Simulated change in body fatness affects Hologic QDR 4500A whole body and central DXA bone measures

The association of hip bone mineral density (BMD) with incident major osteoporotic and hip fractures varies by body mass index

BACKGROUND

Bone mineral density (BMD) measurement is less precise amongst those with body mass index (BMI) > 30 kg/m2. We hypothesized that the association of BMD with incident hip and major osteoporotic fractures (MOF; hip, clinical vertebral, forearm, or humerus) becomes weaker with increasing BMI.

METHODOLOGY

Our study population was 75,391 individuals age ≥ 50 years who had a bone density test in the province of Manitoba 1998 to 2018. BMD of the total hip was assessed on GE Lunar densitometers. Incident MOF and hip fractures were ascertained using linked health claims data over a mean (SD) follow-up of 8.6 (5.3) years. The associations of total hip BMD with incident major osteoporotic and hip fractures were estimated with Cox proportional hazards models including an interaction term between BMI category and BMD to test if the association of BMD with incident fractures varies by BMI.

RESULT

The multivariable adjusted associations of total hip BMD with incident MOF did not vary by BMI (hazard ratio [HR] 1.56, 95 % C.I. 1.30, 1.85 for BMI ≥ 40 kg/m2; HR 1.36, 95 % C.I. 1.17, 1.58 for BMI <18.5 kg/m2; p-value for interaction 0.14). However, the association of total hip BMD with incident hip fracture was stronger for those with BMI ≥ 35 kg/m2 (HR 2.16, 95 % C.I. 1.71, 2.74) compared to those with BMI <18.5 kg/m2 (HR 1.48, 95 % C.I. 1.19, 1.84, p-value 0.001 for interaction).

CONCLUSION

The associations of total hip BMD with incident major osteoporotic and hip fracture are as strong for those with very high BMI as for those with normal BMI. However, total hip BMD may have a weaker association with incident hip fracture among underweight individuals. Further studies to confirm and explain this finding are warranted.

Synthetic phantoms enable calibration between abattoir based dual energy X-ray absorptiometers used for prediction of lamb carcass composition

Dual energy x-ray absorptiometry (DXA) devices were installed at two Australian abattoirs to predict computed tomography (CT) determined fat % and lean % of lamb carcasses. This study tested three algorithms developed for these devices, termed β1, β2 and β3, and assessed their accuracy and precision in predicting CT composition. Algorithm β3 included the use of a plastic phantom calibration block scanned by both DXA devices to adjust prediction equations, resulting in superior accuracy to the algorithms without phantom calibration (β1 and β2). When compared to the gold-standard CT composition, the bias of the DXA predictions was lowest when using algorithm β3 at the two sites (-1.17%, -0.49% for fat %, 0.11%, -0.37% for lean %). The difference of DXA composition predictions between sites was lowest when using algorithm β3, which demonstrated between site differences of 0.59 CT fat %, and 0.46 CT lean%. In contrast, algorithm β1 and β2 produced differences of 23.7% and 30.8% for CT fat, and 17.3% and 21.9% for CT lean between the two DXA devices. There was a small difference of 0.78% between the fat predictions of the first DXA image compared to the second DXA image for each carcass. The precision of predictions improved slightly using algorithm β3. This work demonstrates that the in-line DXA systems can produce comparable results across sites.

"The least significant change on bone mineral density scan increased in patients with higher degrees of obesity"

BACKGROUND

The least significant change (LSC) threshold of 0.03 g/cm² is used to interpret bone mineral density (BMD) scans in the general population. Our working hypothesis was that the current LSC threshold would not be applicable in obese populations.

AIMS

The aim of this study was to calculate the LSC in an obese population.

METHODS

We performed an interventional study among 120 obesity patients, in whom two measurements of BMD were performed at 3 sites. Pairs of measures were used to calculate the LSC, using the Bland and Altman method.

RESULTS

We calculated that the LSC was 0.046 g/cm² at the lumbar spine, 0.069 g/cm² at the femoral neck, and 0.06 g/cm² at the total hip. We also calculated the LSC for each class of obesity and observed an increase in LSC with increasing body mass index (BMI). We calculated a LSC of 0.05 g/cm² in patients with class 2 or class 3 obesity, whereas the LSC in patients with class 1 obesity is similar to the threshold used in the general population.

DISCUSSION

In obese population, like BMD, LSC is higher than the threshold value of the general population, and increases with increasing BMI.

CONCLUSION

LSC of 0.05 g/cm² could be used in clinical practice in patients with class 2 or 3 obesity. These findings should help to improve the interpretation of BMD scans in these patients and optimize their management.

TRIAL REGISTRATION NUMBER

Comité de Protection des Personnes Ile-de France VII, France.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Bone mineral density 5 to 11 years after metabolic and bariatric surgery in adolescents with severe obesity compared to peers

Objective

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

Methods

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

Results

Compared to controls, adjusted mean DXA-BMD of the RYGB (n = 58) and VSG (n = 48) groups were lower at the hip (-10.0% and - 6.3%), femoral neck (-9.6% and - 5.7%) and ultra-distal radius (-7.9% and - 7.0%; all p < 0.001), respectively. DXA-BMD did not differ between RYGB and VSG groups. Trabecular volumetric BMD at the radius and tibia were lower in the RYGB (-30% and - 26%) and VSG (-15% and - 14%) groups compared to the control group (p < 0.001). Greater time since MBS was associated with lower BMD Z-scores at the hip (p = 0.05) and femoral neck (p = 0.045). Percent change in body mass index (BMI) from baseline or in the first year after MSB were not associated with bone measures at a median of 9.3 years post MSB.

Conclusion

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

The Significance of Dual-Energy X-ray Absorptiometry (DXA) Examination in Cushing's Syndrome-A Systematic Review

In recent years, the usefulness of dual-energy X-ray absorptiometry (DXA) as a valuable complementary method of assessing the content and distribution of adipose and lean tissue as well as bone mineral density and estimating the risk of fractures has been increasingly confirmed. The diagnosis and treatment of Cushing's syndrome remain challenging, and monitoring the effects of treatment is often necessary. DXA tests offer a potential solution to many problems related to the availability of a quick, detailed, and reliable analysis of changes in the content and distribution of individual body composition components. The article discusses total body DXA scans (FMI, VAT, ALMI), lumbar spine scans (VFA, TBS), and osteoporosis scans (BMD, T-score, Z-score)-all are of potential interest in Cushing's syndrome. The article discusses the use of the most important indicators obtained from a DXA test (FMI, VAT, ALMI, BMD, T-score, Z-score, VFA, TBS) and their clinical significance in Cushing's syndrome was verified. The literature from the last decade was used for the study, available in MEDLINE, Web of Science, and ScienceDirect.

