Age Of Peak Bone Mass Research Articles

Osteocyte lacunae in transiliac bone biopsy samples across life span

Osteocytes act as bone mechanosensors, regulators of osteoblast/osteoclast activity and mineral homeostasis, however, knowledge about their functional/morphological changes throughout life is limited. We used quantitative backscattered electron imaging (qBEI) to investigate osteocyte lacunae sections (OLS) as a 2D-surrogate characterizing the osteocytes. OLS characteristics, the density of mineralized osteocyte lacunae (i.e., micropetrotic osteocytes, md.OLS-Density in nb/mm2) and the average degree of mineralization (CaMean in weight% calcium) of cortex and spongiosa were analyzed in transiliac biopsy samples from healthy individuals under 30 (n=59) and over 30 years (n=50) (i.e., before and after the age of peak bone mass, respectively). We found several differences in OLS-characteristics: 1). Inter-individually between the age groups: OLS-Density and OLS-Porosity were reduced by about 20% in older individuals in spongiosa and in cortex versus younger probands (both, p<0.001). 2). Intra-individually between bone compartments: OLS-Density was higher in the cortex, +18.4%, p<0.001 for younger and +7.6%, p<0.05 for older individuals. Strikingly, the most frequent OLS nearest-neighbor distance was about 30 µm in both age groups and at both bone sites revealing a preferential organization of osteocytes in clusters. OLS-Density was negatively correlated with CaMean in both spongiosa and cortex (both, p<0.001). Few mineralized OLS were found in young individuals along with an increase of md.OLS-Density with age. In summary, this transiliac bone sample analysis of 200000 OLS from 109 healthy individuals throughout lifespan reveals several age-related differences in OLS characteristics. Moreover, our study provides reference data from healthy individuals for different ages to be used for diagnosis of bone abnormalities in diseases. STATEMENT OF SIGNIFICANCE: Osteocytes are bone cells embedded in lacunae within the mineralized bone matrix and have a key role in the bone metabolism and the mineral homeostasis. Not easily accessible, we used quantitative backscattered electron imaging to determine precisely number and shape descriptors of the osteocyte lacunae in 2D. We analyzed transiliac biopsy samples from 109 individuals with age distributed from 2 to 95 years. Compact cortical bone showed constantly higher lacunar density than cancellous bone but the lacunar density in both bone tissue decreased with age before the peak bone mass age at 30 years and stabilized or even increased after this age. This extensive study provides osteocyte lacunae reference data from healthy individuals usable for bone pathology diagnosis.

Influences on Skeletal Health and Bone Mineralization in Children.

Bone is in its most active formation phase of mineralization in the pediatric and adolescent population. Peak bone mass is achieved around the late teens to early 20s. Deficient bone mineralization and decreased peak bone mass acquisition predispose an individual to childhood fractures or lifelong fracture risk. Adolescent fragility or stress fractures should prompt a secondary evaluation for the causes of a low bone mineral content, the root of a fracture. The purpose of this article is to review published literature that discusses the risk factors associated with a decreased bone mineral content in children from birth to the age of peak bone mass. The article also includes a public health planning model for pediatric osteoporosis.

Bone density in youth with prediabetes: results from the National Health and Nutrition Examination Survey, 2005-2006.

Type 2 diabetes might adversely influence bone health around the age of peak bone mass, but it is unknown whether diabetes-related effects on areal bone mineral density (aBMD) are evident in youth with prediabetes. We compared age-related trends in aBMD and associations between lean body mass (LBM) and aBMD between children and adolescents with prediabetes vs. normal glucose regulation. Cross-sectional analysis of data from the National Health and Nutrition Examination Survey (2005-2006) in youth ages 12-20years (49% female, 34% black) with prediabetes (n = 267) and normal glucose regulation (n = 1664). Whole body aBMD and LBM were assessed via DXA. LBM index (LBMI) and Z-scores for aBMD and LBMI were computed. Unadjusted between-group comparisons revealed greater mean weight and LBMI Z-scores in youth with prediabetes vs. normal glucose regulation, but similar bone Z-scores between the two groups. While accounting for differences in BMI Z-score, there was a significant interaction between prediabetes status and age with respect to whole body aBMD Z-score (P < 0.05), such that children with prediabetes tended to have increased aBMD but adolescents and young adults with prediabetes tended have lower aBMD. Furthermore, the positive association between LBMI and whole body aBMD was moderated in youth with prediabetes (P < 0.001), who had slightly lower whole body aBMD for a given LBMI (P = 0.068). Lumbar spine bone measures did not differ between the two groups. Type 2 diabetes-related threats to peak bone mass might occur prior to disease onset, therefore potentially impacting a considerable proportion of US youth.

