Bone size and bone strength are increased in obese male adolescents

Bone mineral density in young adults 5 to 11 years after adolescent metabolic and bariatric surgery for severe obesity compared to peers

OBJECTIVE

Metabolic and bariatric surgery (MBS) is associated with decreased bone mineral density (BMD) in adults. The long-term impact of MBS during adolescence on BMD is unknown. We report bone health status 5 to 11 years after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) from the Teen-LABS study cohort.

METHODS

Between 2016 and 2022, BMD was measured by dual energy x-ray absorptiometry (DXA) in 106 young adults who had undergone MBS as adolescents. Volumetric BMD by peripheral quantitative computed tomography was measured on a subset. Ninety-one controls who had not undergone MBS were recruited for comparison.

RESULTS

In cases (RYGB: mean age 26.8 ± 1.9 years, mean BMI 42.1 ± 9.9 kg/m2, VSG: mean age 25.1 ± 2.1 years, mean BMI 37.1 ± 8.4 kg/m2), compared to controls (mean age 26.5 ± 2.7 years, mean BMI 40.2 ± 8.7 kg/m2) (age p < 0.001, BMI p = 0.02), adjusted mean DXA-BMD (g/cm2) of the RYGB (n = 58) and VSG (n = 48) groups were lower at the hip (-10.0% and -6.3%), femoral neck (-9.6% and -5.7%) and ultra-distal radius (-7.9% and -7.0%; all p < 0.001), respectively. DXA-BMD did not differ between RYGB and VSG groups. Trabecular volumetric BMD at the radius and tibia were lower in the RYGB (-30% and -26%) and VSG (-15% and -14%) groups compared to the control group (p < 0.001). Greater time since MBS was associated with lower BMD Z-scores at the hip (p = 0.05) and femoral neck (p = 0.045). Percent change in body mass index (BMI) from baseline or in the first year after MBS were not associated with bone measures at a median of 9.3 years post MBS.

CONCLUSION

BMD, especially of the hip and femoral neck, was lower in young adults who underwent MBS during adolescence compared to matched peers who had not undergone MBS. BMD Z-scores of the femoral neck were inversely associated with time since MBS but were not associated with BMI change.

Assessment of Biochemical Bone Turnover Markers in Polish Healthy Children and Adolescents

BACKGROUND

Assessing bone turnover in paediatric populations is crucial for understanding the physiological changes occurring during skeletal development and identifying potential abnormalities. The objective of this study was to assess osteocalcin (OC), bone alkaline phosphatase (BALP), and C-terminal telopeptide of type I collagen (CTX-I) levels reflecting bone formation and resorption for age and sex in Polish healthy children and adolescents.

MATERIALS AND METHODS

A total of 355 healthy normal-weight children and adolescents (46.5% girls) aged 1-18 years old were recruited. Total body less head (TBLH) and spine L1-L4 were used in children to assess bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). Bone marker concentrations were determined by immunoenzymatic methods.

RESULTS

Bone marker levels in girls and boys started with higher values in the first year of life and subsequently decreased until reaching a nadir during the prepubertal period. The pubertal peak values of bone markers were reached at 11-13 years old in boys and at 9-11 years old in girls. After puberty, the adolescents showed a gradual decline in bone marker concentrations to the values observed in adults. We found positive correlations between OC level and TBLH-BMD (r = 0.329, p = 0.002), TBLH-BMD Z-score (r = 0.245, p = 0.023), and L1-L4 BMD (r = 0.280, p = 0.009) in the prepubertal group.

CONCLUSIONS

We showed serum levels of bone turnover markers-BALP, OC, and CTX-I-in relation to age and sex in healthy Polish children and adolescents. The age intervals of these markers for girls and boys aged 1-18 years old may be clinically useful in the assessment of bone metabolism in individuals with skeletal disorders.

The Importance of Healthy Habits to Compensate for Differences between Adolescent Males and Females in Anthropometric, Psychological and Physical Fitness Variables

Adolescence is a crucial stage in human development, and differences in psychological, physical and body composition variables between males and females have been amply demonstrated. However, the role played by certain healthy habits, such as the practice of physical activity, adherence to the Mediterranean diet (AMD) or the maintenance of an adequate weight status, in compensating for the differences found between males and females in these variables, is not well known. For this reason, the study aimed to analyze whether the practice of physical activity, optimal AMD, and adequate weight status can compensate for the differences between adolescent males and females in anthropometric variables, psychological state, and physical fitness. The sample was composed of 791 adolescents (404 males and 387 females) aged twelve to sixteen years old, whose anthropometric, psychological (autonomy, competence, relatedness, and life satisfaction), and physical fitness variables (cardiorespiratory fitness, upper strength and explosive lower limb power, hamstring and lower back flexibility, and speed) were measured. All measurements were carried out in a single day using the sports pavilion of the four participating schools. The most novel results of this research show that the practice of physical activity was determinant mainly in females, as it reduced the differences found in comparison with males in psychological (p < 0.001−0.045) and anthropometric variables (p < 0.001). Regarding weight status and AMD, these were still relevant for the adolescent population, mainly the achievement of optimal AMD, but males continued to present higher values in physical fitness tests (p < 0.001) and lower values in fat accumulation (p < 0.001), regardless of weight status or AMD. Thus, physical activity seems to be the most determining factor that compensates for the differences between adolescent boys and girls.

Body weight influences musculoskeletal adaptation to long-term voluntary wheel running during aging in female mice

Frailty is the hallmark of aging that can be delayed with exercise. The present studies were initiated based on the hypothesis that long-term voluntary wheel running (VWR) in female mice from 12 to 18 or 22 months of age would have beneficial effects on the musculoskeletal system. Mice were separated into high (HBW) and low (LBW) body weight based on final body weights upon termination of experiments. Bone marrow fat was significantly higher in HBW than LBW under sedentary conditions, but not with VWR. HBW was more protective for soleus size and function than LBW under sedentary conditions, however VWR increased soleus size and function regardless of body weight. VWR plus HBW was more protective against muscle loss with aging. Similar effects of VWR plus HBW were observed with the extensor digitorum longus, EDL, however, LBW with VWR was beneficial in improving EDL fatigue resistance in 18 mo mice and was more beneficial with regards to muscle production of bone protective factors. VWR plus HBW maintained bone in aged animals. In summary, HBW had a more beneficial effect on muscle and bone with aging especially in combination with exercise. These effects were independent of bone marrow fat, suggesting that intrinsic musculoskeletal adaptions were responsible for these beneficial effects.

Physical, Psychological, and Body Composition Differences between Active and Sedentary Adolescents According to the "Fat but Fit" Paradigm

The practice of physical activity during adolescence is essential for the proper development of the population. In recent decades, the relevance of physical activity has been increasing, due to the development of the "fat but fit" paradigm. This paradigm shows that adolescents with a high level of physical fitness are healthier than adolescents with poorer physical fitness, regardless of their weight, giving importance to sports practice over other aspects. However, few previous studies have analyzed the differences in physical and body composition between active and sedentary adolescents in this paradigm. For this reason, the objectives of the present study were to establish the differences in body composition, physical performance, and adherence to the Mediterranean diet between active and sedentary adolescents; and to analyze the differences between active and sedentary adolescents according to the "fat but fit" paradigm. The sample consisted of 791 adolescent whose body composition, level of physical activity, adherence to the Mediterranean diet, and physical fitness were measured. It was found significant between active and sedentary adolescents in most of the anthropometric, AMD, and physical fitness variables, with a significant effect of the covariates gender, age, BMI, and biological maturation on the model. The binary logistic regression analysis performed shows that anthropometric variables, AMD, and VO2 max can be considered as primary outcomes to distinguish between active and sedentary groups of adolescents. Furthermore, the results showed that the active adolescents, regardless of their weight status, had lower fat mass and greater muscle mass, as well as a higher performance in the physical fitness tests, and greater adherence to the Mediterranean diet than the sedentary adolescents. To conclude, the practice of physical activity is a determinant for the improvement of body composition, physical performance, and adherence to the Mediterranean diet of the adolescent population, regardless of their gender, age, weight, or maturity status.

Forearm Fractures in Overweight-Obese Children and Adolescents: A Matter of Bone Density, Bone Geometry or Body Composition?

