Bone Mass Measurements Research Articles

Longitudinal practice patterns of prophylaxis of glucocorticoid-induced osteoporosis in patients with polymyalgia rheumatica.

The aim of this study was to analyze the longitudinal practice patterns of prophylaxis of glucocorticoid-induced osteoporosis in patients with polymyalgia rheumatica (PMR). Patients diagnosed with PMR were collected retrospectively in two rheumatology departments. In addition to demographic and diagnostic criteria, the chart review included the following information at baseline and at follow-up: doses of prednisone, prescription of calcium, vitamin D and bisphosphonates, bone mass measurement (BMD) and fragility fractures. We analyzed the percentage of patients undergoing BMD and were prescribed a bisphosphonate over the years. We evaluated 158 patients: 117 of them were women, mean age was 73 years, and they had an average follow-up of 4.8 years. 104 patients (66 %) received osteoporosis medication during the first visit, 44 of them were given bisphosphonate. During follow-up, another 30 treatments with bisphosphonate were added (46 % overall) while 37 cases (23 %) received no treatment with calcium or bisphosphonate. BMD was performed in 111 patients (69 %; 53 % of males and 76 % of females). Factors associated with the use of bisphosphonates were female sex (OR 4.4, 95 % CI 4.02-4.86), BMD (OR 2.4, 95 % CI 2.05-2.78) and commencement of treatment after the year 2005 (54 vs 37 %, OR 1.93, 95 % CI 1.60-2.26). No significant differences were found with age, initial doses of prednisone or the hospital. According to recent prevention guidelines, treatment with biphosphonate should have been administered in more than 90 % of patients. Although prophylaxis of glucocorticoid-induced osteoporosis in patients with PMR has increased in the recent years, many patients do not receive prophylaxis with bisphosphonate during the first visit.

O18. DXA Measures of Bone Mass in Mother, Father and Offspring: Results from the Southampton Women’s Survey

O18. DXA Measures of Bone Mass in Mother, Father and Offspring: Results from the Southampton Women’s Survey

Resorption of fibula bone following mandibular reconstruction for osteoradionecrosis

The free fibular flap is commonly used for mandibular reconstruction because of its length, consistent blood supply, and relative ease of harvest. The bone has been shown to maintain mass over time, which confers a potential advantage over other osseous flaps. We know of no published papers on changes in height of fibular bone in patients treated for osteoradionecrosis (ORN). We measured the change in bony height over time as an indirect measure of bone mass. We identified 17 patients (mean age 65, range 49–80 years) who had had reconstruction with a free fibular flap for mandibular ORN. Of them, 10 had fixation with a reconstruction plate, and serial radiographs were available for inclusion in the study. Three measurements were taken on at least 2 rotational tomograms for each patient. Two observers recorded measurements at 25, 50, and 75% of the distance along the bone. Mean change in fibular height (mm) and percentage change were calculated. The interval between radiographs ranged from 5 months 4 days to 20 months 14 days. There was a reduction in fibular height in 8/10 cases, with a mean reduction of 1.5mm (range 2.6–0.3), or 11%. Our results show a moderate reduction in fibular height, which is comparable with a previously published series of patients without ORN who had reconstruction with miniplates. The stress shielding effects of reconstruction plates were less evident in our patients than in previously published material.

Longitudinal Tracking of Dual-Energy X-ray Absorptiometry Bone Measures Over 6 Years in Children and Adolescents: Persistence of Low Bone Mass to Maturity

