In vivo precision of the GE Lunar iDXA densitometer for the measurement of total-body, lumbar spine, and femoral bone mineral density in adults

Bone mineral density in adults with arthrogryposis multiplex congenita: a retrospective cohort analysis

The primary objective of this study was to evaluate the prevalence of low femoral and lumbar spine bone mineral density (BMD) in adults with arthrogryposis multiplex congenita (AMC). We performed a retrospective cohort analysis of adults with AMC who were enrolled in the French Reference Center for AMC and in the Pediatric and Adult Registry for Arthrogryposis (PARART, NCT05673265). Patients who had undergone dual-energy X-ray absorptiometry (DXA) and/or vitamin D testing were included in the analysis. Fifty-one patients (mean age, 32.9 ± 12.6 years) were included; 46 had undergone DXA. Thirty-two (32/51, 62.7%) patients had Amyoplasia, and 19 (19/51, 37.3%) had other types of AMC (18 distal arthrogryposis, 1 Larsen). Six patients (6/42, 14.3%) had a lumbar BMD Z score less than - 2. The mean lumbar spine Z score (- 0.03 ± 1.6) was not significantly lower than the expected BMD Z score in the general population. Nine (9/40, 22.5%) and 10 (10/40, 25.0%) patients had femoral neck and total hip BMD Z scores less than - 2, respectively. The mean femoral neck (- 1.1 ± 1.1) and total hip (- 1.2 ± 1.2) BMD Z scores in patients with AMC were significantly lower than expected in the general population (p < 0.001). Femoral neck BMD correlated with height (rs = 0.39, p = 0.01), age (rs = - 0.315, p = 0.48); total hip BMD correlated with height (rs = 0.331, p = 0.04) and calcium levels (rs = 0.41, p = 0.04). Twenty-five patients (25/51, 49.0%) reported 39 fractures. Thirty-one (31/36, 86.1%) patients had 25-hydroxyvitamin D levels less than 75 nmol/l, and 6 (6/36, 16.7%) had 25-hydroxyvitamin D levels less than 75 nmol/l. Adults with AMC had lower hip BMD than expected for their age, and they more frequently showed vitamin D insufficiency. Screening for low BMD by DXA and adding vitamin D supplementation when vitamin D status is insufficient should be considered in adults with AMC, especially if there is a history of falls or fractures.

Reporting Fewer Than Four Vertebrae: 2023 Official Positions of the International Society for Clinical Densitometry

The precision for spine bone mineral density (BMD) worsens as vertebrae are excluded, so recommendations are needed for least significant change (LSC) for spine BMDs based on fewer than 4 vertebrae. The task force recommends re-analysis of each facility's L1-L4 in-house precision study to determine the precision in order to calculate the LSC for each combination of 2 or 3 reported vertebrae. The task force recommended not reporting spine BMDs based on single vertebral bodies for either the diagnosis or monitoring of osteoporosis. Specific data for studies assessing the precision of two non-contiguous vertebrae are mixed, but ultimately the task force recommended that spine BMD based on 2 non-contiguous vertebrae can be used for the diagnosis and monitoring of osteoporosis.

Comparison of the Lunar Prodigy and Stratos DR Dual-Energy X-Ray Absorptiometers to Assess Regional Bone Mineral Density

PURPOSE

The first objective of the study was to assess the agreement between the Stratos DR (DMS) and the GE Prodigy (GE) DXAs in determining femoral neck, total hip and lumbar spine aBMD. The second objective was to assess the potential impact of leg positioning (hip flexed at 90° or not) on lumbar spine aBMD.

METHODS

Forty-six individuals (n=42 women, 91.3%), with a mean age of 59.7 ± 13 years and mean BMI of 23.8 ± 4.7 kg/m², were scanned consecutively on the same day using the two devices. In a subgroup (n=30), two consecutive Stratos DR scans (with hip flexed at 90° or not) at the lumbar spine were conducted. Predictive equations for hip and lumbar spine aBMD were derived from linear regression of the data.

RESULTS

Correlation coefficients for aBMD measured with the two DXAs were characterised by an R² of 0.76 for the femoral neck, 0.89 for the total hip, and 0.86 for the lumbar spine. However, the derived equations for aBMD determination showed an intercept significantly different from 0 for hip aBMD, and a slope significantly different from 1 for lumbar spine aBMD. These results highlight a bias between the two measurements, thus requiring the determination of specific cross-calibration equations for hip and lumbar spine, femoral neck excepted. When compared with values on the Prodigy, mean aBMD on the Stratos DR was higher at the femoral neck (+4.8%, p&lt;0.001) and total hip (+9.6%, p&lt;0.001) and lower at L2-L4 (-8.8%, p&lt;0.001). The coefficient of variation (CV%) for the two consecutive measures at lumbar spine (with different positioning) with the Stratos DR was 2.9%.

CONCLUSIONS

The difference in aBMD measured with the two DXAs illustrates the need to define cross-calibration equations when comparing data across systems in order to avoid erroneous conclusions.

Clinical bone health among adults with cerebral palsy: moving beyond assessing bone mineral density alone

AIM

To understand associations among bone mineral density (BMD), bone mineral content (BMC), and bone area, and their association with fractures in adults with cerebral palsy (CP).

METHOD

This retrospective cohort study included 78 adults with CP with a hip dual energy X-ray absorptiometry (DXA) from 1st December 2012 to 3rd May 2021 performed at the University of Michigan. Data-driven logistic regression techniques identified which, if any, DXA-derived bone traits (e.g. age/sex/ethnicity-based z-scores) were associated with fracture risk by sex and severity of CP. BMC-area associations were examined to study the structural mechanisms of fragility.

RESULTS

Femoral neck area was associated with lower age-adjusted odds ratios (ORs) of fracture history (OR 0.72; 95% confidence interval [CI] 0.49-1.06; p=0.098), while higher BMD was associated with higher odds of incident fracture (OR 3.08; 95% CI 1.14-8.33; p=0.027). Females with fracture had lower area than females without fracture but similar BMC, whereas males with fracture had larger area and higher BMC than males without fracture. The paradoxical BMD-fracture association may be due to artificially elevated BMD from BMC-area associations that differed between females and males (sex interaction, p˂0.05): males had higher BMC at lower area values and lower BMC at higher area values compared to females.

INTERPRETATION

BMD alone may not be adequate to evaluate bone strength for adults with CP. Further research into associations (or integration) between BMC and area is needed.

Modestly degraded microarchitecture and high serum levels of osteopontin in Swedish females with anorexia nervosa

PURPOSE

Adult women with long-time anorexia nervosa (AN) are believed to have osteopenia (T-score ≤ 1.0) in 93 % and osteoporosis (T-score ≤ 2.5) in 38 %. Bone microarchitecture assessed by Trabecular Bone Score (TBS) predicts osteoporotic fractures. Our aim was to evaluate the microarchitecture in adult females with AN by determining TBS and to identify factors potentially associated with TBS, such as bone turnover markers.

METHODS

20 female patients with AN (DSM IV), aged 27.8 ± 4.4 years, BMI 16.6 ± 0.6 kg/m² and duration of illness of 8.5 ± 5 years had previously been evaluated with dual-energy X-ray absorptiometry (DXA). TBS measurements were now obtained, using iNsight software, from spinal DXA images. Serum levels of bone turnover markers were determined in patients and healthy normal-weight controls.

RESULTS

Compared to controls serum values of osteopontin were higher (p = 0.009). BMD in patients with AN was reduced by at least 1.0 SD at one or more skeletal sites in 65 % of patients and by at least 2.5 SD in 20 %. Only one of the patients (5%) had suffered a fracture. TBS (mean 1.35 ± 0.06; median 1.36 (1.23-1.44) was in the lower normal range (≥ 1.35). 40 % of patients showed partially (> 1.20 and < 1.35) but none showed a fully degraded micro-architecture.

CONCLUSIONS

In Swedish AN patients we found a low reduction of BMD and fracture history. The bone microarchitecture, evaluated for the first time for this group by TBS, was only modestly compromised, and to a lesser extent than expected for this group of patients with AN.

LEVEL OF EVIDENCE

Level V; cross-sectional descriptive study.

The Non-invasive Diagnosis of Bone Disorders in CKD

Abnormal bone metabolism is an integral part of the chronic kidney disease-mineral bone disorder (CKD-MBD). For several reasons, the difficult bone compartment was neglected for some time, but there has been renewed interest as a result of the conception of bone as a new endocrine organ, the increasing recognition of the cross-talk between bone and vessels, and, especially, the very high risk of osteoporotic fractures (and associated mortality) demonstrated in patients with CKD. Therefore, it has been acknowledged in different guidelines that action is needed in respect of fracture risk assessment and the diagnosis and treatment of osteoporosis in the context of CKD and CKD-MBD, even beyond renal osteodystrophy. These updated guidelines clearly underline the need to improve a non-invasive approach to these bone disorders in order to guide treatment decisions aimed at not only controlling CKD-MBD but also decreasing the risk of fracture. In this report, we review the current role of the most often clinically used or promising biochemical circulating biomarkers such as parathyroid hormone, alkaline phosphatases, and other biochemical markers of bone activity as alternatives to some aspects of bone histomorphometry. We also mention the potential role of classic and new imaging techniques for CKD patients. Information on many aspects is still scarce and heterogeneous, but many of us consider that it is indeed time for action, recognizing our definitely limited ability to base certain treatment decisions only on our current non-comprehensive knowledge.