Forearm fractures in children and adolescents are associated with increased body mass index (BMI). This bone site is non-weight-bearing and therefore is appropriate to explore the effect of BMI on bone mineral density (BMD) and bone geometry, avoiding the confounding effect of increased weight-associated mechanical loading. The aim of this review was to summarize available evidence on bone indices and body composition assessed by peripheral quantitative computed tomography (pQCT) or dual X-ray absorptiometry (DXA) at the forearm level in overweight (Ow) or obese (Ob) subjects. We conducted a review of the literature according to the PICOS model. A total of 46 studies were identified following the literature search. A final number of 12 studies were included in this review. pQCT studies evidenced that Ow and Ob children typically have normal or increased volumetric BMD (vBMD), total bone area and cortical area, with normal or reduced cortical thickness at the forearm. Outcomes from DXA evaluations are less conclusive. In almost all the studies fat mass and lean mass area at the forearm are increased. A higher fat-to-lean mass ratio has been observed in few studies. Bone strength was reported as normal or increased compared to normal weight peers. In Ow or Ob children-adolescents, vBMD, bone size and bone strength are not reduced compared to normal weight peers. The local higher fat-to-lean mass ratio may give a mismatch between bone strength and the load experienced by the distal forearm during a fall, resulting in increased risk of forearm fractures.

Bone mineral density and body composition in normal weight, overweight and obese children

BACKGROUND

There is a possibility that excess body fat affects bone mass gain and may compromise skeletal health in obese children. The purpose of the study was to identify the relationship between bone mineral density (BMD) and body composition in normal weight, overweight and obese children.

METHODS

This was a cross-sectional study of 6- to 11-year-old children who attended the hospital's outpatient clinic. They were apparently healthy and had no history of prematurity, low birth weight, or chronic diseases. Body mass index (BMI) was used to identify subjects as normal weight, overweight or obese. BMD and body composition were assessed by dual energy X-ray absorptiometry. The BMD values (total and lumbar spine) were compared between normal weight, overweight and obese children. Correlation coefficients were calculated, and multivariate models were performed.

RESULTS

Forty-nine children were included: 16 with normal weight, 15 that were overweight and 18 with obesity; the mean age was 8.4 ± 1.7 years. All the participants had a normal BMD (> - 2 SD). BMD was higher in obese children and had a positive correlation with total and trunk lean mass in the three study groups (p < 0.001). In obese children, an inverse correlation of lumbar spine BMD (Z score) with total and trunk fat mass (p < 0.05) was identified. In the multivariate models (with the whole group), the total lean mass was the only significant variable that explained BMD variability.

CONCLUSIONS

BMD in obese children was higher than that in normal weight children, which is explained by their greater lean mass and not by excess body fat. In obese children, a higher fat mass was related to a lower lumbar spine BMD. Lean mass had a direct correlation with BMD in the three study groups and was the most important predictor of BMD, reflecting the importance of strengthening the muscular system through performing physical activity and practicing a healthy lifestyle.

Biomechanics of immature human cortical bone: A systematic review

The whole bone geometry, microstructure, and mechanical properties of mature human bone are widely reported; however, immature bone (0-18 years) has not been similarly robustly characterized. There is an interest in analyzing and predicting the mechanical loading conditions associated with long bone diaphyseal fractures attributed to trauma in children. Thus, understanding the mechanical properties of immature bone in a temporal reference frame is an essential first step to understand diaphyseal fractures of pediatric long bones. The purpose of this systematic review was to ask, what is the state of knowledge regarding the 1) evolution of whole bone geometry and microstructure of immature pediatric bone as a function of maturation and 2) cortical bone density and experimental quasi-static mechanical properties at the tissue level in the diaphyseal region of immature pediatric long bones? The systematic search yielded 36 studies of the whole bone geometry, microstructure, and mechanical properties of immature pediatric long bones. The elastic modulus, yield stress, and ultimate stress were shown to generally increase with maturation, whereas the yield strain was approximately invariant; however, the specific year-to-year progression of these properties could not be characterized from the limited studies available. The results of this systematic search indicate there is a dearth of knowledge associated with the biomechanics of cortical bone from immature pediatric long bones; it also provides a basis for computational studies of immature human long bones. Additional biomechanical studies of immature human bone are necessary to develop a robust catalogue, which can be used in broad applications to understand fracture mechanics, bone pathologies, and athletic injury in the pediatric setting.

Inverse association of plasma leptin with cortical thickness at distal radius determined with a quantitative ultrasound device in patients with type 2 diabetes mellitus

AIMS/INTRODUCTION

Osteoporosis is known to be intimately related to sympathetic nerve activity. We examined the relationship of plasma leptin with cortical and trabecular bone components in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

The present cross-sectional study included 182 type 2 diabetes mellitus patients (93 men, 89 women). Cortical thickness (CoTh) and trabecular bone mineral density (BMD) were determined at the 5.5% distal radius using an LD-100 ultrasonic bone densitometry device. Plasma leptin along with physical and laboratory measurements was simultaneously determined.

RESULTS

Plasma leptin, but not body mass index (BMI), was inversely correlated with CoTh (ρ = -0.487, P < 0.001), while BMI, but not plasma leptin, was positively correlated with trabecular BMD (ρ = 0.369, P < 0.001). In multivariable regression analysis, after adjustments for age, sex, duration of diabetes, glycated hemoglobin A1c, albumin, estimated glomerular filtration rate, parathyroid hormone and handgrip strength, plasma leptin was inversely associated with CoTh (β = -0.258, P < 0.001), but not trabecular BMD. Furthermore, plasma leptin level retained a significant association with CoTh after further adjustment for BMI (β = -0.237, P < 0.001) and BMI plus waist-to-hip ratio (β = -0.243, P < 0.001). In contrast, the "sex × leptin" interaction was not significant (P = 0.596).

CONCLUSIONS

Leptin level in plasma, independent of BMI and BMI plus waist-to-hip ratio, was shown to be inversely associated with CoTh, but not trabecular BMD, suggesting that hyperleptinemia resulting from obesity might contribute to cortical porosis in patients with type 2 diabetes mellitus.

Influência da obesidade nos critérios de classificação de sarcopenia em idosos

Resumo Objetivo identificar a prevalência de obesidade sarcopênica em idosos residentes na comunidade e analisar a relação da obesidade com os critérios de classificação da sarcopenia. Método Trata-se de um corte transversal analítico vinculado ao projeto “Atenção Integral à Saúde do Idoso”. A avaliação da sarcopenia foi realizada a partir dos critérios do Consenso Europeu de Sarcopenia. Para classificação dos idosos como obesos sarcopênicos considerou-se aqueles que se apresentaram como provável sarcopênico, sarcopênico ou sarcopênico severo associado ao percentual de gordura >27% para homens e >38% para mulheres. Os dados foram analisados utilizando estatística bivariada e um modelo de regressão linear. Resultados Dos 209 idosos residentes na comunidade foi verificado uma prevalência de 23,9% de sarcopenia, 28,2% de obesidade e 4,3% de obesidade sarcopênica. Ainda, pode-se observar que os homens apresentaram maior prevalência de sarcopenia (p=0,006) e de obesidade (p=0,005) que as mulheres; os obesos tiveram menor prevalência de perda de massa muscular que os idosos não obesos (p<0,001); e os obesos apresentaram incremento na força (p=0,003) e na massa muscular (p<0,001) em relação aos não obesos, mesmo quando ajustado para sexo, faixa etária, multicomorbidades e incapacidade funcional. Conclusão levando em consideração a prevalência de obesidade sarcopênica na população estudada e a influência positiva da obesidade na predição de força e massa muscular, destaca-se a importância da avaliação multidimensional do idoso, a fim de averiguar a real necessidade de intervenções para perda de peso corporal, com intuito de prevenção de perda de força e massa muscular.

