to operate in men during adulthood for bone mass maintenance via the modulation of bone formation and resorption in men. This threshold should be better identified in-between the ranges of 15 and 25 pg/mL. Future basic and clinical research will optimize strategies for the management of bone diseases related to estrogen deficiency in men.

Effect of bisphosphonate use on risk of postmenopausal breast cancer: results from the randomized clinical trials of alendronate and zoledronic acid

IMPORTANCE

Studies have shown that bisphosphonates may have antitumor and antimetastatic properties. Recently, observational studies have suggested a possible protective effect of bisphosphonates on breast cancer, but the effect of bisphosphonate use on risk of breast cancer has not been tested in randomized trials.

OBJECTIVE

To assess the relationship of postmenopausal breast cancer incidence and bisphosphonate use using data from 2 randomized (1:1), double-blind, placebo-controlled trials.

DESIGN, SETTING, AND PARTICIPANTS

The Fracture Intervention Trial (FIT) randomly assigned 6459 women aged 55 to 81 years to alendronate or placebo for a mean follow-up of 3.8 years. The Health Outcomes and Reduced Incidence With Zoledronic Acid Once Yearly-Pivotal Fracture Trial (HORIZON-PFT) randomly assigned 7765 women aged 65 to 89 years to annual intravenous zoledronic acid or placebo for a mean follow-up of 2.8 years. Data were collected at clinical centers in the United States (FIT and HORIZON-PFT) and in Asia and the Pacific, Europe, North America, and South America (HORIZON-PFT). Women, in either study, with recurrent breast cancer or who reported a history of breast cancer were excluded from analyses. In each trial, a blinded review was conducted of each cancer adverse event report to verify incident invasive breast cancer cases. The primary analysis compared events in the active vs placebo group using a log-rank test.

INTERVENTION

Alendronate vs placebo (FIT) or zoledronic acid vs placebo (HORIZON-PFT).

MAIN OUTCOMES AND MEASURES

Hazard ratio for incident breast cancer in the bisphosphonate treatment group compared to the placebo group.

RESULTS

There was no significant difference in the rate of breast cancer in FIT: 1.5% (n = 46) in the placebo group and 1.8% (n = 57) in the alendronate group (hazard ratio [HR], 1.24 [95% CI, 0.84-1.83]). In HORIZON-PFT, there was also no significant difference: 0.8% (n = 29) in the placebo group and 0.9% (n = 33) in the zoledronic acid group (HR, 1.15 [95% CI, 0.70-1.89]). There was also no significant difference when the data from FIT and HORIZON-PFT were pooled (HR, 1.20 [95% CI, 0.89-1.63]).

CONCLUSIONS AND RELEVANCE

These 2 randomized clinical trials do not support the findings from observational research. Contrary to the results from observational studies, we found that 3 to 4 years of bisphosphonate treatment did not decrease the risk of invasive postmenopausal breast cancer.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00049829 (HORIZON-PFT).

Measuring fecal testosterone in females and fecal estrogens in males: comparison of RIA and LC/MS/MS methods for wild baboons (Papio cynocephalus)

The development of non-invasive methods, particularly fecal determination, has made possible the assessment of hormone concentrations in wild animal populations. However, measuring fecal metabolites needs careful validation for each species and for each sex. We investigated whether radioimmunoassays (RIAs) previously used to measure fecal testosterone (fT) in male baboons and fecal estrogens (fE) in female baboons were well suited to measure these hormones in the opposite sex. We compared fE and fT concentrations determined by RIA to those measured by liquid chromatography combined with triple quadropole mass spectrometry (LC/MS/MS), a highly specific method. Additionally, we conducted a biological validation to assure that the measurements of fecal concentrations reflected physiological levels of the hormone of interest. Several tests produced expected results that led us to conclude that our RIAs can reliably measure fT and fE in both sexes, and that within-sex comparisons of these measures are valid: (i) fTRIA were significantly correlated to fTLC/MS/MS for both sexes; (ii) fTRIA were higher in adult than in immature males; (iii) fTRIA were higher in pregnant than non-pregnant females; (iv) fERIA were correlated with 17β-estradiol (fE2) and with estrone (fE1) determined by LC/MS/MS in pregnant females; (v) fERIA were significantly correlated with fE2 in non-pregnant females and nearly significantly correlated in males; (vi) fERIA were higher in adult males than in immature males. fERIA were higher in females than in males, as predicted, but unexpectedly, fTRIA were higher in females than in males, suggesting a difference in steroid metabolism in the two sexes; consequently, we conclude that while within-sex comparisons are valid, fTRIA should not be used for intersexual comparisons. Our results should open the field to important additional studies, as to date the roles of testosterone in females and estrogens in males have been little investigated.

Bone turnover markers in patients with prostate carcinoma: influence of sex steroids levels

