Older men with low serum estradiol and high serum SHBG have an increased risk of fractures

Genetic Determinants of Circulating Estrogen Levels and Evidence of a Causal Effect of Estradiol on Bone Density in Men

Context

Serum estradiol (E2) and estrone (E1) levels exhibit substantial heritability.

Objective

To investigate the genetic regulation of serum E2 and E1 in men.

Design, Setting, and Participants

Genome-wide association study in 11,097 men of European origin from nine epidemiological cohorts.

Main Outcome Measures

Genetic determinants of serum E2 and E1 levels.

Results

Variants in/near CYP19A1 demonstrated the strongest evidence for association with E2, resolving to three independent signals. Two additional independent signals were found on the X chromosome; FAMily with sequence similarity 9, member B (FAM9B), rs5934505 (P = 3.4 × 10-8) and Xq27.3, rs5951794 (P = 3.1 × 10-10). E1 signals were found in CYP19A1 (rs2899472, P = 5.5 × 10-23), in Tripartite motif containing 4 (TRIM4; rs17277546, P = 5.8 × 10-14), and CYP11B1/B2 (rs10093796, P = 1.2 × 10-8). E2 signals in CYP19A1 and FAM9B were associated with bone mineral density (BMD). Mendelian randomization analysis suggested a causal effect of serum E2 on BMD in men. A 1 pg/mL genetically increased E2 was associated with a 0.048 standard deviation increase in lumbar spine BMD (P = 2.8 × 10-12). In men and women combined, CYP19A1 alleles associated with higher E2 levels were associated with lower degrees of insulin resistance.

Conclusions

Our findings confirm that CYP19A1 is an important genetic regulator of E2 and E1 levels and strengthen the causal importance of E2 for bone health in men. We also report two independent loci on the X-chromosome for E2, and one locus each in TRIM4 and CYP11B1/B2, for E1.

Comparative analysis of serum proteome in congenital scoliosis patients with TBX6 haploinsufficiency - a first report pointing to lipid metabolism

Congenital scoliosis (CS) is a three‐dimensional deformity of the spine affecting quality of life. We have demonstrated TBX6 haploinsufficiency is the most important contributor to CS. However, the pathophysiology at the protein level remains unclear. Therefore, this study was to explore the differential proteome in serum of CS patients with TBX6 haploinsufficiency. Sera from nine CS patients with TBX6 haploinsufficiency and nine age‐ and gender‐matched healthy controls were collected and analysed by isobaric tagged relative and absolute quantification (iTRAQ) labelling coupled with mass spectrometry (MS). In total, 277 proteins were detected and 20 proteins were designated as differentially expressed proteins, which were submitted to subsequent bioinformatics analysis. Gene Ontology classification analysis showed the biological process was primarily related to ‘cellular process’, molecular function ‘structural molecule activity’ and cellular component ‘extracellular region’. IPA analysis revealed ‘LXR/RXR activation’ was the top pathway, which is a crucial pathway in lipid metabolism. Hierarchical clustering analysis generated two clusters. In summary, this study is the first proteomic research to delineate the total and differential serum proteins in TBX6 haploinsufficiency‐caused CS. The proteins discovered in this experiment may serve as potential biomarkers for CS, and lipid metabolism might play important roles in the pathogenesis of CS.

Sex hormones and quantitative ultrasound parameters at the heel in men and women from the general population

Purpose/introduction

The present study investigates potential associations between liquid chromatography-mass spectrometry (LC-MS) measured sex hormones, dehydroepiandrosterone sulphate, sex hormone-binding globulin (SHBG) and bone ultrasound parameters at the heel in men and women from the general population.

Methods

Data from 502 women and 425 men from the population-based Study of Health in Pomerania (SHIP-TREND) were used. Cross-sectional associations of sex hormones including testosterone (TT), calculated free testosterone (FT), dehydroepiandrosterone sulphate (DHEAS), androstenedione (ASD), estrone (E1) and SHBG with quantitative ultrasound (QUS) parameters at the heel, including broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness index (SI) were examined by analysis of variance (ANOVA) and multivariable quantile regression models.

Results

Multivariable regression analysis showed a sex-specific inverse association of DHEAS with SI in men (Beta per SI unit = − 3.08, standard error (SE) = 0.88), but not in women (Beta = − 0.01, SE = 2.09). Furthermore, FT was positively associated with BUA in men (Beta per BUA unit = 29.0, SE = 10.1). None of the other sex hormones (ASD, E1) or SHBG was associated with QUS parameters after multivariable adjustment.

Conclusions

This cross-sectional population-based study revealed independent associations of DHEAS and FT with QUS parameters in men, suggesting a potential influence on male bone metabolism. The predictive role of DHEAS and FT as a marker for osteoporosis in men warrants further investigation in clinical trials and large-scale observational studies.

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Population-based data of healthy men and women from the general population

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Sex hormone panel measured by liquid chromatography-mass spectrometry (LC-MS)

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Associations of dehydroepiandrosterone sulphate and free testosterone with bone ultrasound parameters in men

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Estrone, androstenedione and SHBG were not associated with bone ultrasound parameters in both sexes.

Low Serum DHEAS Predicts Increased Fracture Risk in Older Men: The MrOS Sweden Study

The adrenal-derived hormones dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are the most abundant circulating hormones and their levels decline substantially with age. DHEAS is considered an inactive precursor, which is converted into androgens and estrogens via local metabolism in peripheral target tissues. The predictive value of serum DHEAS for fracture risk is unknown. The aim of this study was, therefore, to assess the associations between baseline DHEAS levels and incident fractures in a large cohort of older men. Serum DHEAS levels were analyzed with mass spectrometry in the population-based Osteoporotic Fractures in Men study in Sweden (n = 2568, aged 69 to 81 years). Incident X-ray validated fractures (all, n = 594; non-vertebral major osteoporotic, n = 255; hip, n = 175; clinical vertebral, n = 206) were ascertained during a median follow-up of 10.6 years. DHEAS levels were inversely associated with the risk of any fracture (hazard ratio [HR] per SD decrease = 1.14, 95% confidence interval [CI] 1.05-1.24), non-vertebral major osteoporotic fractures (HR = 1.31, 95% CI 1.16-1.48), and hip fractures (HR = 1.18, 95% CI 1.02-1.37) but not clinical vertebral fractures (HR = 1.09, 95% CI 0.95-1.26) in Cox regression models adjusted for age, body mass index (BMI) and prevalent fractures. Further adjustment for traditional risk factors for fracture, bone mineral density (BMD), and/or physical performance variables as well as serum sex steroid levels only slightly attenuated the associations between serum DHEAS and fracture risk. Similarly, the point estimates were only marginally reduced after adjustment for FRAX estimates with BMD. The inverse association between serum DHEAS and all fractures or major osteoporotic fractures was nonlinear, with a substantial increase in fracture risk (all fractures 22%, major osteoporotic fractures 33%) for those participants with serum DHEAS levels below the median (0.60 μg/mL). In conclusion, low serum DHEAS levels are a risk marker of mainly non-vertebral fractures in older men, of whom those with DHEAS levels below 0.60 μg/mL are at highest risk. © The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Aging and sex hormones in males

Several large cohort studies have disclosed the trajectories of sex steroids changes overtime in men and their clinical significance. In men the slow, physiological decline of serum testosterone (T) with advancing age overlaps with the clinical condition of overt, pathological hypogonadism. In addition, the increasing number of comorbidities, together with the high prevalence of chronic diseases, all further contribute to the decrease of serum T concentrations in the aging male. For all these reasons both the diagnosis of late-onset hypogonadism (LOH) in men and the decision about starting or not T replacement treatment remain challenging. At present, the biochemical finding of T deficiency alone is not sufficient for diagnosing hypogonadism in older men. Coupling hypogonadal symptoms with documented low serum T represents the best strategy to refine the diagnosis of hypogonadism in older men and to avoid unnecessary treatments.