The Bones of Children With Obesity

Excess adiposity in childhood may affect bone development, ultimately leading to bone frailty. Previous reports showing an increased rate of extremity fractures in children with obesity support this fear. On the other hand, there is also evidence suggesting that bone mineral content is higher in obese children than in normal weight peers. Both adipocytes and osteoblasts derive from multipotent mesenchymal stem cells (MSCs) and obesity drives the differentiation of MSCs toward adipocytes at the expense of osteoblast differentiation. Furthermore, adipocytes in bone marrow microenvironment release a number of pro-inflammatory and immunomodulatory molecules that up-regulate formation and activation of osteoclasts, thus favoring bone frailty. On the other hand, body adiposity represents a mechanical load, which is beneficial for bone accrual. In this frame, bone quality, and structure result from the balance of inflammatory and mechanical stimuli. Diet, physical activity and the hormonal milieu at puberty play a pivotal role on this balance. In this review, we will address the question whether the bone of obese children and adolescents is unhealthy in comparison with normal-weight peers and discuss mechanisms underlying the differences in bone quality and structure. We anticipate that many biases and confounders affect the clinical studies conducted so far and preclude us from achieving robust conclusions. Sample-size, lack of adequate controls, heterogeneity of study designs are the major drawbacks of the existing reports. Due to the increased body size of children with obesity, dual energy absorptiometry might overestimate bone mineral density in these individuals. Magnetic resonance imaging, peripheral quantitative CT (pQCT) scanning and high-resolution pQCT are promising techniques for the accurate estimate of bone mineral content in obese children. Moreover, no longitudinal study on the risk of incident osteoporosis in early adulthood of children and adolescents with obesity is available. Finally, we will address emerging dietary issues (i.e., the likely benefits for the bone health of polyunsaturated fatty acids and polyphenols) since an healthy diet (i.e., the Mediterranean diet) with balanced intake of certain nutrients associated with physical activity remain the cornerstones for achieving an adequate bone accrual in young individuals regardless of their adiposity degree.

Dilemmas in Vitamin D Management in Children and Adolescents

The importance of vitamin D and its role in several biological processes has been a topic of interest in recent years. Vitamin D is an essential nutrient that is needed for metabolic bone health and for maintaining bone calcium homeostasis. It is primarily synthesized in the skin on exposure to sunlight. Of late, vitamin D deficiency has been associated with conditions such as obesity, poor control of asthma and other autoimmune diseases, which has led to questions about its potential role in causation and management of these conditions. Given the increase in data about this topic, providers may often have questions about whom to screen and what to tell patients. In this article, we address screening guidelines for vitamin D in children and adolescents, management of vitamin D deficiency, and current literature on the role of vitamin D in conditions such as obesity, asthma, and type 1 diabetes mellitus. [Pediatr Ann. 2019;48(8):e298-e303.].

Associations between body mass index, body composition and bone density in young adults: findings from a southern Brazilian cohort

BACKGROUND

This study aimed to evaluate the association of body composition components and obesity with bone density.

METHODS

Prospective study with data on 2968 members of the 1993 Pelotas Birth Cohort from follow-ups at 18 and 22 years of age. Areal bone mineral density (aBMD, g/cm²) was evaluated for whole body, lumbar spine, and femoral neck at 22 years using dual-energy X-ray absorptiometry. Simple and multiple linear regression, stratified by sex, were used to assess the effect of BMI, fat mass (FMI) and lean mass index (LMI), evaluated at 18 and 22 years, and obesity trajectories classified by FMI and categorized as "never", "only at 18 years", "only at 22 years" or "always" on aBMD.

RESULTS

Among men, the largest coefficients were observed for BMI, followed by lean mass and fat mass. Compared to fat mass, lean mass presented the largest coefficients for all sites, with the strongest associations observed for the femoral neck (β: 0.035 g/cm²; 95% CI: 0.031; 0.039 for both follow-ups), while the largest effect for FMI was observed for whole-body aBMD at 18 years (β: 0.019 g/cm²; 95% CI: 0.014; 0.024). Among women, the strongest associations were observed for LMI. The largest coefficients for LMI and FMI were observed for femoral neck at age 18, presented β: 0.030 g/cm², 95% CI: 0.026, 0.034 for LMI and β: 0.012 g/cm²; 95% CI: 0.009; 0.015) for FMI. Men who were "always obese" according to FMI had smallest aBMD for spine (β: -0.014; 95%CI: - 0.029; - 0.001). Women who were obese "only at 18 years" had smallest aBMD for the whole-body (β: -0.013; 95%CI: - 0.023; - 0.002), whereas those who were obese "only at 22 years" had larger whole-body and femoral neck aBMD (β: 0.013; 95%CI: 0.009; 0.017 and β: 0.027; 95%CI: 0.016; 0.038, respectively) and those "always obese" for whole-body aBMD (β: 0.005; 95%CI: 0.001; 0.011) compared to the reference category.

CONCLUSIONS

The indexes were positively associated with aBMD in this sample. Fat mass had smaller positive influence on these outcomes than lean mass, suggesting the most important body composition component for bone density is the lean mass.

Testicular Function and Bone in Young Men with Severe Childhood-Onset Obesity

BACKGROUND

Previous studies suggest increased risk for hypoandrogenism and fractures in men with obesity. We aimed to describe the effects of severe childhood-onset obesity on the cross talk between metabolic state, testes, and skeleton at late puberty.

METHODS

A cohort of adolescent and young adult males with severe childhood-onset obesity (n = 21, mean age 18.5 years) and an age-matched control group were assessed for testicular hormones and X-ray absorptiometry-derived bone mass.

RESULTS

Current median body mass indexes for the obese and control subjects were 37.4 and 22.9. Severe early-onset obesity manifested with lower free testosterone (median [interquartile range] 244 [194-332] vs. 403 [293-463] pmol/L, p = 0.002). Lower insulin-like 3 (1.02 [0.82-1.23] vs. 1.22 [1.01-1.46] ng/mL, p = 0.045) and lower ratio of testosterone to luteinizing hormone (2.81 [1.96-3.98] vs. 4.10 [3.03-5.83] nmol/IU, p = 0.008) suggested disrupted Leydig cell function. The degree of current obesity inversely correlated with free testosterone (τ = -0.516, p = 0.003), which in turn correlated positively with bone area at all measurement sites in males with childhood-onset obesity.

CONCLUSIONS

Severe childhood-onset obesity is associated with impaired Leydig cell function in young men and lower free testosterone may contribute to impaired skeletal characteristics.

A longitudinal study of serum insulin-like growth factor-I levels over 6 years in a large cohort of children and adolescents with type 1 diabetes mellitus: A marker reflecting diabetic retinopathy

OBJECTIVE

To evaluate longitudinal serum insulin-like growth factor-I (IGF-I) in a large cohort of children and adolescents with type 1 diabetes in relation to hemoglobin A1c (HbA1c), age, diabetes duration, and body mass index (BMI), its association to height and retinopathy, and in comparison with healthy subject references.

METHODS

A total of 2683 serum IGF-I values were obtained from 806 children and adolescents with T1DM, from annual blood samples for up to 6 consecutive years.

RESULTS

In a multiple regression analysis IGF-I values were negatively correlated to HbA1c and diabetes duration, and positively correlated to BMI (P < .001, P < .001, and P < .001, respectively, adjusted r²  = 0.102). Children and adolescents with T1DM had lower mean IGF-I levels and reference interval limits compared to healthy subjects. In boys, mean (SD) IGF-I SD score (SDS) levels were -1.04 (±1.3) calculated from the healthy reference. IGF-I peaked at 15 years of age, similarly to healthy controls, but with markedly lower levels in late puberty. Girls were more affected at later stages of puberty but with a slightly less depressed overall mean IGF-I SDS of -0.69 (±1.2). In a subgroup of 746 subjects with fundus photography, a negative correlation was seen between individual mean IGF-I SDS and preproliferative retinopathy (P = .004, adjusted r²  = 0.021). In another subgroup of 84 adolescents, no correlation was seen between individual mean IGF-I SDS and target height SDS or distance to target height SDS.

CONCLUSION

Poor metabolic control and diabetes duration impact negatively on serum IGF-I levels. A low individual mean IGF-I level was associated with progression of retinopathy independently of HbA1c, age, gender, and diabetes duration. Disease, sex and age related IGF-I SDS may become clinical helpful as a supplement to HbA1c in predicting the long-term outcome for children and adolescents with T1DM.

Gait Pattern, Impact to the Skeleton and Postural Balance in Overweight and Obese Children: A Review

The article reviews the biomechanical factors that may cause overweight/obese children to reduce their level of physical activity, while increasing their risk of overuse injuries and exercise-related pain. Recommendations would be to screen those children for any gait or postural impairments before they join any exercise program, and to provide them with specific gait treatments and/or physical exercise programs, in order to decrease their risk for future musculoskeletal injuries and pain.