The impact of obesity on the accuracy of DXA BMD for DXA-equivalent BMD estimation

INTRODUCTION

As the radiomics technique using texture features in CT is adopted for accessing DXA-equivalent bone mineral density (BMD), this study aims to compare BMD by DXA and predicted BMD to investigate the impact of obesity and central obesity in general patients.

MATERIALS AND METHODS

A total of 710 cases (621 patients) obtained from May 6, 2012, to June 30, 2021, were used in the study. We focused both their abdomen & pelvis CT's first lumbar vertebrae axial cuts to predict estimated BMD and bone mineral content (BMC). In each patient's CT, we extracted the largest trabecular region of the L1 vertebral body as a region of interest (ROI) using the gray-level co-occurrence matrices (GLCM) technique, and linear regression was applied to predict the indices. Cases were divided by central obesity/overall obesity and normal group by body mass index (BMI), waist circumference (WC), or index of central obesity (ICO) standard.

RESULTS

The coefficients were all above 0.73, respectively. P-values from ICO were over 0.05 when the measures were Hip BMD and Hip BMC. In contrast, those from ICO were 0.0131 and 0.0351 when the measures were L1 BMD and L1 BMC, respectively, which show a difference between the two groups.

CONCLUSIONS

The CT HU texture analysis method was an effective and economical method for measuring estimated BMD and BMC and evaluating the impact of obesity. We found that central obesity especially exerted an effect on the disturbance of the clinical BMD measurements since groups were significantly different under the ICO standard.

Changes in volumetric bone mineral density and bone quality after Roux-en-Y gastric bypass: A meta-analysis with meta-regression

This meta-analysis aimed to assess the effect of Roux-en-Y gastric bypass (RYGB) on three-dimensionally assessed volumetric bone mineral density (vBMD) with the effect of time on these changes, on bone quality, and the agreement of dual-energy X-ray absorptiometry (DXA) with quantitative computed tomography (QCT) or high-resolution peripheral QCT (HR-pQCT) estimates of bone loss. We searched PubMed, Web of Science, Cochrane, Scopus, and EBSCO. Longitudinal studies on adults undergoing RYGB in which vBMD was assessed by QCT or HR-pQCT with ≥6 months follow-up were included. Total hip (TH) changes were reported in four studies, lumbar spine (LS) in eight, radius in eight, and tibia in seven. Significant post-RYGB vBMD reductions occurred at all skeletal sites analyzed. Meta-regression revealed that time post-RYGB was significantly associated with vBMD deterioration in all skeletal sites except at the TH. RYGB also led to significant deterioration on bone quality. DXA underestimated LS and overestimated TH bone losses post-RYGB. In conclusion, RYGB was associated with significant vBMD loss, which makes screening of bone mass progression by three-dimensional technology a crucial clinical issue to prevent fracture risk and osteoporosis.

BMDs Derived From Total Body DXA are Strongly Correlated With Dedicated Hip and Spine BMD and are Associated With Prior Fractures in NHANES

Dedicated dual energy X-ray absorptiometry (DXA) bone mineral density (BMD) of the hip and spine are strongly associated with fractures, but it is not clear whether total body (TB) DXA measures correlate with dedicated DXA or relate to fractures. Using National Health and Nutrition Examination Survey (NHANES) data from years 2013-2014 and 2017-2018, we assessed Pearson correlations between dedicated and TB DXA measures. Associations with fractures were examined using self-reported prior fractures or fractures found on vertebral fracture assessment (VFA) using logistic regression models while controlling for age, gender, race/ethnicity, and body mass index. Among 1418 subjects from NHANES 2013-2014, we found signification correlations between all dedicated DXA BMD and TB DXA BMD measures. For dedicated spine BMD, the TB site with the strongest correlation was TB lumbar spine (r = 0.87, p < 0.001), while for dedicated total hip and femoral neck BMD, total body, pelvis, leg, and trunk BMD had the strongest correlations (r = 0.67-0.75, p < 0.001 for all). There were relatively few differences by sex or race/ethnicity. Findings were similar in 481 subjects from NHANES 2017-2018. In NHANES 2013-2014, there were 438 prior fractures in 370 subjects (26.3%). When controlling for age, gender, race/ethnicity, and body mass index, the adjusted odds ratio for fracture per T-score decrease of BMD were similar for TB BMD measures as for dedicated BMD measures (OR 1.10-1.28). In conclusion, total body DXA measures are correlated with hip and spine DXA and are strongly associated with prior fracture. Our results suggest that total body DXA measures are valid alternative sites to study BMD and fracture risk.

Fat Mass Has Negative Effects on Bone, Especially in Men: A Cross-sectional Analysis of NHANES 2011-2018

CONTEXT

The effect of high levels of obesity on bone health are not clear.

OBJECTIVE

We aimed to examine the associations of body composition and bone mineral density (BMD) in a large, nationally representative population with a wide range of body mass index.

METHODS

We analyzed 10 814 subjects aged 20-59 from NHANES 2011-2018 who had total body BMD and body composition data. Body composition was examined as lean mass index (LMI) and fat mass index (FMI). Linear regression models were created with BMD as the outcome, while examining LMI and FMI and controlling for age, gender, race/ethnicity, height, and smoking status.

RESULTS

In multivariable modeling, every 1 kg/m2 additional LMI was associated with 0.19 higher T-score, while every additional 1 kg/m2 in FMI was associated with 0.10 lower T-score (P < .001 for both). The negative association of FMI with BMD was mainly seen when adjusting for LMI. Effects of LMI were similar in men and women, but the effect of FMI was more negative in men (0.13 lower T-score per additional 1 kg/m2 of FMI in men vs 0.08 lower BMD T-score in women, P for interaction < .001).

