Bone mass and density in preadolescent boys with and without Down syndrome

Summary

Preadolescent boys with Down syndrome at 7–10 years of age have lower bone mass and density in the pelvis than age-matched children without Down syndrome. However, bone mass and density of total body less head and lumbar spine are not different between these two groups.

Introduction

This study aimed to assess bone mineral content (BMC) and density (BMD) in preadolescent boys with and without Down syndrome (DS) at 7–10 years of age.

Methods

Eleven preadolescent boys with DS and eleven age-matched children without DS participated in this study. Dual-energy X-ray absorptiometry was used to measure BMC and BMD in whole body and lumbar spine. Both BMC and BMD of total body less head (TBLH) and lumbar spine (vertebrae L2–L4) were compared between the two groups, with and without adjusting for physical characteristics such as bone area, body height, and total lean mass. Two bone mineral apparent density (BMAD) variables were calculated to estimate volumetric BMD in the lumbar spine.

Results

Both BMC and BMD in the pelvis were lower in the DS group, after adjusting for physical characteristics. However, with and without adjusting for physical characteristics, the two groups were not different in BMC and BMD of the arms, legs, and TBLH from the whole body scan and in BMC, BMD, and BMAD of the lumbar spine from the lumbar spine scan.

Conclusions

These findings indicate that the pelvis may be the first site to show the significant difference in BMC and BMD between preadolescent boys with and without DS. It also suggests that significantly lower BMC and BMD in whole body and lumbar spine, which is usually observed in young adults with DS, may not occur before adolescence.     

Bone mineral density by age, gender, pubertal stages, and socioeconomic status in healthy Lebanese children and adolescents

Gender, ethnicity, and lifestyle factors affect bone mass acquisition during childhood, thus the need for age- and sex-adjusted Z scores using ethnic-specific data for bone mineral density (BMD) measurement. This study aimed at establishing normative data for BMD in healthy Lebanese children and adolescents. Three hundred sixty-three healthy children aged 10 to 17 years (mean+/-SD: 13.1+/-2.0) were studied. BMD, bone mineral content (BMC), and lean mass were measured by dual-energy X-ray absorptiometry (DXA) using a Hologic 4500A device, and apparent volumetric BMD (BMAD) of the lumbar spine and the femoral neck were calculated. BMD, BMC, and BMAD were expressed by age groups and Tanner stages for boys and girls separately. There was a significant effect of age and puberty on all bone parameters, except at the femoral neck BMAD in boys. BMC and BMD were higher at cortical sites in boys, including subtotal body and hip; whereas, in girls, it was higher at a site more enriched in trabecular bone, namely the lumbar spine. At several skeletal sites, girls had significantly higher BMD adjusted for lean mass than boys. By the end of puberty, adolescents had a mean BMD that was 43-66% higher at the lumbar spine and 25-41% higher at cortical sites than pre-pubertal children, depending on the gender. Mean BMD values in the study group were significantly lower (P<0.01) than Western normative values, with Z scores ranging between -0.2 and -1.1. In both genders, children of lower socioeconomic status tended to have lower BMD than those from a higher socioeconomic background. This study allows additional insight into gender dimorphism in mineral accretion during puberty. It also provides a valuable reference database for the assessment of BMD in children with pubertal or growth disorders who are of Middle Eastern origin.     

High bone mineral apparent density in children with X-linked hypophosphatemia

Summary

Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck.

Introduction

BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients.

Methods

A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated.

Results

Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3–2.7); p?<?0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (?0.0 to 2.1); p?=?0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p?=?0.02). BMAD of the spine was evaluated according to the Molgaard’s approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of ?0.4 (?1.0 to 0.1); p?=?0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8–2.1); p?<?0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach.

Conclusions

Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.     

Diagnostic evaluation of bone densitometric size adjustment techniques in children with and without low trauma fractures

Summary

Several established methods are used to size adjust dual-energy X-ray absorptiometry (DXA) measurements in children. However, there is no consensus as to which method is most diagnostically accurate. All size-adjusted bone mineral density (BMD) values were more diagnostically accurate than non-size-adjusted values. The greatest odds ratio was estimated volumetric BMD for vertebral fracture.