There are limited data about bone turnover markers (BTM) in androgen deprivation therapy (ADT)-treated prostate cancer (PCa) patients, and the relationship between sex steroids, bone mass, and BTM has not been explored. Our objective was to analyze the influence of sex steroids levels on BTM in patients with PCa treated with or without ADT. We performed a cross-sectional study including 83 subjects with PCa (54% with ADT). BTM, bone mineral density (BMD), and sex steroids were determined. BTM were inversely related to serum level of estrogens. Tartrate-specific acid phosphatase (TRAP-5b) showed a negative correlation with free estradiol (Free E) (r = -0.274, p = 0.014) and Bio E (r = -0.256, p = 0.022) that remained after adjustment for age: Free E (β = -0.241, p = 0.03) and Bio E (β = -0.213, p = 0.063). Bone-specific alkaline phosphatase (BSAP) concentrations were inversely related to Free E (r = -0.281, p = 0.011, age-adjusted β = -0.256, p = 0.024). There was a negative correlation between osteocalcin (OC) levels and Free E (r = -0.195, p = 0.082; age-adjusted β = -0.203, p = 0.076) and Bio E (r = -0.215, p = 0.054; age-adjusted β = -0.240, p = 0.039). BTM and androgens were inversely related to TRAP-5b: total testosterone (total T) (r = -0.238, p = 0.033), Free T (r = -0.309, p = 0.05), and Bio T (r = -0.310, p = 0.05), but these correlations disappeared after age-adjustment. We did not find any relationship between BMD at different locations and sex steroids. In conclusion, in patients with PCa, estrogen levels influence bone resorption and bone formation whereas androgens may exert actions only in bone resorption. These results suggest that estradiol is the main sex steroid that regulates bone metabolism in males with prostate carcinoma.

The pathogenesis, treatment and prevention of osteoporosis in men

Testosterone stimulates longitudinal and appositional growth during childhood, whereas estrogen induces epiphysial closure. During adulthood, testosterone continues to stimulate periosteal growth, whereas estrogen is important for the maintenance of trabecular bone mass and structure. In males, testosterone is aromatized to estradiol. Both free and bioavailable plasma levels of testosterone and estradiol decrease with age in males, and fracture risk is associated with low estradiol levels. Testosterone may increase muscle mass and prevent fractures related to falls. Younger hypogonadal males should be treated with testosterone to attain peak bone mass and increase bone mineral density (BMD). Older hypogonadal males should be treated in cases of osteoporosis, reduced muscle strength and increased risk of falling. Secondary hyperparathyroidism caused by calcium and vitamin D insufficiency may reduce bone mass and strength and increase fracture risk and should be avoided. Since calcium supplementation has been associated with an increased risk of cardiovascular complications and renal stones, the dose should be tailored to the habitual daily calcium intake. Lifestyle-related risk factors (smoking, alcohol consumption, lack of physical activity and low body weight) should be addressed. The antifracture efficacy of antiresorptive and anabolic treatment for osteoporosis has not been documented in larger randomized controlled studies. However, changes in BMD and bone markers suggest similar effects in males and females of bisphosphonates (alendronate, risedronate, ibandronate, zoledronic acid), nasal calcitonin, denosumab and teriparatide (parathyroid hormone [1-34]). The antiresorptive drugs should be used in males with BMD T-score less than -2.5 and one or more risk factors, or with hip and vertebral fractures. It seems appropriate to recommend a higher cut-off T-score (e.g. less than -1.0 standard deviation [SD]) in glucocorticoid-induced osteoporosis and in patients receiving androgen deprivation therapy because of the fast initial bone loss. Anabolic treatment should be used in more severe spinal fracture cases, including glucocorticoid-induced osteoporosis.

SHBG levels are associated with bone loss and vertebral fractures in patients with prostate cancer

SUMMARY

Fractures are increased among prostate cancer patients. No data have been reported in patients with prostate cancer about the relation between serum sex hormone-binding globulin (SHBG) and bone metabolism. We found that SHBG levels were inversely related to bone mass and vertebral fractures in this population.

INTRODUCTION

Fractures are increased among prostate cancer patients, especially those on androgen deprivation therapy (ADT), but few data are available on the role of SHBG in their bone status. Our objective was to analyze the relation between serum SHBG and bone metabolism in prostate cancer patients.

METHODS

This is a cross-sectional study including 91 subjects with prostate cancer (54 % with ADT). We measured serum levels of SHBG and sex steroids, bone mineral density (BMD) by dual-energy X-ray absorptiometry, and prevalent radiographic vertebral fractures.

RESULTS

SHBG levels were inversely related to BMD (femoral neck: r = -0.299, p = 0.00; total hip: r = -0.259, p = 0.019). Subjects with osteoporosis had higher SHBG concentrations than patients without osteoporosis (60.97 ± 39.56 vs 44.45 ± 23.32 nmol/l, p = 0.022). Patients with SHBG levels in the first quartile (>57.6 nmol/l) had an odds ratio (OR) for osteoporosis of 2.59 (95 % CI, 1.30-5.12; p = 0.009) compared with patients with lower SHBG levels. In patients with SHBG >57.6 nmol/l, the OR for vertebral fractures was 2.34 (95 % CI, 1.15-4.78; p = 0.034). The calculated OR was higher after adjustment for age (OR, 5.16; 95 % CI, 1.09-24.49; p = 0.039), estrogens (OR, 6.45; 95 % CI, 1.44-28.95; p = 0.023), and androgens (OR, 5.51; 95 % CI, 1.36-22.37; p = 0.017).

CONCLUSIONS

In prostate cancer patients, SHBG levels were inversely related to bone mass and vertebral fractures. Determination of the serum SHBG level may constitute a useful and straightforward marker for predicting the severity of osteoporosis in these patients.

Male osteoporosis: A review

Osteoporosis in men is a heterogeneous disease that has received little attention. However, one third of worldwide hip fractures occur in the male population. This problem is more prevalent in people over 70 years of age. The etiology can be idiopathic or secondary to hypogonadism, vitamin D deficiency and inadequate calcium intake, hormonal treatments for prostate cancer, use of toxic and every disease or drug use that alters bone metabolism.Risk factors such as a previous history of fragility fracture should be assessed for the diagnosis. However, risk factors in men are very heterogeneous. There are significant differences in the pharmacological treatment of osteoporosis between men and women fundamentally due to the level of evidence in published trials supporting each treatment. New treatments will offer new therapeutic prospects. The goal of this work is a revision of the present status knowledge about male osteoporosis.

