Abdominal fat is associated with lower bone formation and inferior bone quality in healthy premenopausal women: a transiliac bone biopsy study

Effect of Obesity on Bone Healing After Foot and Ankle Long Bone Fractures

As obesity has become more common, fractures in the obese population have become more frequent. Concern exists regarding alterations in bone health and healing in obese patients. A matched case-control study was performed at 1 institution to evaluate whether an association exists between nonunion and a high body mass index in metatarsal and ankle fractures. A total of 48 patients with nonunion were identified, and control patients matched 2 to 1 (n = 96) were selected. The control patients were matched for age, sex, and fracture type. No association was identified between nonunion and the continuous body mass index (p = .23) or morbid obesity, with a body mass index of ≥40 kg/m² (p = .51). However, the results from both univariate and multivariate analysis suggested that patients with a current alcohol problem or a history of an alcohol problem might have a greater risk of nonunion. The odds ratio of a patient with a history of alcohol use experiencing nonunion was 2.7 (95% confidence interval 1.2 to 6.2). Further studies are warranted to confirm these findings.

Obesity is a concern for bone health with aging

Accumulating evidence supports a complex relationship between adiposity and osteoporosis in overweight/obese individuals, with local interactions and endocrine regulation by adipose tissue on bone metabolism and fracture risk in elderly populations. This review was conducted to summarize existing evidence to test the hypothesis that obesity is a risk factor for bone health in aging individuals. Mechanisms by which obesity adversely affects bone health are believed to be multiple, such as an alteration of bone-regulating hormones, inflammation, oxidative stress, the endocannabinoid system, that affect bone cell metabolism are discussed. In addition, evidence on the effect of fat mass and distribution on bone mass and quality is reviewed together with findings relating energy and fat intake with bone health. In summary, studies indicate that the positive effects of body weight on bone mineral density cannot counteract the detrimental effects of obesity on bone quality. However, the exact mechanism underlying bone deterioration in the obese is not clear yet and further research is required to elucidate the effect of adipose depots on bone and fracture risk in the obese population.

Osteopontin: Relation between Adipose Tissue and Bone Homeostasis

Osteopontin (OPN) is a multifunctional protein mainly associated with bone metabolism and remodeling. Besides its physiological functions, OPN is implicated in the pathogenesis of a variety of disease states, such as obesity and osteoporosis. Importantly, during the last decades obesity and osteoporosis have become among the main threats to health worldwide. Because OPN is a protein principally expressed in cells with multifaceted effects on bone morphogenesis and remodeling and because it seems to be one of the most overexpressed genes in the adipose tissue of the obese contributing to osteoporosis, this mini review will highlight recent insights about relation between adipose tissue and bone homeostasis.

Visceral Adipose Tissue Is Associated With Bone Microarchitecture in the Framingham Osteoporosis Study

Obesity has been traditionally considered to protect the skeleton against osteoporosis and fracture. Recently, body fat, specifically visceral adipose tissue (VAT), has been associated with lower bone mineral density (BMD) and increased risk for some types of fractures. We studied VAT and bone microarchitecture in 710 participants (58% women, age 61.3 ± 7.7 years) from the Framingham Offspring cohort to determine whether cortical and trabecular BMD and microarchitecture differ according to the amount of VAT. VAT was measured from CT imaging of the abdomen. Cortical and trabecular BMD and microarchitecture were measured at the distal tibia and radius using high-resolution peripheral quantitative computed tomography (HR-pQCT). We focused on 10 bone parameters: cortical BMD (Ct.BMD), cortical tissue mineral density (Ct.TMD), cortical porosity (Ct.Po), cortical thickness (Ct.Th), cortical bone area fraction (Ct.A/Tt.A), trabecular density (Tb.BMD), trabecular number (Tb.N), trabecular thickness (Tb.Th), total area (Tt.Ar), and failure load (FL) from micro-finite element analysis. We assessed the association between sex-specific quartiles of VAT and BMD, microarchitecture, and strength in all participants and stratified by sex. All analyses were adjusted for age, sex, and in women, menopausal status, then repeated adjusting for body mass index (BMI) or weight. At the radius and tibia, Ct.Th, Ct.A/Tt.A, Tb.BMD, Tb.N, and FL were positively associated with VAT (all p-trend <0.05), but no other associations were statistically significant except for higher levels of cortical porosity with higher VAT in the radius. Most of these associations were only observed in women, and were no longer significant when adjusting for BMI or weight. Higher amounts of VAT are associated with greater BMD and better microstructure of the peripheral skeleton despite some suggestions of significant deleterious changes in cortical measures in the non-weight bearing radius. Associations were no longer significant after adjustment for BMI or weight, suggesting that the effects of VAT may not have a substantial effect on the skeleton independent of BMI or weight. © 2016 American Society for Bone and Mineral Research.

Visfatin is a positive predictor of bone mineral density in young survivors of acute lymphocytic leukemia

Bone mass acquisition may be compromised in survivors of childhood acute lymphocytic leukemia due to various factors, including adiposity. Fat accumulation can affect bone through the direct effect of adipokines or indirectly through the state of chronic inflammation. The aim of this study was to evaluate the effect of body composition and adipokines on bone mass in survivors of acute lymphocytic leukemia. This was a cross-sectional study of 56 survivors aged between 15 and 24 years, 44.6 % of whom received cranial radiotherapy (18-24 Gy), assessed according to body fat, lean mass, and bone mineral density (dual energy X-ray absorptiometry), computed tomography scan-derived abdominal adipose tissue, and adipokines by a multiple regression analysis. Both lumbar spine L₁-L₄ (trabecular bone) and total body (cortical bone) bone mineral density were positively correlated with visfatin (p < 0.050). Lean mass index was positively correlated, while waist-to-height ratio was negatively correlated with cortical bone (p < 0.010). Low bone mineral density for chronological age was detected in 5.4 % of patients in total body, and 8.9 % at the lumbar spine. In survivors of acute lymphocytic leukemia, visfatin may play an important role in the complex relationship between body composition and bone. At present, visfatin may represent a model for further study of bone metabolism, and could possibly explain the unknown mechanisms linking bone metabolism and cancer.

Visceral fat measured by DXA is associated with increased risk of non-spine fractures in nonobese elderly women: a population-based prospective cohort analysis from the São Paulo Ageing & Health (SPAH) Study

The present study investigates the relationship between visceral fat measured by dual-energy X-ray absorptiometry (DXA) and the incidence of non-spine fractures in community-dwelling elderly women. We demonstrated a potential negative effect of visceral fat on bone health in nonobese women.

INTRODUCTION

The protective effect of obesity on bone health has been questioned because visceral fat has been demonstrated to have a deleterious effect on bone. The aim of this study was to investigate the association of visceral fat measured by DXA with the incidence of non-spine fractures in community-dwelling elderly women.

METHODS

This longitudinal prospective population-based cohort study evaluated 433 community-dwelling women aged 65 years or older. A specific clinical questionnaire, including personal history of a fragility fracture in non-spine osteoporotic sites, was administered at baseline and after an average of 4.3 years. All incidences of fragility fractures during the study period were confirmed by affected-site radiography. Visceral adipose tissue (VAT) was measured in the android region of a whole-body DXA scan.

RESULTS

The mean age was 72.8 ± 4.7 years, and 28 incident non-spine osteoporotic fractures were identified after a mean follow-up time of 4.3 ± 0.8 years. According to the Lipschitz classification for nutritional status in the elderly, 38.6 % of women were nonobese (BMI ≤ 27 kg/m²) and 61.4 % were obese/overweight. Logistic regression models were used to estimate the relationship between VAT and non-spine fractures in elderly women. After adjusting for age, race, previous fractures, and BMD, VAT (mass, area, volume) had a significant association with the incidence of non-spine fractures only in nonobese elderly women (VAT mass: OR, 1.42 [95 % CI, 1.09-1.85; p = 0.010]; VAT area: OR, 1.19 [95 % CI, 1.05-1.36; p = 0.008]; VAT volume: OR, 1.40 [95 % CI, 1.09-1.80; p = 0.009]).

CONCLUSION

This study suggests a potential negative effect of visceral adiposity on bone health in nonobese women.

Osteoporosis among household women: A growing but neglected phenomenon

Background

Osteoporosis is associated with variable morbidity and socio-economic burden and referred as a "silent epidemic" with increasing risk among Indian women. The present study was conducted to find prevalence of osteoporosis.

Methods

A descriptive cross-sectional study was conducted in Ranchi city with household women as participants. Data was collected by means of pre-tested structured questionnaire in Hindi language and bone status was screened utilizing calcaneal quantitative ultrasound as a diagnostic tool to estimate bone mineral density from 223 participants and statistical analysis was performed with SPSS software.

Results

The mean age of the participants was 37.9 (5.63) and majority (52.5%) of them were vegetarian. The prevalence of osteoporosis was 8.5% (5.2-13%) while 45.7% (39-52.5%) had osteopenia. We found no significant association of osteoporosis and osteopenia with income, physical activity, and dietary patterns on univariate analysis. There was no statistical significant difference between mean age and BMI of participant among normal, osteoporosis, and osteopenia participant (p value >0.5). Multivariate logistic regression analysis shows that 20% increase chances of risk with five years increase in age, the protective effect of physical activity (22%) and non-vegetarian diet (18%) though not statistically significant.