Low physical performance determined by chair rising test muscle mechanography is associated with prevalent fragility fractures

This study examined associations between physical performance assessed by chair rising test muscle mechanography and DXA T-score as well as body composition in a large patient cohort. Next to various significant interrelationships between these muscle and bone parameters, lower physical performance was associated with prevalent fragility fractures.

PURPOSE

Although the interaction between muscle and bone has been demonstrated in various aspects, the clinical focus in the diagnosis of musculoskeletal disorders mainly lies on the skeletal assessments. Accordingly, the association between muscle function, bone mineral density (BMD), and fragility fractures remains to be further elucidated with a feasible muscle assessment in a clinical setting.

METHODS

Patient data (2076 patients, 1538 women, 538 men) were evaluated retrospectively from a large dual energy X-ray absorptiometry (DXA) database as well as from chair rising test (CRT) that was performed on a muscle mechanograph. To determine potential predictors of the CRT time and maximum force, a multivariate regression analysis was performed including age, DXA T-score, and body composition indices. Furthermore, CRT results were compared between non-fracture and fracture cases.

RESULTS

We determined independent predictors for CRT time such as age, femoral DXA T-score, and total fat mass, whereas CRT force was only influenced by total lean mass. Both women and men with previous fragility fractures displayed a longer CRT time (women p = 0.009, men p = 0.001) and lower CRT force (women p < 0.001, men p < 0.001) than those with no fractures, while no clear differences in CRT results could be detected between normal BMD, osteopenia, and osteoporosis based on DXA T-scores.

CONCLUSIONS

Our study demonstrates that in addition to the associations between chair rising time and femoral T-score assessed by DXA, low muscle strength is associated with previous fragility fractures.

Obesity in Pediatric Trauma

Obese children with high-energy injuries present with more severe injuries, more extremity injuries, and higher Injury Severity Scores. They are at increased risk for complications, prolonged ventilation, and ICU stay and have increased mortality. Obesity is associated with altered bone mass accrual and higher fracture rates. Obese patients have a higher risk of loss of reduction of forearm fractures, more severe supracondylar fractures, and a higher likelihood of lateral condyle fractures. Obese patients are more likely to have complications with femur fractures and have higher rates of foot and ankle fracture.

The effect of weight loss on body composition, serum bone markers, and adipokines in prepubertal obese children after 1-year intervention

Purpose/Aim: The influence of weight loss on bone turnover and bone quality in childhood remains controversial, but it may implicate interactions between adiposity and bone metabolism. Therefore, we studied the relationships between bone markers and adipokines during weight loss in obese children.

MATERIALS AND METHODS

We determined serum leptin, soluble leptin receptor, adiponectin, bone alkaline phosphatase (BALP), C-terminal telopeptide of type I collagen (CTX-I), osteocalcin (OC), carboxylated-OC (Gla-OC), undercarboxylated-OC (Glu-OC), sclerostin, body composition, and bone mineral density (BMD) in 40 obese prepubertal children before and after therapy. The control group, matched for sex and age, consisted of 40 non-obese children.

RESULTS

We found that values of the total body less head-bone mineral content (TBLH-BMC) and TBLH-BMD were significantly increased, but TBLH-BMD Z-score was decreased by 25% (p = 0.002) in obese children with weight loss after therapy. We observed increases of CTX-I to OC ratio (p = 0.009), and Gla-OC concentrations (p = 0.049). Changes in TBLH-BMD Z-score in patients were positively correlated with changes in BMI Z-score (p = 0.001), percentage of fat mass (p = 0.004), and BALP activity (p = 0.01). Changes in BALP activity were negatively correlated (p < 0.001) with changes in adiponectin concentrations, while changes in sclerostin levels were positively correlated (p = 0.001) with leptin changes.

CONCLUSIONS

We suggest that alterations in adipokines metabolism were associated with a lower rate of bone mineral accrual as a result of decreased bone formation rather than increased bone resorption. The lower rate of bone mass accrual in weight losing children may be an effect of reduced BALP levels related to increase in adiponectin levels.

Growth, sexual and bone development in a boy with bilateral anorchia under testosterone treatment guided by the development of his monozygotic twin

BACKGROUND

Sex steroids are essential for sexual maturation, linear growth and bone development. However, there is no consensus on the optimal timing, dosage and dosage interval of testosterone therapy to induce pubertal development and achieve a normal adult height and bone mass in children with hypogonadism.

CASE PRESENTATION

A monozygotic monochorial male twin pair, of which one boy was diagnosed with anorchia at birth due to testicular regression syndrome was followed from the age of 3 until the age of 18 years. Low dose testosterone substitution (testosterone esters 25 mg/2 weeks) was initiated in the affected twin based on the start of pubertal development in the healthy twin and then gradually increased accordingly. Both boys were followed until age 18 and were compared as regards to linear growth, sexual maturation, bone maturation and bone development. Before puberty induction both boys had a similar weight and height. During puberty, a slightly faster weight and height gain was observed in the affected twin. Both boys ended up however, with a similar and normal (near) adult height and weight and experienced a normal development of secondary sex characteristics. At the age of 17 and 18 years, bone mineral density, body composition and volumetric bone parameters at the forearm and calf were evaluated in both boys. The affected boy had a higher lean mass and muscle cross-sectional area. The bone mineral density at the lumbar spine and whole body was similar. Trabecular and cortical volumetric bone parameters were comparable. At one cortical site (proximal radius), however, the affected twin had a smaller periosteal and endosteal circumference with a thicker cortex.

CONCLUSIONS

In conclusion, a low dose testosterone substitution in bilateral anorchia led to a normal onset of pubertal development and (near) adult height. Furthermore, there was no difference in bone mineral density at the age of 17 and 18 years.

Effects of a Randomized Weight Loss Intervention Trial in Obese Adolescents on Tibia and Radius Bone Geometry and Volumetric Density

Obese adolescents have increased fracture risk, but effects of alterations in adiposity on bone accrual and strength in obese adolescents are not understood. We evaluated 12-month changes in trabecular and cortical volumetric bone mineral density (vBMD) and cortical geometry in obese adolescents undergoing a randomized weight management program, and investigated the effect of body composition changes on bone outcomes. Peripheral quantitative computed tomography (pQCT) of the radius and tibia, and whole-body dual-energy X-ray absorptiometry (DXA) scans were obtained at baseline, 6 months, and 12 months in 91 obese adolescents randomized to standard care versus behavioral intervention for weight loss. Longitudinal models assessed effects of body composition changes on bone outcomes, adjusted for age, bone length, and African-American ancestry, and stratified by sex. Secondary analyses included adjustment for physical activity, maturation, vitamin D, and inflammatory biomarkers. Baseline body mass index (BMI) was similar between intervention groups. Twelve-month change in BMI in the standard care group was 1.0 kg/m² versus -0.4 kg/m² in the behavioral intervention group (p < 0.01). Intervention groups were similar in bone outcomes, so they were combined for subsequent analyses. For the tibia, BMI change was not associated with change in vBMD or structure. Greater baseline lean body mass index (LBMI) associated with higher cortical vBMD in males, trabecular vBMD in females, and polar section modulus (pZ) and periosteal circumference (Peri-C) in both sexes. In females, change in LBMI positively associated with gains in pZ and Peri-C. Baseline visceral adipose tissue (VFAT) was inversely associated with pZ in males and cortical vBMD in females. Change in VFAT did not affect bone outcomes. For the radius, BMI and LBMI changes positively associated with pZ in males. Thus, in obese adolescents, weight loss intervention with modest changes in BMI was not detrimental to radius or tibia bone strength, and changes in lean, but not adiposity, measures were beneficial to bone development. © 2017 American Society for Bone and Mineral Research.

The Relationship of Disordered Eating Attitudes with Stress Level, Bone Turnover Markers, and Bone Mineral Density in Obese Adolescents

OBJECTIVE

To investigate the effect of stress caused by disordered eating attitudes on bone health in obese adolescents.

METHODS

A cross-sectional study comprising 80 obese adolescents was performed from November 2013 to September 2014. Twenty-four-hour urinary free cortisol levels were measured as a biological marker of stress. Bone turnover was evaluated using bone-specific alkaline phosphatase, serum osteocalcin, and urinary N-telopeptide concentrations. Bone mineral density was measured using dual-energy X-ray absorptiometry. The Eating Disorder Examination Questionnaire, Dutch Eating Behavior Questionnaire, Children's Depression Inventory, and the State-Trait Anxiety Inventory for Children were used to assess eating disorders, depression, and anxiety. Psychiatric examinations were performed for binge eating disorders.