Vertebral Anomalies in Retired Rugby Players and the Impact on Bone Density Calculation of the Lumbar Spine

Dual energy X-ray absorptiometry (DXA) lumbar spine bone mineral density (BMD) measurements are subject to artificial elevation in the presence of structural abnormalities that are more common with age and injury, including osteoarthritis, fracture and osteophytes. The aims of this study were to investigate the presence of vertebral abnormalities on DXA scans in retired rugby players and a nonrugby control group, and to explore the effect of vertebral exclusion on the BMD diagnostic outcome. Eigty-seven male retired rugby players and 51 non-rugby controls from the UK Rugby Health Project participated in the study. Lumbar spine, total hip and femoral neck BMD were measured by DXA and scans were analyzed pre and post exclusion of anomalous vertebrae. Data were analyzed by age group to enable application of T-scores (≥50 y) and Z-scores (<50 y). From 138 lumbar spine scans, 66 required adjustment. One hundred twenty-two vertebral exclusions were made, and 12 lumbar spine scans (10 in retired rugby athletes) were un-reportable (<2 evaluable vertebrae). Vertebral exclusion significantly lowered lumbar spine BMD across all groups (p<0.01) and lowered the overall lowest T/Z-score. This effect was more pronounced in rugby groups (age <50 y, p < 0.001; age ≥50 y, p = 0.031) than in the control groups (age <50y, p = 0.125; age ≥50 y, p = 0.250). Vertebral abnormalities detected on lumbar spine scans, were highly prevalent and impacted final the T/Z-score in this cohort of retired rugby players. Current guidelines recommend exclusion of abnormalities from lumbar spine scans in adults aged ≥50 years. Our findings suggest that vertebral exclusions should also be applied to lumbar spine scans performed in those aged <50 years, particularly in former contact sports athletes, given their high risk for vertebral deformity.

Does Bone Mineral Density Differ between Fan-Beam and Pencil-Beam?: A Meta-Analysis and Systemic Review

Background

Dual energy X-ray absorptiometry (DXA) has evolved from pencil-beam (PB) to narrow fan-beam (FB) densitometers. We performed a meta-analysis of the available observational studies to determine how different modes of DXA affect bone mineral density (BMD) measurements.

Methods

A total of 1,233 patients (808 women) from 14 cohort studies were included. We evaluated the differences in BMD according to the DXA mode: PB and FB. Additionally, we evaluated the differences in BMD between the 2 types of FB mode: FB (Prodigy) and the most recent FB (iDXA). Pairwise meta-analysis was performed, and weighted mean differences (WMD) were calculated for (total lumbar, total hip, and total body).

Results

No significant difference was observed in total lumbar (pooled WMD, −0.013; P=0.152) and total hip BMD (pooled WMD, −0.01; P=0.889), between PB and FB. However, total body BMD was significantly lower in the PB compared to the FB group (pooled WMD, −0.014; P=0.024). No significant difference was observed in lumbar BMD (pooled WMD, −0.006; P=0.567), total hip (pooled WMD, −0.002; P=0.821), and total body (pooled WMD, 0.015; P=0.109), between Prodigy and iDXA.

Conclusions

The results of this study warrant the recommendation that correction equations should not be used when comparing BMD from different modes. Further research is still needed to highlight the ways in which differences between DXA systems can be minimized.

Adiposity Without Obesity: Associations with Osteoporosis, Sarcopenia, and Falls in the Healthy Ageing Initiative Cohort Study

OBJECTIVE

Obesity is commonly defined by BMI rather than adiposity, which may have differential effects on musculoskeletal health. Musculoskeletal outcomes were compared in older adults with normal adiposity and normal BMI (NA-NBMI), those with high adiposity but normal BMI (HA-NBMI), and those with high adiposity and high BMI (HA-HBMI).

METHODS

In 3,411 70-year-olds, obesity was defined as BMI ≥ 30 kg/m² and adiposity as body fat percentage ≥ 25% (men) or ≥ 35% (women) from dual-energy x-ray absorptiometry. Bone parameters were measured by dual-energy x-ray absorptiometry and peripheral quantitative computed tomography. Sarcopenia was defined as low handgrip strength with or without low appendicular lean mass. Falls were self-reported 6 and 12 months later.

RESULTS

Prevalence of NA-NBMI, HA-NBMI, and HA-HBMI was 14.2%, 68.1%, and 17.7%, respectively. Compared with HA-HBMI, HA-NBMI had increased likelihood for sarcopenia (adjusted odds ratio: 3.99; 95% CI: 1.41-11.32) and osteoporosis (2.91; 95% CI: 2.35-3.61) but similar likelihood of falls (P > 0.05). HA-NBMI had lower values for bone geometry parameters, as well as grip strength, than both NA-NBMI and HA-HBMI (all P < 0.05).

CONCLUSIONS

High adiposity without high BMI is more common than BMI-defined obesity in older Swedish adults but does not provide similar protection from osteoporosis and sarcopenia.

Bone Mineral Density Precision for Individual and Combined Vertebrae Configurations From Lumbar Spine Dual-Energy X-Ray Absorptiometry Scans

The accurate interpretation of repeat DXA scan measurements and the understanding of what constitutes a true and meaningful change require knowledge of measurement error (precision) and least significant change. The interpretation of lumbar spine bone mineral density in particular can be confounded by artefacts and as such, the International Society for Clinical Densitometry (ISCD) recommends exclusion of individual vertebrae if they are affected by local structural change or an artefact. The aim of this study was to determine the precision of bone mineral density measures of individual and various configurations of vertebrae from PA lumbar spine scans. The study group comprised of 30 women (age 36.3 ± 6.5 years; height: 165.2 ± 5.7 cm; weight: 67.7 ± 12.6 kg) who each received 2 consecutive anterior-posterior lumbar spine scans (Lunar iDXA, GE Healthcare, Madison, WI), with repositioning. Precision errors varied by individual vertebrae and by different configurations of vertebrae but all were within the ISCD acceptable range of precision. For vertebrae configurations containing at least 2 vertebrae, precision error ranged from 0.005 to 0.008 RMS-SD (0.44%-0.70% CV). Of the individual vertebrae, the lowest precision error was observed at L4, and from the different configurations, for L2L3L4 and L1L2L3L4. In conclusion, this study group demonstrated excellent precision for BMD measurements of individual and various configurations of L1-L4 vertebrae using the GE Lunar iDXA densitometer.

Objectively-measured sedentary time, habitual physical activity and bone strength in adults aged 62 years: the Newcastle Thousand Families Study

BACKGROUND

The influence of sedentary time and habitual physical activity on the bone health of middle aged adults is not well known.

METHODS

Bone mineral density (BMD) and hip bone geometry were evaluated in 214 men (n = 92) and women (n = 112) aged 62.1 ± 0.5 years from the Newcastle Thousand Families Study birth cohort. Accelerometry was used to measure physical activity (PA) and sedentary time over 4 days. Regression models were adjusted for clinical risk factor covariates.

RESULTS

Men were more sedentary than women (P < 0.05), and sedentary time was negatively associated with spine BMD in men, with 84 minutes more sedentary time corresponding to 0.268 g.cm-2 lower BMD (β = -0.268; P = 0.017). In men, light PA and steps/day were positively associated with bone geometry and BMD. Steps/day was positively associated with bone geometry and femur BMD in women, with a positive difference of 1415 steps/day corresponding to 0.232 g.cm-2 greater BMD (β = 0.232, P = 0.015).

CONCLUSIONS

Sedentary time was unfavourably associated with bone strength in men born in North East England at age 62 years. Higher volumes of light PA, and meeting the public health daily step recommendations (10 000 steps/day) was positively associated with bone health in both sexes.

Gut microbiota alterations associated with reduced bone mineral density in older adults

Objective

To investigate compositional differences in the gut microbiota associated with bone homeostasis and fractures in a cohort of older adults.

Methods

Faecal microbiota profiles were determined from 181 individuals with osteopenia (n = 61) or osteoporosis (n = 60), and an age- and gender-matched group with normal BMD (n = 60). Analysis of the 16S (V3-V4 region) amplicon dataset classified to the genus level was used to identify significantly differentially abundant taxa. Adjustments were made for potential confounding variables identified from the literature using several statistical models.

Results

We identified six genera that were significantly altered in abundance in the osteoporosis or osteopenic groups compared with age- and gender-matched controls. A detailed study of microbiota associations with meta-data variables that included BMI, health status, diet and medication revealed that these meta-data explained 15–17% of the variance within the microbiota dataset. BMD measurements were significantly associated with alterations in the microbiota. After controlling for known biological confounders, five of the six taxa remained significant. Overall microbiota alpha diversity did not correlate to BMD in this study.

Conclusion

Reduced BMD in osteopenia and osteoporosis is associated with an altered microbiota. These alterations may be useful as biomarkers or therapeutic targets in individuals at high risk of reductions in BMD. These observations will lead to a better understanding of the relationship between the microbiota and bone homeostasis.

Digital radiography as an alternative method in the evaluation of bone density in uremic rats

INTRODUCTION

Digital radiography (DRx) may provide a suitable alternative to investigate mineral and bone disorder (MBD) and loss of bone density (BD) in rodent models of chronic kidney disease (CKD). The objective of this study was to use DRx to evaluate BD in CKD rats, and to evaluate the correlation between DRx findings and serum MBD markers and bone histomorphometry.

METHODS

Uremia was induced by feeding Wistar rats an adenine-enriched diet (0.75% for 4 weeks/0.10% for 3 weeks); outcomes were compared to a control group at experimental weeks 3, 4, and 7. The following biochemical markers were measured: creatinine clearance (CrC), phosphate (P), calcium (Ca), fractional excretion of P (FeP), alkaline phosphatase (ALP), fibroblast growth factor-23 (FGF-23), and parathyroid hormone (PTH). DRx imaging was performed and histomorphometry analysis was conducted using the left femur.