Relationship of sex steroid hormones with body size and with body composition measured by dual-energy X-ray absorptiometry in US men

PURPOSE

To evaluate the association of body size-captured via whole-body dual-energy X-ray absorptiometry (DXA) and physical measurement-with serum sex steroid hormones and sex hormone binding globulin (SHBG), we utilized cross-sectional data and serum samples from the National Health and Nutrition Examination Survey (NHANES; 1999-2004).

METHODS

Testosterone, androstanediol glucuronide (3-alpha-diol-G), estradiol, and SHBG were measured via immunoassay in serum samples from a total of 898 adult men (ages 20-90) participating in the morning examination. As part of the NHANES data collection, DXA scans and measurements of weight, height, and waist circumference were performed by trained staff. Linear regression was used to estimate associations between body size and hormone levels adjusted for potential confounders and NHANES sampling procedures.

RESULTS

Total bone area (cm(2)) was inversely associated with total testosterone (ng/mL) [beta = -0.12; p value < 0.01], while bone mineral density (g/cm(2)) was inversely associated with SHBG (nmol/L) [beta = -17.16; p value = 0.01]. Increased percent body fat was associated with lower concentrations of total testosterone [beta = -0.16; p value < 0.01] and SHBG [beta = -1.11; p value < 0.01] and higher concentrations of free estradiol (fg/mL) [beta = 12.52; p value < 0.01].

CONCLUSIONS

Clinical measures of body fat (measured via DXA scan) and anthropometric measures of body fat (BMI and waist circumference) provided similar inferences regarding the association between increased body fat and hormone levels in men. Increased body fat was associated with lower circulating levels of testosterone (total and free) and SHBG and higher circulating levels of free estradiol in men, while decreased bone mineral density was associated with higher circulating levels of SHBG.

The association of concurrent vitamin D and sex hormone deficiency with bone loss and fracture risk in older men: the osteoporotic fractures in men (MrOS) study

Low 25-hydroxyvitamin D (VitD), low sex hormones (SH), and high sex hormone binding globulin (SHBG) levels are common in older men. We tested the hypothesis that combinations of low VitD, low SH, and high SHBG would have a synergistic effect on bone mineral density (BMD), bone loss, and fracture risk in older men. Participants were a random subsample of 1468 men (mean age 74 years) from the Osteoporotic Fractures in Men Study (MrOS) plus 278 MrOS men with incident nonspine fractures studied in a case-cohort design. "Abnormal" was defined as lowest quartile for VitD (<20 ng/mL), bioavailable testosterone (BioT, <163 ng/dL), and bioavailable estradiol (BioE, <11 pg/mL); and highest quartile for SHBG (>59 nM). Overall, 10% had isolated VitD deficiency; 40% had only low SH or high SHBG; 15% had both SH/SHBG and VitD abnormality; and 35% had no abnormality. Compared to men with all normal levels, those with both SH/SHBG and VitD abnormality tended to be older, more obese, and to report less physical activity. Isolated VitD deficiency, and low BioT with or without low VitD, was not significantly related to skeletal measures. The combination of VitD deficiency with low BioE and/or high SHBG was associated with significantly lower baseline BMD and higher annualized rates of hip bone loss than SH abnormalities alone or no abnormality. Compared to men with all normal levels, the multivariate-adjusted hazard ratio (95% confidence interval [CI]) for incident nonspine fracture during 4.6-year median follow-up was 1.2 (0.8-1.8) for low VitD alone; 1.3 (0.9-1.9) for low BioE and/or high SHBG alone; and 1.6 (1.1-2.5) for low BioE/high SHBG plus low VitD. In summary, adverse skeletal effects of low sex steroid levels were more pronounced in older men with low VitD levels. The presence of low VitD in the presence of low BioE/high SHBG may contribute substantially to poor skeletal health.

Diagnosis and treatment of sexual dysfunctions in late-onset hypogonadism

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

Emerging therapies to prevent skeletal morbidity in men with prostate cancer

Skeletal morbidity is a prominent burden to men with advanced prostate cancer throughout the natural history of the disease. Bone metastases can cause pain and greatly elevate the risk for fractures and other structural complications. Distinct from the problem of metastases, treatment-related osteoporosis and associated fragility fractures are potential complications of androgen-deprivation therapy. Bone-targeted therapies for prostate cancer have therefore been the focus of considerable research and drug development efforts. The osteoclast is a validated therapeutic target in the management of prostate cancer. Osteoclast inhibition with zoledronic acid (a bisphosphonate) or with denosumab (a monoclonal antibody to RANK ligand) reduces risk for skeletal events in men with castration-resistant prostate cancer metastatic to bone. Osteoclast inhibition with any of several bisphosphonates improves bone mineral density, a surrogate for osteoporotic fracture risk. Denosumab and toremifene (a selective estrogen receptor modulator) have each been shown to reduce osteoporotic fracture risk among men receiving androgen-deprivation therapy. Beta-emitting radiopharmaceuticals reduce pain due to metastatic disease. Investigations involving alpha-emitting radium-223, endothelin-A receptor antagonists atrasentan and zibotentan, proto-oncogene tyrosine-protein kinase (SRC) inhibitor dasatinib, and tyrosine kinase inhibitor cabozantinib (XL184) are ongoing in clinical trials and are also discussed.

Sex and gender considerations in male patients with osteoporosis

BACKGROUND

Osteoporosis remains underrecognized and undertreated in both men and women, but men who sustain fragility fractures experience greater morbidity and mortality. While men exhibit advanced comorbidity at the time of hip fracture presentation, there are distinct sex- and gender-specific factors related to the pathophysiology and treatment of osteoporosis that further influence morbidity and mortality.