Conclusion

This study shows that significant number of women had osteopenia/osteoporosis within 35-40 years age group. Intensive information, education, and communication activities with regard to osteoporosis causative factors and preventive measures targeted to household women may play an important role, if started at young age.

Age-Adjusted Dual X-ray Absorptiometry-Derived Trabecular Bone Score Curve for the Lumbar Spine in Thai Females and Males

Trabecular bone score (TBS), which has been shown to discriminate patients with fractures from healthy individuals, decreases with age. This study was conducted to derive an age-adjusted normative TBS curve for each gender aged 30-80 + years to serve as reference data for Thai males and females. A cross-sectional study was conducted among employees from the Electricity Generating Authority of Thailand cohorts, after excluding those with conditions potentially affecting bone metabolism and analysis. The values of TBS at L1-L4 vertebrae were analyzed using a commercial software. Age-adjusted TBS curves were constructed using segmental linear regression analysis for each gender. Additional analysis was also performed on TBS with age, body mass index, and body mineral density (BMD) at L1-L4 vertebrae as covariates. A database of 848 healthy subjects (341 females and 507 males) aged 30-80+ years was created. The BMDs of both male and female subjects in the youngest decade were not statistically different from previous reports (p = 0.31 and 0.22 for females and males, respectively). In this age group, the mean TBS was higher in females, albeit not statistically significant (p = 0.12). Between the ages of 30-80+ years, female and male TBS dropped by 19.8% (0.40% per year) and 10.1% (0.20% per year), respectively. The association with TBS was weak for body mass index and moderate for BMD (coefficients of about -0.01 and 0.4-0.5, respectively). The age-adjusted reference curves for healthy Thai females and males aged 30-80+ years have been established.

Skeletal Metabolism, Fracture Risk, and Fracture Outcomes in Type 1 and Type 2 Diabetes

Fracture risk is significantly increased in both type 1 and type 2 diabetes, and individuals with diabetes experience worse fracture outcomes than normoglycemic individuals. Factors that increase fracture risk include lower bone mass in type 1 diabetes and compromised skeletal quality and strength despite preserved bone density in type 2 diabetes, as well as the effects of comorbidities such as diabetic macro- and microvascular complications. In this Perspective, we assess the developing scientific knowledge regarding the epidemiology and pathophysiology of skeletal fragility in patients with diabetes and the emerging data on the prediction, treatment, and outcomes of fractures in individuals with type 1 and type 2 diabetes.

Body composition predictors of skeletal integrity in obesity

OBJECTIVE

To determine body composition predictors of skeletal integrity in overweight/obese subjects using dual energy X-ray absorptiometry (DXA). We hypothesized that visceral adiposity would be negatively, and lean mass positively, associated with DXA measures of skeletal integrity in obesity.

MATERIALS AND METHODS

Our study was institutional review board (IRB)-approved and Health Insurance Portability and Accountability Act (HIPAA)-compliant and written informed consent was obtained. We studied 82 overweight or obese, but otherwise healthy premenopausal women and men of similar age who were part of a clinical trial (mean age: 37 ± 10 years, mean BMI: 34 ± 7 kg/m(2)). All subjects underwent DXA of the spine and hip for assessment of bone mineral density (BMD), trabecular bone score (TBS), and hip structural analysis (HSA), and of the whole body for the assessment of body composition, including estimated visceral adipose tissue (VAT).

RESULTS

Sixty-three subjects (77 %) had normal BMD and 19 subjects (23 %) had osteopenia. There were strong age-, sex-, and BMD-independent positive associations between lean mass and HSA parameters (r = 0.50 to r = 0.81, p < 0.0001), whereas there was no association with TBS. There were strong age-, sex- and BMD-independent inverse associations between total fat and VAT mass and TBS (r = -0.60 and r = -0.72, p < 0.0001 for both correlations), whereas there were no associations with HSA parameters.

CONCLUSION

Lean mass is a positive predictor of hip geometry, whereas fat and VAT mass are negative predictors of trabecular microarchitecture in overweight/obese subjects.

BMI and BMD: The Potential Interplay between Obesity and Bone Fragility

Recent evidence demonstrating an increased fracture risk among obese individuals suggests that adipose tissue may negatively impact bone health, challenging the traditional paradigm of fat mass playing a protective role towards bone health. White adipose tissue, far from being a mere energy depot, is a dynamic tissue actively implicated in metabolic reactions, and in fact secretes several hormones called adipokines and inflammatory factors that may in turn promote bone resorption. More specifically, Visceral Adipose Tissue (VAT) may potentially prove detrimental. It is widely acknowledged that obesity is positively associated to many chronic disorders such as metabolic syndrome, dyslipidemia and type 2 diabetes, conditions that could themselves affect bone health. Although aging is largely known to decrease bone strength, little is yet known on the mechanisms via which obesity and its comorbidities may contribute to such damage. Given the exponentially growing obesity rate in recent years and the increased life expectancy of western countries it appears of utmost importance to timely focus on this topic.

Vaspin regulates the osteogenic differentiation of MC3T3-E1 through the PI3K-Akt/miR-34c loop

Vaspin (visceral adipose tissue-derived serine protease inhibitor) is a newly discovered adipokine that widely participates in diabetes mellitus, polycystic ovarian syndrome and other disorders of metabolism. However, the effect of vaspin on the regulation of osteogenesis and the mechanism responsible are still unclear. Here, we found that vaspin can attenuate the osteogenic differentiation of the preosteoblast cell line MC3T3-E1 in a dose-dependent way; also, during this process, the expression of miRNA-34c (miR-34c) was significantly increased. Down-regulation of the expression of miR-34c in MC3T3-E1 diminished the osteogenic inhibitory effect of vaspin, while the up-regulation of miR-34c increased this effect through its target gene Runx2. Meanwhile, we found that vaspin could also activate the PI3K-Akt signalling pathway. Blocking the PI3K-Akt signalling pathway with specific inhibitors could decrease the osteogenic inhibitory effect of vaspin as well as the expression level of miR-34c. Furthermore, knock-down of miR-34c could promote the activation of Akt, which was probably realised by targeting c-met expression. Thus, PI3K-Akt and miR-34c constituted a modulation loop and controlled the expression of each other. Taken together, our study showed that vaspin could inhibit the osteogenic differentiation in vitro, and the PI3K-Akt/miR-34c loop might be the underlying mechanism.

A High Amount of Local Adipose Tissue Is Associated With High Cortical Porosity and Low Bone Material Strength in Older Women

Obesity is associated with increased risk of fractures, especially at skeletal sites with a large proportion of cortical bone, such as the humerus and ankle. Obesity increases fracture risk independently of BMD, indicating that increased adipose tissue could have negative effects on bone quality. Microindentation assesses bone material strength index (BMSi) in vivo in humans. The aim of this study was to investigate if different depots of adipose tissue were associated with BMSi and cortical bone microstructure in a population based group of 202 women, 78.2 ± 1.1 (mean ± SD) years old. Bone parameters and subcutaneous (s.c.) fat were measured at the tibia with an XtremeCT device. BMSi was assessed using the OsteoProbe device, and based on at least 11 valid reference point indentations at the mid-tibia. Body composition was measured with dual X-ray absorptiometry. BMSi was inversely correlated to body mass index (BMI) (r = -0.17, p = 0.01), whole body fat mass (r = -0.16,p = 0.02), and, in particular, to tibia s.c. fat (r = -0.33, p < 0.001). Tibia s.c. fat was also correlated to cortical porosity (Ct.Po; r = 0.19, p = 0.01) and cortical volumetric BMD (Ct.vBMD; r = -0.23, p = 0.001). Using linear regression analyses, tibia s.c. fat was found to be independent of covariates (age, height, log weight, bisphosphonates or glucocorticoid use, smoking, calcium intake, walking speed, and BMSi operator) and associated with BMSi (β = -0.34,p < 0.001), Ct.Po (β = 0.18, p = 0.01), and Ct.vBMD (β = -0.32, p < 0.001). BMSi was independent of covariates associated with cortical porosity (β = -0.14, p = 0.04) and cortical volumetric BMD (β = 0.21, p = 0.02) at the distal tibia, but these bone parameters could only explain 3.3% and 5.1% of the variation in BMSi, respectively. In conclusion, fat mass was independently and inversely associated with BMSi and Ct.vBMD, but positively associated with Ct.Po, indicating a possible adverse effect of adipose tissue on bone quality and bone microstructure. Local s.c. fat in tibia was most strongly associated with these bone traits, suggesting a local or paracrine, rather than systemic, negative effect of fat on bone.