A clinical approach to parasellar lesions in the transition age.

Many reviews have summarised the pathology and management of the parasellar region in adult patients, although an analysis of these aspects in the transition years, from puberty onset to the age of peak bone mass, has been lacking. A comprehensive search of English-language original articles, published from 2000 to 2020, was conducted in the MEDLINE database (December 2019 to March 2020). We selected all studies regarding epidemiology, diagnosis and management of the following parasellar lesions: germinoma, craniopharyngioma, Langerhans cell histiocytosis, optic glioma, hypothalamic hamartoma, tuber cinereum hamartoma, cranial chordoma, Rathke cleft cyst, hypophysitis and hypothalamitis during the transition age from childhood to adulthood. In the present review, we provide an overview of the principal parasellar lesions occurring in the transition age. Symptoms are usually a result of the mass effect of the lesions on nearby structures, as well as anterior pituitary deficits. Diabetes insipidus occurs frequently in these patients. In this age group, pubertal developmental disorders may be more evident compared to other stages of life. Parasellar lesions in the transition age mostly include neoplastic lesions such as germinomas, hamartomas, optic gliomas, craniopharyngiomas Langerhans cell histiocytosis and chordomas, and rarely inflammatory lesions (hypophysitis, hypothalamitis). There are limited data on the management of parasellar lesions in the transition age. Endocrine evaluation is crucial for identifying conditions that require hormonal treatment so that they can be treated early to improve the quality of life of the individual patient in this complex age range. The clinical approach to parasellar lesions involves a multidisciplinary effort.

Bone health in young adult survivors born extremely preterm or extremely low birthweight in the post surfactant era.

Most infants born extremely preterm (EP; <28weeks' gestation) or extremely low birthweight (ELBW; <1000g birthweight) in the post surfactant era (early 1990s) are now surviving into adulthood. Preterm birth/low birthweight are risk factors for reduced bone growth and mineralisation in infants and children. However, little is known about their bone health around peak bone mass and through adult life. To compare bone health (bone mineral measures, bone structure and strength) in young adults born EP/ELBW with controls (>2499g birthweight), and within the EP/ELBW group examine perinatal and later variables associated with long term bone health. A geographic cohort comprising all 297 survivors born EP/ELBW in 1991-92 in the state of Victoria, Australia, and 260 contemporaneous controls (>2499g birthweight) were recruited into a longitudinal study from birth. At age 25years, investigations included dual energy X ray absorptiometry and peripheral quantitative computed tomography to measure bone, muscle and soft tissue variables, and fasting blood samples to measure serum 25 hydroxyvitamin D (25(OH)D) and bone turnover markers (BTM). Linear regression analysis, with models fitted using generalised estimating equations, was used to compare outcomes between groups, adjusting for height and weight. Compared with controls (n=129), young adults born EP/ELBW (n=162) had lower areal bone mineral density (g/cm2) (mean difference [MD] -0.044; 95% confidence interval [CI] -0.076,-0.013) and Z-scores (MD -0.53; 95% CI -0.75, -0.30) in the femoral neck, and lower total hip Z-score (MD -0.35; 95% CI -0.54, -0.15) after adjusting for height and weight. EP/ELBW males generally displayed more bone and soft tissue deficits than females, compared with their respective controls. Within the EP/ELBW group, early growth, male sex, height and lean mass, muscle measures, 25(OH)D levels, and BTM were independently associated with bone mineral measures, structure or strength. Young adults born EP/ELBW had evidence of impaired bone health around the age of peak bone mass compared with controls. Further follow-up of the EP/ELBW groups will determine if they have a heightened low-trauma fracture risk in later life.

Bone Mass and Density in Youth With Type 2 Diabetes, Obesity, and Healthy Weight.