RESULTS

In the Pearson's correlation test, a positive correlation was found between the 24-hour urinary cortisol level and Dutch Eating Behavior Questionnaire total and restrained eating subscale scores (p<0.05 for both). In linear regression analyses, the Dutch Eating Behavior Questionnaire total and restrained eating subscale scores were found to be significant contributors for urinary cortisol level (β=1.008, p=0.035; β=2.296, p=0.014, respectively). The femoral neck areal bone mineral density was found to be significantly higher in subjects who had binge eating disorder compared with those without binge eating disorder (p=0.049).

CONCLUSION

Despite the lack of apparent effects on bone turnover and bone mineral density in our obese adolescents at the time of the study, our results suggest that disordered eating attitudes, and especially restrained eating attitudes, might be a source of stress. Therefore, studies in this area should continue.

Determinants of Advanced Bone Age in Childhood Obesity

BACKGROUND

Childhood obesity is associated with advanced bone age (BA). Previous studies suggest that androgens, oestrogens, sex hormone-binding globulin, and insulin are responsible for this phenomenon, but results are contradictory and might be biased by confounders. We aim to elucidate this matter by applying a multivariate approach.

METHOD

We performed a correlation analysis of BA standard deviation score (SDS) with age- and sex-specific SDS for androgens, oestrogens, and with indicators of insulin secretion derived from oral glucose tolerance testing, in a group of obese children. A multivariate analysis was performed to investigate which parameters were independently predictive of BA SDS.

RESULTS

In this cohort (n = 101; mean age 10.9 years; mean BA 11.8 years; mean BMI SDS 3.3), BMI SDS was significantly correlated to BA SDS (r = 0.55, p < 0.001). In a regression analysis in the total cohort (B = 0.27, p < 0.001) as well as in females (B = 0.34, p = 0.042), males (B = 0.31, p = 0.006), and pubertal children (B = 0.32, p = 0.046), dehydroepiandrosterone sulphate (DHEAS) showed a positive, independent association with BA SDS. No association with indicators of insulin secretion was found.

CONCLUSION

BMI SDS is highly correlated to BA SDS in obese children. Increased DHEAS has a central role in advanced BA in obese children.
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Bone Density in the Obese Child: Clinical Considerations and Diagnostic Challenges

The prevalence of obesity in children has reached epidemic proportions. Concern about bone health in obese children, in part, derives from the potentially increased fracture risk associated with obesity. Additional risk factors that affect bone mineral accretion, may also contribute to obesity, such as low physical activity and nutritional factors. Consequences of obesity, such as inflammation, insulin resistance, and non-alcoholic fatty liver disease, may also affect bone mineral acquisition, especially during the adolescent years when rapid increases in bone contribute to attaining peak bone mass. Further, numerous pediatric health conditions are associated with excess adiposity, altered body composition, or endocrine disturbances that can affect bone accretion. Thus, there is a multitude of reasons for considering clinical assessment of bone health in an obese child. Multiple diagnostic challenges affect the measurement of bone density and its interpretation. These include greater precision error, difficulty in positioning, and the effects of increased lean and fat tissue on bone health outcomes. Future research is required to address these issues to improve bone health assessment in obese children.

Associations Between Body Composition and Bone Health in Children and Adolescents: A Systematic Review

More clarification on the associations between children's and adolescents' lean and fat mass (LM and FM) on the one hand and their bone health on the other hand is needed, given the rising prevalence of overweight and obesity in this population. This systematic literature review aimed to describe the current evidence on these associations. Data sources were Medline/PubMed, EMBASE, CINAHL and The Cochrane Library (up to November 2014). Search items included LM, FM, children and adolescents (0-18 years), bone health measured with dual-energy X-ray absorptiometry and peripheral quantitative computed tomography (pQCT) and search items concerning study design: observational and longitudinal studies. The study populations were healthy children and adolescents including obese children. Children with other diseases and clinical series of study subjects were excluded. Based on the studies included in this review (n = 19), there is a consensus that the contribution of LM to the variance of the different bone parameters is larger than the contribution of FM and that an increase in LM is associated with an increase in bone parameters. Most of the studies indicated that the increase in bone parameters seen in overweight and obese children and adolescents is due to an increase in LM and not to greater FM. The results on the association between body fat and bone parameters were contradictory and depended on children's age and sex. Still more data from studies with a longitudinal study design using (high resolution) pQCT and a representative sample are needed to get further insight in the associations between body fat and bone parameters in children, specifically concerning differences in sex, skeletal site and fat depots.

Factors influencing bone mass accrual: focus on nutritional aspects

Until recently, much of the research exploring the role of nutrition on bone mass accrual has focused on single nutrients. Although randomised controlled trials have provided key information about the effects of calcium and vitamin D on bone, they also have limitations, e.g. generalisation, implementation of the results and long-term consequences. Human subjects do not eat single nutrients, but foods, and describing healthy food patterns for optimising bone mineral accrual is warranted. Recent advances in research suggest that the effects of whole diet are larger than those of single nutrients on bone health. Research should focus on younger age groups to identify the life-course determinants of osteoporosis during prenatal, infancy, childhood and adolescence that would help to maximise peak bone mass. Food patterns that describe the variability, quality and choices of individuals give broader insight and may provide new strategies for preventing osteoporosis.

Timing of low bone mineral density and predictors of bone mineral density trajectory in children on long-term warfarin: a longitudinal study

We studied bone mineral density (BMD) of children exposed to long-term warfarin. BMD Z-scores ≤ -2.0 were estimated to occur in less than one fifth of the patients after 10 years of warfarin exposure, and BMI and growth hormone deficiency predicted BMD changes over time. These predictors can help identify high-risk patients.

INTRODUCTION

Children with chronic diseases are at increased risk of developing thrombosis, which may require long-term warfarin therapy. Warfarin could further jeopardize the bone health of a population already at risk for bone fragility. Our objective was to investigate the occurrence and timing of low bone mineral density (BMD) and the predictors that influence BMD trajectory in children receiving warfarin for >1 year.

METHODS

We analyzed the results of an institutional protocol that includes dual-energy X-ray absorptiometry, with or without spinal X-rays and laboratory biomarkers, as required.

RESULTS

Low BMD (age, sex, race, and height-for-age-Z-score adjusted BMD Z-score ≤ -2.0) was detected in 13 % (9/70) of the patients at some point during their follow-up; these patients were more likely to have complex underlying medical conditions and low body mass index (BMI) percentile. BMD Z-scores remained within normal range in 87 % of children. Survival analysis showed that the estimated 10-year abnormal BMD-free rate for the entire group was 81 % (95 % confidence interval [CI] 69 to 93 %). Trajectory analysis revealed that BMI percentiles at baseline and growth hormone deficiency (GHD) were associated with lower BMD Z-scores at the first assessment, whereas baseline BMI percentile was the only predictor of BMD Z-score over time.

CONCLUSIONS

Our findings identified BMI and GHD as risk factors influencing BMD in children exposed to long-term warfarin, creating an opportunity for early detection and intervention in these patients.

Associations of anthropometric measures on breast cancer risk in pre- and postmenopausal women--a case-control study

Background

The type of silhouette and quantity of fat tissue are correlated with hormonal imbalance which plays a substantial role in breast carcinogenesis. The goal of the study was to investigate the association between various anthropometric characteristics and breast cancer risk.

Methods

Detailed anthropometric assessment was conducted on 487 women of whom 193 had diagnosed breast cancer and were consecutive patients in the Oncology Center, Cracow, Poland between 2002 and 2004. Measurements were divided into four categories: overall body size (body mass index [BMI], waist circumference [WC], waist-hip ratio [WHR]), regional body sizes (skinfold thicknesses, circumferences), thickness of the skeleton (widths, chest diameters), and body proportions. Additionally, results were analyzed in regard to menopausal status. Differences between groups were assessed using Student’s t test and Mann-Whitney’s test. Models of logistic regression for selected data were built to estimate the odds ratio. Results were considered statistically significant when the P value was less than 0.05.