Estrogens in Male Physiology

Estrogens have historically been associated with female reproduction, but work over the last two decades established that estrogens and their main nuclear receptors (ESR1 and ESR2) and G protein-coupled estrogen receptor (GPER) also regulate male reproductive and nonreproductive organs. 17β-Estradiol (E2) is measureable in blood of men and males of other species, but in rete testis fluids, E2 reaches concentrations normally found only in females and in some species nanomolar concentrations of estrone sulfate are found in semen. Aromatase, which converts androgens to estrogens, is expressed in Leydig cells, seminiferous epithelium, and other male organs. Early studies showed E2 binding in numerous male tissues, and ESR1 and ESR2 each show unique distributions and actions in males. Exogenous estrogen treatment produced male reproductive pathologies in laboratory animals and men, especially during development, and studies with transgenic mice with compromised estrogen signaling demonstrated an E2 role in normal male physiology. Efferent ductules and epididymal functions are dependent on estrogen signaling through ESR1, whose loss impaired ion transport and water reabsorption, resulting in abnormal sperm. Loss of ESR1 or aromatase also produces effects on nonreproductive targets such as brain, adipose, skeletal muscle, bone, cardiovascular, and immune tissues. Expression of GPER is extensive in male tracts, suggesting a possible role for E2 signaling through this receptor in male reproduction. Recent evidence also indicates that membrane ESR1 has critical roles in male reproduction. Thus estrogens are important physiological regulators in males, and future studies may reveal additional roles for estrogen signaling in various target tissues.

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.

Low serum iron is associated with high serum intact FGF23 in elderly men: The Swedish MrOS study

BACKGROUND

Fibroblast growth factor (FGF23) is a protein that is produced by osteoblasts and osteocytes. Increased serum levels of FGF23 have been associated with increased risks of osteoporotic fractures and cardiovascular disease, particularly in participants with poor renal function. Serum iron (Fe) has been suggested as a regulator of FGF23 homeostasis.

OBJECTIVE

To determine whether Fe and iron status are determinants of the levels of intact FGF23 (iFGF23) in elderly men.

METHODS

The MrOS study is a population-based study of elderly men (N=1010; mean age, 75.3years; range, 69-81years). The levels of Fe, transferrin saturation (TS), and ferritin were evaluated in relation to the serum concentrations of iFGF23 before and after adjustments for confounders.

RESULTS

TS <15% was found in 3.5% (34/977) of the participants, who had a higher median level iFGF23 compared with the remaining subjects (47.4μmol/L vs. 41.9μmol/L, p=0.008). The levels of iFGF23 correlated negatively (un-adjusted) with the levels of Fe (r=-0.17, p<0.001), TS (r=-0.16, p<0.001) and serum ferritin (r=-0.07, p=0.022). In addition, in participants with estimated glomerular filtration rate eGFRCystatin C>60mL/min, the levels of iFGF23 correlated (age-adjusted) negatively with the levels of Fe (r=-0.15, p<0.001) and TS (r=-0.17, p<0.001). The level of iFGF23 correlated positively (un-adjusted) with lumbar spine bone mineral density (BMD) (r=0.14, p<0.001), total body BMD (r=0.11, p=0.001), and total hip BMD (r=0.09, p=0.004). The corresponding correlations, when adjusted for age, weight, and height were: r=0.08, p=0.018; r=0.05, p=0.120; and r=0.02, p=0.624, respectively. No associations were found between BMD and the levels of Fe or TS. Multiple step-wise linear regression analyses [adjusting for age, body mass index (BMI), comorbidity index, cystatin C, C-reactive protein (hs-CRP), serum vitamin D 25-OH (25OHD), phosphate, calcium, parathyroid hormone (PTH), erythropoietin, hemoglobin, lumbar spine BMD, apolipoprotein B/A1 ratio] were performed in three separate models with Fe, TS or ferritin as potential explanatory variables. Fe and TS, but not ferritin, were independent predictors of iFGF23 level (standardized β-values: -0.10, p<0.001; -0.10, p<0.001; and -0.05, p=0.062, respectively).

CONCLUSION

Low levels of Fe in elderly men are associated with high levels of iFGF23, independently of markers of inflammation and renal function, suggesting an iron-related pathway for FGF23 regulation.

Pathologic fracture of the thoracic spine in a male master ultra-marathoner due to the combination of a vertebral hemangioma and osteopenia

Vertebral hemangiomas are the most common benign vertebral neoplasms and are generally asymptomatic. In the present study, we report the case of a 52-year-old male master ultra-marathoner suffering from a pathologic fracture of the thoracic spine due to a vertebral hemangioma. A further examination in the athlete revealed an accompanying osteopenia, which was most likely due to a deficiency in both vitamin D and testosterone. The treatment of the fracture consisted of percutaneous vertebroplasty. Shortly after the operation the athlete was able to continue running. The most likely reason for the pathologic fracture of the vertebral body was the combination of the vertebral hemangioma and osteopenia. The further treatment consisted of supplementation of both vitamin D and testosterone. Athletes and physicians should be aware that male master ultra-marathoners older than 50 years might suffer from osteopenia, where a deficiency in vitamin D and testosterone could be contributing factors for osteopenia development in general.

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.

The Limited Clinical Utility of Testosterone, Estradiol, and Sex Hormone Binding Globulin Measurements in the Prediction of Fracture Risk and Bone Loss in Older Men

Measurement of serum testosterone (T) levels is recommended in the evaluation of osteoporosis in older men and estradiol (E2) and sex hormone binding globulin (SHBG) levels are associated with the rate of bone loss and fractures, but the clinical utility of sex steroid and SHBG measurements for the evaluation of osteoporosis in men has not been examined. To evaluate whether measurements of T, E2, and/or SHBG are useful for the prediction of fracture risk or the rate of bone loss in older men, we analyzed longitudinal data from 5487 community-based men participating in the Osteoporotic Fractures in Men (MrOS) study in the United States, Sweden, and Hong Kong. Serum T, E2, and SHBG levels were assessed at baseline; incident fractures were self-reported at 4-month intervals with radiographic verification (US), or ascertained via national health records (Sweden, Hong Kong). Rate of bone loss was assessed by serial measures of hip bone mineral density (BMD). We used receiver operating characteristic (ROC) curves, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) to assess improvement in prediction. Mean age at baseline was 72 to 75 years and the prevalence of low T levels (<300 ng/dL) was 7.6% to 21.3% in the three cohorts. There were 619 incident major osteoporotic and 266 hip fractures during follow-up of approximately 10 years. Based on ROC curves, there were no improvements in fracture risk discrimination for any biochemical measure when added to models, including the Fracture Risk Assessment Tool (FRAX) with BMD. Although minor improvements in NRI were observed for the dichotomous parameters low bioavailable E2 (BioE2) (<11.4 pg/mL) and high SHBG (>59.1 nM), neither sex steroids nor SHBG provided clinically useful improvement in fracture risk discrimination. Similarly, they did not contribute to the prediction of BMD change. In conclusion, there is limited clinical utility of serum E2, T, and SHBG measures for the evaluation of osteoporosis risk in elderly men. © 2016 American Society for Bone and Mineral Research.

Extra-nuclear effects of estrogen on cortical bone in males require ERαAF-1

Estradiol (E2) signaling via estrogen receptor alpha (ERα) is important for the male skeleton as demonstrated by ERα inactivation in both mice and man. ERα mediates estrogenic effects not only by translocating to the nucleus and affecting gene transcription but also by extra-nuclear actions e.g., triggering cytoplasmic signaling cascades. ERα contains various domains, and the role of activation function 1 (ERαAF-1) is known to be tissue specific. The aim of this study was to determine the importance of extra-nuclear estrogen effects for the skeleton in males and to determine the role of ERαAF-1 for mediating these effects. Five-month-old male wild-type (WT) and ERαAF-1-inactivated (ERαAF-1⁰) mice were orchidectomized and treated with equimolar doses of 17β-estradiol (E2) or an estrogen dendrimer conjugate (EDC), which is incapable of entering the nucleus and thereby only initiates extra-nuclear ER actions or their corresponding vehicles for 3.5 weeks. As expected, E2 treatment increased cortical thickness and trabecular bone volume per total volume (BV/TV) in WT males. EDC treatment increased cortical thickness in WT males, whereas no effect was detected in trabecular bone. In ERαAF-1⁰ males, E2 treatment increased cortical thickness, but did not affect trabecular bone. Interestingly, the effect of EDC on cortical bone was abolished in ERαAF-1⁰ mice. In conclusion, extra-nuclear estrogen signaling affects cortical bone mass in males, and this effect is dependent on a functional ERαAF-1. Increased knowledge regarding estrogen signaling mechanisms in the regulation of the male skeleton may aid the development of new treatment options for male osteoporosis.