Youth-onset type 2 diabetes is an aggressive condition with increasing incidence. Adults with type 2 diabetes have increased fracture risk despite normal areal bone mineral density (aBMD), but the influence of diabetes on the growing skeleton is unknown. We compared bone health in youth with type 2 diabetes to control patients with obesity or healthy weight. Cross-sectional study of youth (56% African American, 67% female) ages 10-23 years with type 2 diabetes (n = 180), obesity (BMI >95th; n = 226), or healthy weight (BMI <85th; n = 238). Whole-body (less head) aBMD and lean mass as well as abdominal visceral fat were assessed via DXA. Lean BMI (LBMI) and aBMD SD scores (z scores) were computed using published reference data. We observed age-dependent differences in aBMD and LBMI z scores between the healthy weight, obese, and type 2 diabetes groups. In children, aBMD and LBMI z scores were greater in the type 2 diabetes group versus the obese group, but in adolescents and young adults, aBMD and LBMI z scores were lower in the type 2 diabetes group versus the obese group (age interactions P < 0.05). In the type 2 diabetes group and the obese group, aBMD was about 0.5 SDs lower for a given LBMI z score compared with healthy weight control patients (P < 0.05). Further, aBMD was lower in those with greater visceral fat (β = -0.121, P = 0.047). These results suggest that type 2 diabetes may be detrimental to bone density around the age of peak bone mass. Given the increased fracture risk in adults with type 2 diabetes, there is a pressing need for longitudinal studies aimed at understanding the influence of diabetes on the growing skeleton.

Previous Adolescent Pregnancy and Breastfeeding Does Not Negatively Affect Bone Mineral Density at the Age of Peak Bone Mass.

To determine bone mineral density (BMD) at the age of peak bone mass in women who previously experienced pregnancy and breastfeeding during adolescence. In this retrospective study, female volunteers aged 24-30 years who were pregnant during the age of 15-19 years and have had one to two babies were recruited. All of them experienced breastfeeding without history of bone- or calcium-related problems, such as fracture or low calcium intake. BMD was determined at the femur and L1-L4 spine by dual-energy X-ray absorptiometry. We found that both volunteers who previously experienced breastfeeding and age-matched control volunteers had similar BMD at the L1-L4 spines and femora. Further analysis for site-specific changes of lumbar and femoral BMDs showed that the values of the breastfeeding group were not different from those of the control group except at L1 and L2, where BMD values were greater in breastfeeding group compared with the control group. At both femoral and vertebral sites, T- and Z-scores were apparently similar between the two groups. In addition, the BMD at peak bone mass had no significant correlation with breastfeeding duration. Teenage pregnancy and breastfeeding did not negatively affect BMD later at the age of peak bone mass. Therefore, breastfeeding can be encouraged in teenage mothers.

Bone Geometric Properties of the Femoral Neck in Underweight Eumenorrheic Women

The aim of this study was to describe femoral neck (FN) geometry among eumenorrheic underweight women around the age of peak bone mass. Proximal femur geometry and body composition were assessed in 12 underweight women and in 24 healthy controls using dual-energy X-ray absorptiometry. The Hip Structural Analysis program was used to determine bone geometry at the FN. The cross-sectional area (CSA) and the cross-sectional moment of inertia (CSMI) were significantly lower in underweight women than in controls (p < 0.05). There was a trend toward lower sectional modulus (Z) and strength index in underweight women (p < 0.15). Body weight, body mass index, and lean mass (LM) were positively correlated with CSA, CSMI, Z, and neck-shaft angle (r = 0.428–0.611, p < 0.05). After controlling for body weight, body mass index, and LM, the differences in CSA, CSMI, Z, and neck-shaft angle were no more statistically significant between the 2 groups. The multivariate analysis retained LM as the main predictor of CSA, CSMI, and Z in the whole population. The present study suggests that thinness is associated with low resistance to axial forces (CSA) and bending load (Z and CSMI) in adult eumenorrheic women. LM seems to be a key determinant of FN geometry in underweight women.

Insulin Resistance Is Associated With Smaller Cortical Bone Size in Nondiabetic Men at the Age of Peak Bone Mass.