Introduction

The size dependence of areal bone density (BMD_a) complicates the use of DXA in children with abnormal stature. Despite several size adjustment techniques being proposed, there is no consensus as to the most appropriate size adjustment technique for estimating fracture risk in children. The aim of this study was to establish whether size adjustment techniques improve the diagnostic ability of DXA in a cohort of children with chronic diseases.

Methods

DXA measurements were performed on 450 children, 181 of whom had sustained at least one low trauma fracture. Lumbar spine (L₂–L₄) and total body less head (TBLH) Z-scores were calculated using different size adjustment techniques, namely BMD_a and volumetric BMD for age (bone mineral apparent density (BMAD)); bone mineral content (BMC) and bone area for height; BMC for bone area; BMC for lean mass (adjusted for height); and BMC for bone and body size.

Results

Unadjusted L₂–L₄ and TBLH BMD_a were most sensitive but least specific at distinguishing children with fracture. All size adjustments reduced sensitivity but increased post-test probabilities, from a pre-test probability of 40 % to between 58 and 77 %. The greatest odds ratio for fracture was L₂–L₄ BMAD for a vertebral fracture and TBLH for lean body mass (LBM) (adjusted for height) for a long bone fracture with diagnostic odds ratios of 9.3 (5.8–14.9) and 6.5 (4.1–10.2), respectively.

Conclusion

All size adjustment techniques improved the predictive ability of DXA. The most accurate method for assessing vertebral fracture was BMAD for age. The most accurate method for assessing long bone fracture was TBLH for LBM adjusted for height.     

Calcium and vitamin D for osteoprotection in children with new-onset nephrotic syndrome treated with steroids: a prospective,randomized, controlled,interventional study

Background

There are no robust guidelines on strategies to prevent the adverse skeletal effects of glucocorticoids in children.

Objectives

To evaluate the role of prophylactic calcium and vitamin D on bone health in children with new-onset nephrotic syndrome (NS) treated with short-term (12 weeks), high-dose glucocorticoids.

Methods

Prospective, randomized, controlled, single blind, interventional study conducted on 41 steroid-naïve pre-pubertal children (29 boys, 12 girls). All children received prednisolone for 12 weeks (60 mg/m²/day daily for 6 weeks, followed by 40 mg/m²/day alternate days for 6 weeks). Recruited children were randomized into the intervention group (IG; vitamin D 1,000 IU/day and elemental calcium 500 mg/day) and the control group (CG). Bone mineral content (BMC) and bone mineral density (BMD) at the lumbar spine (L1–L4) were estimated at baseline and at 12 weeks. Mean percentage changes in BMC and BMD in IG and CG were compared.

Results

Children in the IG showed an increase of 11.2 % in BMC versus the CG, who showed an 8.9 % fall (p?<?0.0001). Net intervention-attributable difference in BMC was 20.1 %. BMD increased in both groups (IG 2.8 % vs CG 0.74 %), but the difference was not statistically significant (p?=?0.27).

Conclusions

Short-term, high-dose glucocorticoid therapy decreases the BMC of the lumbar spine in steroid-naïve children with NS. Vitamin D and calcium co-administration not only prevents this decline, but also enhances BMC of the lumbar spine.     

Revised reference curves of bone mineral density according to age and sex for Iranian children and adolescents

Summary

Bone health evaluation in children requires an appropriate reference database. We have shown higher curves for spine aBMD in Iranian subjects than Americans, but lower curves for femoral neck and total body. These results can be used as reference values to assist Iranian clinicians in interpreting and monitoring bone densitometry results.

Purpose

Bone health evaluation requires an appropriate reference database that can identify the bone deficit according to age, sex, puberty, and race. The aim of this study was to determine bone mineral density Z-scores in Iranian children and adolescents and their comparability with other reference data.