Fracture Risk Is Decreased in Women With Polycystic Ovary Syndrome: A Register-Based and Population-Based Cohort Study

Hyperandrogenism, obesity, and hyperinsulinemia may protect against osteoporosis, whereas amenorrhea, increased cortisol, and low growth hormone may be associated with higher fracture risk in polycystic ovary syndrome (PCOS). The objective of this study was to investigate fracture risk in PCOS. In the PCOS Denmark study, women with PCOS and/or hirsutism were identified in the Danish National Patient Register (1995-2012). Each patient was assigned three age-matched controls on the index date of PCOS diagnosis. Individuals with a previous endocrine diagnosis were excluded. Within PCOS Denmark, we embedded a well-characterized subcohort of patients, PCOS OUH, diagnosed with PCOS at Odense University Hospital (n = 1217). We identified incident fractures by International Classification of Diseases, 10th Revision (ICD-10) codes and used conditional Cox regression analyses to compare fracture risk. In the PCOS Denmark study, there were 19,199 women with PCOS and 57,483 controls were included, mean age 30.6 years (range, 12-60 years). Fracture rates were decreased in PCOS Denmark (10.3/1000 patient years) versus controls (13.6/1000 patient years). The adjusted ORs were 0.76 (95% CI, 0.71 to 0.80) for all fractures, 0.82 (95% CI, 0.74 to 0.92) for major osteoporotic fractures, and 0.57 (95% CI, 0.47 to 0.70) for fractures of head and face. The risk reduction was more pronounced below the age of 30 years at diagnosis. Women with PCOS had significant more hospital contacts due to strains and sprains. In the PCOS OUH subcohort, the risk reduction of fractures did not differ between PCOS women with elevated versus normal testosterone levels and the risk reduction was nominally smaller in overweight versus normal weight PCOS women. Women with PCOS had reduced risk of fractures, in particular of the appendicular skeleton. The risk reduction was greater in women with younger age at diagnosis suggesting that the skeletal effects of PCOS may be greater in women who have not yet reached peak bone mass. Reduced participation in sports activities was probably not the reason for the reduced risk of fractures.

Assessment of bone turnover and bone quality in type 2 diabetic bone disease: current concepts and future directions

Substantial evidence exists that in addition to the well-known complications of diabetes, increased fracture risk is an important morbidity. This risk is probably due to altered bone properties in diabetes. Circulating biochemical markers of bone turnover have been found to be decreased in type 2 diabetes (T2D) and may be predictive of fractures independently of bone mineral density (BMD). Serum sclerostin levels have been found to be increased in T2D and appear to be predictive of fracture risk independent of BMD. Bone imaging technologies, including trabecular bone score (TBS) and quantitative CT testing have revealed differences in diabetic bone as compared to non-diabetic individuals. Specifically, high resolution peripheral quantitative CT (HRpQCT) imaging has demonstrated increased cortical porosity in diabetic postmenopausal women. Other factors such as bone marrow fat saturation and advanced glycation endproduct (AGE) accumulation might also relate to bone cell function and fracture risk in diabetes. These data have increased our understanding of how T2D adversely impacts both bone metabolism and fracture risk.

Vertebral Strength and Estimated Fracture Risk Across the BMI Spectrum in Women

Somewhat paradoxically, fracture risk, which depends on applied loads and bone strength, is elevated in both anorexia nervosa and obesity at certain skeletal sites. Factor-of-risk (Φ), the ratio of applied load to bone strength, is a biomechanically based method to estimate fracture risk; theoretically, higher Φ reflects increased fracture risk. We estimated vertebral strength (linear combination of integral volumetric bone mineral density [Int.vBMD] and cross-sectional area from quantitative computed tomography [QCT]), vertebral compressive loads, and Φ at L4 in 176 women (65 anorexia nervosa, 45 lean controls, and 66 obese). Using biomechanical models, applied loads were estimated for: 1) standing; 2) arms flexed 90°, holding 5 kg in each hand (holding); 3) 45° trunk flexion, 5 kg in each hand (lifting); 4) 20° trunk right lateral bend, 10 kg in right hand (bending). We also investigated associations of Int.vBMD and vertebral strength with lean mass (from dual-energy X-ray absorptiometry [DXA]) and visceral adipose tissue (VAT, from QCT). Women with anorexia nervosa had lower, whereas obese women had similar, Int.vBMD and estimated vertebral strength compared with controls. Vertebral loads were highest in obesity and lowest in anorexia nervosa for standing, holding, and lifting (p < 0.0001) but were highest in anorexia nervosa for bending (p < 0.02). Obese women had highest Φ for standing and lifting, whereas women with anorexia nervosa had highest Φ for bending (p < 0.0001). Obese and anorexia nervosa subjects had higher Φ for holding than controls (p < 0.03). Int.vBMD and estimated vertebral strength were associated positively with lean mass (R = 0.28 to 0.45, p ≤ 0.0001) in all groups combined and negatively with VAT (R = -[0.36 to 0.38], p < 0.003) within the obese group. Therefore, women with anorexia nervosa had higher estimated vertebral fracture risk (Φ) for holding and bending because of inferior vertebral strength. Despite similar vertebral strength as controls, obese women had higher vertebral fracture risk for standing, holding, and lifting because of higher applied loads from higher body weight. Examining the load-to-strength ratio helps explain increased fracture risk in both low-weight and obese women.

Simulated increased soft tissue thickness artefactually decreases trabecular bone score: a phantom study

BACKGROUND

Trabecular bone score (TBS), which has been proposed to be used in complementary with bone mineral density (BMD) to improve the assessment of fracture risk, is negatively associated with body mass index (BMI). The effect of soft tissue, which is expected to be thicker in subjects with high BMI, on TBS was studied using three scan types: Hologic with fast array mode (Hfa), Hologic with high definition mode (Hhd), and GE-Lunar iDXA.

METHODS

A spine phantom provided by Hologic for routine quality control procedure was scanned using three scan types: Hfa, Hhd, and iDXA. The phantom was scanned with an overlying soft tissue equivalent material (bolus used in radiotherapy) of 0 (without), 1, 2.5, 3.5, 5 and 7.5 cm thick. For each setting, 30 acquisitions were performed in the same way as for the quality control procedure. TBS was calculated using TBS iNsight® software version 2.1 on the same regions of interest as those used for lumbar spine BMD.

RESULTS

Mean ± SD TBS of the phantom (without overlying soft tissue) were 1.379 ± 0.018, 1.430 ± 0.009, and 1.423 ± 0.005 using Hfa, Hhd, and iDXA, respectively. A one-way repeated measures ANOVA showed that there were statistically differences in TBS due to different thicknesses of soft tissue equivalent materials for all three scan types (p < 0.001). A Tukey post-hoc test revealed that the decrease in TBS was statistically significant (p < 0.001) when the soft tissue thickness was 1 cm (-0.0246 ± 0.0044, -0.0319 ± 0.0036, and -0.0552 ± 0.0015 for Hfa, Hhd, and iDXA, respectively). Although to a lesser degree, the effects were also statistically significant for BMD (p < 0.05): an increase for Hfa and Hhd but a decrease for iDXA. However, these changes did not exceed the least significant change (LSC) derived from patients.

CONCLUSIONS

Increased soft tissue thickness results in lower TBS value. Although BMD is also affected, it is unlikely to pose a clinical problem because the change is unlikely to exceed the patient-derived LSC.

Exercise Regulation of Marrow Adipose Tissue

Despite association with low bone density and skeletal fractures, marrow adipose tissue (MAT) remains poorly understood. The marrow adipocyte originates from the mesenchymal stem cell (MSC) pool that also gives rise to osteoblasts, chondrocytes, and myocytes, among other cell types. To date, the presence of MAT has been attributed to preferential biasing of MSC into the adipocyte rather than osteoblast lineage, thus negatively impacting bone formation. Here, we focus on understanding the physiology of MAT in the setting of exercise, dietary interventions, and pharmacologic agents that alter fat metabolism. The beneficial effect of exercise on musculoskeletal strength is known: exercise induces bone formation, encourages growth of skeletally supportive tissues, inhibits bone resorption, and alters skeletal architecture through direct and indirect effects on a multiplicity of cells involved in skeletal adaptation. MAT is less well studied due to the lack of reproducible quantification techniques. In recent work, osmium-based 3D quantification shows a robust response of MAT to both dietary and exercise intervention in that MAT is elevated in response to high-fat diet and can be suppressed following daily exercise. Exercise-induced bone formation correlates with suppression of MAT, such that exercise effects might be due to either calorie expenditure from this depot or from mechanical biasing of MSC lineage away from fat and toward bone, or a combination thereof. Following treatment with the anti-diabetes drug rosiglitazone - a PPARγ-agonist known to increase MAT and fracture risk - mice demonstrate a fivefold higher femur MAT volume compared to the controls. In addition to preventing MAT accumulation in control mice, exercise intervention significantly lowers MAT accumulation in rosiglitazone-treated mice. Importantly, exercise induction of trabecular bone volume is unhindered by rosiglitazone. Thus, despite rosiglitazone augmentation of MAT, exercise significantly suppresses MAT volume and induces bone formation. That exercise can both suppress MAT volume and increase bone quantity, notwithstanding the skeletal harm induced by rosiglitazone, underscores exercise as a powerful regulator of bone remodeling, encouraging marrow stem cells toward the osteogenic lineage to fulfill an adaptive need for bone formation. Thus, exercise represents an effective strategy to mitigate the deleterious effects of overeating and iatrogenic etiologies on bone and fat.

Body composition, lung function, and prevalent and progressive bone deficits among adults with cystic fibrosis

INTRODUCTION

Cystic fibrosis (CF) is associated with osteoporosis and incident fracture. This study assessed independent predictors of baseline and 2-year changes in bone mineral density (BMD) in adults with CF.