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.

Progressive Temporal Change in Serum SHBG, But Not in Serum Testosterone or Estradiol, Is Associated With Bone Loss and Incident Fractures in Older Men: The Concord Health and Ageing in Men Project

This study aimed to examine progressive temporal relationships between changes in major reproductive hormones across three waves of a cohort study of older men and (1) changes in bone mineral density (BMD) and (2) incident fractures (any, hip or non-vertebral) over an average of 6 years of follow-up. The CHAMP cohort of men aged 70 years and older were assessed at baseline (2005 to 2007, n = 1705), 2-year follow-up (n = 1367), and 5-year follow-up (n = 958). Serum testosterone (T), dihydrotestosterone (DHT), estradiol (E2), and estrone (E1) (by liquid chromatography-tandem mass spectrometry [LC-MS/MS]), and sex hormone-binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) (by immunoassay) were measured at all time-points, whereas free testosterone (cFT) was calculated using a well-validated formula. Hip BMD was measured by dual-energy X-ray absorptiometry (DXA) at all three time-points, and fracture data were verified radiographically. Statistical modeling was done using general estimating equations (GEEs). For total hip BMD, univariable analyses revealed inverse associations with temporal changes in serum SHBG, FSH, and LH and positive associations for serum E1 and cFT across the three time-points. In models adjusted for multiple covariables, serum SHBG (β = -0.029), FSH (β = -0.065), LH (β = -0.049), E1 (β = 0.019), and cFT (β = 0.033) remained significantly associated with hip BMD. However for femoral neck BMD, only FSH (β = -0.048) and LH (β = -0.036) remained associated in multivariable-adjusted models. Temporal change in serum SHBG, but not T, E2, or other hormonal variables, was significantly associated with any, nonvertebral or hip fracture incidence in univariable analyses. In multivariable-adjusted models, temporal increase in serum SHBG over time remained associated with any fracture (β = 0.060) and hip fracture (β = 0.041) incidence, but not nonvertebral fracture incidence. These data indicate that a progressive increase in circulating SHBG over time predicts bone loss and fracture risk in older men. Further studies are warranted to further characterize changes in circulating SHBG as a mechanism and/or biomarker of bone health during male ageing. © 2016 American Society for Bone and Mineral Research.

Low serum vitamin D is associated with higher cortical porosity in elderly men

BACKGROUND

Bone loss at peripheral sites in the elderly is mainly cortical and involves increased cortical porosity. However, an association between bone loss at these sites and 25-hydroxyvitamin D has not been reported.

OBJECTIVE

To investigate the association between serum levels of 25-hydroxyvitamin D, bone microstructure and areal bone mineral density (BMD) in elderly men.

METHODS

A population-based cohort of 444 elderly men (mean ± SD age 80.2 ± 3.5 years) was investigated. Bone microstructure was measured by high-resolution peripheral quantitative computed tomography, areal BMD by dual-energy X-ray absorptiometry and serum 25-hydroxyvitamin D and parathyroid hormone levels by immunoassay.

RESULTS

Mean cortical porosity at the distal tibia was 14.7% higher (12.5 ± 4.3% vs. 10.9 ± 4.1%, P < 0.05) whilst cortical volumetric BMD, area, trabecular bone volume fraction and femoral neck areal BMD were lower in men in the lowest quartile of vitamin D levels compared to the highest. In men with vitamin D deficiency (<25 nmol L^-1 ) or insufficiency [25-49 nmol L^-1 , in combination with an elevated serum level of parathyroid hormone (>6.8 pmol L^-1 )], cortical porosity was 17.2% higher than in vitamin D-sufficient men (P < 0.01). A linear regression model including age, weight, height, daily calcium intake, physical activity, smoking vitamin D supplementation and parathyroid hormone showed that 25-hydroxyvitamin D independently predicted cortical porosity (standardized β = -0.110, R² = 1.1%, P = 0.024), area (β = 0.123, R² = 1.4%, P = 0.007) and cortical volumetric BMD (β = 0.125, R² = 1.4%, P = 0.007) of the tibia as well as areal BMD of the femoral neck (β = 0.102, R² = 0.9%, P = 0.04).

CONCLUSION

Serum vitamin D is associated with cortical porosity, area and density, indicating that bone fragility as a result of low vitamin D could be due to changes in cortical bone microstructure and geometry.

High plasma osteocalcin is associated with low blood haemoglobin in elderly men: the MrOS Sweden Study

BACKGROUND

It has been suggested that osteoblasts are involved in the regulation of haematopoietic stem cells. Whether osteocalcin, which is derived from osteoblasts and is metabolically active, influences blood haemoglobin (Hb) levels is not known.

OBJECTIVE

To determine whether plasma osteocalcin is a determinant of Hb in elderly men.

METHODS

A total of 993 men (mean age 75.3 ± 3.2 years) participated in the population-based MrOS (osteoporotic fractures in men) study. Plasma osteocalcin concentration was evaluated in relation to Hb and adjustments were made for potential confounders (i.e. age, body mass index, erythropoietin, total oestradiol, fasting insulin, adiponectin, ferritin and cystatin C).

RESULTS

Hb correlated (age adjusted) negatively with osteocalcin in the total study group (r = -0.12, P < 0.001) as well as in the subgroup of nondiabetic men (r = -0.16, P < 0.001). In nondiabetic men with higher osteocalcin levels, it was more likely that Hb would be in the lowest quartile (odds ratio per SD decrease in osteocalcin 1.32, 95% confidence interval 1.13-1.53). Quartiles of Hb were negatively associated (age adjusted) with osteocalcin (P < 0.001). Anaemic men (47/812) (Hb <130 g L(-1) ) had significantly higher mean osteocalcin levels than nonanaemic men (33.9 vs. 27.1 μg L(-1) , P < 0.001). In multiple stepwise linear regression analyses (adjusted for age, body mass index, total oestradiol, adiponectin, erythropoietin, fasting insulin, cystatin C, leptin, ferritin and holotranscobalamin), osteocalcin was an independent predictor of Hb concentration in nondiabetic men (P < 0.05).

CONCLUSIONS

These data add further support to the evidence indicating that the bone-specific protein osteocalcin has several endocrine functions targeting the pancreas, testes, adipocytes, brain. An additional novel finding is that osteocalcin may also have a paracrine function as a regulator of haematopoiesis.

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 Antipsychotics on Bone Mineral Density in Patients with Schizophrenia: Gender Differences

Low bone mineral density (BMD) and osteoporosis are common in patients with schizophrenia and detrimental to illness prognosis and life quality. Although the pathogenesis is not fully clear, series of studies have revealed factors related to low BMD such as life style, psychotic symptoms, medication use and the activity of bone absorption markers. It has been known that antipsychotic-induced hyperprolactinemia plays a critical role on decreased BMD. However, it remains uncertain whether the risk factors differ between men and women. According to the effect on prolactin, antipsychotics can be classified into two groups: prolactin-sparing (PS) and prolactin-raising (PR). Our previous study has demonstrated that clozapine which is among the PS antipsychotics is beneficial for BMD when compared with PR antipsychotics in women with chronic schizophrenia. We have also found that risks factors associated with low BMD are different between men and women, suggesting that gender-specific risk factors should be considered for intervention of bone loss in patients with schizophrenia. This article reviews the effects of antipsychotics use on BMD with particular discussion for the differences on gender and age, which implicate the alterations of sex and other related hormones. In addition, currently reported protective and risk factors, as well as the effects of medication use on BMD including the combination of antipsychotics and other psychotropic agents and other potential medications are also reviewed.