Early assessment of bone mass may be useful for predicting future osteoporosis risk if bone measures "track" during growth. This prospective longitudinal multicenter study examined tracking of bone measures in children and adolescents over 6 years to sexual and skeletal maturity. A total of 240 healthy male and 293 healthy female patients, ages 6-17 years, underwent yearly evaluations of height, weight, body mass index, skeletal age, Tanner stage, and dual-energy x-ray absorptiometry (DXA) bone measurements of the whole body, spine, hip, and forearm for 6 years. All subjects were sexually and skeletally mature at final follow-up. Correlation was performed between baseline and 6-year follow-up measures, and change in DXA Z-scores was examined for subjects who had baseline Z < -1.5. DXA Z-scores (r = 0.66-0.87) had similar tracking to anthropometric measures (r = 0.64-0.74). Tracking was stronger for bone mineral density compared with bone mineral content and for girls compared with boys. Tracking was weakest during mid- to late puberty but improved when Z-scores were adjusted for height. Almost all subjects with baseline Z < -1.5 had final Z-scores below average, with the majority remaining less than -1.0. Bone status during childhood is a strong predictor of bone status in young adulthood, when peak bone mass is achieved. This suggests that bone mass measurements in children and adolescents may be useful for early identification of individuals at risk for osteoporosis later in life.

A 6-Year Exercise Program Improves Skeletal Traits Without Affecting Fracture Risk: A Prospective Controlled Study in 2621 Children

Most pediatric exercise intervention studies that evaluate the effect on skeletal traits include volunteers and follow bone mass for less than 3 years. We present a population-based 6-year controlled exercise intervention study in children with bone structure and incident fractures as endpoints. Fractures were registered in 417 girls and 500 boys in the intervention group (3969 person-years) and 835 girls and 869 boys in the control group (8245 person-years), all aged 6 to 9 years at study start, during the 6-year study period. Children in the intervention group had 40 minutes daily school physical education (PE) and the control group 60 minutes per week. In a subcohort with 78 girls and 111 boys in the intervention group and 52 girls and 54 boys in the control group, bone mineral density (BMD; g/cm(2) ) and bone area (mm(2) ) were measured repeatedly by dual-energy X-ray absorptiometry (DXA). Peripheral quantitative computed tomography (pQCT) measured bone mass and bone structure at follow-up. There were 21.7 low and moderate energy-related fractures per 1000 person-years in the intervention group and 19.3 fractures in the control group, leading to a rate ratio (RR) of 1.12 (0.85, 1.46). Girls in the intervention group, compared with girls in the control group, had 0.009 g/cm(2) (0.003, 0.015) larger gain annually in spine BMD, 0.07 g (0.014, 0.123) larger gain in femoral neck bone mineral content (BMC), and 4.1 mm(2) (0.5, 7.8) larger gain in femoral neck area, and at follow-up 24.1 g (7.6, 40.6) higher tibial cortical BMC (g) and 23.9 mm(2) (5.27, 42.6) larger tibial cross-sectional area. Boys with daily PE had 0.006 g/cm(2) (0.002, 0.010) larger gain annually in spine BMD than control boys but at follow-up no higher pQCT values than boys in the control group. Daily PE for 6 years in at study start 6- to 9-year-olds improves bone mass and bone size in girls and bone mass in boys, without affecting the fracture risk.

Bone health in HIV-infected children, adolescents and young adults: a systematic review.

Children and adolescents, who either acquire HIV infection perinatally, from contaminated blood products or via sexual transmission early in life, have the greatest cumulative exposure to the negative direct and indirect effects of HIV infection and ART on bone, which may lead to increased lifetime risk for osteoporosis and fracture. We conducted a systematic review to evaluate the literature on bone health in children and adolescents with HIV. We performed a comprehensive search of the Medline, Scopus, and Cochrane Library databases (up to April 1, 2014) for studies that reported on bone imaging or bone fractures in HIV-infected children, adolescents, or young adults. A total of 32 publications met our inclusion criteria. Seventeen studies were cross-sectional and 15 were longitudinal. The majority of studies were conducted in high-income countries, three in middle-income countries and none in low-income countries. Overall, the studies we reviewed indicate that measures of bone mass are reduced, with increased prevalence of low BMD in children and adolescents with HIV. However, the studies are highly variable with respect to comparison sources, measurement methods, adjustment techniques for body size or growth retardation, and highlighted risk factors, including aspects related to medication exposures as well as the effects of HIV infection per se. HIV infection appears to be associated with decreased bone accrual throughout childhood and adolescence. Initial studies indicate that sub-optimal bone accrual may be persistent and result in reduced peak bone mass, an important determinant of future risk of osteoporosis and fracture. Important areas for future research include evaluation of bone mass, bone quality and fracture risk across the life course among those with early-life infection with HIV, particularly in resource-limited settings where the majority of children with HIV live.