In type 2 diabetes mellitus, fracture risk is increased despite preserved areal bone mineral density. Although this apparent paradox may in part be explained by insulin resistance affecting bone structure and/or material properties, few studies have investigated the association between insulin resistance and bone geometry. We aimed to explore this association in a cohort of nondiabetic men at the age of peak bone mass. Nine hundred ninety-six nondiabetic men aged 25 to 45 years were recruited in a cross-sectional, population-based sibling pair study at a university research center. Insulin resistance was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR), with insulin and glucose measured from fasting serum samples. Bone geometry was assessed using peripheral quantitative computed tomography at the distal radius and the radial and tibial shafts. In age-, height-, and weight-adjusted analyses, HOMA-IR was inversely associated with trabecular area at the distal radius and with cortical area, periosteal and endosteal circumference, and polar strength strain index at the radial and tibial shafts (β ≤ -0.13, P < 0.001). These associations remained essentially unchanged after additional adjustment for dual-energy X-ray absorptiometry-derived body composition, bone turnover markers, muscle size or function measurements, or adiponectin, leptin, insulin-like growth factor 1, or sex steroid levels. In this cohort of nondiabetic men at the age of peak bone mass, insulin resistance is inversely associated with trabecular and cortical bone size. These associations persist after adjustment for body composition, muscle size or function, or sex steroid levels, suggesting an independent effect of insulin resistance on bone geometry.

Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta

During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstntm1Sjl/+) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstntm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2oim), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2oim/+ offspring from natural mating of Mstntm1Sjl/+ dams to Col1a2oim/+sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2oim/+ dams to Col1a2oim/+ sires. Finally, increased bone biomechanical strength of Col1a2oim/+ offspring that had been transferred into Mstntm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta.

A neglected requirement for optimizing treatment of age-related osteoporosis: Replenishing the skeleton’s base reservoir with net base-producing diets

Osteoporosis is a disorder of bone in which the mass of the bone is reduced and the bone’s architecture at the microscopic level is disordered. Together those abnormalities predispose affected individuals to experience fractures despite only minimal trauma (i.e., fragility fractures). Age related osteoporosis is a common type of osteoporosis that occurs with aging in both men and women usually beginning after the age of peak bone mass. Research has found that the disorder can be partially reversed by reducing the net amount of acid that is produced when consuming typical Western diets. However, the amelioration that results has not been so dramatic or so consistent that physicians have adopted the procedure as part of the standard treatment for age-related osteoporosis. We propose that reducing the net acid load from the diet is not sufficient to reverse age related osteoporosis because it fails to supply base needed to restore the large amount of base in bone that had been lost by reacting with the net acid load of the diet that had been consumed for years or decades. Reducing the net acid load from the diet might be expected to have little ameliorative effect or merely slow the progression of the disorder. We hypothesize that both to restore osteoporotic bone to, or nearly to, its pre-disease state, as well as to eliminate the risk of fragility fractures, requires consuming diets that produce net amounts of base to restore the base lost from years to decades of consuming diets that produce net amounts of acid. We hypothesize also that the excess base and attendant subclinical metabolic alkalosis will both stimulate the cellular process of bone formation and suppress the cellular process of bone resorption, and thereby implement the restorative process.

Inter-correlation of knowledge, attitude, and osteoporosis preventive behaviors in women around the age of peak bone mass.

BackgroundAs silent and preventable in nature, postmenopausal osteoporosis awareness should be raised among young women prior to an irreversible period of declining bone mass. We therefore decided to assess the inter-correlation of knowledge, attitude and osteoporosis preventive behaviors in women around the age of peak bone mass.MethodsA cross-sectional study was conducted in 430 women aged 20–35 years. The participants’ knowledge, attitude and behaviors concerning osteoporosis prevention were assessed along with demographic data using a four-part questionnaire. The items in this questionnaire were established by extensive literature review, including the Guideline for Management of Osteoporosis of the Thai Osteoporosis Foundation (TOPF) 2010. The content was validated by experts in osteoporosis and reliability was obtained with a Cronbach’s alpha score of 0.83.ResultsThe mean age of women in this study was 29.4 ± 4.6 years. Half of the participants (49.5%) had heard about osteoporosis, mostly from television (95.3%, n = 203/213) and the internet (72.8%, n = 155/213). Most women had certain knowledge (85.2%) and positive attitude towards osteoporosis (53.3%). Nevertheless, 80% of the studied population did not have appropriate osteoporosis behaviors. We found significant correlation between the level of attitudes and osteoporosis behaviors (adjusted odd ratio = 3.3 with 95% confidence interval of 1.9-5.7); attitude and educational level (adjusted odd ratio = 2.2 with 95% confidence interval of 1.4-3.4); and attitude and knowledge (adjusted odd ratio = 3.5 with 95% confidence interval of 1.8-6.8).ConclusionDespite having certain knowledge about osteoporosis, the young women did not seem to have appropriate osteoporosis preventive behaviors. Developing a right attitude towards osteoporosis may be a key determinant to improving health practices in order to prevent osteoporosis.