RESULTS

As expected, at week 7, uremic rats presented with reduced CrC and higher levels of P, FeP, and ALP compared to controls. DRx confirmed the lower BD in uremic animals (0.57±0.07 vs. 0.68 ± 0.06 a.u.; p = 0.016) compared to controls at the end of week 7, when MBD was more prominent. A severe form of high-turnover bone disease accompanied these biochemical changes. BD measured on DRx correlated to P (r=-0.81; p = 0.002), ALP (r = -0.69, p = 0.01), PTH (r = -0.83, p = 0.01), OS/BS (r = -0.70; p = 0.02), and ObS/BS (r = -0.70; p = 0.02).

CONCLUSION

BD quantified by DRx was associated with the typical complications of MBD in CKD and showed to be viable in the evaluation of bone alterations in CKD.

Assessment of Renal Osteodystrophy via Computational Analysis of Label-free Raman Detection of Multiple Biomarkers

Accurate clinical evaluation of renal osteodystrophy (ROD) is currently accomplished using invasive in vivo transiliac bone biopsy, followed by in vitro histomorphometry. In this study, we demonstrate that an alternative method for ROD assessment is through a fast, label-free Raman recording of multiple biomarkers combined with computational analysis for predicting the minimally required number of spectra for sample classification at defined accuracies. Four clinically relevant biomarkers: the mineral-to-matrix ratio, the carbonate-to-matrix ratio, phenylalanine, and calcium contents were experimentally determined and simultaneously considered as input to a linear discriminant analysis (LDA). Additionally, sample evaluation was performed with a linear support vector machine (LSVM) algorithm, with a 300 variable input. The computed probabilities based on a single spectrum were only marginally different (~80% from LDA and ~87% from LSVM), both providing an unacceptable classification power for a correct sample assignment. However, the Type I and Type II assignment errors confirm that a relatively small number of independent spectra (7 spectra for Type I and 5 spectra for Type II) is necessary for a p < 0.05 error probability. This low number of spectra supports the practicality of future in vivo Raman translation for a fast and accurate ROD detection in clinical settings.

Severe Phenotype of APECED (APS1) Increases Risk for Structural Bone Alterations

Objective: Immunological abnormalities, the resulting endocrinopathies and their treatments may impact bone health in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED, APS1). The aim of the present study was to describe skeletal characteristics in patients with APECED and the prevalence and risk factors of compromised bone health. Patients and methods: We performed a cross-sectional study on 44 patients (27 females) with APECED and 82 age-, gender- and ethnicity-matched control subjects (54 females). We determined the prevalence of osteoporosis by dual-energy X-ray absorptiometry and skeletal characteristics by peripheral quantitative computed tomography at radius and tibia. Results: Patients were examined at the median age of 37.8 years (range, 7.0-70.1). Dual-energy X-ray absorptiometry indicated osteoporosis in four adult patients (9%); radiographs showed vertebral fractures in three patients. The prevalence of multiple non-spinal fractures was higher in patients than in controls. On peripheral quantitative computed tomography, bone characteristics at distal and proximal radius did not differ between the groups. At distal tibia, patients had lower total (p = 0.009) and trabecular (p = 0.033) volumetric bone mineral density. At the proximal tibia, patients had lower cortical thickness (p < 0.001) than controls. Severity of APECED phenotype influenced both radial and tibial characteristics: cortical thickness and total and trabecular volumetric bone mineral density were lower in patients with ≥7 disease manifestations as compared with more mildly affected patients, whose values were similar to controls. Conclusions: APECED associated with bone structural alterations, especially in patients with a high number of disease manifestations. This may increase the risk of fractures with aging, but symptomatic osteoporosis was rare.

Bone Stress Injuries Are Associated With Differences in Bone Microarchitecture in Male Professional Soldiers

Bone stress injuries are commonly due to repetitive loading, as often described in competitive athletes or military recruits. The underlying pathophysiology of bone stress injuries is multifactorial. The present cross-sectional study investigated (i) cortical and trabecular bone microstructure as well as volumetric bone mineral density in subjects with bone stress injuries at the tibial diaphysis, measured at the distal tibia and the distal radius by means of high-resolution peripheral quantitative computed tomography (CT), (ii) areal bone mineral density using dual-energy X-ray absorptiometry as well as calcaneal dual X-ray absorptiometry and laser, and (iii) the influence on bone turnover markers of formation and resorption at the early phase after injury. A total of 26 Caucasian male professional soldiers with post-training bone stress injury at the tibial diaphysis were included (case group). A total of 50 male, Caucasian professional soldiers from the same military institution served as controls (control group). High-resolution peripheral quantitative CT revealed a higher total area at the radius within the case group. Cortical bone mineral density was reduced at the radius and tibia within the case group. The trabecular number and trabecular thickness were reduced at the tibia in the case group. The trabecular network was more inhomogeneous at the radius and tibia within the case group. Calcaneal dual X-ray absorptiometry and laser was significantly reduced in the case group. This study quantified differences in bone microstructure among otherwise healthy individuals. Differences in bone microarchitecture may impair the biomechanical properties by increasing the susceptibility to sustain bone stress injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2516-2523, 2019.

Bone metabolism, bone mineral density and low-energy fractures 10 years after Roux-en-Y gastric bypass

BACKGROUND

Roux-en-Y gastric bypass (RYGB) is a common surgical procedure for treatment of morbid obesity. RYGB induces considerable and sustained weight loss, and remission of obesity related-comorbidities. While studies have suggested negative effects of RYGB on bone health, long-term data are lacking. We aimed to evaluate the prevalence of aBMD below the expected range for age, osteopenia, osteoporosis and low-energy fractures in a defined patient cohort 10 years after RYGB. Secondly, we wanted to identify factors associated with increased risk of aBMD z-score or t-score of -1.1 or lower 10 years after RYGB.

METHODS

Patients undergoing RYGB surgery from June 2004 to December 2006 at the Department of Morbid Obesity and Bariatric Surgery, Oslo University Hospital, a tertiary referral centre for treatment of morbid obesity, were invited to a 10 year follow-up. Follow-up visits included morning fasting blood samples, clinical examination, anthropometric measures and dual energy X-ray absorptiometry (DXA).

RESULTS

Out of 194 patients eligible for the study, 124 attended the 10 year follow-up and 122 (63%) were examined with DXA. Mean (SD) age was 50.3 (9.0) years, 118 (97%) were of Caucasian ethnicity, 94 were females (77%), of whom 41 (44%) were postmenopausal. Secondary hyperparathyroidism (SHPT) was noted in 37 participants (31%) and vitamin D deficiency (value below 50 nmol/L) and insufficiency (value below 75 nmol/L) in 40 (33%) and 91 (75%), respectively. Among the 63 participants who were premenopausal females or males 49 years or younger the prevalence of areal bone mineral density (aBMD) in the lower range of normal (z-score -1.1- to -1.9) was 30% (n = 19) and aBMD below the expected range for age (z-score ≤ -2.0) was noted in 8% (n = 5). Among the 59 participants who were postmenopausal females or males 50 years or older, the prevalence of osteopenia (t-score -1.1 to -2.4) was 51% (n = 30) and osteoporosis (t-score ≤ -2.5) was 27% (n = 16). The bone resorption markers CTX-1 and PINP were higher in participants with aBMD z-score or t-score of -1.1 or lower compared to participants with aBMD z-score or t-score of -1.0 or higher. Preoperative hypothyroidism, or higher age, postmenopausal status, BMI < 35 kg/m², SHPT or higher PINP levels at 10 year follow-up were independently associated with aBMD z-score or t-score of -1.1 or lower 10 years after RYGB. Eighteen participants (15%) reported a clinical low-energy fracture after RYGB. In addition, vertebral fracture assessment by DXA revealed that 10 participants (8%) had experienced at least one moderate to severe morphometric vertebral fracture.

CONCLUSION

Ten years after RYGB 27% of postmenopausal females and males 50 years or older were osteoporotic, and 8% of premenopausal females and males 49 years or younger exhibited aBMD below the expected range for age. The prevalence of fragility fractures was high. SHPT, higher age, postmenopausal status or higher PINP levels at 10 years and preoperative hypothyroidism were all independent risk factors for aBMD z-score or t-score of -1.1 or lower 10 years after RYGB.

Associations of Sarcopenia and Its Components with Bone Structure and Incident Falls in Swedish Older Adults

The aim of this study was to compare bone structure parameters and likelihood of falls across European Working Group on Sarcopenia in Older People (EWGSOP2) sarcopenia categories. 3334 Swedish 70-year olds had appendicular lean mass (normalized to height; ALMHt), lumbar spine and total hip areal BMD (aBMD) estimated by dual-energy X-ray absorptiometry. Volumetric BMD (vBMD) and structure at the distal and proximal tibia and radius were estimated by peripheral quantitative computed tomography. Hand grip strength and timed up-and-go were assessed, and sarcopenia was defined according to EWGSOP2 criteria. Incident falls were self-reported 6 and 12 months after baseline. Only 0.8% and 1.0% of participants had probable and confirmed sarcopenia, respectively. Almost one-third of participants with confirmed sarcopenia reported incident falls, compared with 20% for probable sarcopenia and 14% without sarcopenia (P = 0.025). Participants with confirmed sarcopenia had poorer bone parameters (all P < 0.05) except endosteal circumference at the proximal radius and tibia, while those with probable sarcopenia had lower cortical area at the proximal radius (B = - 5.9; 95% CI - 11.7, - 0.1 mm²) and periosteal and endosteal circumferences at the proximal tibia (- 3.3; - 6.4, - 0.3 and - 3.8; - 7.5, - 0.1 mm², respectively), compared with those without sarcopenia. Compared with probable sarcopenia, confirmed sarcopenic participants had significantly lower lumbar spine and total hip aBMD, distal radius and tibia total vBMD, and proximal radius and tibia cortical vBMD, area and thickness (all P < 0.05). Swedish 70-year olds with confirmed sarcopenia demonstrate poorer BMD and bone architecture than those with probable and no sarcopenia, and have increased likelihood of incident falls.