METHODS

Sixty-four adult patients with CF, ages 18-57, were recruited from the Massachusetts General Hospital Cystic Fibrosis Care Center. Dual-energy X-ray absorptiometry (DXA) was performed at the spine and radius at baseline and 2 years (in 39 subjects). Estimates of fat-free mass index (FFMI) and fat mass index (FMI) were determined using height, weight, and tetrapolar bioelectric impedance analysis. All subjects completed lung spirometry within 1 month of the study visit. Linear regression models evaluated predictors of baseline BMD Z-scores and change in PA spine BMD Z-score over 2 years. Two definitions of low BMD were studied based on Z-score (≤-1.0 and ≤-2.0).

RESULTS

Low BMD was present in 52% of subjects. Subjects with low BMD were more likely to be male (67% vs. 32%, P=0.009), were more likely to be currently using glucocorticoids (21% vs. 0%, P<0.001), had lower percent body fat (P=0.04), and were more likely to have had a previous fracture (60% vs. 46%, P=0.007). In multivariable models, greater FFMI and height, but not greater FMI, were associated with greater BMD. In multivariable models, low forced vital capacity (FVC) and greater FMI were associated with greater loss of BMD at the PA spine over two years.

CONCLUSIONS

Male sex, short stature, and low lean mass are associated with low BMD in CF. Greater adiposity and lower lung function are predictors of negative change in BMD Z-score over 2 years.

The obesity of bone

During the last decades, obesity and osteoporosis have become important global health problems, and the belief that obesity is protective against osteoporosis has recently come into question. In fact, some recent epidemiologic and clinical studies have shown that a high level of fat mass might be a risk factor for osteoporosis and fragility fractures. Several potential mechanisms have been proposed to explain the complex relationship between adipose tissue and bone. Indeed, adipose tissue secretes various molecules, named adipokines, which are thought to have effects on metabolic, skeletal and cardiovascular systems. Moreover, fat tissue is one of the major sources of aromatase, an enzyme that synthesizes estrogens from androgen precursors, hormones that play a pivotal role in the maintenance of skeletal homeostasis, protecting against osteoporosis. Moreover, bone cells express several specific hormone receptors and recent observations have shown that bone-derived factors, such as osteocalcin and osteopontin, affect body weight control and glucose homeostasis. Thus, the skeleton is considered an endocrine target organ and an endocrine organ itself, likely influencing other organs as well. Finally, adipocytes and osteoblasts originate from a common progenitor, a pluripotential mesenchymal stem cell, which has an equal propensity for differentiation into adipocytes or osteoblasts (or other lines) under the influence of several cell-derived transcription factors. This review will highlight recent insights into the relationship between fat and bone, evaluating both potential positive and negative influences between adipose and bone tissue. It will also focus on the hypothesis that osteoporosis might be considered the obesity of bone.

Metabolic Syndrome and Osteoporosis in Relation to Muscle Mass

This study aimed to examine the relationship between metabolic syndrome (MetS) and osteoporosis according to muscle mass levels and the joint relationship of MetS and muscle mass with osteoporosis in a representative population-based sample from the Korea National Health and Nutrition Examination Survey in 2010-2011. In 1654 men and 1979 women aged 50-93 years, body composition and bone mineral density at the femur and lumbar spine were measured using dual-energy X-ray absorptiometry. Low- and high-muscle mass groups were identified using the mean sex-specific muscle mass of appendicular muscle mass/height(2). The covariates were age, health behaviors, serum 25-OH vitamin D and parathyroid hormone, calcium intake, and hormone replacement therapy for women. Men and women with MetS (defined by the Adult Treatment Panel III) had 43 and 31% lower odds for osteoporosis, respectively, compared with their MetS-free counterparts after adjusting for muscle mass and covariates. When stratified by muscle mass, MetS was not associated with osteoporosis in men, while associated in women with higher muscle mass (OR 0.65, 95% CI 0.46-0.91). Compared with MetS-free men and women with lower muscle mass, the odds for osteoporosis were 45% and 23, 52 and 15%, and 72 and 46% lower among those with low muscle mass and MetS, high muscle mass without MetS, and high muscle mass and MetS, respectively (P for trend <0.001). Combination of high muscle mass and MetS was associated with lower prevalence of osteoporosis in Korean men and women.

Marrow adiposity assessed on transiliac crest biopsy samples correlates with noninvasive measurement of marrow adiposity by proton magnetic resonance spectroscopy ((1)H-MRS) at the spine but not the femur

Measurement of marrow fat (MF) is important to the study of bone fragility. We measured MF on iliac biopsies and by spine/hip magnetic resonance spectroscopy in the same subjects. Noninvasively assessed spine MF and histomorphometrically assessed MF correlated well. MF quantity and relationships with bone volume differed by measurement site.

INTRODUCTION

Excess marrow fat has been implicated in the pathogenesis of osteoporosis in several populations. In the bone marrow, adipocytes and osteoblasts share a common precursor and are reciprocally regulated. In addition, adipocytes may secrete toxic fatty acids and adipokines that adversely affect osteoblasts. Measurement of marrow fat is important to the study of mechanisms of bone fragility. Marrow fat can be quantified on bone biopsy samples by histomorphometry and noninvasively by proton magnetic resonance spectroscopy ((1)H-MRS). In this study, we evaluate relationships between marrow fat assessed using both methods in the same subjects for the first time.

METHODS

Sixteen premenopausal women, nine with idiopathic osteoporosis and seven normal controls, had marrow fat measured at the iliac crest by bone biopsy and at the lumbar spine (L3) and proximal femur by (1)H-MRS.

RESULTS

At L3, fat fraction by (1)H-MRS correlated directly and significantly with marrow fat variables on iliac crest biopsies (r = 0.5-0.8). In contrast, there were no significant correlations between fat fraction at the femur and marrow fat on biopsies. Marrow fat quantity (%) was greater at the femur than at L3 and the iliac crest and correlated inversely with total hip and femoral neck BMD by DXA.

CONCLUSIONS

In summary, measurement of marrow fat in transiliac crest biopsies correlates with marrow fat at the spine but not the proximal femur by (1)H-MRS. There were site-specific differences in marrow fat quantity and in the relationships between marrow fat and bone volume.

Greater Adipose Tissue Distribution and Diminished Spinal Musculoskeletal Density in Adults With Cerebral Palsy

OBJECTIVES

To examine differences in adipose tissue distribution, lumbar vertebral bone mineral density (BMD), and muscle attenuation in adults with and without cerebral palsy (CP), and to determine the associations between morphologic characteristics.

DESIGN

Cross-sectional, retrospective analyses of archived computed tomography scans.

SETTING

Clinical treatment and rehabilitation center.

PARTICIPANTS

Adults (N=352) with CP (age, 38.8±14.4y; body mass, 61.3±17.1kg; Gross Motor Function Classification System levels, I-V) and a matched cohort of neurotypical adults. Of the 41 adults with CP included in the study, 10 were not matchable because of low body masses.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Computed tomography scans were assessed for visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas, psoas major area and attenuation in Hounsfield units (Hu), and cortical and trabecular BMDs.

RESULTS

Adults with CP had lower cortical (β=-63.41 Hu, P<.001) and trabecular (β=-42.24 Hu, P<.001) BMDs and psoas major areas (β=-374.51mm(2), P<.001) and attenuation (β=-9.21 Hu, P<.001) after controlling for age, sex, and body mass. Adults with CP had greater VAT (β=3914.81mm(2), P<.001) and SAT (β=4615.68mm(2), P<.001). Muscle attenuation was significantly correlated with trabecular (r=.51, P=.002) and cortical (r=.46, P<.01) BMD, whereas VAT was negatively associated with cortical BMD (β=-.037 Hu/cm(2), r(2)=.13, P=.03).

CONCLUSIONS

Adults with CP had lower BMDs, smaller psoas major area, greater intermuscular adipose tissue, and greater trunk adiposity than neurotypical adults. VAT and cortical BMD were inversely associated.

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.

Adverse Fat Depots and Marrow Adiposity Are Associated With Skeletal Deficits and Insulin Resistance in Long-Term Survivors of Pediatric Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem-cell transplantation (alloHSCT) survivors treated with total body irradiation (TBI) exhibit bone deficits and excess adiposity, potentially related to altered mesenchymal stem cell differentiation into osteoblasts or adipocytes. We examined associations among fat distribution, bone microarchitecture, and insulin resistance in alloHSCT survivors after TBI. This was a cross-sectional observational study of 25 alloHSCT survivors (aged 12 to 25 years) a median of 9.7 (4.3 to 19.3) years after alloHSCT compared to 25 age-, race-, and sex-matched healthy controls. Vertebral MR spectroscopic imaging and tibia micro-MRI were used to quantify marrow adipose tissue (MAT) and trabecular microarchitecture. Additional measures included DXA whole-body fat mass (WB-FM), leg lean mass (Leg-LM), trunk visceral adipose tissue (VAT), and CT calf muscle density. Insulin resistance in alloHSCT survivors was estimated by HOMA-IR. AlloHSCT survivors had lower Leg-LM (p < 0.001) and greater VAT (p < 0.01), MAT (p < 0.001), and fat infiltration of muscle (p = 0.04) independent of WB-FM, versus matched controls; BMI did not differ. Survivors had lower bone volume fraction and abnormal microarchitecture including greater erosion and more rod-like structure versus controls (all p = 0.04); 14 had vertebral deformities and two had compression fractures. Greater WB-FM, VAT, MAT, and muscle fat infiltration were associated with abnormal trabecular microarchitecture (p < 0.04 for all). AlloHSCT HOMA-IR was elevated, associated with younger age at transplantation (p < 0.01), and positively correlated with WB-FM and VAT (both p < 0.01). In conclusion, the markedly increased marrow adiposity, abnormal bone microarchitecture, and abnormal fat distribution highlight the risks of long-term treatment-related morbidity and mortality in alloHSCT recipients after TBI. Trabecular deterioration was associated with marrow and visceral adiposity. Furthermore, long-term survivors demonstrated sarcopenic obesity, insulin resistance, and vertebral deformities. Future studies are needed to identify strategies to prevent and treat metabolic and skeletal complications in this growing population of childhood alloHSCT survivors.