SERMs have substance-specific effects on bone, and these effects are mediated via ERαAF-1 in female mice

The bone-sparing effect of estrogens is mediated primarily via estrogen receptor (ER)α, which stimulates gene transcription through activation function (AF)-1 and AF-2. The role of ERαAF-1 for the estradiol (E2) effects is tissue specific. The selective ER modulators (SERMs) raloxifene (Ral), lasofoxifene (Las), and bazedoxifene (Bza) can be used to treat postmenopausal osteoporosis. They all reduce the risk for vertebral fractures, whereas Las and partly Bza, but not Ral, reduce the risk for nonvertebral fractures. Here, we have compared the tissue specificity of Ral, Las, and Bza and evaluated the role of ERαAF-1 for the effects of these SERMs, with an emphasis on bone parameters. We treated ovariectomized (OVX) wild-type (WT) mice and OVX mice lacking ERαAF-1 (ERαAF-1(0)) with E2, Ral, Las, or Bza. All three SERMs increased trabecular bone mass in the axial skeleton. In the appendicular skeleton, only Las increased the trabecular bone volume/tissue volume and trabecular number, whereas both Ral and Las increased the cortical bone thickness and strength. However, Ral also increased cortical porosity. The three SERMs had only a minor effect on uterine weight. Notably, all evaluated effects of these SERMs were absent in ovx ERαAF-1(0) mice. In conclusion, all SERMs had similar effects on axial bone mass. However, the SERMs had slightly different effects on the appendicular skeleton since only Las increased the trabecular bone mass and only Ral increased the cortical porosity. Importantly, all SERM effects require a functional ERαAF-1 in female mice. These results could lead to development of more specific treatments for osteoporosis.

Low-Level Cadmium Exposure Is Associated With Decreased Bone Mineral Density and Increased Risk of Incident Fractures in Elderly Men: The MrOS Sweden Study

One risk factor for osteoporosis that has attracted increasing attention in recent years is exposure to cadmium. The aim of this study was to examine the associations between low-level cadmium exposure, from diet and smoking, and bone mineral density (BMD) and incident fractures in elderly men. The study population consisted of 936 men from the Swedish cohort of the Osteoporotic Fractures in Men (MrOS) study, aged 70 to 81 years at inclusion (years 2002 to 2004), with reliable data on cadmium in urine (U-Cd) analyzed using inductively coupled plasma mass spectrometry in baseline samples. The participants also answered a questionnaire on lifestyle factors and medical history. BMD was measured at baseline using dual-energy X-ray absorptiometry (DXA) in the total body, hip, and lumbar spine. During the follow-up period (until 2013), all new fractures were registered by date and type. Associations between BMD and U-Cd were assessed using multiple linear regression, and associations between incident fractures and baseline U-Cd were analyzed using Cox regression. In both cases, a number of potential confounders and other risk factors (eg, age, smoking, body mass index [BMI], and physical activity) were included in the models. We found significant negative associations between U-Cd and BMD, with lower BMD (4% to 8%) for all sites in the fourth quartile of U-Cd, using the first quartile as the reference. In addition, we found positive associations between U-Cd and incident fractures, especially nonvertebral osteoporosis fractures in the fourth quartile of U-Cd, with hazard ratios of 1.8 to 3.3 in the various models. U-Cd as a continuous variable was significantly associated with nonvertebral osteoporosis fractures (adjusted hazard ratio 1.3 to 1.4 per μg Cd/g creatinine), also in never-smokers, but not with the other fracture groups (all fractures, hip fractures, vertebral fractures, and other fractures). Our results indicate that even relatively low cadmium exposure through diet and smoking increases the risk of low BMD and osteoporosis-related fractures in elderly men.

Characteristics of Prevalent Vertebral Fractures Predict New Fractures in Elderly Men

BACKGROUND

Studies have shown that specific characteristics of prevalent vertebral fractures are associated with a markedly low bone mineral density. This study evaluates if these characteristics also predict subsequent fractures.

METHODS

MrOS (Mister Osteoporosis) Sweden is a population-based, prospective observational study that includes 3014 community-living men who are sixty-nine to eighty-one years of age. At baseline, 1453 men underwent lateral thoracic and lumbar spine radiography; radiographs of 1427 men were readable. A radiologist identified and characterized prevalent vertebral fractures. Incident fractures during the next five and ten years were objectively registered with use of radiographs. The annual fracture incidence and relative risk of sustaining new fractures were assessed for men with and without baseline prevalent vertebral fracture. Data are presented as the mean and the 95% confidence interval.

RESULTS

There were 215 men (15.1%) with at least one prevalent vertebral fracture. During the five-year follow-up, these men had a relative risk of 3.3 (95% confidence interval, 2.6 to 4.3) of sustaining new fractures. The relative risk of sustaining any fracture was especially high in men with two or more prevalent vertebral fractures at 5.5 (95% confidence interval, 3.7 to 7.8), in men with different types of prevalent vertebral fractures at 5.7 (95% confidence interval, 3.6 to 8.5), in men with prevalent fractures in both the thoracic and lumbar regions at 6.4 (95% confidence interval, 4.5 to 8.8), and in men with prevalent fractures with a degree of vertebral body compression in the three worst quartiles, with the relative risk for the worst quartile at 4.0 (95% confidence interval, 2.6 to 5.9).

CONCLUSIONS

Older men with a prevalent vertebral fracture have three times increased risk of sustaining new fractures compared with men without a vertebral fracture. Older men with two or more prevalent vertebral fractures, different types of fractures (wedge, biconcave, and/or crush), fractures in both the thoracic and lumbar regions, and a degree of vertebral body compression in the three worst quartiles are at an especially high risk of sustaining new fractures. Older men with prevalent vertebral fractures should be considered for fracture-prevention efforts.

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.

Serum total estradiol, but not testosterone is associated with reduced bone mineral density (BMD) in HIV-infected men: a cross-sectional, observational study

SUMMARY

By investigating the relationship between serum testosterone, estradiol, and bone mineral density (BMD) in a large cohort of HIV-infected men, estradiol was associated with BMD, relative estrogen deficiency being involved in bone loss in men with hypogonadism, in addition to all HIV-related factors. Increased aromatization in adipose tissue does not counteract HIV-related bone loss.

INTRODUCTION

The purpose of this study is to evaluate the relationship between serum testosterone, estradiol, and BMD in a large cohort of HIV-infected men.

METHODS

We investigated biochemical, hormonal parameters, and BMD in 1204 HIV-infected men (age 45.64 ± 7.33 years) participating in a cross-sectional, observational study. Among other parameters, the main outcome measures were serum total testosterone and estradiol, gonadotropins, 25-hydroxyvitamin D [25(OH)D], parathormone (PTH), calcium, phosphorous, femoral, and lumbar BMD.

RESULTS

In men with HIV, the prevalence of osteoporosis and osteopenia is 15.1 and 63.2% with 25(OH)D insufficiency being very common (60.1%). After age adjustment, BMD is positively associated with estradiol, but not testosterone, at linear (p < 0.001) and stepwise (p < 0.05) multiple regression. Lumbar BMD significantly increases across the estradiol quartiles but not among testosterone quartiles. Femoral and lumbar BMD are significantly higher in men with estradiol ≥ 27 pg/mL than in those with estradiol <27 pg/mL. Apart from estradiol, only age, calcium, and BMI predict BMD at stepwise linear multiple regression, but the strength of this association is weak.

CONCLUSIONS

Estradiol, but not testosterone, is associated with BMD in HIV-infected men and exerts a protective role on bone especially when it is above 27 pg/mL. Relative estrogen deficiency is a potential mechanism involved in bone loss in hypogonadal HIV-infected men, in addition to all HIV-related factors. Increased aromatization in adipose tissue does not counteract HIV-related bone loss. Finally, reduced BMD in young-to-middle-aged HIV-infected men might be considered a peculiar hallmark of HIV infection due to its relevant prevalence, representing one of the several pieces composing the complicated puzzle of premature aging related to HIV infection.

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.