Low Bone Mass Is a Risk Factor in Periodontal Disease-Related Tooth Loss in Patients with Intellectual Disability

Teeth are fundamental to maintaining good quality of life, but are often lost prematurely in individuals with intellectual disability. Furthermore, since bone mass decreases in menopausal women, women with intellectual disability have an augmented risk of losing their teeth. However, the relationship between periodontal disease-related tooth loss and bone mass has never been studied specifically in patients with intellectual disability. This study evaluated this relationship in a retrospective cohort study. Participants were female dental patients aged between 20 and 50 years and with an intellectual disability, who were treated in the Special Needs Dentistry unit of the Okayama University Hospital from January 2009 to March 2010. Logistic regression analysis was used to analyze which factors affect periodontal disease-related tooth loss. Information relating to 12 predictor variables, including age and bone mass level, was derived from medical records. The 27 subjects had a total of 704 teeth at the time of initial examination, but 20 teeth (2.8%) had been lost owing to periodontal disease by the time bone mass measurements were recorded. Results of the multinomial logistic regression analysis indicated a significant odds ratio for three items: number of missing teeth at the time of initial examination, bone mass, and living environment. This result suggests that low bone mass is an independent risk factor in tooth loss secondary to periodontal disease in patients with intellectual disability. Dentists should thus take account of this heightened risk of tooth loss when caring for post-menopausal women with intellectual disability.

Exercise and cancer.

There are an estimated 13.7 million cancer survivors in the United States. Persistent and late effects of cancer therapy have contributed to an increased risk for co-morbid illness and higher all-cause mortality. Physical exercise is a targeted rehabilitative intervention following cancer therapy and a health promotion risk reduction intervention for patients as they transition into survivorship. This chapter provides a brief overview of the research on exercise and cancer survivor outcomes with a specific focus on randomized controlled trials (RCT) on the effects of exercise on body composition and bone health. There were 17 RCT trials that were identified with body composition outcomes. There was no change in weight in 16/17 trials, 4 reported decreases in percent fat mass and 2 reported increases in lean mass. Eight exercise trials were identified with bone outcomes, two of which had pharmacologic comparison arms. These trials demonstrated preservation of bone in the intervention group compared with loss in the usual care or placebo control group. The majority of trials were with breast cancer survivors, the largest survivor group. Many are overweight or obese at diagnosis; weight gain continues to increase after therapy; and treatment is associated with bone loss. The findings of the 25 trials reviewed suggest that exercise maintains weight and bone mass in a high risk population. However, differences in design, measurement of body composition and bone mass and lack of targeted exercise to the specific outcomes warrants additional research to improve the quality of life for survivors.

Microstructural Failure Mechanisms in the Human Proximal Femur for Sideways Fall Loading