Results

The BMI in both groups was negatively associated with the risk of cancer. Among premenopausal women, WHR increased the risk of breast cancer (WHR > 0.83, OR, 2.72; 95 % CI, 1.01–7.27). Anthropometric indices of hip-to-shoulder ratio in postmenopausal (≥84.2 mm, OR, 0.02; 95 % CI, 0.01–0.11) and trunk-to-height ratio in both premenopausal women (≥32.76, OR, 0.09; 95 % CI, 0.03–0.28) and postmenopausal women (≥32.76, OR, 0.13; 95 % CI, 0.05–0.33) were strongly related to a decreased risk of breast cancer. Thicknesses of the triceps and subscapular skinfolds increased the risk of breast cancer.

Conclusions

Women with breast cancer present with an obese type of silhouette with a specific concentration of fat tissue in the central and upper parts of the body.

Obesity does not aggravate osteoporosis or osteoblastic insulin resistance in orchiectomized rats

The present study aimed to test the hypothesis that testosterone deprivation impairs osteoblastic insulin signaling, decreases osteoblast survival, reduces bone density, and that obesity aggravates those deleterious effects in testosterone-deprived rats. Twenty four male Wistar rats underwent either a bilateral orchiectomy (O, n=12) or a sham operation (S, n=12). Then the rats in each group were further divided into two subgroups fed with either a normal diet (ND) or a high-fat diet (HF) for 12 weeks. At the end of the protocol, blood samples were collected to determine metabolic parameters and osteocalcin ratios. The tibiae were collected to determine bone mass using microcomputed tomography and for osteoblast isolation. The results showed that rats fed with HF (sham-operated HF-fed rats (HFS) and ORX HF-fed rats (HFO)) developed peripheral insulin resistance and had decreased trabecular bone density. In ND-fed rats, only the ORX ND-fed rats (NDO) group had decreased trabecular bone density. In addition, osteoblastic insulin resistance, as indicated by a decrease in tyrosine phosphorylation of the insulin receptor and Akt, were observed in all groups except the sham-operated ND-fed rats (NDS) rats. Those groups, again with the exception of the NDS rats, also had decreased osteoblastic survival. No differences in the levels of osteoblastic insulin resistance and osteoblastic survival were found among the NDO, HFS, and HFO groups. These findings suggest that either testosterone deprivation or obesity alone can impair osteoblastic insulin signaling and decrease osteoblastic survival leading to the development of osteoporosis. However, obesity does not aggravate those deleterious effects in the bone of testosterone-deprived rats.

Skeletal muscle and pediatric bone development

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent clinical findings surrounding the muscle-bone relationships in children, while considering muscle adiposity, endocrine factors, and lifestyle influences (i.e., diet and exercise) involved in pediatric musculoskeletal development.

RECENT FINDINGS

Positive relationships between cortical bone geometry and muscle mass, size and function have been reported. Prospective studies in particular have helped clarify some of the inconsistent relationships between muscle and cortical bone volumetric density. Muscle fat is associated with impaired glucose handling and muscular functionality, which may in turn have a downstream effect on cortical bone growth during adolescence. Lifestyle factors such as healthful diets and higher impact physical activities can promote optimal skeletal development by improving the muscular phenotype and endocrine profile.

SUMMARY

Muscle and bone are two intricately-related tissue types; however, factors such as sex, maturation, study design, and outcome measures studied can modify this relationship. Further research is warranted to understand the impact of muscle adiposity on cardiometabolic health, muscle function and, subsequently, pediatric musculoskeletal development and fracture risk. Following age-specific diet and physical activity recommendations should be a major focus in obtaining optimal muscle and bone development throughout maturation.

Bone-adiposity cross-talk: implications for pediatric obesity. A narrative review of literature

The rising prevalence of overweight and obesity among pediatric populations has become a major global concern. The objective of this review is to demonstrate potential interactions between the products released by fat tissue and the hormonal production of bone tissue in obese children and adolescents. Advancing the understanding of the complex interactions between adipocyte and osteocyte activities may contribute to the mechanistic understanding of the body's responses to weight loss during adolescence. This knowledge could also reveal any side effects encountered with these interventions. Currently, the concept of bone-adiposity crosstalk has not been fully elucidated, and the mechanisms remain controversial. Understanding the local interactions between the released products by fat tissue and hormones produced in bone tissue requires further investigations.

Differences in childhood adiposity influence upper limb fracture site

INTRODUCTION

Although it has been suggested that overweight and obese children have an increased risk of fracture, recent studies in post-menopausal women have shown that the relationship between obesity and fracture risk varies by fracture site. We therefore assessed whether adiposity and overweight/obesity prevalence differed by upper limb fracture site in children.

METHODS

Height, weight, BMI, triceps and subscapular skinfold thickness (SFT) were measured in children aged 3-18 years with an acute upper limb fracture. Data was compared across three fracture sites (hand, forearm and upper arm/shoulder [UA]), and to published reference data.

RESULTS

401 children (67.1% male, median age 11.71 years, range 3.54-17.27 years) participated. 34.2%, 50.6% and 15.2% had fractures of the hand, forearm and UA, respectively. Children with forearm fractures had higher weight, BMI, subscapular SFT and fat percentage z-scores than those with UA fractures (p<0.05 for all). SFT and fat percentage z-scores were also higher in children with forearm fractures compared to hand fractures, but children with hand and UA fractures did not differ. Overweight and obesity prevalence was higher in children with forearm fractures (37.6%) than those with UA fractures (19.0%, p=0.009). This prevalence was also higher than the published United Kingdom population prevalence (27.9%, p=0.003), whereas that of children with either UA (p=0.13) or hand fractures (29.1%, p=0.76) did not differ. These differences in anthropometry and overweight/obesity prevalence by fracture site were evident in boys, but not present in girls.

CONCLUSION

Measurements of adiposity and the prevalence of overweight/obesity differ by fracture site in children, and in particular boys, with upper limb fractures.

Bone Characteristics and Their Determinants in Adolescents and Young Adults with Early-Onset Severe Obesity

Childhood obesity is associated with compromised bone health. We studied bone characteristics and their determinants in obese young adults. The study included 68 subjects with early-onset severe obesity and 73 normal-weight controls. Data on physical activity (PA), diet and smoking were collected. Bone characteristics were measured using peripheral QCT. The obese and control subjects were similar in age (mean 19.6 ± 2.6 years) and height but BMIs differed (39.7 and 22.6 kg/m(2)). A clustering of unhealthy lifestyles was marked: Obese subjects reported less supervised PA in childhood, adolescence and currently (p < 0.03) and were more likely to smoke (p = 0.005), and had a lower healthy eating index (HEI) (p = 0.007) but similar alcohol consumption compared with controls. In obese women, all crude bone characteristics were higher than in controls; in men, the differences were smaller. Associations of lifestyle factors with bone characteristics were tested using partial correlations. Independently of BMI, supervised PA in adolescence and alcohol consumption were related positively to bone characteristics in both groups. HEI associated positively with bone characteristics only in controls, while smoking was a positive determinant of bone characteristics only in obese subjects. The multivariate model showed that the contribution of lifestyle factors to bone characteristics was minimal compared with BMI. Early-onset obesity is accompanied by poor dietary quality, sedentary lifestyle, and more frequent smoking, but the overall contribution of these lifestyle factors to bone strength is limited. Bone strength is more likely to be compromised in men and in unloaded bone sites in subjects with early-onset severe obesity. The impact of obesity-related endocrine changes on bone characteristics need to be evaluated in future studies.

Pediatric reference values for tibial trabecular bone mineral density and bone geometry parameters using peripheral quantitative computed tomography

The purpose of this study was to establish reference data, in relation to age and body height, for tibial trabecular and cortical volumetric bone mineral density, bone mineral content, and cross-sectional bone geometry in healthy children and adolescents using peripheral quantitative computed tomography (pQCT). Over a 2-year period, 432 (207 male and 225 female) healthy children, with an age range of 5 to 19 years, from 6 different geographic areas in Belgium were recruited. Multislice pQCT scanning (XCT2000(®), Stratec Medizintechnik, Pforzheim, Germany) was performed at the distal metaphysis (at the 4% site) and the distal diaphysis (14 and 38% sites) of the tibia of the dominant leg. Gender-specific centile curves in relation to age and body height were generated with the LMS method for total and trabecular volumetric bone mineral density (at 4% site), bone mineral content, total bone cross-sectional area, periosteal circumference (all at 4, 14, and 38% site), cortical volumetric bone mineral density, endosteal circumference, and cortical thickness (at the 14 and the 38% site). These centile curves can be used for the interpretation of pQCT results at the 4, 14, and 38% site of the tibia in European children and adolescents, at least when a similar methodology is used.