CONCLUSION

In subjects under 60 years old, lean mass had a strong positive association with BMD. Conversely, fat mass had a moderate, negative association with BMD that was most notable in men at high levels of fat. Our results emphasize the importance of bone health in obesity and may explain site-specific increases in fracture rates in some studies of obese subjects.

Computed Tomography-Based L1 Bone Mineral Density in 624 Dutch Trauma Patients—Are North American Reference Values Valid in Europe?

Opportunistic screening for bone mineral density (BMD) of the first lumbar vertebra (L1) using computed tomography (CT) is increasingly used to identify patients at risk for osteoporosis. An extensive study in the United States has reported sex-specific normative values of CT-based BMD across all ages. The current study aims to validate North American reference values of CT-based bone mineral density in a Dutch population of level-1 trauma patients. All trauma patients aged 16 or older, admitted to our level-1 trauma center during 2017, who underwent a CT scan of the chest or abdomen at 120 kVp within 7 days of hospital admission, were retrospectively included. BMD measurements in Hounsfield Units (HU) were performed manually in L1 or an adjacent vertebra. Student’s t-tests were performed to compare the Dutch mean BMD value per age group to the North American reference values. Linear regression analysis and Pearson’s correlation coefficient (ρ) calculations were performed to assess the correlation between BMD and age. In total, 624 patients were included (68.4% men, aged 16–95). Mean BMD decreased linearly with 2.4 HU per year of age (ρ = −0.77). Sex-specific analysis showed that BMD of premenopausal women was higher than BMD of men at these ages. Dutch mean BMD values in the age groups over 35 years were significantly lower than the North American reference values. Our findings indicate that using North American BMD thresholds in Dutch clinical practice would result in overdiagnosis of osteoporosis and osteopenia. Dutch guidelines may benefit from population-specific thresholds.

Using opportunistic screening with abdominal CT to identify osteoporosis and osteopenia in patients with diabetes

Opportunistic osteoporosis screening involves measuring the attenuation of L1 vertebrae on abdominal computed tomography (CT), which correlates with DXA T-score. We found that this approach is useful for detecting low bone mass in patients with diabetes and propose L1 attenuation ≤ 135 Hounsfield units (HU) as a threshold for which DXA should be strongly considered.

INTRODUCTION

Attenuation of the L1 vertebrae on computer tomography (CT) images done for other reasons ("Opportunistic Osteoporosis Screening") has been found to correlate well with DXA-derived T-score. However, the method and the thresholds have never been tested specifically in those with diabetes mellitus (DM), in whom the fracture risk is greater than explained by BMD.

METHODS

In a retrospective study of subjects with DM who had both abdominal CT and DXA within 6 months of each other, we compared L1 attenuation and DXA T-score to define the sensitivity and specificity of thresholds previously established in the general population.

RESULTS

There were 313 subjects among whom 18 (5.8%) had prior major osteoporotic fracture (MOF). Subjects with MOF had lower T-scores (- 2.3 ± 1.4 vs. - 0.9 ± 1.4, p < 0.001) and L1 attenuation (104 HU ± 46 vs. 149 HU ± 47, p < 0.001) than non-fracture subjects. L1 attenuation ≤ 160 HU was 91% sensitive for osteoporosis, while ≤ 110 HU was 80% specific. For a higher T-score of ≤ - 1.5, L1 attenuation ≤ 135 HU showed balanced sensitivity and specificity (65% and 69%, respectively).

CONCLUSION

Opportunistic osteoporosis screening with abdominal CT is useful in determining the need for DXA screening in subjects with diabetes. We propose L1 attenuation ≤ 135 HU as a reasonable threshold for detecting the T-score of ≤ - 1.5, which is likely associated with increased fragility in DM.

The effect of excessive fat tissue on the measure of bone mineral density by dual X-ray absorptiometry: the impact of substantial weight loss following sleeve gastrectomy

PURPOSE

Dual-energy X-ray absorptiometry (DXA) is used in clinical routine to determine areal bone mineral density (aBMD). However, it is not clear whether excessive fat mass or substantial weight loss modify the aBMD measurements. The aim of this study was to evaluate the effect of soft tissue composition on aBMD measured by DXA using a clinical model (i.e. sleeve gastrectomy: SG) that induces substantial body weight loss.

METHODS

Areal bone mineral density and body composition (fat mass: FM and lean tissue mass: LTM) were determined by DXA in 41 obese patients (33 women, 80.5%) just before SG and 1 month later.

RESULTS

One month after SG, mean weight loss was -9.8 ± 2.6 kg, with a significant decrease in LTM and FM (kg) ranging from -7.3% to -9.5%. The relative variation in aBMD was increased at the lumbar spine (2.45 ± 3.44%) and decreased at the hip (-1.47 ± 2.28%), whereas no variation was observed for the whole body and radius. The variation in aBMD at the lumbar spine was inversely correlated with variations in weight, whole-body FM and trunk FM, but not LTM.

CONCLUSION

This study shows evidence of a potential effect of body composition, particularly FM, on aBMD. However, given the modest change in aBMD, which was close to the precision error of aBMD measurements, it appears that significant weight loss does not have a clinically significant impact on the evaluation of aBMD using DXA.

Independent relationships between bone mineral density, regional body fat and insulin sensitivity in white males

BACKGROUND

Adiposity and insulin sensitivity may affect bone mineral density (BMD), but the confounding effect of weight hinders discrimination of independent associations. We explored whether regional fat masses and insulin sensitivity are independently related to BMD.

MATERIALS AND METHODS

Relationships between total and regional body fat, insulin sensitivity and measures of BMD in 8 different regions were evaluated in a cross section of 590 generally healthy, white males, 274 of whom received measurement of insulin sensitivity (Si) using the intravenous glucose tolerance test. Measurements included total, android and gynoid fat and lean body mass and regional BMDs by dual-energy X-ray absorptiometry. Linear regression analyses were combined in a mediation analysis to explore associations with each regional BMD.