The etiology of hip fractures remains unclear but might be elucidated by an improved understanding of the microstructural failure mechanisms of the human proximal femur during a sideways fall impact. In this context, we biomechanically tested 12 cadaver proximal femurs (aged 76 ± 10 years; 8 female, 4 male) to directly measure strength for a sideways fall and also performed micro-computed tomography (CT)-based, nonlinear finite element analysis of the same bones (82-micron-sized elements, ∼120 million elements per model) to estimate the amount and location of internal tissue-level failure (by ductile yielding) at initial structural failure of the femur. We found that the correlation between the directly measured yield strength of the femur and the finite element prediction was high (R(2) = 0.94, p < 0.0001), supporting the validity of the finite element simulations of failure. In these simulations, the failure of just a tiny proportion of the bone tissue (1.5% to 6.4% across all bones) led to initial structural failure of the femur. The proportion of failed tissue, estimated by the finite element models, decreased with decreasing measured femoral strength (R(2) = 0.88, p < 0.0001) and was more highly correlated with measured strength than any measure of bone volume, mass, or density. Volume-wise, trabecular failure occurred earlier and was more prominent than cortical failure in all femurs and dominated in the very weakest femurs. Femurs with low measured strength relative to their areal bone mineral density (BMD) (by dual-energy X-ray absorptiometry [DXA]) had a low proportion of trabecular bone compared with cortical bone in the femoral neck (p < 0.001), less failed tissue (p < 0.05), and low structural redundancy (p < 0.005). We conclude that initial failure of the femur during a sideways fall is associated with failure of just a tiny proportion of the bone tissue, failure of the trabecular tissue dominating in the very weakest femurs owing in part to a lack of structural redundancy.

Bone mass, bone microarchitecture and anthropometric measurements during childhood growth in Spanish girls

Bone mass, bone microarchitecture and anthropometric measurements during childhood growth in Spanish girls

Voluntary Wheel Running in Growing Rats Does Not Protect Against Doxorubicin-induced Osteopenia

There is growing concern regarding the long-term negative side effects of chemotherapy in childhood cancer survivors. Doxorubicin (DOX) is commonly used in the treatment of childhood cancers and has been shown to be both cardiotoxic and osteotoxic. It is unclear whether exercise can attenuate the negative skeletal effects of this chemotherapy. Rat pups were treated with saline or DOX. Animals remained sedentary or voluntarily exercised. After 10 weeks, femoral bone mineral content and bone mineral density were measured using dual-energy x-ray absorptiometry. Cortical and cancellous bone architecture was then evaluated by microcomputed tomography. DOX had a profound negative effect on all measures of bone mass and cortical and cancellous bone architecture. Treatment with DOX resulted in shorter femora and lower femoral bone mineral content and bone mineral density, lower cross-sectional volume, cortical volume, marrow volume, cortical thickness, and principal (IMAX, IMIN) and polar (IPOLAR) moments of inertia in the femur diaphysis, and lower cancellous bone volume/tissue volume, trabecular number, and trabecular thickness in the distal femur metaphysis. Exercise failed to protect bones from the damaging effects of DOX. Other modalities may be necessary to mitigate the deleterious skeletal effects that occur in juveniles undergoing treatment with anthracyclines.

Causal inference of the effect of adiposity on bone mineral density in adults

The causal effect of adipose tissue on bone mass and the direction of its net influence have not been directly assessed in adult humans. Using the Mendelian randomization analysis, we assessed the causality of adiposity in measurements of bone mass in adult males and females. Subjects consisted of 2154 adults aged 25-54years from a cross-sectional cohort of the employees of the Electricity Generating Authority of Thailand. Body composition was determined after at least 3h of fasting using multifrequency bioelectrical impedance analysis. Bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry. A polymorphism in the fat mass and obesity-associated gene (FTO rs9939609) was used as an instrument in the Mendelian randomization analysis. The genotype distribution of the FTO rs9939609 polymorphism was 61·1% TT, 33·9% AT and 5·0% AA. The average body mass index (BMI), body fat mass and percentage body fat were 23·9kg/m(2) (SD=3·6), 17·9kg (SD=6·6) and 26·8% (SD=7·2), respectively. The FTO rs9939609 polymorphism was significantly correlated with BMI (coefficient=0·673kg/m(2) , P<0·001), body fat mass (coefficient=0·948kg, P<0·001) and percentage body fat (coefficient=0·759%, P<0·01). An instrumental variable (IV) regression model, using BMI as the intermediate phenotype, suggested that FTO was a strong IV. Also, the FTO-BMI polymorphism was significantly associated with total hip and femoral neck BMD but was not correlated with total spine BMD, with estimated correlation coefficients of 0·0189 (95% CI: 0·0046, 0·0332), 0·0149 (95% CI: 0·0030, 0·0268) and 0·0025 (95% CI: -0·0131, 0·0136)g/cm(2) , respectively. The variances of BMDs explained by the FTO-BMI were 19·0%, 21·3% and 1·1%, respectively. Similar trends were also observed for the FTO-body fat mass and FTO-percentage body fat correlations. Mendelian randomization analysis suggests that adiposity might be causally related to BMD at the femur but not at the spine.