Associations between IGF-I, IGF-binding proteins and bone turnover markers in prepubertal obese children

OBJECTIVE

To assess the relationships between components of the growth hormone axis, body composition, and bone markers in obese children.

METHODS

We determined the levels of bone alkaline phosphatase (BALP), C-terminal telopeptide of type I collagen (CTX-I), insulin-like growth factor-I (IGF-I), and IGF-binding proteins (IGFBPs) by immunoenzymatic methods, and body composition by dual-energy X-ray absorptiometry in 45 obese and 20 non-obese children.

RESULTS

IGF-I and functional IGFBP-3 levels, IGF-I/total IGFBP-3, and functional IGFBP-3/total IGFBP-3 molar ratios were significantly higher in obese patients than in controls. Multivariate regression analysis in obese patients showed significant associations of BALP with IGF-I (p=0.047) and percent of body fat mass (p=0.002).

CONCLUSION

The relationship of IGF-I and functional IGFBP-3 to BALP may support the concept of IGF-I influence on accelerated bone formation process in obesity. Moreover, IGF-I and percentage of body fat mass may be significant predictors of BALP in obese during the prepubertal period.

Tibia and radius bone geometry and volumetric density in obese compared to non-obese adolescents

Childhood obesity is associated with biologic and behavioral characteristics that may impact bone mineral density (BMD) and structure. The objective was to determine the association between obesity and bone outcomes, independent of sexual and skeletal maturity, muscle area and strength, physical activity, calcium intake, biomarkers of inflammation, and vitamin D status. Tibia and radius peripheral quantitative CT scans were obtained in 91 obese (BMI>97th percentile) and 51 non-obese adolescents (BMI>5th and <85th percentiles). Results were converted to sex- and race-specific Z-scores relative to age. Cortical structure, muscle area and muscle strength (by dynamometry) Z-scores were further adjusted for bone length. Obese participants had greater height Z-scores (p<0.001), and advanced skeletal maturity (p<0.0001), compared with non-obese participants. Tibia cortical section modulus and calf muscle area Z-scores were greater in obese participants (1.07 and 1.63, respectively, both p<0.0001). Tibia and radius trabecular and cortical volumetric BMD did not differ significantly between groups. Calf muscle area and strength Z-scores, advanced skeletal maturity, and physical activity (by accelerometry) were positively associated with tibia cortical section modulus Z-scores (all p<0.01). Adjustment for muscle area Z-score attenuated differences in tibia section modulus Z-scores between obese and non-obese participants from 1.07 to 0.28. After multivariate adjustment for greater calf muscle area and strength Z-scores, advanced maturity, and less moderate to vigorous physical activity, tibia section modulus Z-scores were 0.32 (95% CI -0.18, 0.43, p=0.06) greater in obese, vs. non-obese participants. Radius cortical section modulus Z-scores were 0.45 greater (p=0.08) in obese vs. non-obese participants; this difference was attenuated to 0.14 with adjustment for advanced maturity. These findings suggest that greater tibia cortical section modulus in obese adolescents is attributable to advanced skeletal maturation and greater muscle area and strength, while less moderate to vigorous physical activities offset the positive effects of these covariates. The impact of obesity on cortical structure was greater at weight bearing sites.

Leptin may play a role in bone microstructural alterations in obese children

CONTEXT

Bone mass is low and fracture risk is higher in obese children. Hormonal changes in relation to skeletal microstructure and biomechanics have not been studied in obese children.

OBJECTIVE

The objective of the study was to ascertain the relationships of obesity-related changes in hormones with skeletal microstructure and biomechanics.

DESIGN

High resolution peripheral quantitative computed tomography (HR-pQCT) was used to compare three-dimensional cortical and trabecular microstructure and biomechanics at load-bearing and nonload bearing sites in obese and lean children. The relationship between leptin, adiponectin, testosterone, estrogen, osteocalcin and sclerostin and skeletal microstructure was also determined.

SETTING

The study was conducted at a tertiary pediatric endocrine unit in the United Kingdom.

PARTICIPANTS

Obese and lean children were matched by gender and pubertal stage.

RESULTS

Radial cortical porosity (mean difference -0.01 [95% CI: -0.02, -0.004], P = .003) and cortical pore diameter (mean difference -0.005 mm [95% CI: -0.009, -0.001], P = .011) were lower in obese children. Tibial trabecular thickness was lower (mean difference -0.009 mm [95% CI: -0.014, -0.004], P = .003), and trabecular number was higher (mean difference 0.23 mm(-1) [95% CI: 0.08, 0.38], P = .004) in obese children. At the radius, fat mass percentage negatively correlated with cortical porosity (r = -0.57, P < .001) and pore diameter (r = -0.38, P = .02) and negatively correlated with trabecular thickness (r = -0.62, P < .001) and trabecular von Mises stress (r = -0.39, P = .019) at the tibia. No difference was observed in the other biomechanical parameters of the radius and tibia. Leptin was higher in obese children (805.3 ± 440.6 pg/ml vs 98.1 ± 75.4 pg/ml, P < .001) and was inversely related to radial cortical porosity (r = 0.60, 95% CI: [-0.80, -0.30], P < .001), radial cortical pore diameter (r = 0.51, 95% CI [-0.75, -0.16], P = .002), tibial trabecular thickness (r = 0.55, 95% CI: [-0.78, -0.21], P = .001) and tibial trabecular von Mises stress (r = -0.39, 95% CI: -0.65, 0.04, P = .02).

CONCLUSION

Childhood obesity alters radial and tibial microstructure. Leptin may direct these changes. Despite this, the biomechanical properties of the radius and tibia do not adapt sufficiently in obese children to withstand the increased loading potential from a fall. This may explain the higher incidence of fracture in obese children.

The clinical epidemiology of male osteoporosis: a review of the recent literature

Osteoporosis, a musculoskeletal disease characterized by decreased bone mineral density (BMD) and an increased risk of fragility fractures, is now recognized as an important public health problem in men. Osteoporotic fractures, particularly of the hip, result in significant morbidity and mortality in men and lead to considerable societal costs. Many national and international organizations now address screening and treatment for men in their osteoporosis clinical guidelines. However, male osteoporosis remains largely underdiagnosed and undertreated. The objective of this paper is to provide an overview of recent findings in male osteoporosis, including pathophysiology, epidemiology, and incidence and burden of fracture, and discuss current knowledge about the evaluation and treatment of osteoporosis in males. In particular, clinical practice guidelines, fracture risk assessment, and evidence of treatment effectiveness in men are addressed.

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.

Associations of fat mass and fat distribution with bone mineral density in Chinese obese population

The purpose of the study was to investigate the associations of fat mass (FM) and fat distribution with bone mineral density (BMD) in Chinese obese population. Three hundred and forty-seven Chinese obese females and 339 males aged 20-39 years were analyzed. Lean mass (LM), FM, percent body fat (%BF), android FM, gynoid FM, and total and regional BMD were measured using dual-energy X-ray absorptiometry. Fat distribution was assessed by android-to-gynoid FM ratio (AOI). As a result, increased central body fat had an inverse association with total and leg BMD in females but not in males. Increased FM and %BF were positively associated with arm, trunk, and pelvic BMD in Chinese obese females. Increased FM was positively associated with total, rib, and trunk BMD in Chinese obese males. The results remained almost unchanged after adjusting for LM, and LM was significantly positively associated with spine BMD in female group. FM was positively associated with trunk BMD in male group after adjusting for LM. AOI was inversely associated with total and leg BMD, and %BF was positively associated with arm, trunk, and pelvic BMD when replacing FM with %BF in female group. The results remained almost unchanged after adjusting for LM. There is no significant association in male group when replacing FM with %BF. In conclusion, our findings demonstrate that there are different associations of FM and fat distribution with BMD, and AOI has a negative association with BMD.