Waist Circumference: A Key Determinant of Bone Mass in University Students

This study aimed to assess bone mineral density (BMD) status, and to explore association between lifestyle behaviors, body mass index (BMI), waist circumference (WC) and BMD status of 217 students (55 males and 162 females) aged between 17 - 23 years studying at Walailak University. The BMD was measured at distal-third radius, and confirmed at mid-shaft tibia by Quantitative ultrasound analysis. BMI and WC were recorded to assess obesity, and lifestyle behaviors were evaluated using a questionnaire. Results showed 10.9 % males and 16 % females had low BMD (Z-score < -1) at both sites, while 29.1 % males and 11.8 % females were classified in the risk group. Proportions of the obese subjects assessed by BMI and WC were found to be greater in males (10.9 and 21.8 %) than females (6.8 and 18.5 %). Lifestyle behaviors of both genders were not much different. Only 45.2 % consumed milk ³ 3 packs/week. Most subjects (87.1 %) consumed high cholesterol diets (³ 3 days/week), while 24 % did exercise ³ 3 times/week. Both factors are of concern for the obese group. Crude analysis showed BMI, WC and milk intake are potential determinants of BMD. Final analysis indicated students with normal WC are found greater in a high BMD group than in a normal BMD group (RRR = 4.38), and the expected risk in the BMD group is lower for female students (RRR = 0.37). We suggest that to prevent osteoporosis in later life, healthy lifestyle practices should be promoted and obesity must be careful monitored during the age of peak bone mass.

Influence of vitamin D levels on bone mineral density and osteoporosis

BACKGROUND AND OBJECTIVES:The effects of vitamin D on bone mass remain to be understood. This study was conducted with the objective of evaluating the influence of 25-hydroxyvitamin D (25OHD) levels on bone mineral density (BMD) among Saudi nationals.DESIGN AND SETTING:Cross-sectional study carried out at university hospital from 1 February 2008 to 31 May 2008.SUBJECTS AND METHODS:Healthy Saudi men and women in the peak bone mass (PBM) age group and those aged ≥50 years were recruited from the outpatient department of King Fahd University Hospital, Al Khobar, Saudi Arabia, between February 1, 2008, and May 31, 2008. Patient age and sex were documented, and body mass index was calculated. Hematological, biochemical, and serum 25OHD tests were performed. BMD was determined by dual-energy x-ray absorptiometry of the upper femur and lumbar spine. Patients were divided into three groups, based on their 25OHD level.RESULTS:Data from 400 patients were analyzed. Among individuals with a normal 25OHD level, 50% of women and 7% of men in the PBM age group and 26.4% of women and 49.2% of men aged ≥50 years had low bone mass. In patients with 25OHD insufficiency, 84.2% of women and 88.9% of men in the PBM age group and 83.3% of women and 80% of men aged ≥50 years had low bone mass. Results for patients with 25OHD deficiency revealed that none of the men and women in the PBM age group or ≥50 years old had normal BMD. Significant positive correlations between 25OHD level and BMD and significant negative correlations with parathyroid hormone were shown in most of the groups.CONCLUSIONS:This study showed that the vitamin D level significantly influences BMD reading among Saudi individuals. Evaluation and treatment of hypovitaminosis D should be considered during management of low bone mass.

Bone turnover at the spine and hip measured using 18F-PET

Bone turnover at the spine and hip measured using 18F-PET

Thyroid hormone status within the euthyroid range is associated with bone mass and density in healthy young men at the age of peak bone mass

Thyroid hormone status within the euthyroid range is associated with bone mass and density in healthy young men at the age of peak bone mass

Thyroid hormone status within the physiological range affects bone mass and density in healthy men at the age of peak bone mass