Calcium turnover and nutrition through the life cycle.

Ca nutritional requirements and bone Ca turnover can be assessed using numerous techniques. Among these techniques are bone mass measurements, tracer kinetic studies, bone histomorphometry and biochemical studies. Stable-isotope-based kinetic studies offer unique advantages in their ability to assess both Ca absorption and turnover. This approach is safe and readily applicable to subjects of all ages. Ca is essential for growth and maintenance of bone mineral throughout life. During pregnancy, increased intestinal absorption of Ca by the mother provides much of the Ca supplied to the fetus. During infancy, Ca supplied in human milk is primarily derived from maternal bone stores, which are quickly replenished during and after weaning. Early childhood is a time of relatively slow bone growth, with a rapid increase occurring during puberty. Recent kinetic studies demonstrate an increase in both Ca absorption and bone Ca deposition associated with early puberty. Bone Ca deposition reaches a maximum in females shortly before menarche. At that time the bone Ca deposition rate is approximately five times that of adulthood. The decline in bone Ca deposition rate is gradual after menarche. Ca absorption from the diet shows a gradual decline in adulthood as well. Ca supplementation, in the presence of adequate vitamin D, is effective in enhancing bone mineral content in childhood and in helping to maintain bone mineral content in adults. Maintaining adequate Ca nutriture throughout life may be necessary to minimize the risk of bone-loss disorders.

Bone Mineral Density and Body Composition of Adult Premenopausal Women with Three Levels of Physical Activity

Weight-bearing and resistance physical activities are recommended for osteoporosis prevention, but it is unclear whether an intensity level above current recommendations has a positive effect on adult premenopausal women. Body composition and bone mineral density (BMD) by DXA were compared in three groups of women as follows: Sedentary, Maintenance exercise, and federated Sport Team (n = 16 for each group). Physical activity was estimated from the International Physical Activity Questionnaire (IPAQ). The groups did not differ in age, height, weight, or body mass index. Bone mineral content and non-fat soft tissue mass were higher and fat mass was lower in the Sport Team group than in the other groups. The same was true for BMD of total skeleton, lumbar spine, femoral neck, and total hip. A test for linear trend of body composition and BMD showed significant results when including all three groups. Simple and multiple regression analyses showed significant associations between physical activity level (or alternatively, years of participation in programmed physical activity) and bone mass measures at all sites except for the middle third of radius. It is concluded that a level of physical activity higher than that usually recommended benefits bone health in adult premenopausal women.

Cortical and trabecular bone structure analysis at the distal radius—prediction of biomechanical strength by DXA and MRI

The purpose of this study was to investigate whether the combination of dual-energy X-ray absorptiometry (DXA)-based bone mass and magnetic resonance imaging (MRI)-based cortical and trabecular structural measures improves the prediction of radial bone strength. Thirty-eight left forearms were harvested from formalin-fixed human cadavers. Bone mineral content (BMC) and bone mineral density (BMD) of the distal radius were measured using DXA. Cortical and trabecular structural measures of the distal radius were computed in high-resolution 1.5T MR images. Cortical measures included average cortical thickness and cross-sectional area. Trabecular measures included morphometric and texture parameters. The forearms were biomechanically tested in a fall simulation to measure absolute radial bone strength (failure load). Relative radial bone strength was determined by dividing radial failure loads by age, body mass index, radius length, and average radius cross-sectional area, respectively. DXA derived BMC and BMD showed statistically significant (p<0.05) correlations with absolute and relative radial bone strength (r≤0.78). Correlation coefficients for cortical and trabecular structural measures with absolute and relative radial bone strength amounted up to r=0.59 and r=0.74, respectively, (p<0.05). In combination with DXA-based bone mass, trabecular but not, cortical structural measures, added in multiple regression models significant (p<0.05) information in predicting absolute and relative radial bone strength (up to R adj=0.88). Thus, a combination of DXA-based bone mass and MRI-based trabecular structural measures most accurately predicted absolute and relative radial bone strength, whereas structural measures of the cortex did not provide significant additional information in combination with DXA.