QUESTIONS/PURPOSES

With a selective review of the literature, we evaluated sex- and gender-based differences contributing to increased morbidity and mortality in men with osteoporosis. WHERE ARE WE NOW?: Sex-specific differences in bone biology and morphology may affect the pathophysiology of osteoporosis, choice of pharmacotherapy, and surgical implant selection. Additionally, estrogen metabolism may play a key role in both fracture prevention and healing. Gender-based differences in recommendations for screening and prevention between men and women may influence the severity at which osteoporosis is recognized. Primary, secondary, and tertiary prevention efforts in men lag behind those of women. This may be due to a lack of consensus regarding screening guidelines for osteoporosis in men but may be attributed to lack of awareness in the physician and patient about osteoporosis and its potentially debilitating consequences. WHERE DO WE NEED TO GO?: These disparities are a call to action for healthcare providers to raise awareness for early prevention and treatment of this potentially debilitating disease, particularly in men. HOW DO WE GET THERE?: Continued prospective research on the differences between men and women diagnosed with osteoporosis is needed, as well as sex-specific stratification of data in all studies on osteoporosis.

Aromatase activity and bone loss in men

Aromatase is a specific component of the cytochrome P450 enzyme system responsible for the transformation of androgen precursors into estrogens. This enzyme is encoded by the CYP19A1 gene located at chromosome 15q21.2, that is, expressed in ovary and testis, but also in many extraglandular sites such as the placenta, brain, adipose tissue, and bone. The activity of aromatase regulates the concentrations of estrogens with endocrine, paracrine, and autocrine effects on target issues including bone. Importantly, extraglandular aromatization of circulating androgen precursors is the major source of estrogen in men. Clinical and experimental evidences clearly indicate that aromatase activity and estrogen production are necessary for longitudinal bone growth, the attainment of peak bone mass, pubertal growth spurt, epiphyseal closure, and normal bone remodeling in young individuals. Moreover, with aging, individual differences in aromatase activity may significantly affect bone loss and fracture risk in men.

Factors associated with vertebral fractures in men treated with androgen deprivation therapy for prostate cancer

PURPOSE

Androgen deprivation therapy for prostate cancer causes accelerated loss of bone mineral density and is associated with increased fracture risk. We evaluated risk factors associated with vertebral fractures among men enrolled in a fracture prevention trial.

MATERIALS AND METHODS

Analysis included men receiving androgen deprivation therapy for prostate cancer and enrolled in a phase III fracture prevention trial. All men were 70 years old or older or had a low bone mineral density (T-score less than -1.5 for the lumbar spine or total hip). We analyzed demographic and laboratory characteristics of men with and those without vertebral fractures at study entry.

RESULTS

Of the 1,244 subjects 162 (13.0%) had a vertebral fracture at baseline. The 2 factors significantly associated with vertebral fractures were white race (p=0.028 compared with nonwhite race) and osteoporosis (p=0.002 for osteoporosis at any site, p=0.053 for osteoporosis at the spine, p=0.002 for osteoporosis at the hip). Lower bone mineral density was also significantly associated with vertebral fractures when analyzed as a continuous variable. Factors not associated with vertebral fractures included age, country of residence, androgen deprivation therapy duration at baseline, androgen deprivation therapy mode, body mass index, testosterone, estradiol, C-telopeptide, bone specific alkaline phosphatase and osteocalcin. Results were similar in analyses limited to men 70 years old or older.

CONCLUSIONS

White race and low bone mineral density were significantly associated with vertebral fractures in this study of men treated with androgen deprivation for prostate cancer. These observations should inform the assessment and management of fracture risk among such men.

Estrogen receptor α36 mediates a bone-sparing effect of 17β-estrodiol in postmenopausal women

Recently, a membrane-based estrogen receptor (ER), ER-α36, was identified and cloned that transduces membrane-initiated estrogen signaling such as activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway. Here we show that the postmenopausal level of estradiol (E2) induces mitogenic, antiapoptotic, and antiosteogenic effects and proapoptotic effects in postmenopausal osteoblasts and osteoclasts with high levels of ER-α36 expression, respectively. We also found that ER-α36 mediated the effects of postmenopausal-level E(2) on proliferation, apoptosis, and differentiation of osteoblasts through transient activation of the MAPK/ERK pathway, whereas ER-α36-mediated postmenopausal-level E(2) induces apoptosis of osteoclasts through prolonged activation of the MAPK/ERK pathway with the involvement of reactive oxygen species. We also show that the levels of ER-α36 expression in bone are positively associated with bone mineral density but negatively associated with bone biochemical markers in postmenopausal women. Thus the higher levels of ER-α36 expression are required for preserving bone mass in postmenopausal and menopausal women who become osteoporotic if ER-α36-mediated activities are dysregulated.

Testosterone and the male skeleton: a dual mode of action

Testosterone is an important hormone for both bone gain and maintenance in men. Hypogonadal men have accelerated bone turnover and increased fracture risk. In these men, administration of testosterone inhibits bone resorption and maintains bone mass. Testosterone, however, is converted into estradiol via aromatization in many tissues including male bone. The importance of estrogen receptor alpha activation as well of aromatization of androgens into estrogens was highlighted by a number of cases of men suffering from an inactivating mutation in the estrogen receptor alpha or in the aromatase enzyme. All these men typically had low bone mass, high bone turnover and open epiphyses. In line with these findings, cohort studies have confirmed that estradiol contributes to the maintenance of bone mass after reaching peak bone mass, with an association between estradiol and fractures in elderly men. Recent studies in knock-out mice have increased our understanding of the role of androgens and estrogens in different bone compartments. Estrogen receptor activation, but not androgen receptor activation, is involved in the regulation of male longitudinal appendicular skeletal growth in mice. Both the androgen and the estrogen receptor can independently mediate the cancellous bone-sparing effects of sex steroids in male mice. Selective KO studies of the androgen receptor in osteoblasts in male mice suggest that the osteoblast in the target cell for androgen receptor mediated maintenance of trabecular bone volume and coordination of bone matrix synthesis and mineralization. Taken together, both human and animal studies suggest that testosterone has a dual mode of action on different bone surfaces with involvement of both the androgen and estrogen receptor.