Osteoporosis in men: findings from the Osteoporotic Fractures in Men Study (MrOS)

The lifespan of men is increasing and this is associated with an increased prevalence of osteoporosis in men. Osteoporosis increases the risk of bone fracture. Fractures are associated with increased disability and mortality, and public health problems. We review here the study of osteoporosis in men as obtained from a longitudinal cohort of community-based older men, the Osteoporotic Fractures in Men Study (MrOS).

The association between sex hormone-binding globulin gene polymorphism with bone mineral density

To investigate the impact of single nucleotide polymorphisms (SNPs) of SHBG gene the neighboring genes on SHBG levels, bone mineral density (BMD) and osteoporosis in Chinese males. A group of Chinese men, aged ⩾ 45 years were included in the analysis. BMD was measured with dual-energy X-ray absorptiometry (DXA), SHBG and total testosterone (TT) was measured using chemiluminescent immunoassay, and free testosterone (FT) was calculated. SNPs of SHBG gene and the neighboring genes were studied by means of improved multiple ligase detection reaction (iMLDR). A total of 404 men were included in our study. In the single locus analysis, significant associations were found between SHBG levels and four polymorphisms (rs11078701, rs9901675, rs9898876 and rs2541012) in age- and BMI-adjusted models. In addition, statistically significant difference was found between osteoporosis patients and control subjects in genotype distributions of rs9898876, rs2541012, rs6259 and rs3853894. In the models with or without adjustment for confounders (age, BMI, SHBG and free testosterone (FT) levels), carriers of variant genotype of rs9898876, rs2541012 and rs6259 had lower BMD and were more likely to suffer from osteoporosis, as compare to carriers of common genotype. Subjects with variant genotype of rs3853894 had higher BMD and were less likely to suffer from osteoporosis, as compared to subjects with common genotype. In the haplotypes analysis, CCGGT (constituted by rs11078701C, rs1017163C, rs9898876G, rs62059836G and rs2541012T) and haplotype CGGT (constituted by rs858521C, rs858518G, rs6259G and rs727428T) was associated with a significant risk effect for osteoporosis. Polymorphisms of SHBG or the neighboring genes were associated with SHBG levels or BMD and osteoporosis, suggesting the involvement of genetic variation of SHBG in bone health.

Enzalutamide Reduces the Bone Mass in the Axial But Not the Appendicular Skeleton in Male Mice

Testosterone is a crucial regulator of the skeleton, but the role of the androgen receptor (AR) for the maintenance of the adult male skeleton is unclear. In the present study, the role of the AR for bone metabolism and skeletal growth after sexual maturation was evaluated by means of the drug enzalutamide, which is a new AR antagonist used in the treatment of prostate cancer patients. Nine-week-old male mice were treated with 10, 30, or 100 mg/kg·d of enzalutamide for 21 days or were surgically castrated and were compared with vehicle-treated gonadal intact mice. Although orchidectomy reduced the cortical bone thickness and trabecular bone volume fraction in the appendicular skeleton, these parameters were unaffected by enzalutamide. In contrast, both enzalutamide and orchidectomy reduced the bone mass in the axial skeleton as demonstrated by a reduced lumbar spine areal bone mineral density (P < .001) and trabecular bone volume fraction in L5 vertebrae (P < .001) compared with vehicle-treated gonadal intact mice. A compression test of the L5 vertebrae revealed that the mechanical strength in the axial skeleton was significantly reduced by enzalutamide (maximal load at failure -15.3% ± 3.5%; P < .01). The effects of enzalutamide in the axial skeleton were associated with a high bone turnover. In conclusion, enzalutamide reduces the bone mass in the axial but not the appendicular skeleton in male mice after sexual maturation. We propose that the effect of testosterone on the axial skeleton in male mice is mainly mediated via the AR.

FRAX predicts incident falls in elderly men: findings from MrOs Sweden

Falls and fractures share several common risk factors. Although past falls is not included as an input variable in the FRAX calculator, we demonstrate that FRAX probability predicts risk of incident falls in the MrOs Sweden cohort.

INTRODUCTION

Although not included in the FRAX® algorithm, it is possible that increased falls risk is partly dependent on other risk factors that are incorporated into FRAX. The aim of the present study was to determine whether fracture probability generated by FRAX might also predict risk of incident falls and the extent that a falls history would add value to FRAX.

METHODS

We studied the relationship between FRAX probabilities and risk of falls in 1836 elderly men recruited to the MrOS study, a population-based prospective cohort of men from Sweden. Baseline data included falls history, clinical risk factors, bone mineral density (BMD) at femoral neck, and calculated FRAX probabilities. Incident falls were captured during an average of 1.8 years of follow-up. An extension of Poisson regression was used to investigate the relationship between FRAX, other risk variables, and the time-to-event hazard function of falls. All associations were adjusted for age and time since baseline.

RESULTS

At enrolment, 15.5 % of the men had fallen during the preceding 12 months (past falls) and 39 % experienced one or more falls during follow-up (incident falls). The risk of incident falls increased with increasing FRAX probabilities at baseline (hazard ratio (HR) per standard deviation (SD), 1.16; 95 % confidence interval (95%CI), 1.06 to 1.26). The association between incident falls and FRAX probability remained after adjustment for past falls (HR per SD, 1.12; 95%CI, 1.03 to 1.22). High compared with low baseline FRAX score (>15 vs <15 % probability of major osteoporotic fracture) was strongly predictive of increased falls risk (HR, 1.64; 95%CI, 1.36 to 1.97) and remained stable with time. Whereas past falls were a significant predictor of incident falls (HR, 2.75; 95%CI, 2.32 to 3.25), even after adjustment for FRAX, the hazard ratio decreased markedly with increasing follow-up time.

CONCLUSIONS

Although falls are not included as an input variable, FRAX captures a component of risk for future falls and outperforms falls history with an extended follow-up time.

Risk of Fractures and Falls during and after 5-α Reductase Inhibitor Use: A Nationwide Cohort Study

Background

Lower urinary tract symptoms are common among older men and 5-α reductase inhibitors (5-ARI) are a group of drugs recommended in treating these symptoms. The effect on prostate volume is mediated by a reduction in dihydrotestosterone; however, this reduction is counterbalanced by a 25% rise in serum testosterone levels. Therefore, 5-ARI use might have systemic effects and differentially affect bone mineral density, muscular mass and strength, as well as falls, all of which are major determinants of fractures in older men.

Methods

We conducted a nationwide cohort study of all Swedish men who used 5-ARI by comparing their risk of hip fracture, any type of fracture and of falls with matched control men randomly selected from the population and unexposed to 5-ARI.

Results

During 1 417 673 person-years of follow-up, 10 418 men had a hip fracture, 19 570 any type of fracture and 46 755 a fall requiring hospital care. Compared with unexposed men, current users of 5-ARI had an adjusted hazard ratio (HR) of 0.96 (95% CI 0.91–1.02) for hip fracture, an HR of 0.94 (95% CI 0.90–0.98) for all fracture and an HR of 0.99 (95% CI 0.96–1.02) for falls. Former users had an increased risk of hip fractures (HR 1.10, 95% CI 1.01–1.19).

Conclusion

5-ARI is safe from a bone health perspective with an unaltered risk of fractures and falls during periods of use. After discontinuation of 5-ARI, there is a modest increase in the rate of fractures and falls.

The number and characteristics of prevalent vertebral fractures in elderly men are associated with low bone mass and osteoporosis

We sought to determine whether specific characteristics of vertebral fractures in elderly men are associated with low bone mineral density (BMD) and osteoporosis. Mister Osteoporosis Sweden is a population based cohort study involving 3014 men aged 69 to 81 years. Of these, 1427 had readable lateral radiographs of the thoracic and lumbar spine. Total body (TB) BMD (g/cm²) and total right hip (TH) BMD were measured by dual energy x-ray absorptiometry. The proportion of men with osteoporosis was calculated from TH BMD. There were 215 men (15.1%) with a vertebral fracture. Those with a fracture had lower TB BMD than those without (p < 0.001). Among men with a fracture, TB BMD was lower in those with more than three fractures (p = 0.02), those with biconcave fractures (p = 0.02) and those with vertebral body compression of > 42% (worst quartile) (p = 0.03). The mean odds ratio (OR) for having osteoporosis when having any type of vertebral fracture was 6.1 (95% confidence interval (CI) 3.9 to 9.5) compared with those without a fracture. A combination of more than three fractures and compression in the worst quartile had a mean OR of 114.2 (95% CI 6.7 to 1938.3) of having osteoporosis compared with those without a fracture. We recommend BMD studies to be undertaken in these subcohorts of elderly men with a vertebral fracture.