Bone microarchitecture and bone turnover in hepatic cirrhosis

Liver cirrhosis leads to bone loss. To date, information on bone quality (three-dimensional microarchitecture) and, thus, bone strength is scarce. We observed decreased bone quality at both assessed sites, independent of disease severity. Therefore, all patients should undergo early-stage screening for osteoporosis.

INTRODUCTION

Recent studies found low bone mineral density in cirrhosis, but data on bone microstructure are scarce. This study assessed weight-bearing and non-weight-bearing bones in patients with cirrhosis and healthy controls. The primary objective was to evaluate trabecular and cortical microarchitecture.

METHODS

This was a single-center study in patients with recently diagnosed hepatic cirrhosis. Thirty-two patients and 32 controls participated in this study. After determining the type of cirrhosis, the parameters of bone microarchitecture were assessed by high-resolution peripheral quantitative computed tomography.

RESULTS

Both cortical and trabecular microarchitectures showed significant alterations. At the radius, trabecular bone volume fraction was 17% lower (corrected p = 0.028), and, at the tibia, differences were slightly more pronounced. Trabecular bone volume fraction was 19% lower (p = 0.024), cortical bone mineral density 7% (p = 0.007), and cortical thickness 28% (p = 0.001), while cortical porosity was 32% higher (p = 0.023), compared to controls. Areal bone mineral density was lower (lumbar spine - 13%, total hip - 11%, total body - 9%, radius - 17%, and calcaneus - 26%). There was no correlation between disease severity and microarchitecture. Areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) correlated well with parameters of cortical and trabecular microarchitecture.

CONCLUSIONS

Hepatic cirrhosis deteriorates both trabecular and cortical microarchitecture, regardless of disease severity. Areal bone mineral density is diminished at all sites as a sign of generalized affection. In patients with hepatic cirrhosis, regardless of its origin or disease severity, aBMD measurements are an appropriate tool for osteologic screening.

Obesity, bone density relative to body weight and prevalent vertebral fracture at age 62 years: the Newcastle thousand families study

Obesity increases the likelihood of prevalent vertebral fracture (VF) in men and women at age 62 years. The higher absolute bone mineral density (BMD) observed in obese individuals is disproportionate to body weight, and this may partly explain the greater prevalence of VF in this group.

INTRODUCTION

Obesity is a global epidemic, and there remains uncertainty over the effect of obesity on skeletal health, particularly in the context of osteoporosis. The aim of this study was to investigate associations of body mass index (BMI) and obesity with BMD and prevalent VF in men and women aged 62 years.

METHODS

Three hundred and forty-two men and women aged 62.5 ± 0.5 years from the Newcastle Thousand Families Study birth cohort underwent DXA evaluations of femoral neck and lumbar spine BMD and of the lateral spine for vertebral fracture assessment.

RESULTS

The likelihood of prevalent VF was significantly increased in men when compared to women (OR = 2.7, p < 0.001, 95% Cl 1.7-4.4). As BMI increased in women, so did the likelihood of prevalent any-grade VF (OR = 1.09, p = 0.006, 95% CI 1.02-1.17). Compared to normal weight women, obese women were more likely to have at least one VF (OR = 2.65, p = 0.025, CI 1.13-6.20) and at least one grade 1 vertebral deformity (OR = 4.39, p = 0.005, CI 1.57-12.28). Obese men were more likely to have a grade 2 and/or grade 3 VF compared to men of normal weight (OR = 3.36, p = 0.032, CI 1.11-10.16). In men and women, BMI was negatively associated with femoral neck BMD/weight (R = - 0.65, R = - 0.66, p < 0.001) and lumbar spine BMD/weight (R = - 0.66, R - 0.60, p < 0.001).

CONCLUSIONS

Obesity appears to be a risk factor for prevalent VF, and although absolute BMD is higher in obese individuals, this does not appear commensurate to their increased body weight.

3D Analysis of Cortical and Trabecular Bone From Hip DXA:Precision and Trend Assessment Interval in PostmenopausalWomen

The 3D distribution of the cortical and trabecular bone mass is a critical component in determining the resistance of a bone to fracture that is not assessed in standard dual-energy X-ray absorptiometry (DXA) exams. In this work, we assessed in vivo short-term precision of measurements provided by 3D modeling techniques from DXA scans and trend assessment intervals (TAIs) in postmenopausal women. Subjects included to study precision errors were scanned twice, with repositioning for duplicate hip scans, using either a Lunar iDXA scanner (GE Healthcare, Madison, WI) or a Discovery W scanner (Hologic, Inc., Waltham, MA). Postmenopausal women having baseline and 18-mo follow-up visit were scanned using a Lunar iDXA device to assess TAIs. TAIs indicate what time intervals are required to allow accurate assessment of response to treatment or progression of disease. The 3D-SHAPER software (Galgo Medical, Barcelona, Spain) was used to derive 3D measurements from hip DXA scans. Least significant changes were 10.39 and 8.72 mg/cm³ for integral volumetric bone mineral density (BMD), 9.64 and 9.59 mg/cm³ for trabecular volumetric BMD, and 6.25 and 5.99 mg/cm² for cortical surface BMD, using the Lunar iDXA and Discovery W scanners, respectively. TAIs in postmenopausal women were 2.9 yr (integral volumetric BMD), 2.6 yr (trabecular volumetric BMD), and 3.5 yr (cortical surface BMD), using the Lunar iDXA scanner. As a comparison, TAIs for areal BMD were 2.8 yr at neck and 2.7 yr at total femur. Least significant changes of measurements provided by 3D modeling techniques from DXA were assessed. TAIs in postmenopausal women were similar to those measured for areal BMD measurements. DXA-derived 3D measurements could potentially provide additional indicators to improve patient monitoring in clinical practices.

Clinical evaluation of education relating to nutrition and skeletal loading in competitive male road cyclists at risk of relative energy deficiency in sports (RED-S): 6-month randomised controlled trial

Objective

To clinically evaluate education to improve eating behaviour and skeletal loading exercise in male cyclists at risk of poor bone health and impaired performance due to relative energy deficiency in sports.

Methods

Early race season, 50 competitive male road cyclists were matched, in pairs, based on Z-scores for lumbar spine bone mineral density (BMD). One member of each pair was randomly allocated to receive educational interventions. After the season, 45 cyclists returned for dual-energy X-ray absorptiometry scans and blood tests. Least significant change was applied to identify clinically meaningful BMD changes. Cyclists completed a follow-up sport-specific questionnaire and clinical interview to ascertain adherence to the interventions.

Results

The questionnaire and clinical interview categorised behaviour changes as positive, negative or unchanged. Positive changes in nutrition and skeletal loading were associated with a statistically significant increase of 2.0% in lumbar spine BMD; 7 of 11 cyclists’ increases were clinically meaningful. Negative changes in both behaviours were associated with a significant decrease of 2.7% in lumbar BMD; all nine cyclists’ BMD decreases were clinically meaningful. Regarding performance, taking account of functional threshold power, changes in nutritional behaviour accounted for gains or losses of 95 British Cycling racing points. Cyclists reported psychological barriers to change in behaviours, specifically fear of negatively impacting performance.

Conclusions

Educational nutritional and skeletal loading interventions can improve bone health, well-being and race performance in male cyclists over a 6-month race season. Psychological support may be required to help some athletes change behaviour.

Mid-calf skeletal muscle density and its associations with physical activity, bone health and incident 12-month falls in older adults: The Healthy Ageing Initiative

BACKGROUND

Lower skeletal muscle density, indicating greater infiltration of adipose tissue into muscles, is associated with higher fracture risk in older adults. We aimed to determine whether mid-calf muscle density is associated with falls risk and bone health in community-dwelling older adults.

METHODS

2214 community-dwelling men and women who participated in the Healthy Ageing Initiative (Sweden) study at age 70 were included in this analysis. Mid-calf muscle density (mg/cm³) at the proximal tibia, and volumetric bone mineral density (vBMD) and architecture at the distal and proximal tibia and radius, were assessed by peripheral quantitative computed tomography. Whole-body lean and fat mass, lumbar spine and total hip areal bone mineral density (aBMD) were assessed by dual-energy X-ray absorptiometry. Participants completed seven-day accelerometer measurements of physical activity intensity, and self-reported falls data were collected 6 and 12 months later.

RESULTS

302 (13.5%) participants reported a fall at the 6- or 12-month interview, and 29 (1.3%) reported a fall at both interviews. After adjustment for confounders, each standard deviation decrease in mid-calf muscle density was associated with a trend towards greater likelihood of experiencing a fall (OR 1.13; 95% CI 1.00, 1.29 per SD lower) and significantly greater likelihood of multiple falls (1.61; 1.16, 2.23). Higher muscle density was not associated with total hip aBMD, and was associated with lower lumbar spine aBMD (B = -0.003; 95% CI -0.005, -0.001 per mg/cm³) and higher proximal cortical vBMD (0.74; 0.20, 1.28) at the radius. At the tibia, muscle density was positively associated with distal total and trabecular vBMD, and proximal total and cortical vBMD, cortical thickness, cortical area and stress-strain index (all P < 0.05). Only moderate/vigorous (%) intensity physical activity, not sedentary time or light activity, was associated with higher mid-calf muscle density (0.086; 0.034, 0.138).