Methods

A sample of 476 healthy children and adolescents, aged 9–18 years, from Kawar (an urban community, 50 km east of Shiraz, Iran) was selected and bone mineral measurements of the lumbar spine, femoral neck, and total body (less head) were done. Sex-specific height-for-age, weight-for-age, and BMI-for-age Z-scores, as well as bone mineral density Z-scores, were calculated.

Results

Extended reference curves for bone mineral content (BMC) and areal bone mineral density (aBMD) of the total body less head, lumbar spine, and femoral neck, for ages 9–18 years were constructed relative to sex and age. We found that median, ??2SD, and +?2SD curves for the lumbar spine aBMD were higher in Iranian subjects than in the American participants, but the curves of the femoral neck and total body were lower. Also, we showed that subjects with a lower height-for-age Z-score had a lower BMC and aBMD Z-score in the lumbar spine, femoral neck, and total body (p?<?0.001).

Conclusions

Relevant differences in bone mineral density and its curves exist between Iranian children and adolescents and other databases, revealing a significant potential for misdiagnosis. However, our results can be used to provide reference databases to assist clinicians in interpreting, assessing, and monitoring bone densitometry.

     

Effect of whole body vibration (WBV) therapy on bone density and bone quality in osteopenic girls with adolescent idiopathic scoliosis: a randomized, controlled trial

Summary

The aim of this randomized controlled trial was to determine whether whole body vibration (WBV) therapy was effective for treating osteopenia in adolescent idiopathic scoliosis (AIS) patients. Results showed that WBV was effective for improving areal bone mineral density (aBMD) at the femoral neck of the dominant side and lumbar spine BMC in AIS subjects.

Introduction

AIS is associated with osteopenia. Although WBV was shown to have skeletal anabolic effects in animal studies, its effect on AIS subjects remained unknown. The objective of this study was to determine whether WBV could improve bone mineral density (BMD) and bone quality for osteopenia in AIS subjects.

Methods

This was a randomized, controlled trial recruiting 149 AIS girls between 15 and 25 years old and with bone mineral density (BMD) Z-scores <?1. They were randomly assigned to the Treatment or Control groups. The Treatment group (n?=?61) stood on a low-magnitude high-frequency WBV platform 20 min/day, 5 days/week for 12 months. The Control group (n?=?63) received observation alone. Bone measurement was done at baseline and at 12 months: (1) aBMD and BMC at femoral necks and lumbar spine using dual-energy X-ray absorptiometry (DXA) and (2) bone quality including bone morphometry, volumetric BMD (vBMD), and trabecular bone microarchitecture using high-resolution peripheral quantitative computed tomography (HR-pQCT) for nondominant distal radius and bilateral distal tibiae.

Results

The Treatment group had numerically greater increases in all DXA parameters with a statistically significant difference being detected for the absolute and percentage increases in femoral neck aBMD at the dominant leg (0.015 (SD?=?0.031)g/cm², 2.15 (SD?=?4.32)%) and the absolute increase in lumbar spine BMC (1.17 (SD?=?2.05)g) in the Treatment group as compared with the Control group (0.00084 (SD?=?0.026)g/cm², 0.13 (SD?=?3.62)% and 0.47 (SD?=?1.88)g, respectively). WBV had no significant effect for other bone quality parameters.

Conclusions

WBV was effective for improving aBMD at the femoral neck of the dominant side and lumbar spine BMC in AIS subjects.     

Bone density interpretation and relevance in Caucasian children aged 9-17 years of age: insights from a population-based fracture study.