Energy Excess, Glucose Utilization, and Skeletal Remodeling: New Insights

Skeletal complications have recently been recognized as another of the several comorbidities associated with diabetes. Clinical studies suggest that disordered glucose and lipid metabolism have a profound effect on bone. Diabetes-related changes in skeletal homeostasis result in a significant increased risk of fractures, although the pathophysiology may differ from postmenopausal osteoporosis. Efforts to understand the underlying mechanisms of diabetic bone disease have focused on the direct interaction of adipose tissue with skeletal remodeling and the potential influence of glucose utilization and energy uptake on these processes. One aspect that has emerged recently is the major role of the central nervous system in whole-body metabolism, bone turnover, adipose tissue remodeling, and beta cell secretion of insulin. Importantly, the skeleton contributes to the metabolic balance inherent in physiologic states. New animal models have provided the insights necessary to begin to dissect the effects of obesity and insulin resistance on the acquisition and maintenance of bone mass. In this Perspective, we focus on potential mechanisms that underlie the complex interactions between adipose tissue and skeletal turnover by focusing on the clinical evidence and on preclinical studies indicating that glucose intolerance may have a significant impact on the skeleton. In addition, we raise fundamental questions that need to be addressed in future studies to resolve the conundrum associated with glucose intolerance, obesity, and osteoporosis.

Exercise Regulation of Marrow Fat in the Setting of PPARγ Agonist Treatment in Female C57BL/6 Mice

The contribution of marrow adipose tissue (MAT) to skeletal fragility is poorly understood. Peroxisome proliferator-activated receptor (PPAR)γ agonists, associated with increased fractures in diabetic patients, increase MAT. Here, we asked whether exercise could limit the MAT accrual and increase bone formation in the setting of PPARγ agonist treatment. Eight-week-old female C57BL/6 mice were treated with 20-mg/kg · d rosiglitazone (Rosi) and compared with control (CTL) animals. Exercise groups ran 12 km/d when provided access to running wheels (CTL exercise [CTL-E], Rosi-E). After 6 weeks, femoral MAT (volume of lipid binder osmium) and tibial bone morphology were assessed by microcomputer tomography. Rosi was associated with 40% higher femur MAT volume compared with CTL (P < .0001). Exercise suppressed MAT volume by half in CTL-E mice compared with CTL (P < .01) and 19% in Rosi-E compared with Rosi (P < .0001). Rosi treatment increased fat markers perilipin and fatty acid synthase mRNA by 4-fold (P < .01). Exercise was associated with increased uncoupling protein 1 mRNA expression in both CTL-E and Rosi-E groups (P < .05), suggestive of increased brown fat. Rosi increased cortical porosity (P < .0001) but did not significantly impact trabecular or cortical bone quantity. Importantly, exercise induction of trabecular bone volume was not prevented by Rosi (CTL-E 21% > CTL, P < .05; Rosi-E 26% > Rosi, P < .01). In summary, despite the Rosi induction of MAT extending well into the femoral diaphysis, exercise was able to significantly suppress MAT volume and induce bone formation. Our results suggest that the impact of PPARγ agonists on bone and marrow health can be partially mitigated by exercise.

Positive Association Between Adipose Tissue and Bone Stiffness

Obesity is often considered to have a protective effect against osteoporosis. On the other hand, several recent studies suggest that adipose tissue may have detrimental effects on bone quality. We therefore aimed to investigate the associations between body mass index (BMI), waist circumference (WC), visceral adipose tissue (VAT) or abdominal subcutaneous adipose tissue (SAT), and bone stiffness. The study involved 2685 German adults aged 20-79 years, who participated in either the second follow-up of the population-based Study of Health in Pomerania (SHIP-2) or the baseline examination of the SHIP-Trend cohort. VAT and abdominal SAT were quantified by magnetic resonance imaging. Bone stiffness was assessed by quantitative ultrasound (QUS) at the heel (Achilles InSight, GE Healthcare). The individual risk for osteoporotic fractures was determined based on the QUS-derived stiffness index and classified in low, medium, and high risk. Linear regression models, adjusted for sex, age, physical activity, smoking status, risky alcohol consumption, diabetes, and height (in models with VAT or abdominal SAT as exposure), revealed positive associations between BMI, WC, VAT or abdominal SAT, and the QUS variables broadband-ultrasound attenuation or stiffness index. Moreover, BMI was positively associated with speed of sound. Our study shows that all anthropometric measures including BMI and, WC as well as abdominal fat volume are positively associated with bone stiffness in the general population. As potential predictors of bone stiffness, VAT and abdominal SAT are not superior to easily available measures like BMI or WC.

Adipose, bone and muscle tissues as new endocrine organs: role of reciprocal regulation for osteoporosis and obesity development

The belief that obesity is protective against osteoporosis has recently been revised. In fact, the latest epidemiologic and clinical studies show that a high level of fat mass, but also reduced muscle mass, might be a risk factor for osteoporosis and fragility fractures. Furthermore, increasing evidence seems to indicate that different components such as myokines, adipokines and growth factors, released by both fat and muscle tissues, could play a key role in the regulation of skeletal health and in low bone mineral density and, thus, in osteoporosis development. This review considers old and recent data in the literature to further evaluate the relationship between fat, bone and muscle tissue.

Bone density, microstructure and strength in obese and normal weight men and women in younger and older adulthood

Obesity is associated with greater areal BMD (aBMD) and is considered protective against hip and vertebral fracture. Despite this, there is a higher prevalence of lower leg and proximal humerus fracture in obesity. We aimed to determine if there are site-specific differences in BMD, bone structure, or bone strength between obese and normal-weight adults. We studied 100 individually-matched pairs of normal (body mass index [BMI] 18.5 to 24.9 kg/m2) and obese (BMI >30 kg/m2) men and women, aged 25 to 40 years or 55 to 75 years. We assessed aBMD at the whole body (WB), hip (TH), and lumbar spine (LS) with dual-energy X-ray absorptiometry (DXA), LS trabecular volumetric BMD (Tb.vBMD) by quantitative computed tomography (QCT), and vBMD and microarchitecture and strength at the distal radius and tibia with high-resolution peripheral QCT (HR-pQCT) and micro-finite element analysis. Serum type 1 procollagen N-terminal peptide (P1NP) and collagen type 1 C-telopeptide (CTX) were measured by automated electrochemiluminescent immunoassay (ECLIA). Obese adults had greater WB, LS, and TH aBMD than normal adults. The effect of obesity on LS and WB aBMD was greater in older than younger adults (p < 0.01). Obese adults had greater vBMD than normal adults at the tibia (p < 0.001 both ages) and radius (p < 0.001 older group), thicker cortices, higher cortical BMD and tissue mineral density, lower cortical porosity, higher trabecular BMD, and higher trabecular number than normal adults. There was no difference in bone size between obese and normal adults. Obese adults had greater estimated failure load at the radius (p < 0.05) and tibia (p < 0.01). Differences in HR-pQCT measurements between obese and normal adults were seen more consistently in the older than the younger group. Bone turnover markers were lower in obese than in normal adults. Greater BMD in obesity is not an artifact of DXA measurement. Obese adults have higher BMD, thicker and denser cortices, and higher trabecular number than normal adults. Greater differences between obese and normal adults in the older group suggest that obesity may protect against age-related bone loss and may increase peak bone mass.

Osteocalcin, under-carboxylated osteocalcin and osteopontin are not associated with gestational diabetes mellitus but are inversely associated with leptin in non-diabetic women

OBJECTIVE

To measure serum osteocalcin (OC), under-carboxylated osteocalcin (ucOC), osteopontin (OPN), and leptin in pregnant women with gestational diabetes mellitus (GDM) and in healthy pregnant women during pregnancy and after birth and relate these markers to glucose metabolism.

METHODS

This was a prospective study including 60 women with GDM and 60 subjects with normal gestation who were evaluated at gestational week 30 and 6 weeks postpartum. Serum OC, ucOC, OPN, leptin, insulin and insulin resistance were evaluated during the study.

RESULTS

Bone biomarkers and leptin were similar between GDM and normal pregnancy. After delivery, OC, ucOC and OPN increased in both groups, while leptin decreased only in healthy controls. Bone markers did not correlate with insulin and insulin resistance in the two groups, but leptin was positively correlated with insulin and insulin resistance and negatively correlated with bone biomarkers only in healthy women. Furthermore, the women who developed diabetes postpartum had lower levels of OC than women with normal glucose tolerance.

CONCLUSION

GDM is not associated with OC, ucOC, OPN, and leptin and does not correlate with insulin resistance. At postpartum, women who develop diabetes have lower osteocalcin concentrations. Leptin correlates with insulin resistance and bone biomarkers in non-diabetic women.