CONCLUSIONS

Lower mid-calf muscle density is independently associated with higher likelihood for multiple incident falls and appears to have localised negative effects on bone structure in older adults.

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.

Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists

Objectives

To evaluate the efficacy of a sport-specific energy availability (EA) questionnaire, combined with clinical interview, for identifying male athletes at risk of developing bone health, endocrine and performance consequences of relative energy deficiency in sports (RED-S).

Methods

Fifty competitive male road cyclists, recruited through links of participants in a pilot study, were assessed by a newly developed sport-specific questionnaire and clinical interview (SEAQ-I) and received dual energy X-ray absorptiometry (DXA) bone mineral density (BMD) and body composition scans and blood tests for endocrine markers.

Results

Low EA as assessed using the SEAQ-I, was observed in 28% of cyclists. Low lumbar spine BMD (Z-score<−1.0) was found in 44% of cyclists. EA was the most significant determinant of lumbar spine BMD Z-score (p<0.001). Among low EA cyclists, lack of previous load-bearing sport was associated with the lowest BMD (p=0.013). Low EA was associated with reduced total percentage fat (p<0.019). The 10 cyclists with chronic low EA had lower levels of testosterone compared with those having adequate EA (p=0.024). Mean vitamin D concentration was below the level recommended for athletes (90  nmol/L). Training loads were positively associated with power-to-weight ratios, assessed as 60  min functional threshold power (FTP) per kg (p<0.001). Percentage body fat was not significantly linked to cycling performance.

Conclusions

This study demonstrates that a SEAQ-I is effective for identifying male road cyclists with acute intermittent and chronic sustained low EA. Cyclists with low EA, particularly in the long-term, displayed adverse quantifiable measures of bone, endocrinology and performance consequences of RED-S.

Cross Calibration of the GE Prodigy and iDXA for the Measurement of Total and Regional Body Composition in Adults

Dual-energy X-ray absorptiometry (DXA) body composition measurements are widely performed in both clinical and research settings, and enable the rapid and noninvasive estimation of total and regional fat and lean mass tissues. DXA upgrading can occur during longitudinal monitoring or study; therefore, cross calibration of old and new absorptiometers is required. We compared soft tissue estimations from the GE Prodigy (GE Healthcare, Madison, WI) with the more recent iDXA (GE Healthcare) and developed translational equations to enable Prodigy values to be converted to iDXA values. Eighty-three males and females aged 20.1-63.3 yr and with a body mass index range of 17.0-34.4 kg/m² were recruited for the study. Fifty-nine participants (41 females and 18 males) comprised the cross-calibration group and 24 (14 females and 10 males) comprised the validation group. Total body Prodigy and iDXA scans were performed on each subject within 24 h. Predictive equations for total and regional soft tissue parameters were derived from linear regression of the data. Measures of lean and fat tissues were highly correlated (R² = 0.95-0.99), but significant differences and variability between machines were identified. Bland-Altman analysis revealed significant biases for most measures, particularly for arm, android, and gynoid fat mass (12.3%-22.7%). The derived translational equations reduced biases and differences for most parameters, although limits of agreement exceeded iDXA least significant change. In conclusion, variability in soft tissue estimates between the Prodigy and iDXA were detected, supporting the need for translational equations in longitudinal monitoring. The derived equations are suitable for group analysis but not individual analysis.

Bone Density and Cross-sectional Geometry of the Proximal Femur Are Bilaterally Elevated in Elite Cricket Fast Bowlers

The skeleton of a cricket fast bowler is exposed to a unique combination of gravitational and torsional loading in the form of substantial ground reaction forces delivered through the front landing foot, and anterior-posterior shear forces mediated by regional muscle contractions across the lumbo-pelvic region. The objectives of this study were to compare the hip structural characteristics of elite fast bowlers with recreationally active age-matched controls, and to examine unilateral bone properties in fast bowlers. Dual-energy X-ray absorptiometry of the proximal femur was performed in 26 elite male fast bowlers and 26 normally active controls. Hip structural analysis (GE Lunar; enCORE version 15.0) determined areal bone mineral density (BMD) of the proximal femur, and cross-sectional area, section modulus (Z), cross-sectional moment of inertia, and femoral strength index at the narrow region of the femoral neck. Mean femoral neck and trochanter BMD were greater in fast bowlers than in controls (p <0.001). All bone geometry properties, except for cross-sectional moment of inertia, were superior in fast bowlers (p <0.05) following adjustment for height and lean mass. There were no asymmetries in BMD or bone geometry when considering leg dominance of the fast bowlers (p > 0.05). Elite fast bowlers have superior bone characteristics of the proximal femur, with results inferring enhanced resistance to axial compression (cross-sectional area), and bending (Z) forces, and enhanced strength to withstand a fall impact as indicated by their higher femoral strength index. No asymmetries in hip bone properties were identified, suggesting that both torsional and gravitational loading offer significant osteogenic potential.

Directly measured free 25-hydroxy vitamin D levels show no evidence of vitamin D deficiency in young Swedish women with anorexia nervosa

PURPOSE

Anorexia nervosa (AN) is an eating disorder characterized by low fat mass complicated by osteoporosis. The role of circulating vitamin D in the development of bone loss in AN is unclear. Fat mass is known to be inversely associated with vitamin D levels measured as serum levels of total, protein-bound 25-hydroxyvitamin D, but the importance of directly measured, free levels of 25(OH)D has not been determined in AN. The aim of this study was to investigate vitamin D status, as assessed by serum concentrations of total and free serum 25(OH)D in patients with AN and healthy controls.

METHODS

In female AN patients (n = 20), and healthy female controls (n = 78), total 25(OH)D was measured by LC-MS/MS, and free 25(OH)D with ELISA. In patients with AN bone mineral density (BMD) was determined with DEXA.

RESULTS

There were no differences between patients and controls in total or free S-25(OH)D levels (80 ± 31 vs 72 ± 18 nmol/L, and 6.5 ± 2.5 vs 5.6 ± 1.8 pg/ml, respectively), and no association to BMD was found. In the entire group of patients and controls, both vitamin D parameters correlated with BMI, leptin, and PTH.

CONCLUSIONS

The current study did not demonstrate a vitamin D deficiency in patients with AN and our data does not support vitamin D deficiency as a contributing factor to bone loss in AN. Instead, we observed a trend toward higher vitamin D levels in AN subjects compared to controls. Measurement of free vitamin D levels did not contribute to additional information.

An Investigation Into the Differences in Bone Density and Body Composition Measurements Between 2 GE Lunar Densitometers and Their Comparison to a 4-Component Model

We describe a study to assess the precision of the GE Lunar iDXA and the agreement between the iDXA and GE Lunar Prodigy densitometers for the measurement of regional- and total-body bone and body composition in normal to obese healthy adults. We compare the whole-body fat mass by dual-energy X-ray absorptiometry (DXA) to measurements by a 4-component (4-C) model. Sixty-nine participants, aged 37 ± 12 yr, with a body mass index of 26.2 ± 5.1 kg/cm², were measured once on the Prodigy and twice on the iDXA. The 4-C model estimated fat mass from body mass, total body water by deuterium dilution, body volume by air displacement plethysmography, and bone mass by DXA. Agreements between measurements made on the 2 instruments and by the 4-C model were analyzed by Bland-Altman and linear regression analyses. Where appropriate, translational cross-calibration equations were derived. Differences between DXA software versions were investigated. iDXA precision was less than 2% of the measured value for all regional- and whole-body bone and body composition measurements with the exception of arm fat mass (2.28%). We found significant differences between iDXA and Prodigy (p < 0.05) whole-body and regional bone, fat mass (FM), and lean mass, with the exception of hip bone mass, area and density, and spine area. Compared to iDXA, Prodigy overestimated FM and underestimated lean mass. However, compared to 4-C, iDXA showed a smaller bias and narrower limits of agreement than Prodigy. No significant differences between software versions in FM estimations existed. Our results demonstrate excellent iDXA precision. However, significant differences exist between the 2 GE Lunar instruments, Prodigy and iDXA measurement values. A divergence from the reference 4-C observations remains in FM estimations made by DXA even following the recent advances in technology. Further studies are particularly warranted in individuals with large FM contents.

Metabolic milieu associates with impaired skeletal characteristics in obesity

High leptin concentration, low-grade inflammation, and insulin resistance often coexist in obese subjects; this adverse metabolic milieu may be the main culprit for increased fracture risk and impaired bone quality seen in patients with type 2 diabetes. We examined the associations of leptin, hs (high sensitivity)- CRP and insulin resistance with bone turnover markers (BTMs) and bone characteristics in 55 young obese adults (median BMI 40 kg/m²) and 65 non-obese controls. Mean age of the subjects was 19.5 ± 2.5 years (mean ± SD). Concentrations of leptin, adiponectin, hs-CRP, MMP-8 and TIMP-1, fasting plasma glucose and insulin (to calculate HOMA), BTMs (BAP, P1NP, CTX-1, and TRAC5b) were measured. Bone characteristics were determined with pQCT at radius and tibia, and with DXA for central sites. Leptin, hs-CRP and HOMA correlated inversely with BTMs: the partial coefficients were 1.5–1.9 fold higher in males than in females. After adjusting for age, BMI, and other endocrine factors, leptin displayed an independent effect in males on radial bone mass (p = 0.019), tibial trabecular density (p = 0.025) and total hip BMD (p = 0.043), with lower densities in males with high leptin. In females, the model adjusting for age, BMI, and other endocrine factors, revealed that hs-CRP had independent effects on radial bone mass (p = 0.034) and lumbar spine BMD (p = 0.016), women with high hs-CRP having lower values. Partial correlations of adiponectin and TIMP-1 with bone characteristics were discrepant; MMP-8 showed no associations. In conclusion, in young obese adults and their controls, leptin, hs-CRP and HOMA associate inversely with BTMs and bone characteristics. Leptin appears to be the key independent effector in males, whereas hs-CRP displayed a predominant role in females.