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.

Reproductive Hormones and Longitudinal Change in Bone Mineral Density and Incident Fracture Risk in Older Men: The Concord Health and Aging in Men Project

The objectives of this study were to examine relationships between baseline levels of reproductive hormones in older men and (1) change in bone mineral density (BMD) over 5 years and (2) incident fractures over an average of 6 years' follow-up. A total of 1705 men aged 70 years and older from the Concord Health and Ageing in Men Project (CHAMP) study were assessed at baseline (2005-2007), 2 years follow-up (2007-2009), and 5 years follow-up (2010-2013). At baseline, testosterone (T), dihydrotestosterone (DHT), estradiol (E2), and estrone (E1) were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and sex hormone-binding globulin (SHBG), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) by immunoassay. Hip BMD was measured by dual X-ray absorptiometry (DXA) at all three time-points. Fracture data were collected at 4-monthly phone calls and verified radiographically. Statistical modeling was by general estimating equations and Cox model regression. Univariate analyses revealed inverse associations for serum SHBG, FSH, and LH and positive association for E1 but not DHT or E2 with BMD loss at the hip across the three time points. Serum levels of SHBG (β = -0.071), FSH (β = -0.085), LH (β = -0.070), and E1 (β = 0.107) remained significantly associated with BMD loss in multivariate-adjusted models; however, we were unable to identify any thresholds for accelerated BMD loss according to reproductive steroids. Incident fractures (all, n = 171; hip, n = 44; and nonvertebral, n = 139) were all significantly associated with serum SHBG, FSH, and LH levels in univariate models but none remained significantly associated in multivariate-adjusted model. Serum T, DHT, E2, and E1 levels were not associated with incident fractures in univariate or multivariate-adjusted analyses. In older men, lower serum SHBG, FSH, and LH and higher E1 levels protected against loss of BMD without increasing fracture rate. This means these reproductive variables may be considered as novel biomarkers of bone health during male aging.

Increased Cortical Porosity in Older Men With Fracture

Cortical porosity increases with age and affects bone strength, but its association with fracture in older men is unknown. The aim of this study was to investigate whether cortical porosity is associated with prevalent fractures in older men. A subsample of 456 men aged 80.2 ± 3.5 (mean ± SD) years, with available high-resolution peripheral quantitative computed tomography measurements at the tibia from the 5-year follow-up exam, was drawn from the prospective MrOS Gothenburg study. Dual-energy X-ray absorptiometry was used to measure areal bone mineral density (aBMD). Data on physical activity, calcium intake, medications, diseases, and smoking were collected on questionnaires at the follow-up exam. Of 87 men (19.1%) with fracture at or after age 50 years (all fracture group), 52 (11.4%) had had a self-reported fracture before the baseline exam and 35 (7.7%) had had an X-ray-verified fracture between baseline and follow-up. Men in the all-fracture group and in the X-ray-verified group had 15.8% (13.2% ± 4.9% versus 11.4% ± 3.8%; p < 0.001) and 21.6% (14.1% ± 5.2% versus 11.6% ± 3.9%; p < 0.01) higher cortical porosity, respectively, than men in the nonfracture group. The independent associations between bone microstructure parameters and fracture were tested using multivariate logistic regression with age, height, weight, calcium intake, smoking, physical activity, medications, and diseases as covariates. Cortical porosity was independently associated with any fracture (reported or X-ray-verified; OR per SD increase 1.49; 95% confidence interval (CI), 1.17 to 1.90) and with any X-ray-verified fracture alone (OR 1.73; 95% CI, 1.23 to 2.42). Including aBMD (spine or hip, respectively) in the multivariate logistic regression above revealed that cortical porosity was associated with any fracture (OR 1.54; 95% CI, 1.17 to 2.01) and with X-ray-verified fracture alone (OR 1.49; 95% CI, 1.00 to 2.22). Cortical porosity was associated with prevalence of fracture even after adjustment for aBMD.

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.

High serum adiponectin is associated with low blood haemoglobin in elderly men: the Swedish MrOS study

OBJECTIVES

Blood haemoglobin (Hb) concentration declines in elderly men, whilst the level of the adipocyte-derived protein adiponectin increases with age. The association between erythropoiesis and adiponectin in elderly men is unclear. The aim of this study was to determine whether adipokines such as adiponectin and leptin are associated with anaemia and Hb concentration in elderly community-dwelling men.

DESIGN AND SETTING

The Gothenburg part of the population-based Swedish Osteoporotic Fractures in Men (MrOS) cohort (n = 1010; median age 75.3 years, range 69-81).

MAIN OUTCOME MEASURES

We investigated the associations between levels of adiponectin and Hb before and after adjusting for potential confounders [i.e. age, body composition, erythropoietin (EPO), total oestradiol, leptin, cystatin C and iron and B vitamin status].

RESULTS

In these elderly men, age was negatively associated with Hb (r = -0.12, P < 0.001) and positively associated with adiponectin level (r = 0.13, P < 0.001). In age-adjusted partial correlations, Hb and adiponectin levels were negatively correlated (r = -0.20, P < 0.001); this association remained significant after multivariable adjustment for age, body composition, EPO, fasting insulin, sex hormones, leptin and ferritin. Age-adjusted mean adiponectin concentrations were significantly higher in anaemic men (66/1005; Hb <130 g L(-1) ) compared to nonanaemic men (14.0 vs. 11.7 μg mL(-1) , P < 0.05). In multivariate analysis, adiponectin together with EPO, total oestradiol, insulin, albumin, transferrin saturation, HDL cholesterol, cystatin C, total body fat mass and free thyroxine, but not leptin, explained 35% of the variation in Hb level. These results remained essentially unchanged after exclusion of men with diabetes.

CONCLUSIONS

Serum adiponectin, but not leptin, was negatively and independently associated with Hb. This finding suggests a possible role of adiponectin in the age-related decline in Hb level observed in apparently healthy elderly men.

Low clinical relevance of a prevalent vertebral fracture in elderly men--the MrOs Sweden study

BACKGROUND CONTEXT

The epidemiology, the fracture pattern, and the clinical relevance of prevalent vertebral fractures in old men are debated wherefore we set out to clarify these issues.

METHODS

Mister Osteoporosis (MrOs) Sweden is a population-based cohort of community-living men aged 69-81 years that includes 3,014 men. Out of these, 1,453 men underwent a lateral radiograph of the thoracic and lumbar spine of which 1,427 were readable and classified by a radiologist, that is the sample size in this study. The men also answered a questionnaire evaluating back pain and limitation in activities of daily living (ADLs) because of back pain during the preceding 12 months in addition with fracture history and life style.

RESULTS

Fifteen percentage of the men had at least one prevalent vertebral fracture, but only 1/10th of these were aware of their fracture. Among the men with a fracture, 58% had one, 21% two, 9% three, and 11% four or more fractures. In men with only one fracture, 70% of the fractures were located in the thoracic and 30% in the lumbar spine, 85% had a wedge, 13% a biconcave, and 2% a crush-type configuration; one-quarter had a maximum vertebral body compression degree of less than 24% and one-quarter of more than 38%. Among the men with one or several vertebral fracture, 57% reported back pain compared with 55% in those without a fracture (p=.53). Most ADL functions were similar in the men with or without a prevalent vertebral fracture. In the men with one fracture, there was no difference in the occurrence of back pain depending on the fractured region (p=.49), type of the fracture (p=.77), or degree of compression (p=.85). In men with one or several fractures, there were no significant differences in the presence of back pain in any ages (p=.08), nor there were differences in presence of back pain regarding type (p=.08) or number of fractures (p=.21).