The effects of serum testosterone, estradiol, and sex hormone binding globulin levels on fracture risk in older men

CONTEXT

The relationship between sex steroids and fracture is poorly understood.

OBJECTIVE

The objective of the study was to examine associations between nonvertebral fracture risk and bioavailable estradiol (bioE2), bioavailable testosterone (bioT), and SHBG.

DESIGN

This was a case-cohort study.

SETTING

The Osteoporotic Fractures in Men Study (MrOS) was conducted in a prospective U.S. cohort in 5995 community-dwelling men 65 yr old or older.

PARTICIPANTS

Participants included a subcohort of 1436 randomly chosen white men plus all 446 minorities and all those with incident hip and other nonvertebral fractures.

MAIN OUTCOME MEASURES

Baseline testosterone and estradiol were measured by mass spectrometry (MS) and SHBG by RIA.

RESULTS

Men with the lowest bioE2 (<11.4 pg/ml) or highest SHBG (>59.1 nm) had greater risk of all nonvertebral fractures [adjusted hazard ratio (HR) [95% confidence interval]: 1.5 (1.2-1.9) and 1.4 (1.1-21.8), respectively]. Men with the lowest bioT (<163.5 ng/dl) had no increased fracture risk after adjustment for bioE2 [adjusted HR 1.16 (0.90-1.49)]. A significant interaction between SHBG and bioT (P = 0.03) resulted in men with low bioT and high SHBG having higher fracture risk [HR 2.1 (1.4-3.2)]. Men with low bioE2, low bioT, and high SHBG were at highest risk [HR 3.4 (2.2-5.3)].

CONCLUSIONS

Older men with low bioE2 or high SHBG levels are at increased risk of nonvertebral fracture. When SHBG levels are high, men with low bioT levels have higher risk. The strongest association occurred when all measures were considered in combination.

Estrogens as regulators of bone health in men

Bone metabolism is influenced by sex steroids during growth and adulthood in both men and women. Although this influence is well described in women, the relative importance of androgens and estrogens in the regulation of the male skeleton remains uncertain. Even though estradiol has been considered the 'female hormone', levels of serum estradiol in elderly men are higher than those in postmenopausal women. Estradiol levels are more strongly associated with BMD, bone turnover and bone loss than testosterone levels are in adult men. Case reports of young men with estrogen resistance or aromatase deficiency also suggest a crucial role for estradiol in regulation of skeletal growth in men. Moreover, serum levels of both estrogens and androgens are inversely associated with the risk of fracture in aging men. A large, prospective, population-based study showed that levels of serum estradiol predict the risk of fracture, independently of serum testosterone. Evidence suggests that a threshold level of estradiol exists below which the male skeleton is impaired; rates of bone loss and fracture seem to be increased and bone maturation delayed in men with estradiol levels below this threshold. On the basis of these findings, we propose that not only androgens, but also estrogens, are important regulators of bone health in men.

Fracture prevention in men

The lifetime risk of experiencing a fracture in 50-year-old men is lower (20%) than the risk in women (50%). Consequently, much less research has been carried out on osteoporosis and fracture risk in men. Differences in the risk and incidence of fractures between men and women are related to differences in bone-related and fall-related factors between the sexes. During the past decade, progress has been achieved in case finding and fracture prevention in men. Epidemiology studies have better specified the prevalence and incidence of fractures, and insight into the pathophysiology of osteoporosis and fractures in men has progressed considerably. Case finding for men and women at the highest risk of fracture is now possible using the FRAX algorithm, which includes clinical risk factors, with and without bone mineral density, and allows calculation of an individual's 10-year fracture risk. Although strategies to prevent fractures are much less common in men than in women, several treatment options are now available for this purpose. Bisphosphonates, in particular, consistently demonstrate a positive effect on bone mineral density, and some data also indicate decreased rates of vertebral fractures. For men with severe osteoporosis, treatment with the anabolic agent teriparatide might be an effective option.

The Val432Leu polymorphism of the CYP1B1 gene is associated with differences in estrogen metabolism and bone density