Total and Visceral Adiposity Are Associated With Prevalent Vertebral Fracture in Women but Not Men at Age 62 Years: The Newcastle Thousand Families Study

Low body weight is an established risk factor for osteoporosis and fracture, but the skeletal risks of higher adiposity are unclear and appear sex-specific and site-dependent. The aim of this study was to investigate associations of total fat mass (TFM), visceral adipose tissue (VAT), and C-reactive protein (CRP) with bone mineral density (BMD) and prevalent vertebral fracture (VF) in men and women aged 62 years. A total of 352 men and women aged 62.5 ± 0.5 years from the Newcastle Thousand Families Study cohort received dual-energy X-ray absorptiometry (DXA) evaluations of femoral neck and lumbar spine BMD, of the lateral spine for vertebral fracture assessment, and of the whole body for TFM and VAT (GE Lunar CoreScan, Madison, WI, USA). Plasma CRP, FRAX scores, falls in the last 12 months, and occupation at age 50 years were also included in the analysis. Vertebral fractures were less prevalent in women than in men (odds ratio [OR] = 0.33, p < 0.001) and BMD or FRAX scores did not differ between participants with and without VF. Women with VF were heavier and had higher TFM, VAT, and CRP than women without (p < 0.001). In women, greater (+1 SD) TFM and VAT increased the odds of any grade VF (TFM: OR = 1.06, p = 0.001; VAT: OR = 2.50, p = 0.002), and greater VAT mass increased the odds of prevalent mild VF (OR = 2.60, p = 0.002). In contrast, there were no associations in men. In both sexes, after controlling for body weight, neither VAT nor CRP were associated with BMD. In conclusion, irrespective of BMD, total and visceral adiposity were associated with prevalent VF in women but not in men. High fat mass, particularly if visceral, should be considered when assessing VF risk in women. Risk factors for VF in men require further investigation, particularly given their high prevalence. © 2017 American Society for Bone and Mineral Research.

Circulating microRNA Signatures in Patients With Idiopathic and Postmenopausal Osteoporosis and Fragility Fractures

CONTEXT

Established bone turnover markers do not reflect fracture risk in idiopathic male and premenopausal osteoporosis and the role of microRNAs (miRNAs) in these patients is currently unclear. miRNAs are a class of small non-coding RNAs that regulate gene expression and bone tissue homeostasis. They are considered a new class of endocrine regulators with promising potential as biomarkers.

OBJECTIVE

Evaluation of circulating miRNA signatures in male and female subjects with idiopathic and postmenopausal osteoporotic low-traumatic fractures.

DESIGN, SETTING, AND PATIENTS

This was a case-control study of cross-sectional design of 36 patients with prevalent low-traumatic fractures and 39 control subjects Main Outcome Measures: One hundred eighty-seven miRNAs were quantified in serum by qPCR, compared between groups and correlated with established bone turnover markers.

RESULTS

Significant differences in serum levels of circulating miRNAs were identified in all three subgroups (46 in premenopausal, 52 in postmenopausal, 55 in male). A set of 19 miRNAs was consistently regulated in all three subgroups. Eight miRNAs [miR-152-3p, miR-30e-5p, miR-140-5p, miR-324-3p, miR-19b-3p, miR-335-5p, miR-19a-3p, miR-550a-3p] were excellent discriminators of patients with low-traumatic fractures, regardless of age and sex, with area under the curve values > 0.9. The 11 remaining miRNAs showed area under the curve values between 0.81 and 0.89. Correlation analysis identified significant correlations between miR-29b-3p and P1NP, and miR-365-5p and iPTH, TRAP5b, P1NP and Osteocalcin, as well as BMD_L1-L4 and miR-19b-3p, miR-324-3p, miR-532-5p, and miR-93-5p.

CONCLUSIONS

Specific serum miRNA profiles are strongly related to bone pathologies. Therefore miRNAs might be directly linked to bone tissue homeostasis. In particular, miR-29b-3p has previously been reported as regulator of osteogenic differentiation and could serve as a novel marker of bone turnover in osteoporotic patients as a member of a miRNA signature.

High Cardiorespiratory Fitness Is Associated with Reduced Risk of Low Bone Density in Postmenopausal Women

PURPOSE

The goal of this study was to determine the association between cardiorespiratory fitness (CRF) and bone mineral density (BMD) of the femoral neck (FN) in postmenopausal women using existing Cooper Center Longitudinal Study data.

MATERIALS AND METHODS

A cohort of 1,720 predominantly healthy Caucasian women (57.1 ± 6.9 years) underwent preventive medical examinations that included CRF assessment by maximal Balke treadmill testing and measurement of BMD by dual-energy X-ray absorptiometry. CRF was estimated from total treadmill time and categorized into five categories of CRF (further defined as fitness category 1 = low fitness, 2-3 = moderate fitness, and 4-5 = high fitness). Logistic regression was used to characterize the association between CRF and BMD, adjusting for age, weight, and resistance activity level.

RESULTS

Overall, the mean body-mass index (BMI) for all subjects was 25.0 ± 4.5 kg/m2, although BMI was in the obese range in the low fitness group. The prevalence of osteoporosis (T-score ≤ -2.5 at the FN) was greater in the low fit group than moderate or high fit (5.8% vs. 3.0% or 3.9%, respectively); with a similar pattern seen for prevalence of osteopenia (T-score > -2.5 and ≤ -1.0 at the FN) (47.5% vs. 46.4% or 44.8%, respectively). Higher age and lower weight were associated with low BMD. Fully adjusted logistic regression models showed an inverse association between CRF and low BMD of the FN. For T-score ≤ -1.0, the primary outcome, the odds ratio (OR) was 0.50 (95% confidence interval [CI] 0.32-0.79) for moderate fitness, and OR of 0.32 (95% CI 0.21-0.51) for high fitness was seen. For T-score ≤ -2.5 at the FN, OR was 0.30 (95% CI 0.11-0.80) for moderate fitness, and OR was 0.29 (95% CI 0.12-0.71) for high fitness.

CONCLUSION

Increased CRF levels are associated with reduced risk for low bone density in postmenopausal women.

Serum levels of the bone turnover markers dickkopf-1, sclerostin, osteoprotegerin, osteopontin, osteocalcin and 25-hydroxyvitamin D in Swedish geriatric patients aged 75 years or older with a fresh hip fracture and in healthy controls

BACKGROUND

Bone turnover markers have a potential clinical use in describing bone remodeling and in predicting fractures.

AIMS

In an elderly population ≥75 years with a fresh hip fracture, and in healthy controls, investigate bone turnover markers and their relation to each other, to vitamin D status and to bone mineral density (BMD).

METHODS

In a cross-sectional study serum levels of dickkopf-1 (DKK-1), sclerostin (SOST), osteoprotegerin (OPG), osteopontin (OPN), osteocalcin, 25-hydroxyvitamin D (25(OH)D) were analyzed in 89 Swedish patients with a fresh hip fracture and in 82 healthy volunteers. Serum levels of bone markers were determined by Luminex technique.

RESULTS

S-25-hydroxyvitamin D (S-25(OH)D) was decreased in patients compared to controls (48 ± 21 vs. 76 ± 25 nmol/L, p < 0.001). SOST, but none of the other bone turnover markers correlated with BMD (r = 0.50, p < 0.001). Compared with controls, higher levels of OPG (488 ± 1.4 vs. 191 ± 1.4 ng/L, p < 0.001), OPN (69 ± 1.7 vs. 19 ± 1.4 µg/L, p < 0.001), DKK-1 (273 ± 1.7 vs. 168 ± 1.7 ng/L, p < 0.001), and lower levels of osteocalcin (5.8 ± 3.5 vs. 9.5 ± 3.6 µg/L, p < 0.001), were found in the fracture group. Levels of OPG, DKK-1 and SOST in both groups were positively associated. S-25(OH)D concentration was not found to be strongly associated with any of the bone markers.

CONCLUSIONS

In contrast to findings in other studies, we found no strong correlation between 25(OH)D and the investigated bone markers. Both in patients with a fresh hip fracture and in healthy elderly, DKK-1, SOST and OPG appear to be associated. This suggests a relevance in these relationships meriting further investigation.

The Relationship Between Cardiorespiratory Fitness and Bone Mineral Density in Men: A Cross-sectional Study

OBJECTIVE

To determine the relationship between estimated cardiorespiratory fitness (CRF) and femoral neck (FN) bone mineral density (BMD) in men.

PATIENTS AND METHODS

This cross-sectional study included 2569 men aged 50 to 90 years (mean, 63.5 years) who had at least 1 health examination at a preventive medicine clinic between January 27, 1998, and February 24, 2015. Maximal treadmill tests were conducted using the Balke protocol and were used to estimate CRF. We stratified patients into low, moderate, and high CRF categories. The FN BMD was measured by dual-energy x-ray absorptiometry. Odds ratios (ORs) for T-scores of -2.5 or less (osteoporosis) and -1.0 or less (low BMD) were calculated for categorical CRF and were adjusted for weight, age, and days per week of resistance activity.