The protective effect of calcium on bone mass in postmenopausal women with high selenium intake.

Nutritional factors, especially the two essential nutrients calcium and vitamin D, have been shown to play an important role in bone health. We wanted to determine the possible protective effect of calcium intake in adequate amounts on bone mass as assessed by quantitative ultrasound in postmenopausal women who also have a high intake of selenium. Health district of Cáceres, Spain. PARTICIPANTS AND STUDY DESIGN: 335 postmenopausal women aged 60.9 (SD = 8.1) years. Women were stratified based on the vitamin D, vitamin E, calcium intake and the calcium/protein and calcium/phosphorous index. Bone status (Ad-SoS measured at the phalanges) was assessed with an ultrasound device model DBM Sonic 1200R. Food intake was quantified using dietetic scales, measuring cups, and spoons based on 7 days of diet records. Urine samples were collected the morning of testing after an overnight fast. Venous blood samples for the hematological and biochemical studies were also obtained in the fasting state. In the group of women with Ca intake < 800 mg / d we found a significant and negative relationship between Ad-SoS with age (β= -4.020, F = 23.327) and selenium intake (β = -0.419, F = 10.067), as well as a positive relationship with Ca intake (β= 0.104 and F = 7.084) (p <0.0001 in all). In the group of women with Ca intake > 800 mg / d, age has a significant and negative relationship (β = -4.829 and F = 106.745), whereas folic acid intake has a significant and positive relationship (β = 0.047 and F = 5.858) (p <0.0001 in both). Elevated selenium intake negatively affects bone mass measurements in postmenopausal women over the age of 51 but only if calcium intake is also less than 800 mg / day. When calcium intake is greater than 800 mg/day, selenium did not appear to affect bone mass.

Protocolo diagnóstico de la osteoporosis

Osteoporosis is a disease of complex and multifactorial pathogenesis, and in many cases bone loss and the fracures increased is associated to ageing. Genetic factors can contribute to the adquisition of bone mass peak, as can disorders of development and the skeletal, like sexual steroids in menopause. Upon this other secondary causes as the use of corticoids and disesese that affect bone metabolism can be implicated. The major importance in this disease is diminished bone strength and the increase tendency to fractures, that can increase morbilidity and mortality, increasing in health costs.In the last years, important advances in the concept, diagnosis and treatment, including a better nutrion and lifestyle has been introduced. Although many patients are not diagnosed or treatment, probably because before occurring a fracture the disease is usally asymptomatic.Due to the fact to that bone mass is a relevant determinant of bone strength, the measure of bone mass is considered an objective, with DXA technique recommended. In the year 2008 the WHO introduced the FRAX assessment based in the combination of Risk Factors with or without Hip DXA measurement. The technique allows to recognized the probability of fractures at hip, vertebral, humeral and forearm in 10 years, for the decision of antiresorptive reatment.