The interpretation of bone density measurement in children is difficult due to a number of factors including rapid change in body size and uncertain clinical significance of bone density in children. This study asked two questions. (1) Is there a preferred bone density measurement site or type for fracture risk in children? (2) What is the best way to interpret bone density in children? This population-based case control study included 321 upper limb fracture cases and 321 class- and sex- matched randomly selected controls. Bone density at the hip, spine, and total body (including the arm) was measured by a Hologic QDR2000 densitometer (Waltham, MA) and examined as bone area (BA), bone mineral content (BMC), bone mineral density (BMD), bone mineral apparent density (BMAD), and BMC/lean mass (BMCLM). The only dual-energy X-ray absorptiometry (DXA) variables that were consistently associated with fracture risk in both boys and girls were spine BMD and BMAD for total upper limb fractures, and spine and hip BMAD for wrist and forearm fractures. No significant associations were observed for BA and BMCLM and inconsistent associations for BMC and other BMD sites. Five-yr fracture risk varied from 15–24% depending on site and gender in a child with a Z-score of -3. In the controls, all DXA variables were associated with age, height, and weight, but the weakest associations were with BMAD. In conclusion, in this study the spine BMAD had the strongest and most consistent association with upper limb fracture risk in children. The associations with age and body size imply that age specific Z-scores will be the most convenient for interpretation of DXA measures in children. Five-yr wrist and forearm fracture risk has potential as a clinical endpoint of immediate relevance.     

Pediatric reference data for bone mineral density in the calcaneus for healthy children 2, 4, and 7 years of age by dual-energy x-ray absorptiometry and laser.

Dual-energy X-ray absorptiometry and laser (DXL) Calscan measures bone mineral density (BMD) in the calcaneus. In the present study, the DXL Calscan device has been modified for use in pediatric practice. It includes a function for measuring calcaneal height, which makes it possible to calculate volumetric bone mineral apparent density (BMAD). The aims of the present study were to evaluate the method when used in children, to create pediatric reference values in healthy Swedish 2-, 4-, and 7-yr-old children for BMD, bone mineral content (BMC), and BMAD, and to study whether these parameters were related to auxological data. The method was well tolerated by all children. Intraindividual coefficients of variation for BMC and BMD decreased with increasing age. The mean BMD was 0.17+/-0.003 g/cm2 in 2-yr-old children, 0.22+/-0.003 g/cm2 in 4-yr-old children, and 0.30+/-0.005 g/cm2 in 7-yr-old children. This study provides normative data as percentile values for BMD, BMC, and BMAD in young children measured with DXL Calscan. BMD was significantly correlated with age (p<0.001), height (p=0.001), weight (p<0.001), and body mass index standard deviation score (p<0.001). Seven-year-old girls showed significantly higher BMD than boys.     

Physical activity throughout adolescence and bone mineral density in early adulthood: the 1993 Pelotas (Brazil) Birth Cohort Study

Summary

Association between three physical activity (PA) measurements throughout adolescence and bone density at 18 years of age was investigated. PA was associated with both lumbar spine and femoral neck bone mineral density (BMD) in early adulthood independent of type of PA used in the analysis. The results were more consistent in boys.

Introduction

This study amis to evaluate if PA during adolescence could influence BMD later in life.

Methods

A population-based birth cohort study was carried out. PA was assessed at 11 and 15 years of age by questionnaire and included sports performed while BMD (lumbar spine and femoral neck) was measured by dual-energy X-ray absorptiometry at 18 years. A peak strain score was generated based on ground reaction forces of different PA. PA was measured as peak strain score, peak strain score multiplied by minutes/week and minutes/week. Unadjusted and adjusted analyses were performed using linear regression.

Results

Overall, 3,811 adolescents were studied (1,866 boys and 1,945 girls). The peak strain score at 11 and 15 years was associated with lumbar and femoral neck BMD at 18 years in boys. Among girls, high-impact PA at 11 years was positively associated with lumbar and femoral BMD (p?=?0.01; p?<?0.001). After adjusted analysis, weekly minutes of PA at 11 years were not associated with lumbar spine but were associated with femoral neck BMD (p?<?0.001); at 15 years, weekly minutes of PA were positively associated with BMD at both sites. Regardless of PA status at 11 years of age, attaining the recommendations of PA (300 min/week) at 15 years appears to be important for BMD at 18 years in both sites in boys and girls. The results Appeared to be more consistent in boys.

Conclusions

PA during adolescence was positively associated with both lumbar spine and femoral neck BMD in early adulthood independent of type of PA used in the analysis.     