RESULTS

Weight correlated positively with total fat mass (R²  = 0.67, P < 0.001) and negatively with Si (R²  = 0.14, P < 0.001). Body composition measures were consistently positively related to BMD in all regions except lumbar and thoracic spine. Accounting for body weight rendered negative majority of associations between total and regional fat masses and BMDs. An independent association between android fat and spine BMD was particularly apparent. Si was positively associated with total and limb BMD (P < 0.01) specifically among exercisers. Accounting for Si diminished the associations of total fat (negative) and lean body mass (positive) with total and limb BMD.

CONCLUSION

Android fat is independently negatively associated with spine BMD. Among those taking exercise, increased insulin sensitivity is associated with higher limb BMD and may underlie positive associations between lean body mass and BMD.

Dual-energy X-ray absorptiometry underestimates in vivo lumbar spine bone mineral density in overweight rats

Dual-energy X-ray absorptiometry (DXA) is currently the most widely used technique for measuring areal bone mineral density (BMD). However, several studies have shown inaccuracy, with either overestimation or underestimation of DXA BMD measurements in the case of overweight or obese individuals. We have designed an overweight rat model based on junk food to compare the effect of obesity on in vivo and ex vivo BMD and bone mineral content measurements. Thirty-eight 6-month old male rats were given a chow diet (n = 13) or a high fat and sucrose diet (n = 25), with the calorie amount being kept the same in the two groups, for 19 weeks. L1 BMD, L1 bone mineral content, amount of abdominal fat, and amount of abdominal lean were obtained from in vivo DXA scan. Ex vivo L1 BMD was also measured. A difference between in vivo and ex vivo DXA BMD measurements (P < 0.0001) is evidenced with an underestimation of in vivo BMD by (8.47 ± 10.54)%. This difference was found for the chow and high fat, high sucrose diets (P = 0.008), and a significant interaction between in vivo measurements, ex vivo measurements, and diet was observed (P = 0.030). Also, the data show a positive significant correlation of ex vivo BMD with body weight, perirenal fat, abdominal fat, and abdominal lean. Multiple linear regression analysis shows that body weight, abdominal fat, and abdominal lean were independently related to ex vivo BMD. DXA underestimated lumbar in vivo BMD in overweight rats, and this measurement error is related to body weight and abdominal fat. Therefore, caution must be used when one is interpreting BMD among overweight and obese individuals.

Bone Density in the Obese Child: Clinical Considerations and Diagnostic Challenges

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

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.

Bone Structural Changes and Estimated Strength After Gastric Bypass Surgery Evaluated by HR-pQCT

Roux-en-Y gastric bypass surgery (RYGB) is an effective treatment of morbid obesity, with positive effects on obesity-related complications. The treatment is associated with bone loss, which in turn might increase fracture risk. The aim of this study was to evaluate changes in bone mineral density (BMD) and bone architecture assessed using dual-energy X-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT), 6 and 12 months after RYGB, and correlate them to changes in selected biochemical markers. A prospective cohort study included 25 morbidly obese patients (10 males, 15 females). Patients were examined with DXA of the hip and spine, HR-pQCT of radius and tibia, and blood sampling before and 6 and 12 months after RYGB. Patients lost in average 33.5 ± 12.1 kg (25.8 ± 8.5 %) in 12 months. In tibia, we found significant loss of total, cortical and trabecular volumetric BMD after 12 months (all p < 0.001). Microarchitectural changes involved lower trabecular number, increased trabecular separation, and network inhomogeneity along with thinning of the cortex. Estimated bone failure load was decreased after 12 months (p = 0.005). We found only minor changes in radius. Results demonstrate significant alterations of bone microarchitecture suggesting an accelerated endosteal resorption along with disintegration of the trabecular structure which resulted in a loss of estimated bone strength in tibia. Such changes may underlie the recently reported increased risk of fracture in bariatric patients after surgery. We only observed bone structural changes in the weight-bearing bone, which indicates that mechanical un-loading is the primary mediator.

The Look AHEAD Trial: bone loss at 4-year follow-up in type 2 diabetes

OBJECTIVE

To determine whether an intensive lifestyle intervention (ILI) designed to sustain weight loss and improve physical fitness in overweight or obese persons with type 2 diabetes was associated with bone loss after 4 years of follow-up.

RESEARCH DESIGN AND METHODS

This randomized controlled trial of intensive weight loss compared an ILI with a diabetes support and education (DSE) group among 1,309 overweight or obese subjects. Bone mineral density was assessed at baseline and after 1 year and 4 years of intervention.

RESULTS

ILI was effective in producing significant weight loss (5.3% vs. 1.8% in ILI and DSE, respectively; P < 0.01) and increased fitness (6.4% vs. -0.8%) at year 4. In men, ILI participants had a greater rate of bone loss during the first year (-1.66% vs. -0.09% per year in ILI and DSE, respectively). Differences between groups were diminished by one-half after 4 years (-0.88% vs. -0.05% per year in ILI and DSE, respectively) but remained significant (P < 0.01). The difference in rate of hip bone loss between groups over 4 years was related to increased weight loss in ILI. Among women, the rate of bone loss did not differ between ILI and DSE after 4 years.

CONCLUSIONS

A 4-year weight loss intervention was significantly associated with a modest increase in bone loss at the hip in men but not in women.

Obesity and fractures

Until recently obesity was believed to be protective against fractures. However, a report from a Fracture Liaison Clinic in the UK (2010) reported a surprisingly high proportion of obese postmenopausal women attending the clinic with fractures, and in the GLOW study (2011), a similar prevalence and incidence of fractures in obese and non-obese postmenopausal women was observed. Subsequently, other studies have demonstrated the importance of obesity in the epidemiology of fractures. Obese women are at increased risk of fracture in ankle, leg, humerus, and vertebral column and at lower risk of wrist, hip and pelvis fracture when compared to non-obese women. In men, it has been reported that multiple rib fractures are associated with obesity. Furthermore, falls appear to play an important role in the pathogenesis of fractures in obese subjects. Regarding hip fracture and major fractures, the FRAX algorithm has proven to be a useful predictor in obese individuals. Obese people are less likely to receive bone protective treatment; they have a longer hospital stay and a lower quality of life both before and after fracture. Moreover, the efficacy of antiresorptive therapies is not well established in obese people. The latter is a field for future research.