Polymorphisms of the CYP450 genes that encode for the enzymes that metabolize estrogen are linked to hormone-related cancers. We investigated the impact of two polymorphisms of the CYP1B1 gene previously reported to be associated with hormone-related disorders on estrogen metabolism and bone mineral density (BMD), another hormone-dependent condition, in women from different ethnic backgrounds. Four hundred sixty-eight postmenopausal Caucasian women, 220 from St. Louis, MO, USA (mean age=63.5+/-0.53 years) and 248 from Palermo, Italy (mean age=72.9+/-0.44 years) participated in the study. Measurements of urinary estrogen metabolites by enzyme-linked immunoassay, serum estradiol by ultrasensitive radioimmnunoassay, and serum sex hormone-binding globulin by immunoradiometric assay were performed only in the American women, while BMD by dual energy X-ray absorptiometry and genotyping by pyrosequencing were performed in both American and Italian women. Differences in the levels of metabolites, free estradiol index and BMD were analyzed by analysis of covariance. Analysis among the American participants for the Valine432Leucine polymorphism showed that, compared to women with the Val/Val genotype, women with the Leu allele (Val/Leu and Leu/Leu) had significantly higher log-transformed values of total urinary estrogen metabolite (ng/mg-creatinine) levels (1.23+/-0.04, 1.35+/-0.02, and 1.34+/-0.03; p=0.03), and significantly lower BMD (gm/cm(2)) in the lumbar spine (1.009+/-0.02, 0.955+/-0.01 and 0.931+/-0.02; p=0.03) and the femoral neck (0.748+/-0.02, 0.717+/-0.01 and 0.693+/-001, p=0.03) for the Val/Val, Val/Leu and Leu/Leu genotypes respectively. There were no significant differences in the urinary metabolites and BMD in the different genotypes for the Alanine119Serine polymorphism among the American women. Meanwhile, a separate analysis among the Italian women revealed no significant differences in BMD among the different genotypes for the two polymorphisms investigated. In conclusion, women with the Leu allele for the CYP1B1 Val432polymorphism have increased estrogen catabolism, as indicated by higher urinary estrogen metabolites, compared to those with Val/Val genotype. This may lead to relative hypoestrogenism and lower BMD in the lumbar spine and femoral neck in these women. Our data suggest that through its effect on the rate of estrogen catabolism, the Val432Leu polymorphism of the CYP1B1 gene may represent as a possible genetic risk factor for osteoporosis in American women.

Androgens and bone

Testosterone is the major gonadal sex steroid produced by the testes in men. Testosterone is also produced in smaller amounts by the ovaries in women. The adrenal glands produce the weaker androgens dehydroepiandrosterone, dehydroepiandrosterone sulfate, and androstenedione. These androgens collectively affect skeletal homeostasis throughout life in both men and women, particularly at puberty and during adult life. Because testosterone can be metabolized to estradiol by the aromatase enzyme, there has been controversy as to which gonadal sex steroid has the greater skeletal effect. The current evidence suggests that estradiol plays a greater role in maintenance of skeletal health than testosterone, but that androgens also have direct beneficial effects on bone. Supraphysiological levels of testosterone likely have similar effects on bone as lower levels via direct interaction with androgen receptors, as well as effects mediated by estrogen receptors after aromatization to estradiol. Whether high doses of synthetic, non-aromatizable androgens may, in fact, be detrimental to bone due to suppression of endogenous testosterone (and estrogen) levels is a potential concern that warrants further study.

Relation between serum testosterone, serum estradiol, sex hormone-binding globulin, and geometrical measures of adult male proximal femur strength

CONTEXT

Although previous studies have indicated associations between circulating testosterone (T) or estradiol (E2) concentrations and bone mineral density, the relationship between gonadal steroids and skeletal geometry is not well defined.

OBJECTIVE

Our objective was to uncover the relation between circulating T or E2 and proximal femur geometry in a diverse sample of men.

DESIGN

We used data on 808 men enrolled in the Boston Area Community Health/Bone Study. Serum concentrations of total and calculated free T and E2 were obtained via early-morning blood sampling. The geometry of the proximal femur at three sites (the narrow neck, intertrochanter, and shaft) was obtained using the Hip Structural Analysis technology. Analyses adjusted for subjects' age, height, total body lean mass and fat mass, and level of physical activity were performed.

SETTING

In-home interviews accompanied by subject visits to the General Clinical Research Center at Boston University School of Medicine were performed.

STUDY PARTICIPANTS

A randomly selected cohort of men living in Boston, MA (ages 30-79 yr) was included in the study.

INTERVENTIONS

These were not applicable.

MAIN OUTCOME MEASURES

Bone mineral density and bone outer diameter, cross-sectional area (measuring bone material), and section modulus (an index of bending strength) were calculated.

RESULTS

In age-adjusted models, E2 was positively associated with hip strength parameters, whereas T was not. Adjustment for age and other parameters resulted in substantial reductions in, but not complete elimination of, associations between E2 and hip strength parameters.

CONCLUSION

Circulating E2 is strongly associated with proximal femur strength, an association that is partially mediated by body composition.

Atherosclerosis and osteoporosis: age-dependent degenerative processes or related entities?

Osteoporosis and atherosclerosis, two multifactorial and degenerative entities, are major public health problems. These diseases accompany the aging process and share common risk factors. Furthermore, several common pathophysiological factors have been suggested. These include similar molecular pathways involving bone and vascular mineralization, estrogen deficiency, parathyroid hormone, homocysteine, lipid oxidation products, inflammatory process, as well as vitamin D and K. Moreover, the use of statins, biphosphonates, beta-blockers and experimental dual-purpose therapies based on the biological linkage of the above entities may simultaneously benefit bone loss and vascular disease. This review considers a potential link between osteoporosis and atherosclerosis beyond aging. These common factors may lead to appropriate treatment strategies.

Osteoporosis in men

With the aging of the population, there is a growing recognition that osteoporosis and fractures in men are a significant public health problem, and both hip and vertebral fractures are associated with increased morbidity and mortality in men. Osteoporosis in men is a heterogeneous clinical entity: whereas most men experience bone loss with aging, some men develop osteoporosis at a relatively young age, often for unexplained reasons (idiopathic osteoporosis). Declining sex steroid levels and other hormonal changes likely contribute to age-related bone loss, as do impairments in osteoblast number and/or activity. Secondary causes of osteoporosis also play a significant role in pathogenesis. Although there is ongoing controversy regarding whether osteoporosis in men should be diagnosed based on female- or male-specific reference ranges (because some evidence indicates that the risk of fracture is similar in women and men for a given level of bone mineral density), a diagnosis of osteoporosis in men is generally made based on male-specific reference ranges. Treatment consists both of nonpharmacological (lifestyle factors, calcium and vitamin D supplementation) and pharmacological (most commonly bisphosphonates or PTH) approaches, with efficacy similar to that seen in women. Increasing awareness of osteoporosis in men among physicians and the lay public is critical for the prevention of fractures in our aging male population.