RESULTS

The sample prevalence of osteoporosis in the FN was 4.1% and of low BMD was 49.4%. There was a significant inverse association between higher CRF category and osteoporosis measured at the FN (moderate vs low: OR=0.34; 95% CI, 0.16-0.74; high vs low: OR=0.19; 95% CI, 0.09-0.42) and low BMD (moderate vs low: OR=0.64; 95% CI, 0.43-0.96; high vs low: OR=0.43; 95% CI, 0.29-0.65).

CONCLUSION

In men, CRF is directly associated with BMD. These results suggest that moderate-to-high CRF levels attained through regular physical activity may attenuate age-related decline in BMD. Further studies are needed to determine whether this translates to a lower risk of osteoporotic fracture in more fit men.

Worksite Physical Activity Intervention for Ambulatory Clinic Nursing Staff

Health behaviors, including physical activity (PA), of registered nurses (RNs) and medical assistants (MAs) are suboptimal but may improve with worksite programs. Using a repeated-measures crossover design, the authors explored if integrating a 6-month worksite non-exercise activity thermogenesis (NEAT) intervention, with and without personalized health coaching via text messaging into workflow could positively affect sedentary time, PA, and body composition of nursing staff without jeopardizing work productivity. Two ambulatory clinics were randomly assigned to an environmental NEAT intervention plus a mobile text message coaching for either the first 3 months (early texting group, n = 27) or the last 3 months (delayed texting group, n = 13), with baseline 3-month and 6-month measurements. Sedentary and PA levels, fat mass, and weight improved for both groups, significantly only for the early text group. Productivity did not decline for either group. This worksite intervention is feasible and may benefit nursing staff.

Objectively measured physical activity is associated with parameters of bone in 70-year-old men and women

As the world's population ages, the occurrence of osteoporosis-related fractures is projected to increase. Low areal bone mineral density (aBMD), a well-known risk factor for fractures, may be influenced by physical activity (PA). In this cross-sectional study, we aimed to investigate potential associations between objective measures of PA and bone properties, in a population-based cohort of 1228 70-year-old men and women. We measured volumetric BMD (vBMD, mg/cm(3)) together with cross-sectional area (CSA, mm(2)) by peripheral quantitative computed tomography at sites located 4% and 66% in the distal-proximal trajectory at the tibia and radius. We also measured aBMD (g/cm(2)) by dual energy X-ray absorptiometry at the femoral neck, lumbar spine (L1-L4) and radius. Participants wore triaxial accelerometers for 7 consecutive days to obtain objective estimates of PA. The intensity of the objective PA was divided into light (100-1951 counts/min [CPM]), moderate (1952-5724 cpm) and vigorous (≥ 5725 cpm). Maximal accelerations for the anterior-posterior (z), medio-lateral (x), and vertical (y) axes were also separately assessed. Associations were investigated using bivariate correlations and multiple linear regression, adjusted for height, weight and sex. Vigorous PA showed the strongest association with femoral neck aBMD (β=0.09, p<0.001), while both moderate and vigorous PAs were associated with cortical area and trabecular vBMD in the weight-bearing tibia (all p<0.05). Peak vertical accelerations were associated significantly with cortical area (β=0.09, p<0.001) and trabecular vBMD (β=0.09, p=0.001) of the tibia, whereas peak anterior-posterior accelerations showed no correlation with these properties. No positive association was found between objectively measured PA and bone parameters of the radius. In conclusion, vertical accelerations and moderate to vigorous PA independently predict bone properties, especially in the weight-bearing tibia, in 70-year-old men and women.

Bone structure assessed by HR-pQCT, TBS and DXL in adult patients with different types of osteogenesis imperfecta

Bone microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) was assessed in adult patients with mild, moderate, and severe osteogenesis imperfecta (OI). The trabecular bone score (TBS), bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), and dual X-ray and laser (DXL) at the calcaneus were likewise assessed in patients with OI. Trabecular microstructure and BMD in particular were severely altered in patients with OI.

INTRODUCTION

OI is characterized by high fracture risk but not necessarily by low BMD. The main purpose of this study was to assess bone microarchitecture and BMD at different skeletal sites in different types of OI.

METHODS

HR-pQCT was performed in 30 patients with OI (mild OI-I, n = 18 (41.8 [34.7, 55.7] years) and moderate to severe OI-III-IV, n = 12 (47.6 [35.3, 58.4] years)) and 30 healthy age-matched controls. TBS, BMD by DXA at the lumbar spine and hip, as well as BMD by DXL at the calcaneus were likewise assessed in patients with OI only.

RESULTS

At the radius, significantly lower trabecular parameters including BV/TV (p = 0.01 and p < 0.0001, respectively) and trabecular number (p < 0.0001 and p < 0.0001, respectively) as well as an increased inhomogeneity of the trabecular network (p < 0.0001 and p < 0.0001, respectively) were observed in OI-I and OI-III-IV in comparison to the control group. Similar results for trabecular parameters were found at the tibia. Microstructural parameters were worse in OI-III-IV than in OI-I. No significant differences were found in cortical thickness and cortical porosity between the three subgroups at the radius. The cortical thickness of the tibia was thinner in OI-I (p < 0.001), but not OI-III-IV, when compared to controls.

CONCLUSIONS

Trabecular BMD and trabecular bone microstructure in particular are severely altered in patients with clinical OI-I and OI-III-IV. Low TBS and DXL and their significant associations to HR-pQCT parameters of trabecular bone support this conclusion.

A cross-calibration study of the GE-Lunar iDXA and prodigy for the assessment of lumbar spine and total hip bone parameters via three statistical methods

This study assessed agreement between the GE Lunar iDXA and Prodigy densitometers for bone measurements and used 3 statistical methods to derive cross-calibration equations: linear regression, the Deming method, and multivariate analysis. Compatibility of machines for the measurements of bone mineral density, bone mineral content, and bone area also was explored. Eighty-five adults, age: 45.5 (SD 12.8) years; body mass index: 25.6 (SD 3.7) kg.m(-2) were measured once at the lumbar spine: L1-L4 and total hip on each densitometer, within 24 hours. Both linear regression and Deming analysis indicated that cross-calibration equations were required at the lumbar spine and total hip but not at the femoral neck. Multivariate analysis identified femur thickness and femur percent fat as predictive variables at the femoral neck and total hip. Bland Altman analysis (Prodigy-iDXA) indicated significant positive bone mineral density bias at the lumbar spine and femoral neck. Significant bone mineral content biases were observed at all 3 sites and bone area biases at both hip sites. These initial results suggest there are small significant differences in the bone parameters and that all 3 bone parameters should be evaluated when comparing densitometers, especially when there are differences in pixel size between the densitometers.

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.

Prevalent morphometric vertebral fractures in professional male rugby players

There is an ongoing concern about the risk of injury to the spine in professional rugby players. The objective of this study was to investigate the prevalence of vertebral fracture using vertebral fracture assessment (VFA) dual energy X-ray absorptiometry (DXA) imaging in professional male rugby players. Ninety five professional rugby league (n = 52) and union (n = 43) players (n = 95; age 25.9 (SD 4.3) years; BMI: 29.5 (SD 2.9) kg.m2) participated in the research. Each participant received one VFA, and one total body and lumbar spine DXA scan (GE Lunar iDXA). One hundred and twenty vertebral fractures were identified in over half of the sample by VFA. Seventy four were graded mild (grade 1), 40 moderate (grade 2) and 6 severe (grade 3). Multiple vertebral fractures (≥2) were found in 37 players (39%). There were no differences in prevalence between codes, or between forwards and backs (both 1.2 v 1.4; p>0.05). The most common sites of fracture were T8 (n = 23), T9 (n = 18) and T10 (n = 21). The mean (SD) lumbar spine bone mineral density Z-score was 2.7 (1.3) indicating high player bone mass in comparison with age- and sex-matched norms. We observed a high number of vertebral fractures using DXA VFA in professional rugby players of both codes. The incidence, aetiology and consequences of vertebral fractures in professional rugby players are unclear, and warrant timely, prospective investigation.

In vivo precision of the GE lunar iDXA for the assessment of lumbar spine, total hip, femoral neck, and total body bone mineral density in severely obese patients

No study has evaluated the precision of the GE Lunar iDXATM (GE Healthcare) in measuring bone mineral density (BMD) among severely obese patients. The purpose of the study was to evaluate the precision of the GE Lunar iDXATM for assessing BMD, including the lumbar spine L1-L4, L2-L4, the total hip, femoral neck, and total body in a severely obese population (body mass index [BMI]>40 kg/m(2)). Sixty-four severely obese participants with a mean age of 46 ± 11 yr, BMI of 49 ± 6 kg/m(2), and a mean body mass of 136.8 ± 20.4 kg took part in this investigation. Two consecutive iDXA scans (with repositioning) of the total body (total body BMD [TBBMD]), lumbar spine (L1-L4 and L2-L4), total hip (total hip BMD [THBMD]), and femoral neck (femoral neck BMD [FNBMD]) were conducted for each participant. The coefficient of variation (CV), the root mean square (RMS) averages of standard deviations of repeated measurements, the corresponding 95% least significant change, and intraclass correlations (ICCs) were calculated. In addition, analysis of bias and coefficients of repeatability were calculated. The results showed a high level of precision for total body (TBBMD), lumbar spine (L1-L4), and total hip (THBMD) with values of RMS: 0.013, 0.014, and 0.011 g/cm(2); CV: 0.97%, 1.05%, and 0.99%, respectively. Precision error for the femoral neck was 2.34% (RMS: 0.025 g/cm(2)) but still represented high reproducibility. ICCs in all dual-energy X-ray absorptiometry measurements were 0.99 with FNBMD having the lowest at 0.98. Coefficients of repeatability for THBMD, FNBMD, L1-L4, L2-L4, and TBBMD were 0.0312, 0.0688, 0.0383, 0.0493, and 0.0312 g/cm(2), respectively. The Lunar iDXA demonstrated excellent precision for BMD measurements and is the first study to assess reproducibility of the GE Lunar iDXA with severely obese adults.