Bone metabolism after bariatric surgery

Bariatric surgery is a popular and effective treatment for severe obesity but may have negative effects on the skeleton. This review summarizes changes in bone density and bone metabolism from animal and clinical studies of bariatric surgery, with specific attention to Roux-en-Y gastric bypass (RYGB), adjustable gastric banding (AGB), and sleeve gastrectomy (SG). Skeletal imaging artifacts from obesity and weight loss are also considered. Despite challenges in bone density imaging, the preponderance of evidence suggests that bariatric surgery procedures have negative skeletal effects that persist beyond the first year of surgery, and that these effects vary by surgical type. The long-term clinical implications and current clinical recommendations are presented. Further study is required to determine mechanisms of bone loss after bariatric surgery. Although early studies focused on calcium/vitamin D metabolism and mechanical unloading of the skeleton, it seems likely that surgically induced changes in the hormonal and metabolic profile may be responsible for the skeletal phenotypes observed after bariatric surgery.

Bone loss after bariatric surgery: discordant results between DXA and QCT bone density

Several studies, using dual-energy X-ray absorptiometry (DXA), have reported substantial bone loss after bariatric surgery. However, profound weight loss may cause artifactual changes in DXA areal bone mineral density (aBMD) results. Assessment of volumetric bone mineral density (vBMD) by quantitative computed tomography (QCT) may be less susceptible to such artifacts. We assessed changes in BMD of the lumbar spine and proximal femur prospectively for 1 year using DXA and QCT in 30 morbidly obese adults undergoing Roux-en-Y gastric bypass surgery and 20 obese nonsurgical controls. At 1 year, subjects who underwent gastric bypass surgery lost 37 ± 2 kg compared with 3 ± 2 kg lost in the nonsurgical controls (p < 0.0001). Spine BMD declined more in the surgical group than in the nonsurgical group whether assessed by DXA (-3.3 versus -1.1%, p = 0.034) or by QCT (-3.4 versus 0.2%, p = 0.010). Total hip and femoral neck aBMD declined significantly in the surgical group when assessed by DXA (-8.9 versus -1.1%, p < 0.0001 for the total hip and -6.1 versus -2.0%, p = 0.002 for the femoral neck), but no changes in hip vBMD were noted using QCT. Within the surgical group, serum P1NP and CTX levels increased by 82% ± 10% and by 220% ± 22%, respectively, by 6 months and remained elevated over 12 months (p < 0.0001 for all). Serum calcium, vitamin D, and PTH levels remained stable in both groups. We conclude that moderate vertebral bone loss occurs in the first year after gastric bypass surgery. However, striking declines in DXA aBMD at the proximal femur were not confirmed with QCT vBMD measurements. These discordant results suggest that artifacts induced by large changes in body weight after bariatric surgery affect DXA and/or QCT measurements of bone, particularly at the hip.

Effect of pioglitazone on body composition and bone density in subjects with prediabetes in the ACT NOW trial

AIMS

This study examined the effects of pioglitazone on body weight and bone mineral density (BMD) prospectively in patients with impaired glucose tolerance as pioglitazone (TZD) increases body weight and body fat in diabetic patients and increases the risk of bone fractures.

METHODS

A total of 71 men and 163 women aged 49.3 (10.7) years [mean (s.d.)]; body mass index (BMI), 34.5 (5.9) kg/m(2) were recruited at five sites for measurements of body composition by dual energy X-ray absorptiometry at baseline and at conversion to diabetes or study end, if they had not converted.

RESULTS

Mean follow-up was 33.6 months in the pioglitazone group and 32.1 months in the placebo group. Body weight increased 4.63 ± 0.60 (m ± s.e.) kg in the pioglitazone group compared to 0.98 ± 0.62 kg in the PIO group (p < 0.0001). Body fat rose 4.89 ± 0.42 kg in the pioglitazone group compared to 1.41 ± 0.44 kg, (p < 0.0001) in placebo-treated subjects. The increase in fat was greater in legs and trunk than in the arms. BMD was higher in all regions in men and significantly so in most. PIO decreased BMD significantly in the pelvis in men and women, decreased BMD in the thoracic spine and ribs of women and the lumbar spine and legs of men. Bone mineral content also decreased significantly in arms, legs, trunk and in the total body.

CONCLUSIONS

Pioglitazone increased peripheral fat more than truncal fat and decreased BMD in several regions of the body.

Bariatric surgery, bone loss, obesity and possible mechanisms

Bariatric surgery remains the most effective treatment for severely obese patients. However, the potential long-term effects of bariatric surgical procedures on health, including bone health, are only partially understood. The goal of this review was to present data on the impact of bariatric surgery on bone metabolism and to analyse possible reasons for the loss of bone mass that frequently occurs after bariatric surgery. Such factors include nutritional deficiencies, rapid weight loss per se, effects of fat-derived adipokines and gut-derived appetite-regulatory hormones. However, the relative roles of these factors in skeletal regulation and the mechanisms by which they work are not yet fully defined. Our review was focussed on the complex relationship between body weight, fat mass and bone mass, as well as peripheral and central mediators potentially involved in the dual regulation of both energy and bone homeostasis. We also review the data on the inverse relationship between central obesity, bone marrow fat and osteoporosis. As the number of bariatric operations increases, it is imperative to recognize mechanisms responsible for bariatric surgery-induced bone loss, with careful monitoring of bone health including long-term fracture incidence in patients undergoing these procedures.