Racial differences in the prevalence of vertebral fractures in older men: the Baltimore Men's Osteoporosis Study

Older black men have higher adjusted bone mineral density (BMD) and a lower adjusted rate of decline in hip BMD than older white men. There are few published data on the prevalence of morphometric vertebral fractures in older white men and no published data for older black men. The study's objective was to estimate the prevalence of vertebral fractures in older men and explore differences in prevalence between older white and black men. Subjects included five hundred forty-two men (415 white and 127 black) aged 65 and above (mean age of 74.0+/-5.7 years) participating in the longitudinal component of the Baltimore Men's Osteoporosis Study. Radiographs of the thoracic and lumbar spine were obtained using standard protocols and read for the presence of vertebral deformities using binary semiquantitative techniques. Quantitative morphometry was performed and vertebral fractures were defined using the Melton-Eastell method. BMD was measured at the femoral neck, total hip and lumbar spine. Participants also completed self- and interviewer-administered questionnaires and underwent standardized clinical examinations. One or more vertebral fractures were present in 30 of 514 men with available radiographs: estimated prevalence 5.8% (95% confidence intervals [CI]: 4.0, 8.3%). Prevalence was significantly higher in white than black men, 7.3% vs 0.9% (Fishers' exact p =0.01): age-adjusted odds ratio=8.3 (95% CI: 1.1, 62.5). Among white men, there was no significant difference in age-adjusted femoral neck or total hip BMD or frequency or severity of back pain between men with and without vertebral fractures. In conclusion, older white men have a higher prevalence of vertebral fractures than older black men. This may be related to differences in BMD between these groups.

Effect of aromatase inhibition on bone metabolism in elderly hypogonadal men

Both estrogens and androgens play important roles in skeletal development and maintenance in men. The relative importance of estrogens and androgens in male bone metabolism, however, remains undefined. Anastrozole is an oral aromatase inhibitor that decreases estrogen production and increases androgen production in men. Currently, anastrozole is being investigated as a potential agent for the treatment of hypogonadism in aging men. Because anastrozole lowers estrogen levels and raises androgen levels, its effect on bone metabolism is difficult to predict. To assess the effects of anastrozole on bone turnover, we randomized 37 elderly (ages 62-74) mildly hypogonadal men (serum testosterone <350 ng/dl) to receive either anastrozole 1 mg daily (n=12), anastrozole 1 mg twice weekly (n=11), or daily placebo (n=14) for 12 weeks. Serum gonadal steroid levels, serum and urine biochemical markers of bone turnover, serum osteoprotegerin, and total body bone mineral density were measured at baseline and week 12. Mean serum levels of total and bioavailable testosterone increased substantially in both treated groups. Specifically, mean +/- SD bioavailable testosterone levels increased from 99+/-31 ng/dl to 207+/-65 ng/dl in the group receiving 1 mg of anastrozole daily and from 115+/-37 ng/dl to 178+/-55 ng/dl in the subjects receiving 1 mg of anastrozole twice weekly ( p <0.001 vs placebo for both groups). Serum estradiol levels decreased modestly in both treated groups (from 26+/-8 pg/ml to 17+/-6 pg/ml in the daily treatment group and from 27+/-8 pg/ml to 17+/-5 pg/ml in the twice-weekly treatment group, p <0.001 vs placebo for both groups). Despite these hormonal changes, no increases in biochemical markers of bone resorption were observed. Specifically, mean serum N-telopeptide and urinary deoxypyridinoline concentrations remained stable in both treated groups over the 12-week treatment period. Similarly, serum biochemical markers of bone formation (osteocalcin and amino-terminal propeptide of type 1 collagen), serum osteoprotegerin, and total body bone mineral density did not change. These data demonstrate that although short-term administration of anastrozole decreases serum estradiol levels in elderly men with mild hypogonadism, this intervention does not adversely affect bone metabolism over a 12-week period. This lack of an effect may be due to the concomitant increase in testosterone production, the relative modest effect on estradiol production, or a combination of both factors. These results suggest that anastrozole therapy is unlikely to have an adverse effect on bone metabolism when taken over extended periods and may prove to be a valuable method of normalizing testosterone production in older men.

Prediction of incident osteoporotic fractures in elderly women using the free estradiol index