Determination of Bone Architecture and Strength in Men and Women with Stage 5 Chronic Kidney Disease

Fractures are common in men and women with dialysis-dependent chronic kidney disease (stage 5D CKD) and are associated with substantial morbidity and mortality. The clinical utility of dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), noninvasive measures of bone mass and architecture that reflect fracture risk in healthy men and women, is uncertain in patients with stage 5D CKD. This review will outline the epidemiology and etiology of fractures and will summarize the published data that describe the association between fractures, bone mass, and bone strength in stage 5D CKD. Fracture risk assessment in stage 5D CKD is complicated as the etiology of fractures is multifactorial and includes impairments in bone quantity and quality. Cross-sectional data suggest that bone density by DXA is lower among stage 5D CKD patients with fractures compared with those without, and that this may be particularly true at cortical sites. However, DXA does not capture bone microarchitecture and cannot differentiate between cortical and trabecular bone. Some, but not all studies, that measure cortical and trabecular bone by pQCT in stage 5D CKD, demonstrate a preferential decrease in cortical bone; however, these studies are limited by small sample sizes and cross-sectional study design. No studies have reported on longitudinal relationships between bone architecture, strength, and incident fractures in patients with stage 5D CKD. Further research is needed to identify noninvasive measures of bone strength that can be used for fracture risk assessment in stage 5D CKD.

An altered hormonal profile and elevated rate of bone loss are associated with low bone mass in professional horse-racing jockeys

Horse-racing jockeys are a group of weight-restricted athletes, who have been suggested as undertaking rapid and extreme weight cycling practices in order to comply with stipulated body-mass standards. The aim of this study was to examine bone mass, turnover and endocrine function in jockeys and to compare this group with age, gender and body mass index matched controls. Twenty male professional jockeys and 20 healthy male controls participated. Dual energy X-ray absorptiometry scans and early morning fasting blood and urine samples were used to measure bone mass, turnover and a hormonal profile. Total body bone mineral density (BMD) was significantly lower in jockeys (1.143±0.05 vs. 1.27±0.06gcm(-3), p<0.01). Bone resorptive activity was elevated in the jockey group as indicated by significantly higher urinary NTx/creatinine (76.94±29.52 vs. 55.9±13.9nmolmmol(-1), p<0.01), resulting in a significantly negative uncoupling index between bone resorption and formation. Sex hormone binding globulin (SHBG) levels were significantly higher in jockeys (41.21±9.77 vs. 28.24±9.98nmolL(-1), p<0.01) with a lower percentage of bioavailable testosterone (48.89±7.38 vs. 59.18±6.74%, p<0.01). SHBG and insulin-like growth factor-1 were independent predictors of total body and femoral neck BMD, respectively (p<0.05). In conclusion, it appears that professional jockeys have an elevated rate of bone loss and reduced bone mass that appears to be associated with disrupted hormonal activity. It is likely that this may have occurred in response to the chronic weight cycling habitually experienced by this group.

Adolescent pregnancy is associated with osteoporosis in postmenopausal women

Adolescence is a critical time of life to accumulate bone for peak bone mass. Factors that may interfere with bone mass accrual during this period may increase the risk of osteoporosis. Several studies have reported that pregnancy during adolescence has detrimental effects on bone mass measurements after pregnancy. However, less is known about how adolescent pregnancy affects bone mineral density (BMD) and osteoporosis after menopause. The aim of this study was to evaluate the association between adolescent pregnancy and osteoporosis in postmenopausal Korean women. We conducted a cross-sectional study of 719 postmenopausal women, all of whom were enrolled in the Korean National Health and Nutrition Examination Survey in 2008. BMD was measured using dual-energy x-ray absorptiometry. Postmenopausal women with histories of adolescent pregnancy had lower BMD of the total hip, femoral neck, and lumbar spine than did women without histories of adolescent pregnancy. Multivariate logistic regression analyses revealed that postmenopausal women with history of adolescent pregnancy were at increased risk of osteoporosis (odds ratio, 2.20; 95% CI, 1.12-4.30) compared with women without history of adolescent pregnancy after adjustments for age, body mass index, marital status, education level, household income, alcohol intake, smoking history, exercise, age at menarche, age at menopause, parity, hormone therapy use, intake of energy and calcium, and vitamin D level. Adolescent pregnancy may be a predictor of osteoporosis in postmenopausal women.