The hormonal factors involved in the regulation of peak bone mass (PBM) in men have not been fully investigated. Apart from gonadal steroids and somatotropic hormones, thyroid hormones are known to affect bone maturation and homeostasis and are additional candidate determinants of adult bone mass. We aimed to investigate between-subject physiological variation in free and total thyroid hormone concentrations, TSH, and thyroid binding globulin (TBG) in relation to parameters of bone mass, geometry, and mineral density in healthy men at the age of PBM. We recruited 677 healthy male siblings aged 25-45 years in a cross-sectional, population-based study. Areal and volumetric bone parameters were determined using dual-energy x-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT). Total and free thyroid hormones, TBG, and TSH were determined using immunoassays. Free and total thyroid hormone concentrations were inversely associated with bone mineral density (BMD) and bone mineral content (BMC) at the hip and total body (free triiodothyronine (FT(3)), total T(3) (TT(3)), and total T(4) (TT(4))) and at the spine (FT(3)). TBG was negatively associated with BMC and areal BMD at all sites. At the radius, cortical bone area was inversely associated with TT(3), TT(4), and TBG, and trabecular bone density was inversely associated with free thyroxine, TT(4), and TBG. We observed inverse associations between cortical bone area at the mid-tibia and FT(3), TT(3), TT(4), and TBG. No associations between TSH and DXA or pQCT measurements were found. In healthy men at the age of PBM, between-subject variation in thyroid hormone concentrations affects bone density, with higher levels of FT(3), TT(3), TT(4), and TBG being associated with less favorable bone density and content.

Cortical bone geometry in relation to prevalent fractures in young healthy men at age of peak bone mass

Cortical bone geometry in relation to prevalent fractures in young healthy men at age of peak bone mass

Prevalent fractures are related to cortical bone geometry in young healthy men at age of peak bone mass

Low areal bone mass is a risk factor for fractures in men. Limited data are available on fractures and bone geometry in men, and the relation with sex steroids is incompletely understood. We investigated prevalent fractures in relation to peak bone mass, bone geometry, and sex steroids in healthy young men. Healthy male siblings (n = 677) at the age of peak bone mass (25 to 45 years) were recruited in a cross-sectional population-based study. Trabecular and cortical bone parameters of the radius and cortical bone parameters of the tibia were assessed using peripheral quantitative computed tomography (pQCT). Areal bone mineral density (aBMD) was determined using dual-energy X-ray absorptiometry (DXA). Sex steroids were determined using immunoassays, and fracture prevalence was assessed using questionnaires. Fractures in young men were associated with a longer limb length, shorter trunk, lower trabecular BMD, smaller cortical bone area, and smaller cortical thickness (p < .005) but not with bone-size-adjusted volumetic BMD (vBMD). With decreasing cortical thickness [odds ratio (OR) 1.4/SD, p <or= .001] and decreasing cortical area (OR 1.5/SD, p <or= .001), fracture odds ratios increased. No association between sex steroid concentrations and prevalent fractures was observed. Childhood fractures (<or=15 years) were associated with a thinner bone cortex (-5%, p <or= .005) and smaller periosteal size (-3%, p <or= .005). Fractures occurring later than 15 years of age were associated with a thinner bone cortex (-3%, p <or= .05) and larger endosteal circumference (+3%, p <or= .05) without differences in periosteal bone size. In conclusion, prevalent fractures in healthy young men are associated with unfavorable bone geometry and not with cortical vBMD when adjusting for bone size. Moreover, the data suggest different mechanisms of childhood fractures and fractures during adult life.

Sex Hormone-Binding Globulin as an Independent Determinant of Cortical Bone Status in Men at the Age of Peak Bone Mass

Sex steroids are important determinants of the skeletal development, growth, and maintenance after achievement of peak bone mass. A large fraction of these hormones are bound by SHBG, and previous studies have shown that SHBG could be a determinant of bone characteristics. We investigated associations of serum SHBG levels with cortical and trabecular bone characteristics in young healthy men. A total of 677 healthy male siblings aged 25-45 yr were recruited in a cross-sectional, population-based study. Areal bone parameters were assessed using dual-energy x-ray absorptiometry. Cortical bone parameters at the tibia and radius and trabecular vBMD at the radius were assessed using peripheral quantitative computed tomography. Serum testosterone, estradiol, and SHBG levels were measured using immunoassays. Regression models including age, height, and weight showed that SHBG levels were positively associated with bone area at the hip and the whole body, but not with areal bone mineral density (BMD). Higher SHBG levels were associated with a larger cortical bone area and periosteal and endosteal circumferences at both the tibia and the radius, whereas trabecular volumetric BMD at the radius was negatively associated with SHBG levels. Associations persisted after adjustment for (free) sex steroid levels. No associations were found with cortical volumetric BMD or cortical thickness. In this population of healthy adult men at the age of peak bone mass, SHBG levels were positively associated with cortical bone size, independently from sex-steroid levels. This suggests a possible independent role of SHBG in the determination of adult bone size.