Validation of marrow fat assessment using noninvasive imaging with histologic examination of human bone samples

PURPOSE

The marrow composition throughout the body is heterogeneous and changes with age. Due to heterogeneity, invasive biopsies of the iliac crest do not truly represent the complete physiological status, impeding the clinical effectiveness of this method. Therefore, we aim to provide verification for an in vivo imaging technique using co-registered histologic examinations for assessment of marrow adiposity.

METHODS

Five recently expired (i.e. <24h) human cadavers were scanned with a dual source CT (DECT) scanner in order to measure marrow fat in the lumbar vertebrae. These donors were also imaged using water-fat MRI (wfMRI) which was used to estimate the fraction of yellow marrow. After imaging, lumbar columns were excised and the superior and inferior aspects of 21 vertebrae were removed. The remaining center section was processed for histological examination to find the ratio of adipocyte volume per tissue volume (AV/TV).

RESULTS

Results of DECT and wfMRI had a high correlation (r = 0.88). AV/TV ranged from 0.18 to 0.75 with a mean (SD) of 0.36 (0.18). Inter-evaluator reliability for AV/TV was r > 0.984. There were similar correlations between AV/TV and the imaging modalities, DECT-derived MF and wfMRI (r = 0.802 and 0.772, respectively).

CONCLUSIONS

A high MF variation was seen among the 25 vertebrae imaged. Both DECT and wfMRI have a good correlation with the histologic adipocyte proportion and can be used to measure MF. This makes longitudinal studies possible without painful, less-effective, invasive biopsies.

Anterior hypopituitarism in adult survivors of childhood cancers treated with cranial radiotherapy: a report from the St Jude Lifetime Cohort study

PURPOSE

To estimate the prevalence of and risk factors for growth hormone deficiency (GHD), luteinizing hormone/follicle-stimulating hormone deficiencies (LH/FSHD), thyroid-stimulatin hormone deficiency (TSHD), and adrenocorticotropic hormone deficiency (ACTHD) after cranial radiotherapy (CRT) in childhood cancer survivors (CCS) and assess the impact of untreated deficiencies.

PATIENTS AND METHODS

Retrospective study in an established cohort of CCS with 748 participants treated with CRT (394 men; mean age, 34.2 years [range, 19.4 to 59.6 years] observed for a mean of 27.3 years [range, 10.8 to 47.7 years]). Multivariable logistic regression was used to study associations between demographic and treatment-related risk factors and pituitary deficiencies, as well as associations between untreated deficiencies and cardiovascular health, bone mineral density (BMD), and physical fitness.

RESULTS

The estimated point prevalence was 46.5% for GHD, 10.8% for LH/FSHD, 7.5% for TSHD, and 4% for ACTHD, and the cumulative incidence increased with follow-up. GHD and LH/FSHD were not treated in 99.7% and 78.5% of affected individuals, respectively. Male sex and obesity were significantly associated with LH/FSHD; white race was significant associated with LH/FSHD and TSHD. Compared with CRT doses less than 22 Gy, doses of 22 to 29.9 Gy were significantly associated with GHD; doses ≥ 22 Gy were associated with LH/FSHD; and doses ≥ 30 Gy were associated with TSHD and ACTHD. Untreated GHD was significantly associated with decreased muscle mass and exercise tolerance; untreated LH/FSHD was associated with hypertension, dyslipidemia, low BMD, and slow walking; and both deficits, independently, were associated with with abdominal obesity, low energy expenditure, and muscle weakness.

CONCLUSION

Anterior pituitary deficits are common after CRT. Continued development over time is noted for GHD and LH/FSHD with possible associations between nontreatment of these conditions and poor health outcomes.

Visceral adiposity is negatively associated with bone density and muscle attenuation

BACKGROUND

The storage of adipose tissue in ectopic compartments is a hallmark attribute linking greater body mass index (BMI) with cardiometabolic diseases. Despite ample evidence to confirm that increased visceral adipose tissue (VAT) deposition occurs with obesity, the interrelations between altered fat partitioning and regional muscle and bone quality are less well understood.

OBJECTIVE

We examined the association between adiposity and spinal muscle and bone quality across a large, heterogeneous cohort of adults.

DESIGN

We identified 8833 thoracic or abdominal computed tomography scans from patients in the University of Michigan Health System who were aged 18-64.9 y. We measured trabecular bone densities, cortical bone densities, VAT areas, and subcutaneous adipose tissue (SAT) areas at vertebral levels T7 to L5. Psoas muscle attenuation (an indicator of fat infiltration in muscle) was measured at the L4 level.

RESULTS

Muscle attenuation as well as trabecular and cortical bone densities revealed negative correlations with BMI, SAT, and VAT. The correlation between BMI and psoas attenuation was -0.321, between BMI and the density of cortical bone was -0.250, and between BMI and trabecular bone was -0.143 (all P < 0.001). However, correlations between VAT and lower muscle attenuation were stronger as were those between VAT and lower bone densities. Inverse correlations between VAT and densities of psoas muscle and cortical and trabecular bone were -0.460, -0.407, and -0.434, respectively (P < 0.001). Even after adjustment for age, sex, and BMI, partial correlations between VAT, muscle attenuation, and bone densities remained significant at -0.250, -0.119, and -0.216, respectively (P < 0.001).

CONCLUSIONS

Contrary to previous reports that high body mass is associated with increased bone quality, our data show a significant negative association between BMI and muscle and bone densities, suggesting fat infiltration into these tissues. More importantly, correlations between VAT and decreased bone and muscle densities remained statistically significant even after adjustment for age, sex, and BMI.

Current Protocols in Mouse Biology

Bone is an essential organ that not only confers structural stability to the organism, but also serves as a reservoir for hematopoietic elements and is thought to affect systemic homeostasis through the release of endocrine factors as well as calcium. The loss of bone mass due to an uncoupling of bone formation and bone resorption leads to increased fragility that can result in devastating fractures. Further understanding of the effects of environmental stimuli on the development of bone disease in humans is needed, and can be studied using animal models. In this chapter, we present established and novel methods for the induction of bone loss in mice, including manipulation of diet and environment, drug administration, irradiation, and hormone deficiency. All of these models are directly related to human cases, and can thus be used to investigate the causes of bone loss resulting from these interventions.

Update on osteoporosis from the 2014 Santa Fe Bone symposium

The 2014 Santa Fe Bone Symposium provided a setting for the presentation and discussion of the clinical relevance of recent advances in the fields of osteoporosis and metabolic bone disease. The format included oral presentations of abstracts by endocrinology fellows, plenary lectures, panel discussions and breakout sessions, with ample opportunities for informal discussions before and after scheduled events. Topics addressed in these proceedings included a review of the important scientific publications in the past year, fracture prevention in patients with dysmobility and immobility, fracture liaison services for secondary fracture prevention, management of pre-menopausal osteoporosis, the role of bone microarchitecture in determining bone strength, measurement of microarchitecture in clinical practice and methods to improve the quality of bone density testing. This is a report of the proceedings of the 2014 Santa Fe Bone Symposium.

Obesity-driven disruption of haematopoiesis and the bone marrow niche

Obesity markedly increases susceptibility to a range of diseases and simultaneously undermines the viability and fate selection of haematopoietic stem cells (HSCs), and thus the kinetics of leukocyte production that is critical to innate and adaptive immunity. Considering that blood cell production and the differentiation of HSCs and their progeny is orchestrated, in part, by complex interacting signals emanating from the bone marrow microenvironment, it is not surprising that conditions that disturb bone marrow structure inevitably disrupt both the numbers and lineage-fates of these key blood cell progenitors. In addition to the increased adipose burden in visceral and subcutaneous compartments, obesity causes a marked increase in the size and number of adipocytes encroaching into the bone marrow space, almost certainly disturbing HSC interactions with neighbouring cells, which include osteoblasts, osteoclasts, mesenchymal cells and endothelial cells. As the global obesity pandemic grows, the short-term and long-term consequences of increased bone marrow adiposity on HSC lineage selection and immune function remain uncertain. This Review discusses the differentiation and function of haematopoietic cell populations, the principal physicochemical components of the bone marrow niche, and how this environment influences HSCs and haematopoiesis in general. The effect of adipocytes and adiposity on HSC and progenitor cell populations is also discussed, with the goal of understanding how obesity might compromise the core haematopoietic system.

Muscle-bone and fat-bone interactions in regulating bone mass: do PTH and PTHrP play any role?

Metabolic bone disease occurs when there is a net loss in bone density. Osteoporosis, the most common metabolic bone disease, is a devastating problem and an increasingly major public health issue. A substantial body of evidence in the elderly population indicates that a relationship exists between the components of body weight and various measures of bone/mass, density, and function. Both muscle and fat contribute to the body's total weight and the intimate associations of muscle, fat, and bone are known. But the close functional interactions between muscle and bone or fat and bone are largely unidentified and have drawn much attention in recent years. Each of these tissues not only responds to afferent signals from traditional hormone systems and the central nervous systems but also secretes factors with important endocrine functions. Studies suggest that during growth, development, and aging, the relationship of muscle and fat with the skeleton possibly governs bone homeostasis and turnover. A better understanding of the endocrine function and the cellular and molecular mechanisms and pathways linking muscle or adipose tissues with bone anabolism and catabolism is a new avenue for novel pathways for anabolic drug discovery. These in turn will likely lead to more rational therapy toward increasingly prevalent disorders like osteoporosis. In this review, some of the recent works on the interaction of bone with muscle and fat are highlighted, and in so doing the role of parathyroid hormone (PTH), and PTH-related peptide (PTHrP) is surveyed.