Normative data and percentile curves for Dual Energy X-ray Absorptiometry in healthy Indian girls and boys aged 5-17 years

For the correct interpretation of Dual Energy X-ray Absorptiometry (DXA) measurements in children, the use of age, gender, height, weight and ethnicity specific reference data is crucially important. In the absence of such a database for Indian children, the present study aimed to provide gender and age specific data on bone parameters and reference percentile curves for the assessment of bone status in 5-17 year old Indian boys and girls. A cross sectional study was conducted from May 2006 to July 2010 on 920 (480 boys) apparently healthy children from schools and colleges in Pune City, India. The GE-Lunar DPX Pro Pencil Beam DXA scanner was used to measure bone mineral content (BMC [g]), bone area (BA [cm(2)]) and bone mineral density (BMD [g/cm(2)]) at total body, lumbar spine and left femur. Reference percentile curves by age were derived separately for boys and girls for the total body BMC (TBBMC), total body BA (TBBA), lumbar spine bone mineral apparent density (BMAD [g/cm(3)]), and left femoral neck BMAD. We have also presented percentile curves for TBBA for height, TBBMC for TBBA, LBM for height and TBBMC for LBM for normalizing bone data for Indian children. Mean TBBMC, TBBA and TBBMD were expressed by age groups and Tanner stages for boys and girls separately. The average increase in TBBMC and TBBA with age was of the order of 8 to 12% at each age group. After 16 years of age, TBBMC and TBBA were significantly higher in boys than in girls (p<0.01). Maximal increase in TBBMD occurred around the age of 13 years in girls and three years later in boys. Reference data provided may be used for the clinical assessment of bone status of Indian children and adolescents.     

Apparent bone mineral density estimated from DXA in healthy men and women

The aim of this study was to measure bone mineral density (BMD) in healthy people and examine the influence of age, anthropometry, and postmenopause on calculated bone mineral apparent density (BMAD). The study included 541 healthy subjects (249 men and 292 women), aged 20 to 79 years. Anthropometric measurements included height, weight, and body mass index (BMI). Bone mineral content (BMC) and areal BMD were measured at the lumbar spine and proximal femur, using dual-energy X-ray absorptiometry (DXA). The calculation of volumetric density relied on the formula BMAD=BMD/BA (where BA = bone area). Association between densitometric parameters and age, height, weight, and postmenopause was analyzed with multiple regression. BMC and BMD decreased with age, especially in postmenopausal women. The average annual bone loss in spine was 0.2% in both sexes, whereas femur loss was 0.5% in men and 0.3% in women. Bone area slightly increased with age in both sexes, and BMD loss after the age of 50 could be attributed to bone area increase. To minimize the effect of bone size on bone density, volumetric density and areal density were regressed to age, anthropometry, and postmenopause. Age and postmenopause were significantly associated with BMD and BMAD in the spine and femur. Furthermore, BMD showed a stronger association with height and weight than BMAD, in both regions. Weaker association of body height and weight with BMAD than with BMD suggests that BMD depends on the bone size and body size and that the different BMDs could be the consequence of the difference in those parameters.     

Cortical and trabecular bone at the radius and tibia in male and female adolescents with Down syndrome: a peripheral quantitative computed tomography (pQCT) study

Summary

We aimed to describe the structure and strength of the tibia and radius of adolescents with Down syndrome. We observed that despite higher levels of volumetric bone mineral density in determined skeletal sites, they are at higher risk of developing osteoporotic fractures in the future due to their lower bone strength indexes.

Introduction

The aims of the study were to describe the cortical and trabecular volumetric bone mineral density (vBMD), bone mineral content (BMC), area, and bone strength in adolescents with Down syndrome (DS) and to compare them with adolescents without disabilities.

Methods

Thirty adolescents (11 girls) with DS and 28 without disabilities (10 girls) participated in the study. Peripheral quantitative computed tomography measurements were taken at proximal and distal sites of the tibia and radius. Values of total, trabecular, and cortical BMC; vBMD; and area were obtained of each scan. Cortical thickness and endosteal and periosteal circumferences were also measured, and different bone strength indexes were calculated. Student’s t tests were applied between groups.