A decline in postmenopausal estrogen concentration accelerates postmenopausal bone loss. We have examined the predictive power of endogenous estrogen production, DXA hip bone density (BMD), and heel quantitative ultrasound (QUS) on incident clinical fracture in a prospective 3-year population based, randomised controlled trial of calcium supplementation. Baseline blood testing on 1499 women mean (SD) age 75 (3) years for estradiol and sex hormone binding globulin measurements and ankle QUS measurements (Lunar Achilles) was undertaken. Bone density was measured using DXA (Hologic 4500A) at 1 year. Incident clinical fractures were confirmed by X-ray. At 3 years, 10% had sustained more than one incident fracture. The fracture group had significantly lower levels of free estradiol index (FEI) (0.40+/-0.44 versus 0.49+/-0.54 pmol/nmol), hip BMD (0.776+/-0.129 versus 0.815+/-0.124 g/cm(2)) and measures of QUS (BUA 98+/-8 versus 101+/-8 db/Hz, SOS 1504+/-22 versus 1514 +/-26 m/s; stiffness 67+/-11 versus 71+/-11 % mean young adult), respectively, than the non-fracture group. After adjustment for age, weight, use of topical estrogen, calcium supplementation and prevalent fracture, incident fracture was predicted by free estradiol index (HR per SD: 1.43:95%CI: 1.08-1.91, P=0.013). After adjustment for BMD, SOS or stiffness, the free estradiol index no longer predicted fracture. When examined separately, the presence of a vertebral or an appendicular fracture was associated with an 18% lower free estradiol index compared with no fracture. The risk of vertebral fracture increased with decreased free estradiol index (HR per SD reduction: 1.63:95% CI: 0.91-2.92); the risk of appendicular fracture also increased with decreased free estradiol index (HR per SD reduction: 1.45:95% CI: 1.05-2.01) after adjustment for age, weight, use of topical estrogen, calcium supplementation and prevalent fracture. After further adjustment for hip BMD or QUS measures, the effect of free estradiol index was no longer significant for vertebral or appendicular fractures. Therefore, a low free estradiol index increases the probability of having an incident fracture as a result of decreased BMD. These data confirm the importance of postmenopausal estrogen concentration in the pathogenesis of osteoporosis in elderly women.

Bilateral osteonecrosis of the femoral head in an adult man affected by congenital estrogen deficiency

Osteonecrosis of femoral head is related to different predisposing factors. The pathogenesis is not completely understood, but an ischemic impairment seems to be one of the major determinants of bone necrosis. The association of bilateral necrosis of femoral heads and congenital aromatase deficiency is here reported. The absence of estrogen activity, as well as the persistence of unfused epiphyses for a long period of life, may be involved in the determinism of bilateral necrosis of bone femoral heads. The possibility of development of bone necrosis in patients affected by congenital estrogen deficiency needs to be considered and magnetic resonance imaging can be a useful method for an early detection of this disease.

Osteoporosis

Osteoporosis is characterised by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and consequent increase in fracture risk. It is a common condition affecting one in three women and one in 12 men, resulting in substantial morbidity, excess mortality, and health and social services expenditure. It is therefore important to develop strategies to prevent and treat osteoporosis in both men and women. This paper reviews the pathogenesis of primary and secondary osteoporosis, as well as diagnosis, investigation, and management. This should include lifestyle changes to reduce bone loss and decrease the risk of falls, the identification and treatment of secondary causes of bone loss, and specific treatment for osteoporosis. Hormone replacement therapy, raloxifene, bisphosphonates, calcium and vitamin D, calcitonin, and parathyroid hormone have all been shown to improve bone density and decrease the risk of fracture in specific situations. It is important that treatment is tailored to the individual patient, to ensure compliance and optimise the potential benefits.

Unresolved issues in osteoporosis in men

Fragility fractures in men are a public health problem. The increasing longevity in men is likely to increase the public health burden of fractures in men. This problem remains unrecognized by doctors, the public and governments. About one third of all hip fractures occur in men but the incidence and gender ratio varies from country to country for reasons that are not understood. The prevalence of spine fractures is about half that of women in most studies, but similar to that of women in several other studies. The incidence of spine fractures is uncertain but is likely to be about half that of women except in 80+ year olds, when it appears to be similar. The causes of the higher mortality in men than in women following hip or spine fracture are not well defined. Areal bone mineral density (aBMD) predicts fracture risk in men; the relative risk for spine and hip fracture conferred by a 1 SD lower aBMD, or by a prevalent fracture, is similar in men and women. The age-specific absolute risk (number of cases per 1,000 per year) conferred by a given hip aBMD is similar in men and women. The age-specific absolute risk conferred by aBMD at the calcaneus or radius for spine fracture is similar for men and women. If the absolute and relative risks are similar then the lower incidence of fractures in men than women may reflect the lower proportion of the male population distribution below a given structural determinant of bone fragility. That is, at any age, there may be fewer men than women with smaller bones, lower volumetric bone mineral density (vBMD), thinner trabeculae or cortices, architectural disruption, or higher remodeling rates. Higher mortality and fewer falls may also contribute to the lower incidence of fractures in men. This tail end of the male population distribution (for traits like bone size, vBMD, architecture, and remodeling rates) is the likely source of fracture cases in males. Hypogonadism is a risk factor for osteoporosis. However, the definition, prevalence, causes and structural consequence of hypogonadism are inadequately defined. At what level of testosterone is bone balance negative? What structural determinants of axial and appendicular strength are regulated by testosterone, estrogen, growth hormone (GH), insulin like growth factor 1 (IGF-1) (or their interactions)? Is reduced bone size in men with spine or hip fractures due to failed growth-related or age-related periosteal expansion? If reduced vBMD is due to reduced accrual, is this due to reduced cortical thickness? What factors regulate and coregulate the periosteal and endocortical modeling and remodeling? Are reduced trabecular numbers due to failed formation at the growth plate, excess resorption of primary trabeculae or reduced formation of secondary trabeculae? Is reduced trabecular thickness due to failed prepubertal or pubertal bone formation? Is reduced cortical and trabecular thickness during aging due to excessive endosteal resorption or reduced bone formation? If the former, is this due to increased remodeling sites or increased resorption depth? Most evidence favors reduced bone formation as the cause of bone loss with trabecular bone loss occurring by reduced formation and thinning more than by increased resorption and loss of connectivity. Cortical bone loss is less than in women because endocortical resorption is less and periosteal apposition is greater. If the reduced bone formation is most important, is this due to reduced osteoprogenitors, reduced osteoblast matrix synthesis or early osteoblast apoptosis? Anti-spine-fracture efficacy has been demonstrated in only one randomized heated with alendronate drug in men. The gaps in our knowledge remain large.