Bone health and risk factors of cardiovascular disease--a cross-sectional study in healthy young adults

Objective

Both osteoporosis and cardiovascular disease (CVD) are diseases that comprise a growing medical and economic burden in ageing populations. They share many risk factors, including ageing, low phy-sical activity, and possibly overweight. We aimed to study associations between individual risk factors for CVD and bone mineral density (BMD) and turnover markers (BTMs) in apparently healthy cohort.

Design

A cross-sectional assessment of 155 healthy 32-year-old adults (74 males) was performed for skeletal status, CVD risk factors and lifestyle factors.

Methods

We analysed serum osteocalcin, procollagen I aminoterminal propeptide (P1NP), collagen I carboxy-terminal telopeptide (ICTP) and urine collagen I aminoterminal telopeptide (U-NTX), as well as serum insulin, plasma glucose, triglyceride and HDL-cholesterol levels. BMD, fat and lean mass were asses-sed using DXA scanning. Associations were tested with partial correlations in crude and adjusted mo-dels. Bone status was compared between men with or without metabolic syndrome (defined according to the NCEP-ATPIII criteria) with multivariate analysis.

Results

Osteocalcin and P1NP correlated inversely with insulin (R = −0.243, P = 0.003 and R = −0.187, P = 0.021) and glucose (R = −0.213, P = 0.009 and R = −0.190, P = 0.019), but after controlling for fat mass and lifestyle factors, the associations attenuated with insulin (R = −0.162, P = 0.053 and R = −0.093, P = 0.266) and with glucose (R = −0.099, P = 0.240 and R = −0.133, P = 0.110), respectively. Whole body BMD associated in-versely only with triglycerides in fully adjusted model. In men with metabolic syndrome, whole body BMD, osteocalcin and P1NP were lower compared to healthy men, but these findings disappeared in fully adjusted model.

Conclusions

In young adults, inverse associations between BTM/BMD and risk factors of CVD appeared in crude models, but after adjusting for fat mass, no association continued to be present. In addition to fat mass, lifestyle factors, especially physical activity, modified the associations between CVD and bone charac-teristics. Prospective studies are needed to specify the role of mediators and lifestyle factors in the prevention of CVD and osteoporosis.

Pubertal timing, bone acquisition, and risk of fracture throughout life

Pubertal maturation plays a fundamental role in bone acquisition. In retrospective epidemiological surveys in pre- and postmenopausal women, relatively later menarcheal age was associated with low bone mineral mass and increased risk of osteoporotic fracture. This association was usually ascribed to shorter time exposure to estrogen from the onset of pubertal maturation to peak bone mass attainment. Recent prospective studies in healthy children and adolescents do not corroborate the limited estrogen exposure hypothesis. In prepubertal girls who will experience later menarche, a reduced bone mineral density was observed before the onset of pubertal maturation, with no further accumulated deficit until peak bone mass attainment. In young adulthood, later menarche is associated with impaired microstructural bone components and reduced mechanical resistance. This intrinsic bone deficit can explain the fact that later menarche increases fracture risk during childhood and adolescence. In healthy individuals, both pubertal timing and bone development share several similar characteristics including wide physiological variability and strong effect of heritable factors but moderate influence of environmental determinants such as nutrition and physical activity. Several conditions modify pubertal timing and bone acquisition, a certain number of them acting in concert on both traits. Taken together, these facts should prompt the search for common genetic regulators of pubertal timing and bone acquisition. It should also open epigenetic investigation avenues to pinpoint which environmental exposure in fetal and infancy life, such as vitamin D, calcium, and/or protein supplies, influences both pubertal timing and bone acquisition.

Increasing adiposity is associated with higher adipokine levels and lower bone mineral density in obese older adults

CONTEXT

Although obesity is associated with high bone mass, recent reports suggest an increase in the incidence of fractures in obese patients.

OBJECTIVES

The objectives of the study were to evaluate the influence of increasing body fat on bone mineral density (BMD) and to determine the influence of the different adipokines on BMD in frail obese elderly patients.

DESIGN AND SETTING

This is a cross-sectional study of baseline characteristics of elderly obese patients participating in a lifestyle therapy with diet with or without exercise and conducted in a university setting.

PATIENTS

One hundred seventy-three, elderly (≥65 y old), obese (body mass index of ≥30 kg/m(2)) who were mostly frail participated in the study.

OUTCOME MEASURES

BMD, percentage of total body fat, percentage of fat-free mass, percentage of lean mass, body mass index, adiponectin, leptin, IL-6, bone turnover markers (osteocalcin and C-telopeptide), high-sensitivity C-reactive protein, free estradiol, and 25-hydroxyvitamin D were measured.

RESULTS

Higher tertiles of percentage body fat and lower lean mass were associated with a lower BMD. High-sensitivity C-reactive protein levels were highest in the highest fat tertile (third, 5.5 ± 5.4 vs first, 1.5 ± 1.3 mg/L, P < .05) for women, whereas IL-6 levels were highest in the highest tertile in men (third, 3.5 ± 3.1 vs first, 1.7 ± 0.8 pg/mL, P < .05). Leptin increased with increasing fat tertiles in both genders (P < .05), whereas adiponectin increased with increasing fat tertiles only in men (P < .05). A multivariate analysis revealed adiponectin as an important mediator of the effect of fat mass on BMD. Osteocalcin levels were highest in the highest fat tertile in women but not in men. Physical function test scores decreased with increasing fat tertiles in women (P < .05) but not in men.

CONCLUSIONS

Increasing adiposity together with decreasing lean mass is associated with lower BMD, higher adipokine levels, and worsening frailty in elderly obese adults.

Bone marrow fat accumulation accelerated by high fat diet is suppressed by exercise

Marrow adipose tissue (MAT), associated with skeletal fragility and hematologic insufficiency, remains poorly understood and difficult to quantify. We tested the response of MAT to high fat diet (HFD) and exercise using a novel volumetric analysis, and compared it to measures of bone quantity. We hypothesized that HFD would increase MAT and diminish bone quantity, while exercise would slow MAT acquisition and promote bone formation. Eight week-old female C57BL/6 mice were fed a regular (RD) or HFD, and exercise groups were provided voluntary access to running wheels (RD-E, HFD-E). Femoral MAT was assessed by μCT (lipid binder osmium) using a semi-automated approach employing rigid co-alignment, regional bone masks and was normalized for total femoral volume (TV) of the bone compartment. MAT was 2.6-fold higher in HFD relative to RD mice. Exercise suppressed MAT in RD-E mice by more than half compared with RD. Running similarly inhibited MAT acquisition in HFD mice. Exercise significantly increased bone quantity in both diet groups. Thus, HFD caused significant accumulation of MAT; importantly running exercise limited MAT acquisition while promoting bone formation during both diets. That MAT is exquisitely responsive to diet and exercise, and its regulation by exercise appears to be inversely proportional to effects on exercise induced bone formation, is relevant for an aging and sedentary population.

Suppressed bone turnover in obesity: a link to energy metabolism? A case-control study

CONTEXT

Observations in rodents suggest that osteocalcin (OC) participates in glucose metabolism. Based on human studies, it remains unclear whether circulating OC is simply a bone turnover marker (BTM) or also a mediator in interactions between the skeleton and glucose homeostasis.

OBJECTIVE

The objective of the study was to determine the responses of BTMs, including OC, to oral glucose tolerance test (OGTT) in a case-control setting.

DESIGN AND PATIENTS

Thirty-four normoglycemic young adults [mean age 19 y (SD 2.3)] with severe childhood-onset obesity and their gender- and age-matched nonobese controls underwent a standard 2-hour OGTT.

MAIN OUTCOME MEASURES

Glucose, insulin, and six BTMs including total and carboxylated OC (cOC) were determined at baseline and at 30, 60, 90, and 120 minutes during OGTT.

RESULTS

The obese and control subjects were similar in height; the mean body mass indices were 40.4 and 21.9 kg/m(2), respectively. The homeostasis model assessment index was 2.7 times greater in the obese subjects. All BTMs, except bone-specific alkaline phophatase, were lower in the obese subjects compared with the controls: the differences at baseline were 40%, 35%, 17%, 31%, and 32% for N-terminal propeptides of type I collagen, cross-linked telopeptides of type I collagen, tartrate-resistant acid phosphatase, total OC, and carboxylated OC (P < .05 for all) after adjusting for whole-body bone area. All BTMs decreased during OGTT. The relative values for the OGTT responses for total, but not for cOC (measured as area under the curve) differed between the two groups (P = .029 and P = .139, respectively): the decrease in total OC during the OGTT was less pronounced in the obese subjects. Responses in other BTMs were similar between the groups. No associations were observed between glucose metabolism and OCs during OGTT with linear regression.

CONCLUSIONS

Bone turnover markers were substantially lower in obese subjects compared with controls. Total OC and cOC showed less pronounced decrease during the OGTT in obese subjects compared with controls, whereas other BTMs responded similarly in the two groups. The role of OC, if anything, in glucose homeostasis is indirect and may be mediated via other factors than glucose or insulin.