CONCLUSIONS

A prevalent vertebral fracture is common in old men but has low clinical relevance. There does not seem to be a specific fracture pattern that predisposes for back pain.

Multiple hormonal dysregulation as determinant of low physical performance and mobility in older persons

Mobility-disability is a common condition in older individuals. Many factors, including the age-related hormonal dysregulation, may concur to the development of disability in the elderly. In fact, during the aging process it is observed an imbalance between anabolic hormones that decrease (testosterone, dehydroepiandrosterone sulphate (DHEAS), estradiol, insulin like growth factor-1 (IGF-1) and Vitamin D) and catabolic hormones (cortisol, thyroid hormones) that increase. We start this review focusing on the mechanisms by which anabolic and catabolic hormones may affect physical performance and mobility. To address the role of the hormonal dysregulation to mobility-disability, we start to discuss the contribution of the single hormonal derangement. The studies used in this review were selected according to the period of time of publication, ranging from 2002 to 2013, and the age of the participants (≥65 years). We devoted particular attention to the effects of anabolic hormones (DHEAS, testosterone, estradiol, Vitamin D and IGF-1) on both skeletal muscle mass and strength, as well as other objective indicators of physical performance. We also analyzed the reasons beyond the inconclusive data coming from RCTs using sex hormones, thyroid hormones, and vitamin D (dosage, duration of treatment, baseline hormonal values and reached hormonal levels). We finally hypothesized that the parallel decline of anabolic hormones has a higher impact than a single hormonal derangement on adverse mobility outcomes in older population. Given the multifactorial origin of low mobility, we underlined the need of future synergistic optional treatments (micronutrients and exercise) to improve the effectiveness of hormonal treatment and to safely ameliorate the anabolic hormonal status and mobility in older individuals.

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.

Current and future treatments of osteoporosis in men

One in three osteoporotic fractures occur in men and the consequences of a fracture in men tend to be more severe than in women. Still, only a small minority of men with high risk of fracture are detected and treated. Although there are gender differences in the pathophysiology of osteoporosis, such as in the pattern of bone loss, similarities predominate, which is also the case for clinical risk factors. It seems appropriate to consider treatment for men and women with a similar 10 year fracture risk. Drugs now approved for treatment of osteoporosis in men include the anti-resorptive bisphosphonates alendronate, residronate and zoledronic acid, the anti-resorptive drug denosumab, the bone-forming agent teriparatide, and (not in the US) strontium ranelate with mild opposite effects on resorption and formation. Although the evidence level for efficacy and safety of these drugs in men is still relatively limited, available data indicate that treatment effects in men are very similar to what has been observed in the treatment of postmenopausal osteoporosis. Denosumab is also approved for treatment in men receiving androgen deprivation therapy for non-metastatic prostate cancer; bisphosphonates and teriparatide are also available to clinicians for treatment of glucocorticoid-induced osteoporosis in men. Testosterone treatment may be indicated in men with documented symptomatic hypogonadism, but osteoporosis is neither a sufficient nor a specific indication for testosterone treatment. New compounds with well advanced clinical development include odanacatib, a selective inhibitor of the cysteine protease cathepsin-K, and romosozumab, a monoclonal antibody against sclerostin.

Sex steroid actions in male bone

Sex steroids are chief regulators of gender differences in the skeleton, and male gender is one of the strongest protective factors against osteoporotic fractures. This advantage in bone strength relies mainly on greater cortical bone expansion during pubertal peak bone mass acquisition and superior skeletal maintenance during aging. During both these phases, estrogens acting via estrogen receptor-α in osteoblast lineage cells are crucial for male cortical and trabecular bone, as evident from conditional genetic mouse models, epidemiological studies, rare genetic conditions, genome-wide meta-analyses, and recent interventional trials. Genetic mouse models have also demonstrated a direct role for androgens independent of aromatization on trabecular bone via the androgen receptor in osteoblasts and osteocytes, although the target cell for their key effects on periosteal bone formation remains elusive. Low serum estradiol predicts incident fractures, but the highest risk occurs in men with additionally low T and high SHBG. Still, the possible clinical utility of serum sex steroids for fracture prediction is unknown. It is likely that sex steroid actions on male bone metabolism rely also on extraskeletal mechanisms and cross talk with other signaling pathways. We propose that estrogens influence fracture risk in aging men via direct effects on bone, whereas androgens exert an additional antifracture effect mainly via extraskeletal parameters such as muscle mass and propensity to fall. Given the demographic trends of increased longevity and consequent rise of osteoporosis, an increased understanding of how sex steroids influence male bone health remains a high research priority.

Androgens and estrogens in skeletal sexual dimorphism

Bone is an endocrine tissue expressing androgen and estrogen receptors as well as steroid metabolizing enzymes. The bioactivity of circulating sex steroids is modulated by sex hormone-binding globulin and local conversion in bone tissue, for example, from testosterone (T) to estradiol (E2) by aromatase, or to dihydrotestosterone by 5α-reductase enzymes. Our understanding of the structural basis for gender differences in bone strength has advanced considerably over recent years due to increasing use of (high resolution) peripheral computed tomography. These microarchitectural insights form the basis to understand sex steroid influences on male peak bone mass and turnover in cortical vs trabecular bone. Recent studies using Cre/LoxP technology have further refined our mechanistic insights from global knockout mice into the direct contributions of sex steroids and their respective nuclear receptors in osteoblasts, osteoclasts, osteocytes, and other cells to male osteoporosis. At the same time, these studies have reinforced the notion that androgen and estrogen deficiency have both direct and pleiotropic effects via interaction with, for example, insulin-like growth factor 1, inflammation, oxidative stress, central nervous system control of bone metabolism, adaptation to mechanical loading, etc., This review will summarize recent advances on these issues in the field of sex steroid actions in male bone homeostasis.

Lowered testosterone in male obesity: mechanisms, morbidity and management

With increasing modernization and urbanization of Asia, much of the future focus of the obesity epidemic will be in the Asian region. Low testosterone levels are frequently encountered in obese men who do not otherwise have a recognizable hypothalamic-pituitary-testicular (HPT) axis pathology. Moderate obesity predominantly decreases total testosterone due to insulin resistance-associated reductions in sex hormone binding globulin. More severe obesity is additionally associated with reductions in free testosterone levels due to suppression of the HPT axis. Low testosterone by itself leads to increasing adiposity, creating a self-perpetuating cycle of metabolic complications. Obesity-associated hypotestosteronemia is a functional, non-permanent state, which can be reversible, but this requires substantial weight loss. While testosterone treatment can lead to moderate reductions in fat mass, obesity by itself, in the absence of symptomatic androgen deficiency, is not an established indication for testosterone therapy. Testosterone therapy may lead to a worsening of untreated sleep apnea and compromise fertility. Whether testosterone therapy augments diet- and exercise-induced weight loss requires evaluation in adequately designed randomized controlled clinical trials.

Sex hormone-binding globulin (SHBG) as an independent determinant of bone mineral density (BMD) among Chinese middle-aged and elderly men

The aim of the study was to assess the impact of sex hormone-binding globulin (SHBG) on bone mineral density (BMD) and bone turnover among Chinese middle-aged and elderly men. This cross-sectional study was carried out among 404 Chinese men aged over 45 years. BMD was measured with dual-energy X-ray absorptiometry, and participants' blood was collected for bone-specific alkaline phosphates (BSAP), SHBG and testosterone assay. Osteoporotic men had lower free testosterone (FT) and higher levels of SHBG, and BSAP than the osteopenia and normal groups. When SHBG levels were divided into quartiles, FT levels decreased and prevalence of osteoporosis increased with higher SHBG levels. Compared with subjects in the lowest quartile of SHBG levels (<36.55 nmol/l), subjects in the third quartile [OR (95 % CI) 2.998 (1.460-6.157), p = 0.002] and the highest quartile [OR (95 % CI) 4.439 (2.192-8.991), p < 0.001] were more likely to suffer with osteoporosis. FT was significantly positive related to total hip BMD and total lumbar BMD, whereas there was no association between TT and BMD after adjusting for age, BMI and FT. SHBG levels were also inversely related to BMD. SHBG could explain 1.4-2.1 % of the BMD variance after adjustment for age, BMI and FT. No association was found between BSAP and SHBG, TT and FT. Logistic regression analysis showed that BMI, smoking and FT or SHBG was independently associated with the presence of osteoporosis. Serum FT levels were positively correlated with BMD, while SHBG levels were inversely related to BMD. Increasing SHBG level was an independent risk factor for osteoporosis among Chinese men.