Association between bone mineral density and type 2 diabetes mellitus: a meta-analysis of observational studies

Type 2 diabetes mellitus (T2DM) influences bone metabolism, but the relation of T2DM with bone mineral density (BMD) remains inconsistent across studies. The objective of this study was to perform a meta-analysis and meta-regression of the literature to estimate the difference in BMD (g/cm²) between diabetic and non-diabetic populations, and to investigate potential underlying mechanisms. A literature search was performed in PubMed and Ovid extracting data from articles prior to May 2010. Eligible studies were those where the association between T2DM and BMD measured by dual energy X-ray absorptiometry was evaluated using a cross-sectional, cohort or case–control design, including both healthy controls and subjects with T2DM. The analysis was done on 15 observational studies (3,437 diabetics and 19,139 controls). Meta-analysis showed that BMD in diabetics was significantly higher, with pooled mean differences of 0.04 (95% CI: 0.02, 0.05) at the femoral neck, 0.06 (95% CI: 0.04, 0.08) at the hip and 0.06 (95% CI: 0.04, 0.07) at the spine. The differences for forearm BMD were not significantly different between diabetics and non-diabetics. Sex-stratified analyses showed similar results in both genders. Substantial heterogeneity was found to originate from differences in study design and possibly diabetes definition. Also, by applying meta-regression we could establish that younger age, male gender, higher body mass index and higher HbA_1C were positively associated with higher BMD levels in diabetic individuals. We conclude that individuals with T2DM from both genders have higher BMD levels, but that multiple factors influence BMD in individuals with T2DM.

Association between bone mineral density and type 2 diabetes mellitus: a meta-analysis of observational studies

Type 2 diabetes mellitus (T2DM) influences bone metabolism, but the relation of T2DM with bone mineral density (BMD) remains inconsistent across studies. The objective of this study was to perform a meta-analysis and meta-regression of the literature to estimate the difference in BMD (g/cm(2)) between diabetic and non-diabetic populations, and to investigate potential underlying mechanisms. A literature search was performed in PubMed and Ovid extracting data from articles prior to May 2010. Eligible studies were those where the association between T2DM and BMD measured by dual energy X-ray absorptiometry was evaluated using a cross-sectional, cohort or case-control design, including both healthy controls and subjects with T2DM. The analysis was done on 15 observational studies (3,437 diabetics and 19,139 controls). Meta-analysis showed that BMD in diabetics was significantly higher, with pooled mean differences of 0.04 (95% CI: 0.02, 0.05) at the femoral neck, 0.06 (95% CI: 0.04, 0.08) at the hip and 0.06 (95% CI: 0.04, 0.07) at the spine. The differences for forearm BMD were not significantly different between diabetics and non-diabetics. Sex-stratified analyses showed similar results in both genders. Substantial heterogeneity was found to originate from differences in study design and possibly diabetes definition. Also, by applying meta-regression we could establish that younger age, male gender, higher body mass index and higher HbA(1C) were positively associated with higher BMD levels in diabetic individuals. We conclude that individuals with T2DM from both genders have higher BMD levels, but that multiple factors influence BMD in individuals with T2DM.

Association between bone mineral density and type 2 diabetes mellitus: a meta-analysis of observational studies

Type 2 diabetes mellitus (T2DM) influences bone metabolism, but the relation of T2DM with bone mineral density (BMD) remains inconsistent across studies. The objective of this study was to perform a meta-analysis and meta-regression of the literature to estimate the difference in BMD (g/cm(2)) between diabetic and non-diabetic populations, and to investigate potential underlying mechanisms. A literature search was performed in PubMed and Ovid extracting data from articles prior to May 2010. Eligible studies were those where the association between T2DM and BMD measured by dual energy X-ray absorptiometry was evaluated using a cross-sectional, cohort or case-control design, including both healthy controls and subjects with T2DM. The analysis was done on 15 observational studies (3,437 diabetics and 19,139 controls). Meta-analysis showed that BMD in diabetics was significantly higher, with pooled mean differences of 0.04 (95% CI: 0.02, 0.05) at the femoral neck, 0.06 (95% CI: 0.04, 0.08) at the hip and 0.06 (95% CI: 0.04, 0.07) at the spine. The differences for forearm BMD were not significantly different between diabetics and non-diabetics. Sex-stratified analyses showed similar results in both genders. Substantial heterogeneity was found to originate from differences in study design and possibly diabetes definition. Also, by applying meta-regression we could establish that younger age, male gender, higher body mass index and higher HbA(1C) were positively associated with higher BMD levels in diabetic individuals. We conclude that individuals with T2DM from both genders have higher BMD levels, but that multiple factors influence BMD in individuals with T2DM.

Simulated increases in body fat and errors in bone mineral density measurements by DXA and QCT

Major alterations in body composition, such as with obesity and weight loss, have complex effects on the measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). The effects of altered body fat on quantitative computed tomography (QCT) measurements are unknown. We scanned a spine phantom by DXA and QCT before and after surrounding with sequential fat layers (up to 12 kg). In addition, we measured lumbar spine and proximal femur BMD by DXA and trabecular spine BMD by QCT in 13 adult volunteers before and after a simulated 7.5 kg increase in body fat. With the spine phantom, DXA BMD increased linearly with sequential fat layering at the normal (p < 0.01) and osteopenic (p < 0.01) levels, but QCT BMD did not change significantly. In humans, fat layering significantly reduced DXA spine BMD values (mean ± SD: -2.2 ± 3.7%, p = 0.05) and increased the variability of measurements. In contrast, fat layering increased QCT spine BMD in humans (mean ± SD: 1.5 ± 2.5%, p = 0.05). Fat layering did not change mean DXA BMD of the femoral neck or total hip in humans significantly, but measurements became less precise. Associations between baseline and fat-simulation scans were stronger for QCT of the spine (r(2)= 0.97) than for DXA of the spine (r(2)= 0.87), total hip (r(2) = 0.80), or femoral neck (r(2)= 0.75). Bland-Altman plots revealed that fat-associated errors were greater for DXA spine and hip BMD than for QCT trabecular spine BMD. Fat layering introduces error and decreases the reproducibility of DXA spine and hip BMD measurements in human volunteers. Although overlying fat also affects QCT BMD measurements, the error is smaller and more uniform than with DXA BMD. Caution must be used when interpreting BMD changes in humans whose body composition is changing.

The role of fat and lean mass in bone loss in older men: findings from the CHAMP study

PURPOSE

Weight loss is associated with bone loss; however, it is unclear whether loss of fat or loss of lean body mass plays the key role in this relationship. The aim of this longitudinal analysis was to clarify the relationship between hip BMD, hip BMC and whole body BMC with changes in fat and lean tissue mass in older men.