Fat and bone interactions

Fat and bone have a complicated relationship. Although obesity has been associated with low fracture risk, there is increasing evidence that some of the factors that are released by peripheral fat into the circulation may also have a deleterious effect on bone mass, thus, predisposing to fractures. More importantly, the local interaction between fat and bone within the bone marrow seems to play a significant role in the pathogenesis of age-related bone loss and osteoporosis. This "local interaction" occurs inside the bone marrow and is associated with the autocrine and paracrine release of fatty acids and adipokines, which affect the cells in their vicinity including the osteoblasts, reducing their function and survival. In this review, we explore the particularities of the fat and bone cell interactions within the bone marrow, their significance in the pathogenesis of osteoporosis, and the potential therapeutic applications that regulating marrow fat may have in the near future as a novel pharmacologic treatment for osteoporosis.

Abdominal Fat and Sarcopenia in Women Significantly Alter Osteoblasts Homeostasis In Vitro by a WNT/ β -Catenin Dependent Mechanism

Obesity and sarcopenia have been associated with mineral metabolism derangement and low bone mineral density (BMD). We investigated whether imbalance of serum factors in obese or obese sarcopenic patients could affect bone cell activity in vitro. To evaluate and characterize potential cellular and molecular changes of human osteoblasts, cells were exposed to sera of four groups of patients: (1) affected by obesity with normal BMD (O), (2) affected by obesity with low BMD (OO), (3) affected by obesity and sarcopenia (OS), and (4) affected by obesity, sarcopenia, and low BMD (OOS) as compared to subjects with normal body weight and normal BMD (CTL). Patients were previously investigated and characterized for body composition, biochemical and bone turnover markers. Then, sera of different groups of patients were used to incubate human osteoblasts and evaluate potential alterations in cell homeostasis. Exposure to OO, OS, and OOS sera significantly reduced alkaline phosphatase, osteopontin, and BMP4 expression compared to cells exposed to O and CTL, indicating a detrimental effect on osteoblast differentiation. Interestingly, sera of all groups of patients induced intracellular alteration in Wnt/ β -catenin molecular pathway, as demonstrated by the significant alteration of specific target genes expression and by altered β -catenin cellular compartmentalization and GSK3 β phosphorylation. In conclusion our results show for the first time that sera of obese subjects with low bone mineral density and sarcopenia significantly alter osteoblasts homeostasis in vitro, indicating potential detrimental effects of trunk fat on bone formation and skeletal homeostasis.

Effects of growth hormone administration for 6 months on bone turnover and bone marrow fat in obese premenopausal women

PURPOSE

Abdominal adiposity is associated with low BMD and decreased growth hormone (GH) secretion, an important regulator of bone homeostasis. The purpose of our study was to determine the effects of a short course of GH on markers of bone turnover and bone marrow fat in premenopausal women with abdominal adiposity.

MATERIALS AND METHODS

In a 6-month, randomized, double-blind, placebo-controlled trial we studied 79 abdominally obese premenopausal women (21-45 y) who underwent daily sc injections of GH vs. placebo. Main outcome measures were body composition by DXA and CT, bone marrow fat by proton MR spectroscopy, P1NP, CTX, 25(OH)D, hsCRP, undercarboxylated osteocalcin (ucOC), preadipocyte factor 1 (Pref 1), apolipoprotein B (ApoB), and IGF-1.

RESULTS

GH increased IGF-1, P1NP, 25(OH)D, ucOC, bone marrow fat and lean mass, and decreased abdominal fat, hsCRP, and ApoB compared with placebo (p<0.05). There was a trend toward an increase in CTX and Pref-1. Among all participants, a 6-month increase in IGF-1 correlated with 6-month increase in P1NP (p=0.0005), suggesting that subjects with the greatest increases in IGF-1 experienced the greatest increases in bone formation. A six-month decrease in abdominal fat, hsCRP, and ApoB inversely predicted 6-month change in P1NP, and 6-month increase in lean mass and 25(OH)D positively predicted 6-month change in P1NP (p≤0.05), suggesting that subjects with greatest decreases in abdominal fat, inflammation and ApoB, and the greatest increases in lean mass and 25(OH)D experienced the greatest increases in bone formation. A six-month increase in bone marrow fat correlated with 6-month increase in P1NP (trend), suggesting that subjects with the greatest increases in bone formation experienced the greatest increases in bone marrow fat. Forward stepwise regression analysis indicated that increase in lean mass and decrease in abdominal fat were positive predictors of P1NP. When IGF-1 was added to the model, it became the only predictor of P1NP.

CONCLUSION

GH replacement in abdominally obese premenopausal women for 6 months increased bone turnover and bone marrow fat. Reductions in abdominal fat, and inflammation, and increases in IGF-1, lean mass and vitamin D were associated with increased bone formation. The increase in bone marrow fat may reflect changes in energy demand from increased bone turnover.

Bone loss after bariatric surgery: causes, consequences, and management

Bariatric surgery is an effective and increasingly common treatment for severe obesity and its many comorbidities. The side-effects of bariatric surgery can include detrimental effects on bone and mineral metabolism. Bone disease in patients who have had bariatric surgery is affected by preoperative abnormalities in bone and mineral metabolism related to severe obesity. Changes that arise after bariatric surgery are specific to procedure type: the most pronounced abnormalities in calciotropic hormones and bone loss are noted after procedures that result in the most malabsorption. The most consistent site for bone loss after all bariatric procedures is at the hip. There are limitations of dual-energy x-ray absorptiometry technology in this population, including artefact introduced by adipose tissue itself. Bone loss after bariatric surgery is probably multifactorial. Proposed mechanisms include skeletal unloading, abnormalities in calciotropic hormones, and changes in gut hormones. Few data for fracture risk in the bariatric population are available, and this is a crucial area for additional research. Treatment should be geared toward correction of nutritional deficiencies and study of bone mineral density in high-risk patients. We explore the skeletal response to bariatric surgery, potential mechanisms for changes, and strategies for management.

Association between metabolic syndrome and osteoporosis: a meta-analysis

Metabolic syndrome (MetS) consists of several independent clinically recognisable features that have their own independent effects on bone metabolism, and even a single disease could have apparently contradictory effects on bone metabolism. This meta-analysis aimed to detect a relationship between MetS and osteoporosis. The PubMed, Embase, and Cochrane library databases were searched for relevant studies published before April 1, 2013. On June 22, 2013, the databases were searched again for additional studies. Studies clearly reporting a comparison of bone mineral density (BMD) in subjects with or without MetS were selected for our analysis. From these results, we analysed the crude BMD and the BMD adjusted for all covariates (age, weight, height, alcohol intake, cigarette smoking and exercise). Weighted mean differences were calculated using a random-effects model. Nine studies were included in this meta-analysis. No significant differences were found when analysing the crude lumbar spine BMD and the femoral neck BMD. However, the MetS (-) group showed a significantly higher BMD when all covariates were adjusted for femoral neck BMD (0.02, p=0.0002) and lumbar spine BMD (0.01, p=0.007). Subgroup analysis suggested a negative effect of MetS on BMD in men but not in women. These findings suggest that MetS is a risk factor for developing osteoporosis in men.

Obesity and occupational injury: a prospective cohort study of 69,515 public sector employees

Background

Obesity and overweight are suggested to increase the risk of occupational injury but longitudinal evidence to confirm this is rare. We sought to evaluate obesity and overweight as risk factors for occupational injuries.

Methodology/Principal Findings

A total of 69,515 public sector employees (80% women) responded to a survey in 2000–2002, 2004 or 2008. Body mass index (kg/m²) was derived from self-reported height and weight and was linked to records of subsequent occupational injuries obtained from national registers. Different injury types, locations and events or exposures (the manner in which the injury was produced or inflicted) were analyzed by body mass index category adjusting for baseline socio-demographic characteristics, work characteristics, health-risk behaviors, physical and mental health, insomnia symptoms, and sleep duration. During the mean follow-up of 7.8 years (SD = 3.2), 18% of the employees (N = 12,204) recorded at least one occupational injury. Obesity was associated with a higher overall risk of occupational injury; multivariable adjusted hazard ratio (HR) 1.21 (95% CI 1.14–1.27). A relationship was observed for bone fractures (HR = 1.37; 95% CI: 1.10–1.70), dislocations, sprains and strains (HR = 1.36; 95% CI: 1.25–1.49), concussions and internal injuries (HR = 1.26; 95% CI: 1.11–1.44), injuries to lower extremities (HR = 1.62; 95%: 1.46–1.79) and injuries to whole body or multiple sites (HR = 1.37; 95%: 1.10–1.70). Furthermore, obesity was associated with a higher risk of injuries caused by slipping, tripping, stumbling and falling (HR = 1.55; 95% CI: 1.40–1.73), sudden body movement with or without physical stress (HR = 1.24; 95% CI: 1.10–1.41) and shock, fright, violence, aggression, threat or unexpected presence (HR = 1.33; 95% CI: 1.03–1.72). The magnitude of the associations between overweight and injuries was smaller, but the associations were generally in the same direction as those of obesity.

Conclusions/Significance

Obese employees record more occupational injuries than those with recommended healthy weight.