Prevention of bone loss and vertebral fractures in patients with chronic epilepsy--antiepileptic drug and osteoporosis prevention trial

PURPOSE

To evaluate whether use of a bisphosphonate (risedronate) in addition to calcium and vitamin D in male veterans with epilepsy who were taking antiepileptic drugs (AEDs) long term can prevent the loss of bone mass (BMD, bone mineral density) associated with AED use compared to patients who were treated with a placebo plus calcium and vitamin D. As a secondary end point we studied the incidence of new morphometric vertebral and nonvertebral fractures.

METHODS

Antiepileptic drug and osteoporosis prevention trial (ADOPT) was designed as a prospective 2-year double-blind, randomized placebo controlled study involving 80 male veterans with epilepsy who were being treated with AEDs such as phenytoin, phenobarbital, sodium valproate, or carbamazepine for a minimum of 2 years. All enrolled participants received calcium and vitamin D supplementation, and were randomized to risedronate or matching placebo. Total body, bilateral proximal femora, and anteroposterior (AP) lumbar spine BMDs in addition to morphometric lateral vertebral assessments (LVAs) were evaluated by a dual energy x-ray absorptiometry (DXA) instrument. Comparisons of BMDs were made between baseline, 1 year, and after 2 years of enrollment in the study. The incidence of new vertebral and nonvertebral fractures was secondary end point.

KEY FINDINGS

Of the 80 patients initially enrolled in the study, 53 patients completed the study. Baseline characteristics of the two groups were similar. At the end of the study, in the placebo plus calcium and vitamin D group, we observed a significant improvement in BMD at any of the evaluated sites when compared to their baseline scans in 69% (18/26) of the participants. In the risedronate plus calcium and vitamin D group, we observed significant improvement of BMDs in 70% (19/27) of the participants. At the end of the study, the risedronate group experienced a significant increase of BMD at the lumbar spine L1-4 (1.267-1.332 g/cm(2)), which was significantly larger than that seen in the placebo group) (1.229 g/cm(2) vs. 1.245 g/cm(2) ; p = 0.0066).There were nonsignificant differences between the two groups regarding changes of total body BMD or at the proximal bilateral femora. Five new vertebral fractures and one nonvertebral fracture were observed only in the placebo group.

SIGNIFICANCE

Calcium and vitamin D supplementation or calcium and vitamin D supplementation in addition to risedronate improved BMD in more than 69% of male veterans with epilepsy who were taking AEDs. In the group receiving risedronate plus calcium and vitamin D there was a significant improvement of BMD at the lumbar spine as compared to the placebo group, which also received calcium and vitamin D. The use of risedronate plus calcium and vitamin D prevented the incidence of new vertebral fractures and one nonvertebral fracture in this cohort.

The discriminatory capacity of BMD measurements by DXA and dual X-ray and laser (DXL) at the calcaneus including clinical risk factors for detecting patients with vertebral fractures

Osteoporotic fracture risk depends on bone mineral density (BMD) and clinical risk factors (CRF). Five hundred and eighty-eight untreated female and male outpatient subjects were evaluated, 160 with vertebral fractures. BMD was measured both by using calcaneal dual X-ray and laser (DXL) and dual-energy X-ray absorptiometry (DXA), and CRF were evaluated. Detection frequencies for different BMD methods with or without CRF are presented.

INTRODUCTION

Osteoporotic fracture risk depends on bone mineral density and clinical risk factors. DXA of the spine/hip is considered a gold standard for BMD assessment, but due to degenerative conditions, particularly among the older population, assessment of BMD at the lumbar spine has been shown to be of limited significance. Portable calcaneal dual X-ray technology and laser can be an easily obtainable alternative.

METHODS

Vertebral fractures were evaluated in a baseline analysis of 588 females and males (median age 64.4, range 17.6-93.1 years), comparing BMD measurements by using DXL and DXA and CRF with/without BMD. One hundred and sixty subjects had radiological verified vertebral fractures. Area under receiver-operating characteristic curves (AUROCC) and univariate and multiple logistic regressions were calculated.

RESULTS

AUROCC for detection of vertebral fractures was comparable for DXL at calcaneus and DXA at femoral neck (DXL 0.665 and DXA 0.670). Odds ratio for prevalent vertebral fracture was generally weak for DXA femoral neck (0.613) and DXL (0.521). Univariate logistic regression among CRF without BMD revealed age, prevalent fragility fracture, and body mass index significantly associated with prevalent vertebral fracture (AUROCC = 0.805). Combining BMD and CRF, a prognostic improvement in case of DXA at femoral neck (AUROCC 0.869, p = 0.02), DXL at calcaneus (AUROCC 0.869, p = 0.059), and DXA at total hip (AUROCC 0.861, p = 0.06) was observed.

CONCLUSIONS

DXL was similarly sensitive compared with DXA for identification of subjects with vertebral fragility fractures, and combination of CRF with BMD by DXL or DXA further increased the discriminatory capacity for detection of patients susceptible to vertebral fracture.

Recent advances in the noninvasive diagnosis of renal osteodystrophy

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is the term used to describe a constellation of biochemical abnormalities, bone disturbances that may lead to fractures, and extraskeletal calcification in soft tissues and arteries seen in CKD. This review focuses on the noninvasive diagnosis of renal osteodystrophy, the term used exclusively to define the bone pathology associated with CKD. Transiliac bone biopsy and histomorphometry with double-labeled tetracycline or its derivatives remains the gold standard for diagnosis of renal osteodystrophy. However, histomorphometry provides a 'window' into bone only at a single point in time, and is not clinically practical for studying continuous changes in bone morphology. Furthermore, the etiology of fractures in CKD is multifactorial and not fully explained by histomorphometry findings alone. The propensity of a bone to fracture is determined by bone strength, which is affected by bone mass and bone quality; the latter is a term used to describe the structure and composition of bone. Bone quantity is traditionally assessed by dual X-ray absorptiometry (DXA) and CT-based methods. Bone quality is more difficult to assess noninvasively, but newer techniques are emerging and are described in this review. Ultimately, the optimal diagnostic strategy for renal osteodystrophy may be a combination of multiple imaging techniques and biomarkers that are specific to each gender and race in CKD, with a goal of predicting fracture risk and optimizing therapy.

Precision of a new tool to measure visceral adipose tissue (VAT) using dual-energy X-Ray absorptiometry (DXA)

OBJECTIVE

A new tool to quantify visceral adipose tissue (VAT) over the android region of a total body dual-energy x-ray absorptiometry (DXA) scan has recently been reported. The measurement, CoreScan, is currently available on Lunar iDXA densitometers. The purpose of the study was to determine the precision of the CoreScan VAT measurement, which is critical for understanding the utility of this measure in longitudinal trials.

DESIGN AND METHODS

VAT precision was characterized in both an anthropomorphic imaging phantom (measured on 10 Lunar iDXA systems) and a clinical population consisting of obese women (n = 32).

RESULTS

The intrascanner precision for the VAT phantom across 9 quantities of VAT mass (0-1,800 g) ranged from 28.4 to 38.0 g. The interscanner precision ranged from 24.7 to 38.4 g. There was no statistical dependence on the quantity of VAT for either the inter- or intrascanner precision result (p = 0.670). Combining inter- and intrascanner precision yielded a total phantom precision estimate of 47.6 g for VAT mass, which corresponds to a 4.8% coefficient of variance (CV) for a 1 kg VAT mass. Our clinical population, who completed replicate total body scans with repositioning between scans, showed a precision of 56.8 g on an average VAT mass of 1110.4 g. This corresponds to a 5.1% CV. Hence, the in vivo precision result was similar to the phantom precision result.

CONCLUSIONS

The study suggests that CoreScan has a relatively low precision error in both phantoms and obese women and therefore may be a useful addition to clinical trials where interventions are targeted towards changes in visceral adiposity.

Visceral adipose tissue quantification using Lunar Prodigy

A dual-energy X-ray absorptiometry (DXA) application to measure visceral adipose tissue (VAT) in the android region of a total body DXA scan has recently been developed. This new application, CoreScan, has been validated on the Lunar iDXA (GE Healthcare, Madison, WI) densitometer against volumetric computed tomography. The geometric assumptions underlying the CoreScan model are the same on the Prodigy (GE Healthcare, Madison, WI) densitometer. However, differences between the peak X-ray voltage and detector array configurations may lead to differences in VAT quantification. The purpose of this study was to evaluate the agreement of Prodigy and iDXA CoreScan values and to characterize differences in VAT precision between the instruments. Data from volunteers with paired Prodigy and iDXA measurements were used to define empirical adjustments to the VAT algorithm parameters (n=59) and validate performance on Prodigy (n=62). Prodigy VAT measurements were highly correlated to iDXA (r=0.984). The mean of the Prodigy-iDXA VAT volume differences was -13.8cm³ with a 95% confidence interval of -45 to +17cm³. The Bland-Altman 95% limits of agreement for the 2 methods were -252 to +224cm³. Measurement of short-term precision showed that measurement error variance on iDXA was smaller (p<0.01) than Prodigy (coefficient of variance: 7.3% vs 9.8%). Precision results are in agreement with previous reports on the differences between Prodigy and iDXA for body composition measures. Prodigy and iDXA measures of VAT are similar, but the lower precision of the Prodigy may require investigators to target larger changes in VAT.