METHODS

The Concord Health and Aging in Men Project (CHAMP) is a population-based study in Sydney, Australia, involving 1705 men aged 70-97 years. Bone mineral density (BMD) of the total hip, and bone mineral content (BMC) of the hip and whole body (WB), lean mass and fat mass were measured with Dual X-ray Absorptiometry (DXA). Multivariate linear regression models were used to assess relationships.

RESULTS

Over 2.2 years of follow-up, 368(33%) men lost at least 2% of their body weight, which included a mean loss of 0.8 kg/year of lean body mass and 0.9 kg/year of fat body mass. Fat loss was strongly associated with BMD loss in men who lost weight. As a group, weight losers lost 1.0% of hip BMD annually compared to 0.2% in men who gained weight, with each kilo of fat loss associated with 0.6%/year hip BMD loss (p<0.0001). Lean mass was not associated with hip BMD loss in weight losers, however, lean mass change was associated with BMD change in men who gained weight (0.3% hip BMD increase per kilo increase of lean mass p<0.01).

CONCLUSION

Maintaining body weight is important for bone health in elderly men. Body fat plays an important role in this relationship, which may reflect the additional metabolic function of adipose tissue.

Risk factors for nonvertebral fracture in obese older women

CONTEXT

A high prevalence of obesity has recently been reported in postmenopausal women with low trauma fracture, suggesting that higher bone mineral density (BMD) in obese individuals may not be protective against fracture.

OBJECTIVE

The aim of this study was to compare BMD and other risk factors for nonvertebral fracture in 1377 obese postmenopausal women.

DESIGN

Characteristics of obese women with and without incident nonvertebral fracture were investigated among the prospective cohort in the Study of Osteoporotic Fractures.

SETTING

The Study of Osteoporotic Fractures is a multicenter study of 9704 women (>99% Caucasian) aged 65 yr and over who were recruited between September 1986 and October 1988 from population-based listings at four U.S. clinical centers.

MAIN OUTCOME MEASURE

The main outcome measure was nonvertebral fracture.

RESULTS

BMD T-scores in the spine, femoral neck, and total hip were significantly lower in obese women who experienced fractures than in obese women without fracture: mean differences, -0.56 [95% confidence interval (CI) = -0.73 to -0.39], -0.46 (95% CI = -0.57 to -0.36), and -0.51 (95% CI = -0.62 to -0.39), respectively (P < 0.0001 for all). A previous history of fracture [odds ratio = 1.69 (95% CI = 1.33-2.14); P < 0.0001] and femoral neck BMD [1.62 (95% CI = 1.42-1.85) per sd decrease in BMD; P < 0.0001] were independently associated with incident nonvertebral fracture.

CONCLUSIONS

Obese postmenopausal women who sustain nonvertebral fractures have significantly lower BMD on average than obese women without fracture and are more likely to have a past history of fracture. Fractures in obese postmenopausal women thus exhibit some characteristics of fragility fractures.

Obesity and fractures in postmenopausal women

Low body mass index (BMI) is a recognized risk factor for fragility fracture, whereas obesity is widely believed to be protective. As part of a clinical audit of guidance from the National Institute of Health and Clinical Excellence (NICE), we have documented the prevalence of obesity and morbid obesity in postmenopausal women younger than 75 years of age presenting to our Fracture Liaison Service (FLS). Between January 2006 and December 2007, 1005 postmenopausal women aged less than 75 years with a low-trauma fracture were seen in the FLS. Of these women, 805 (80%) underwent assessment of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA), and values for BMI were available in 799. The prevalence of obesity (BMI 30 to 34.9 kg/m(2)) and morbid obesity (BMI > or = 35 kg/m(2)) in this cohort was 19.3% and 8.4%, respectively. Normal BMD was reported in 59.1% of obese and 73.1% of morbidly obese women, and only 11.7% and 4.5%, respectively, had osteoporosis (p < .0001). Multiple regression analysis revealed significant negative associations between hip T-score and age (p < .0001) and significant positive associations with BMI (p < .0001) and previous fracture (p = .001). Our results demonstrate a surprisingly high prevalence of obesity in postmenopausal women presenting to the FLS with low-trauma fracture. Most of these women had normal BMD, as measured by DXA. Our findings have important public heath implications in view of the rapidly rising increase in obesity in many populations and emphasize the need for further studies to establish the pathogenesis of fractures in obese individuals and to determine appropriate preventive strategies.

Prevalence of osteoporosis and factors affecting bone mineral density among postmenopausal Turkish women with type 2 diabetes

OBJECTIVES

Controversy remains as to the effects of type 2 diabetes on bone metabolism. The aims of this study were to assess the association between type 2 diabetes and bone mineral density (BMD) and to evaluate the possible relationship between chronic diabetic complications and bone density.

METHODS

Bone mineral densities at the lumbar spine, femur, and radius in 206 postmenopausal Turkish women with type 2 diabetes were evaluated by dual-energy X-ray absorptiometry and compared with those in 61 age-matched postmenopausal nondiabetic women. Medical and lifestyle characteristics, body mass index (BMI), hemoglobin A1c level, and status of microvascular and macrovascular diabetic complications were recorded. Frequency of osteoporosis and that of osteopenia as well as the relationship between microvascular and macrovascular complications and BMD were evaluated.

RESULTS

The groups did not differ on BMDs and T scores at the hip, lumbar spine, and radius. Patients with radial and/or lumbar and/or hip osteoporosis had a longer duration of diabetes (P=.000), were older (P=.000), and had a lower BMI (P=.000). No correlation was found between osteopenia or osteoporosis and hemoglobin A1c level, presence of microalbuminuria, retinopathy, neuropathy, peripheral artery disease, cerebrovascular event, and coronary artery disease. Among the three sites, BMD at the hip was positively correlated with BMI (P=.000) but negatively correlated with age (P=.000) and duration of diabetes (P=.000). Presence of microalbuminuria revealed a negative correlation with BMD at the femoral neck (P=.042).

CONCLUSION

There is no evidence that type 2 diabetes influenced BMD in our postmenopausal patient group.

Assessment methods in human body composition

PURPOSE OF REVIEW

The present study reviews the most recently developed and commonly used methods for the determination of human body composition in vivo with relevance for nutritional assessment.