Muscle and bone effects of androgen deprivation therapy: current and emerging therapies

Prostate cancer and treatment with androgen deprivation therapy (ADT) affect significant numbers of the male population. Endocrine effects of ADT are a critical consideration in balancing the benefits and risks of treatment on long-term survival and quality of life. This review highlights the latest advances in androgen manipulation in prostate cancer with an emphasis on the effects of ADT on muscle and bone, which universally affects the health and well-being of men undergoing ADT for prostate cancer. Muscle mass declines with ADT; however, the evidence that this correlates with a decrease in muscle strength or a decrease in physical performance is discordant. Cortical bone decay also occurs in association with an increase in fracture risk, hence optimization of musculoskeletal health in men undergoing ADT is crucial. The role of exercise, and current and emerging anabolic therapies for muscle as well as various new strategies to prevent loss of bone mass in men undergoing ADT are discussed. Future well-designed, prospective, controlled studies are required to elucidate the effects of ADT on physical performance, which are currently lacking, and larger randomized controlled trials are required to test the efficacy of medical therapies and exercise interventions to target proven deficits and to ensure safety in men with prostate cancer.

The effect of estrogen on bone requires ERα in nonhematopoietic cells but is enhanced by ERα in hematopoietic cells

The effects of estrogen on bone are mediated mainly via estrogen receptor (ER)α. ERα in osteoclasts (hematopoietic origin) is involved in the trabecular bone-sparing effects of estrogen, but conflicting data are reported on the role of ERα in osteoblast lineage cells (nonhematopoietic origin) for bone metabolism. Because Cre-mediated cell-specific gene inactivation used in previous studies might be confounded by nonspecific and/or incomplete cell-specific ERα deletion, we herein used an alternative approach to determine the relative importance of ERα in hematopoietic (HC) and nonhematopoietic cells (NHC) for bone mass. Chimeric mice with selective inactivation of ERα in HC or NHC were created by bone marrow transplantations of wild-type (WT) and ERα-knockout (ERα(-/-)) mice. Estradiol treatment increased both trabecular and cortical bone mass in ovariectomized WT/WT (defined as recipient/donor) and WT/ERα(-/-) mice but not in ERα(-/-)/WT or ERα(-/-)/ERα(-/-) mice. However, estradiol effects on both bone compartments were reduced (∼50%) in WT/ERα(-/-) mice compared with WT/WT mice. The effects of estradiol on fat mass and B lymphopoiesis required ERα specifically in NHC and HC, respectively. In conclusion, ERα in NHC is required for the effects of estrogen on both trabecular and cortical bone, but these effects are enhanced by ERα in HC.

Lower urinary tract symptoms are associated with low levels of serum serotonin, high levels of adiponectin and fasting glucose, and benign prostatic enlargement

OBJECTIVE

The aim of this study was to test whether lower urinary tract symptoms (LUTS) and urinary incontinence are associated with the metabolic syndrome (MetS). The association between LUTS and benign prostatic enlargement (BPE) was also investigated.

MATERIAL AND METHODS

A cross-sectional, representative risk factor analysis of LUTS, as measured by the International Prostate Symptom Score (IPSS), and urinary incontinence was conducted. Among 950 representative individuals, aged 69-81 years, the association between clinical, anthropometric, endocrine, metabolic and inflammatory factors on the one hand, as both major and minor aspects of MetS, and LUTS and urinary incontinence, on the other hand, was analysed. The prostate gland volume was measured in a subgroup of 155 randomly selected individuals and the association between LUTS and BPE was estimated.

RESULTS

No significant association was found between LUTS or urinary incontinence and the major aspects of the MetS. However, in a multivariate analysis, serum serotonin showed an independent negative correlation with LUTS and with urinary incontinence while fasting serum glucose and serum adiponectin showed a positive correlation with LUTS. Furthermore, in a subgroup of 155 individuals, the prostate gland volume correlated positively with LUTS.

CONCLUSIONS

The study did not show an association between LUTS or urinary incontinence and the major components of the MetS. However, serum serotonin showed an independent negative correlation with LUTS and with urinary incontinence while fasting serum glucose and serum adiponectin showed a positive correlation with LUTS. The data confirm the general knowledge that BPE may be one of the causative factors of LUTS.

Serum estradiol associates with blood hemoglobin in elderly men: the MrOS Sweden study

CONTEXT

Blood hemoglobin (Hb) declines with age in healthy elderly men, in whom decreasing T has been regarded as part of normal aging. However, the association between Hb and serum estradiol is incompletely known.

OBJECTIVE

To determine whether estradiol is associated with anemia/Hb and established determinants of Hb in elderly men without prostate cancer.

DESIGN, SETTING, AND PARTICIPANTS

The MrOS (Osteoporotic Fractures in Men) is a population-based study (n = 918; median age, 75.3 y; range, 70-81 y).

MAIN OUTCOME MEASURES

We evaluated total estradiol in relation to Hb and adjusted for potential confounders (ie, age, body mass index [BMI], erythropoietin [EPO], total T, cystatin C, and iron and B-vitamin status).

RESULTS

Estradiol correlated negatively with age (r = -0.14; P < .001). Hb correlated (age adjusted) positively with estradiol (r = 0.21; P < .001) and T (r = 0.10; P < .01). Independent predictors for Hb in multivariate analyses were estradiol, EPO, BMI, transferrin saturation, cystatin C, and free T4, but not T. After exclusion of subjects with Hb <130 g/L and/or T < 8 nmol/L (n = 99), the correlation between Hb and T was no longer significant, whereas the associations between Hb and estradiol remained. After adjusting for age, BMI, and EPO, men with lower estradiol levels were more likely to have Hb in the lowest quartile of values (odds ratio per SD decrease in estradiol = 1.61 [95% confidence interval, 1.34-1.93]). Anemic subjects (Hb < 130 g/L) had lower mean estradiol than nonanemic subjects (67.4 vs 79.4 pmol/L; P < .001).

CONCLUSIONS

Estradiol correlated positively and independently with Hb. Decreased estradiol might partly explain the age-related Hb decline observed in healthy elderly men.

Serum estradiol levels are inversely associated with cortical porosity in older men

CONTEXT

The key role of serum estradiol (E2) for bone health in men is well established. The effect of serum sex steroids on bone microstructure, measured by high-resolution peripheral quantitative computed tomography, remains unknown in elderly men.

OBJECTIVE

The objective of the study was to examine the associations between serum sex steroids and bone microstructural parameters in older men.

METHODS

Trabecular and cortical bone microstructure at the tibia was measured by high-resolution peripheral quantitative computed tomography in 440 men (mean 80 y of age) participating in the population-based Osteoporotic Fractures in Men Sweden cohort. Serum levels of E2 and T were analyzed with mass spectrometry and free E2 and free T levels were calculated using law-of-mass-action equations.

RESULTS

Age-adjusted models demonstrated that E2 and free E2 but not T or free T associated significantly inversely with cortical porosity. The associations between E2 and free E2 and cortical porosity remained significant after further adjustment for height, weight, physical activity, calcium intake, and smoking. Models including both serum E2 and T demonstrated that E2 (standardized β = -.12, P < .05) but not T associated independently with cortical porosity. A similar independent association was found for free E2 (standardized β = -.12, P < .05) but not free T. Free E2 associated significantly with trabecular bone volume fraction in the age-adjusted models, but this association did not remain significant after further adjustment.

CONCLUSIONS

Serum E2 levels associated inversely with cortical porosity in 80-year-old men. We propose that low serum E2 may reduce cortical bone strength, at least partly, by increasing cortical porosity and thereby increase fracture risk in older men.