Results

The DS group showed greater vBMD at distal radius, BMC at proximal radius, and total and cortical vBMD at proximal tibia. The non-DS group showed higher total and trabecular area at the distal radius and total, cortical, and trabecular BMC and area at distal tibia. Higher values of periosteal and endosteal circumference and bone strength were also found in non-DS group.

Conclusions

From these results, it can be believed that even with higher vBMD in determined skeletal sites, adolescents with DS are at higher risk of suffering bone fractures due to an increased fragility by lower resistance to load bending or torsion.     

Skeletal findings in children recently initiating glucocorticoids for the treatment of nephrotic syndrome

Summary

Eighty children with nephrotic syndrome underwent lumbar spine densitometry and vertebral morphometry soon after glucocorticoid initiation. We found an inverse relationship between glucocorticoid exposure and spine areal bone mineral density (BMD) Z-score and a low rate of vertebral deformities (8%).

Introduction

Vertebral fractures are an under-recognized complication of childhood glucocorticoid-treated illnesses. Our goal was to study the relationships among glucocorticoid exposure, lumbar spine areal BMD (LS BMD), and vertebral shape in glucocorticoid-treated children with new-onset nephrotic syndrome.

Methods

Lateral thoracolumbar spine radiography and LS BMD were performed in 80 children with nephrotic syndrome (median age 4.4?years; 46 boys) within the first 37?days of glucocorticoid therapy. Genant semiquantitative grading was used as the primary method for vertebral morphometry; the algorithm-based qualitative (ABQ) method was used for secondary vertebral deformity analysis.

Results

Six of the 78 children with usable radiographs (8%; 95% confidence interval 4 to 16%) manifested a single Genant grade 1 deformity each. All deformities were mild anterior wedging (two at each of T6, T7, and T8). Four of the 78 children (5%; 95% confidence interval 2 to 13%) showed one ABQ sign of fracture each (loss of endplate parallelism; two children at T6 and two at T8). Two of the children with ABQ signs also had a Genant grade 1 deformity in the same vertebral body. None of the children with a Genant or ABQ deformity reported back pain. An inverse relationship was identified between LS BMD Z-score and glucocorticoid exposure.

Conclusions

Although we identified an inverse relationship between steroid exposure and LS BMD soon after glucocorticoid initiation for childhood nephrotic syndrome, there was only a low rate of vertebral deformities. The clinical significance of these findings requires further study.     

Milk consumption throughout life and bone mineral content and density in elderly men and women

Summary

Association between bone mineral density and bone mineral content in old age and milk consumption in adolescence, midlife, and old age was assessed. The association was strongest for milk consumption in midlife: those drinking milk daily or more often had higher bone mineral density and content in old age than those drinking milk seldom or never.

Introduction

The role of lifelong milk consumption for bone mineral density (BMD) and bone mineral content (BMC) in old age is not clear. Here we assess the association between hip BMD and BMC in old age and milk consumption in adolescence, midlife, and current old age.

Methods

Participants of the Age, Gene/Environment Susceptibility-Reykjavik Study, aged 66–96 years (N?=?4,797), reported retrospective milk intake during adolescence and midlife as well as in current old age, using a validated food frequency questionnaire. BMC of femoral neck and trochanteric area was measured by volumetric quantitative computed tomography and BMD obtained. Association was assessed using linear regression models. Differences in BMC, bone volume, and BMD in relation to milk intake were portrayed as gender-specific Z-scores.

Results

Men consuming milk?≥?once/day during midlife had 0.21 higher Z-scores for BMD and 0.18 for BMC in femoral neck (95 % confidence interval 0.05–0.39 and 0.01–0.35, respectively) compared with?<?once/week. Results were comparable for trochanter. For women the results were similar, with slightly lower differences according to midlife milk consumption. For current and adolescent milk consumption, differences in Z-scores were smaller and only reached statistical significance in the case of BMD for current consumption in men, while this association was less pronounced for BMC.