RECENT FINDINGS

Body composition measurement methods are continuously being perfected with the most commonly used methods being bioelectrical impedance analysis, dilution techniques, air displacement plethysmography, dual energy X-ray absorptiometry, and MRI or magnetic resonance spectroscopy. Recent developments include three-dimensional photonic scanning and quantitative magnetic resonance. Collectively, these techniques allow for the measurement of fat, fat-free mass, bone mineral content, total body water, extracellular water, total adipose tissue and its subdepots (visceral, subcutaneous, and intermuscular), skeletal muscle, select organs, and ectopic fat depots.

SUMMARY

There is an ongoing need to perfect methods that provide information beyond mass and structure (static measures) to kinetic measures that yield information on metabolic and biological functions. On the basis of the wide range of measurable properties, analytical methods and known body composition models, clinicians and scientists can quantify a number of body components and with longitudinal assessment, can track changes in health and disease with implications for understanding efficacy of nutritional and clinical interventions, diagnosis, prevention, and treatment in clinical settings. With the greater need to understand precursors of health risk beginning in childhood, a gap exists in appropriate in-vivo measurement methods beginning at birth.

Bone metabolism in adolescent boys with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a condition of severe undernutrition associated with low bone mineral density (BMD) in adolescent females with this disorder. Although primarily a disease in females, AN is increasingly being recognized in males. However, there are few or no data regarding BMD, bone turnover markers or their predictors in adolescent AN boys.

HYPOTHESES

We hypothesized that BMD would be low in adolescent boys with AN compared with controls associated with a decrease in bone turnover markers, and that the gonadal steroids, testosterone and estradiol, and levels of IGF-I and the appetite regulatory hormones leptin, ghrelin, and peptide YY would predict BMD and bone turnover markers.

METHODS

We assessed BMD using dual-energy x-ray absorptiometry and measured fasting testosterone, estradiol, IGF-I, leptin, ghrelin, and peptide YY and a bone formation (aminoterminal propeptide of type 1 procollagen) and bone resorption (N-telopeptide of type 1 collagen) marker in 17 AN boys and 17 controls 12-19 yr old.

RESULTS

Boys with AN had lower BMD and corresponding Z-scores at the spine, hip, femoral neck, trochanter, intertrochanteric region, and whole body, compared with controls. Height-adjusted measures (lumbar bone mineral apparent density and whole body bone mineral content/height) were also lower. Bone formation and resorption markers were reduced in AN, indicating decreased bone turnover. Testosterone and lean mass predicted BMD. IGF-I was an important predictor of bone turnover markers.

CONCLUSION

AN boys have low BMD at multiple sites associated with decreased bone turnover markers at a time when bone mass accrual is critical for attainment of peak bone mass.

A diet high in protein, dairy, and calcium attenuates bone loss over twelve months of weight loss and maintenance relative to a conventional high-carbohydrate diet in adults

Weight loss causes bone mineral loss. Higher protein diets continue to be criticized for further potential harmful bone effects, including elevated urinary calcium, but may promote bone health if protein sources include dairy. Overweight middle-aged subjects (n = 130, 59 males) were randomized to a diet providing 1.4 g.kg(-1).d(-1) protein and 3 daily servings of dairy (PRO) or 0.8 g.kg(-1).d(-1) protein and 2 daily servings of dairy (CARB) for 4 mo of weight loss plus 8 mo of weight maintenance. Diets prescribed 6276 kJ/d for females and 7113 kJ/d for males. Bone mineral content and density (BMD) for whole body (WB), lumbar spine (LS) and total hip (TH) were measured using dual X-ray absorptiometry, and dietary intake using 3-d weighed food records. Urinary calcium was measured using 24-h collection at 0 and 8 mo for a subsample (n = 42). Participants lost body weight (mean, 95% CI) of 8.2% (7.5-8.9%) at 4 mo, 10.6% (9.5-11.8%) at 8 mo, and 10.5% (8.9-12.0%) at 12 mo without differences between groups at any time (P = 0.64). At 12 mo, PRO BMD was higher by 1.6% (0.3-3.0%) at WB, 2.1% (0.6-3.7%) at LS, and 1.4% (0.2-2.5%) at TH compared with CARB. PRO calcium intake was higher (PRO: 1140 +/- 58 mg/d, CARB: 766 +/- 46; P < 0.01), as was urinary calcium (PRO: 163 +/- 15 mg/d, CARB: 100 +/- 9.2; P < 0.01). A reduced-energy diet supplying 1.4 g.kg(-1).d(-1) protein and 3 dairy servings increased urinary calcium excretion but provided improved calcium intake and attenuated bone loss over 4 mo of weight loss and 8 additional mo of weight maintenance.

Weight gain and restoration of menses as predictors of bone mineral density change in adolescent girls with anorexia nervosa-1

CONTEXT

Adolescents with anorexia nervosa (AN) have low bone mineral density. However, the effect of disease recovery, first, on bone density measures assessed using the Molgaard approach, which differentiates between reported low bone density resulting from short bones (based on height Z-scores) and that resulting from thin bones [based on measures of bone area (BA) for height] or light bones [based on measures of bone mineral content (BMC) for BA]; and second, on height-adjusted bone density measures, has not been well characterized. We hypothesized that menstrual recovery and weight gain (> or =10% increase in body mass index) would predict an increase in these measures of bone density.

METHODS

In a prospective observational study, lumbar and whole-body (WB) bone density was measured at 0, 6, and 12 months in 34 AN girls aged 12-18 yr and 33 controls. Using Ward's modification of the Molgaard approach, we determined measures of BMC for BA and BA for height at the lumbar spine and WB and also determined spine bone mineral apparent density and WB BMC adjusted for height.

RESULTS

Girls with AN had lower spine BMC for BA Z-scores (P = 0.0009), and lower WB BA for height Z (P < 0.0001), compared with controls. Menstrual recovery and weight gain in AN (AN-recovered) (median 9 months) resulted in a stabilization of BMD measures, whereas BMD continued to decrease in AN who did not gain weight and recover menses (AN-not recovered). AN-recovered also predicted greater increases in spine BMC for BA and WB BA for height, compared with AN-not recovered (P < 0.05).

CONCLUSIONS

Even short-term weight gain with menstrual recovery is associated with a stabilization of BMD measures.