Body composition during childhood and adolescence: relations to bone strength and microstructure

CONTEXT

Numerous studies have examined the association of body composition with bone development in children and adolescents, but none have used micro-finite element (μFE) analysis of high-resolution peripheral quantitative computed tomography images to assess bone strength.

OBJECTIVE

This study sought to examine the relations of appendicular lean mass (ALM) and total body fat mass (TBFM) to bone strength (failure load) at the distal radius and tibia.

DESIGN, PARTICIPANTS, AND SETTING

This was a cross-sectional study of 198 healthy 8- to <15-year-old boys (n = 109) and girls (n = 89) performed in a Clinical Research Unit.

RESULTS

After adjusting for bone age, height, fracture history, ALM, and TBFM, multiple linear regression analyses in boys and girls, separately, showed robust positive associations between ALM and failure loads at both the distal radius (boys: β = 0.92, P < .001; girls: β = 0.66, P = .001) and tibia (boys: β = 0.96, P < .001; girls: β = 0.66, P < .001). By contrast, in both boys and girls the relationship between TBFM and failure load at the distal radius was virtually nonexistent (boys: β = -0.07; P = .284; girls: β = -0.03; P = .729). At the distal tibia, positive, albeit weak, associations were observed between TBFM and failure load in both boys (β = 0.09, P = .075) and girls (β = 0.17, P = .033).

CONCLUSIONS

Our data highlight the importance of lean mass for optimizing bone strength during growth, and suggest that fat mass may have differential relations to bone strength at weight-bearing vs non-weight-bearing sites in children and adolescents. These observations suggest that the strength of the distal radius does not commensurately increase with excess gains in adiposity during growth, which may result in a mismatch between bone strength and the load experienced by the distal forearm during a fall. These findings may explain, in part, why obese children are over-represented among distal forearm fracture cases.

Relation of adrenal-derived steroids with bone maturation, mineral density and geometry in healthy prepubertal and early pubertal boys

BACKGROUND

Little is known about the effects of adrenal steroids on skeletal maturation and bone mass acquisition in healthy prepubertal boys.

OBJECTIVE

To study whether adrenal-derived steroids within the physiological range are associated with skeletal maturation, areal and volumetric bone mineral density (aBMD and vBMD) and bone geometry in healthy prepubertal and early pubertal boys.

METHODS

98 healthy prepubertal and early pubertal boys (aged 6-14 y) were studied cross-sectionally. Androstenedione (A) and estrone (E1) were determined by liquid chromatography tandem mass spectrometry and DHEAS was determined by immunoassay. Whole body and lumbar spine aBMD and bone area were determined by dual-energy X-ray absorptiometry. Trabecular (distal site) and cortical (proximal site) vBMD and bone geometry were assessed at the non-dominant forearm and leg using peripheral QCT. Skeletal age was determined by X-ray of the left hand.

RESULTS

Adrenal-derived steroids (DHEAS, A and E1) are positively associated with bone age in prepubertal and early pubertal children, independently of age. There are no associations between the adrenal-derived steroids and the studied parameters of bone size (lumbar spine and whole body bone area, trabecular or cortical area at the radius or tibia, periosteal circumference and cortical thickness at the radius or tibia) or BMD (aBMD or vBMD).

CONCLUSION

In healthy prepubertal and early pubertal boys, serum adrenal-derived steroid levels, are associated with skeletal maturation, independently of age, but not with bone size or (v)BMD. Our data suggest that adrenal derived steroids are not implicated in the accretion of bone mass before puberty in boys.

Physical activity and bone mineral accrual in boys with different body mass parameters during puberty: a longitudinal study

The aim of our longitudinal study was to investigate the relationships between physical activity and bone mass in boys with different body mass status during the years surrounding pubertal growth spurt. Two hundred and six boys entering puberty took part in this study. The subjects were divided into underweight (BMI < 15.35), normal weight (BMI ≥ 15.35-21.22), overweight (BMI ≥ 21.22-26.02) and obese (BMI > 26.02) groups at baseline according to age related categories. Whole-body DXA scans were performed at baseline, after 12 and 24 months to assess body composition (lean body mass, fat mass), and total body (TB), lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD) parameters. Physical activity was measured by 7-day accelerometry. For longitudinal analysis, multilevel fixed effects regression models were constructed. Biological age, height and lean body mass had an effect for explanation of TB BMD, FN BMD and LS BMD. Moderate to vigorous physical activity (MVPA), vigorous physical activity (VPA) and sedentary time (SED) had the significant effect only on FN BMD. Being an underweight boy at the baseline indicated greater chance (p<0.01) to have lower TB BMD in the future (2 years at follow up) development, compared to normal weight (estimates = -0.038), overweight (estimates = -0.061) and obese boys (estimates = -0.106).

Weight loss and bone mineral density

PURPOSE OF REVIEW

Despite evidence that energy deficit produces multiple physiological and metabolic benefits, clinicians are often reluctant to prescribe weight loss in older individuals or those with low bone mineral density (BMD), fearing BMD will be decreased. Confusion exists concerning the effects that weight loss has on bone health.

RECENT FINDINGS

Bone density is more closely associated with lean mass than total body mass and fat mass. Although rapid or large weight loss is often associated with loss of bone density, slower or smaller weight loss is much less apt to adversely affect BMD, especially when it is accompanied with high intensity resistance and/or impact loading training. Maintenance of calcium and vitamin D intake seems to positively affect BMD during weight loss. Although dual energy X-ray absorptiometry is normally used to evaluate bone density, it may overestimate BMD loss following massive weight loss. Volumetric quantitative computed tomography may be more accurate for tracking bone density changes following large weight loss.

SUMMARY

Moderate weight loss does not necessarily compromise bone health, especially when exercise training is involved. Training strategies that include heavy resistance training and high impact loading that occur with jump training may be especially productive in maintaining, or even increasing bone density with weight loss.

Underweight, overweight, and pediatric bone fragility: impact and management

Skeletal health is modulated by a variety of factors, including genetic makeup, hormonal axes, and environment. Across all ages, extremes of body weight may exert a deleterious effect on bone accretion and increase fracture risk. The incidence of both anorexia nervosa and obesity, each involving extreme alterations in body composition, is rising among youth, and secondary osteoporosis is increasingly being diagnosed among affected children and adolescents. Compared with the elderly, the definition of osteoporosis that stems from any underlying condition differs for the pediatric population and special precautions are required with regard to treatment of young patients. Early recognition and management of both underweight and overweight youth and the accompanying consequences on bone and mineral metabolism are essential for preservation of skeletal health, although prevention of bone loss and optimization of bone mineral accrual remain the most important protective measures.

Associations of sex steroids with bone maturation, bone mineral density, bone geometry, and body composition: a cross-sectional study in healthy male adolescents

BACKGROUND

Although both testosterone (T) and estradiol (E2) are considered essential in the regulation of the male skeleton, there are few data concerning the relative contribution of T and E2 on bone mineral density (BMD), bone geometry, and bone maturation in healthy boys.

OBJECTIVE

The objective of the study was to analyze the relationship between T and E2 and BMD, bone geometry, skeletal maturation, and body composition.

METHODS

This is a cross-sectional study in 199 healthy boys (aged 6-19 y). T and E2 were determined by liquid chromatography tandem mass spectrometry. Whole-body and lumbar areal bone mineral density (aBMD) and bone area, lean mass, and fat mass were determined by dual-energy X-ray absorptiometry. Trabecular (distal site) and cortical (proximal site) volumetric BMD (vBMD) and bone geometry were assessed at the nondominant forearm and leg using peripheral quantitative computed tomography. Skeletal age was determined by an X-ray of the left hand.

RESULTS

T was positively associated with lean mass (P < .001), lumbar and whole-body bone area (P < .001), trabecular and cortical area (P < .01), and periosteal circumference (P < .01) at the radius. E2 was positively associated with lumbar and whole-body aBMD (P < .001), trabecular vBMD at the radius and tibia (P < .01), and cortical thickness at the radius (P < .05). E2 was an independent negative predictor of the endosteal circumference (P < .01). Moreover, E2 was positively associated with bone age advancement (P < .001).

CONCLUSION

Circulating E2 is positively associated with bone maturation and aBMD and vBMD and negatively with endosteal circumference in healthy boys, whereas T is a determinant of lean mass and bone size. These findings underscore the important role of E2 in skeletal development in boys.