Conclusions

Our data suggest that regular milk consumption throughout life, from adolescence to old age, is associated with higher BMC and BMD in old age, with no differences seen in bone volume. The strongest associations are seen for midlife milk consumption in both genders.     

Bone mineral density in prepubertal obese and control children: relation to body weight,lean mass,and fat mass

The aim of the study was to determine the influence of obesity on bone status in prepubertal children. This study included 20 obese prepubertal children (10.7 +/- 1.2 years old) and 23 maturation-matched controls (10.9 +/- 1.1 years old). Bone mineral area, bone mineral content (BMC), bone mineral density (BMD), and calculation of bone mineral apparent density (BMAD) at the whole body and lumbar spine (L1-L4) and body composition (lean mass and fat mass) were assessed by DXA. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) at the calcaneus were measured with a BUA imaging device. Expressed as crude values, DXA measurements of BMD at all bone sites and BUA (69.30 versus 59.63 dB/MHz, P < 0.01) were higher in obese children. After adjustment for body weight and lean mass, obese children displayed lower values of whole-body BMD (0.88 versus 0.96 g/cm2, P < 0.05) and BMC (1190.98 versus 1510.24 g, P < 0.01) in comparison to controls. When results were adjusted for fat mass, there was no statistical difference between obese and control children for DXA and ultrasound results. Moreover, whole-body BMAD was lower (0.086 versus 0.099 g/cm3, P < 0.0001), whereas lumbar spine BMAD was greater (0.117 versus 0.100 g/cm3, P < 0.001) in obese children. Thus, it was observed that, in obese children, cortical and trabecular bone displayed different adaptation patterns to their higher body weight. Cortical bone seems to enhance both size and BMC and trabecular bone to enhance BMC. Finally, considering total body weight and lean mass of obese children, these skeletal responses were not sufficient to compensate for the excess load on the whole body.     

Effect of bone area on spine density in Chinese men and women in Taiwan

Areal bone mineral density (BMD), the quotient of bone mineral content (BMC) divided by the projectional bone area (BA), measured with dual-energy X-ray absorptiometers (DXA), is the most common parameter used today to evaluate spinal osteoporosis. To evaluate whether gender, age, weight, and height can determine spinal BA, and to compare BA and analyze its effects on spinal density in the two genders, we measured BA and BMC, and calculated areal BMD, and the bone mineral apparent density (BMAD = BMD/√BA) of the L-2 to L-4 vertebrate of 604 female and 223 male Chinese volunteers from 20 to 70 years of age using a Norland XR-26 DXA. Standardized for height and weight, BA showed a relatively large variation and a significant increase with increasing age in both genders. On the other hand, BMC stayed unchanged in men > 50 years of age and decreased with aging in postmenopausal women. Younger men (< 51 years) had a much larger mean BA (by 15.5%) and larger mean BMC (only 10%) than that of age-matched women. As a result, younger men had a slightly and significantly lower areal BMD (by 7.1%) and a much lower BMAD (by 16%) (p < 0.0001 for both) than premenopausal women of similar age. Men had higher areal BMD and BMAD values than age-matched women only after age 50 years. Although taller body height, heavier weight, and increasing age were associated with a larger BA, these factors could not explain most of the interindividual variations in BA in both genders. Thus anteroposterior BA of lumbar vertebrate measured with DXA seems to affect the areal BMD and BMAD readings in the two genders. The larger BA caused a low BMAD and probably underestimated the true volumetric spine density in men.     

Two-year changes in bone and body composition in young children with a history of prolonged milk avoidance

No previous longitudinal studies of calcium intake, anthropometry and bone health in young children with a history of avoiding cows milk have been undertaken. We report the 2-year changes of a group of 46 Caucasian children (28 girls, l8 boys) aged 8.1±2.0 years (mean ± SD) who had low calcium intakes at baseline and were short in stature, with elevated body mass index, poor skeletons and lower Z scores for both areal bone mineral density (BMD, in grams per square centimeter) and volumetric density (bone mineral apparent density, BMAD, in grams per cubic centimeter), compared with a reference population of milk drinkers. At follow-up, adverse symptoms to milk had diminished and modest increases in milk consumption and calcium intake had occurred. Total body bone mineral content (BMC) and bone area assessed by dual energy X-ray absorptiometry had increased (P<0.05), and calcium intake from all sources was associated with both these measures (P<0.05). However, although some catch-up in height had taken place, the group remained significantly shorter than the reference population (Z scores –0.39±1.14), with elevated body mass index (Z scores 0.46±1.0). The ultradistal radius BMC Z scores remained low (–0.31±0.98). The Z scores for BMD had improved to lie within the normal range at predominantly cortical sites (33% radius, neck of femur and hip trochanter) but had worsened at predominantly trabecular sites (ultradistal radius and lumbar spine), where values lay below those of the reference group (P<0.05). Similarly, although volumetric BMAD Z scores at the 33% radius had normalized, BMAD Z scores at the lumbar spine remained below the reference population at follow-up (–0.67±1.12, P<0.001). Our results demonstrate persisting height reduction, overweight and osteopenia at the ultradistal radius and lumbar spine in young milk avoiders over 2 years of follow-up.     

Whole body bone mass and body composition in a girl with achondroplasia, at ages 9 through 12.

A 9-yr-old white female with achondroplasia was one of a group of 773 children who were recruited for a study of the accumulation of whole body skeletal mass during four annual measurements. Measurements of bone, fat, and lean mass were obtained with a Hologic 1000W instrument. The following variables are used to compare the subject with the 130 healthy white girls who participated in the study: bone mineral content (BMC), bone mineral density (BMD), and bone mineral apparent density (BMAD). Ratios of BMC to weight or BMC to height, and BMD to weight or height, were also calculated. We found that the BMC of the subject was lower when compared to the reference group, but the ratios of BMC to weight or BMC to height were similar in both. BMD was also lower in the patient, but, when expressed in relation to height and weight, the ratios were similar or slightly higher in the case. BMAD was higher in the subject with achondroplasia at all ages. The subject had a lower percentage fat and higher percentage lean mass than the reference children. We conclude that the accumulation of bone mass in this subject with achondroplasia is appropriate for her reduced body size.     

Effect of once-yearly zoledronic acid on the spine and hip as measured by quantitative computed tomography: results of the HORIZON Pivotal Fracture Trial

Summary

Changes in bone mineral density and bone strength following treatment with zoledronic acid (ZOL) were measured by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA). ZOL treatment increased spine and hip BMD vs placebo, assessed by QCT and DXA. Changes in trabecular bone resulted in increased bone strength.

Introduction

To investigate bone mineral density (BMD) changes in trabecular and cortical bone, estimated by quantitative computed analysis (QCT) or dual-energy X-ray absorptiometry (DXA), and whether zoledronic acid 5 mg (ZOL) affects bone strength.

Methods

In 233 women from a randomized, controlled trial of once-yearly ZOL, lumbar spine, total hip, femoral neck, and trochanter were assessed by DXA and QCT (baseline, Month 36). Mean percentage changes from baseline and between-treatment differences (ZOL vs placebo, t-test) were evaluated.

Results

Mean between-treatment differences for lumbar spine BMD were significant by DXA (7.0%, p?<?0.01) and QCT (5.7%, p?<?0.0001). Between-treatment differences were significant for trabecular spine (p?=?0.0017) [non-parametric test], trabecular trochanter (10.7%, p?<?0.0001), total hip (10.8%, p?<?0.0001), and compressive strength indices at femoral neck (8.6%, p?=?0.0001), and trochanter (14.1%, p?<?0.0001).

Conclusions

Once-yearly ZOL increased hip and spine BMD vs placebo, assessed by QCT vs DXA. Changes in trabecular bone resulted in increased indices of compressive strength.