Whole body bone mineral accretion in healthy children and adolescents.

Data on accretion in bone size and bone mineral content (BMC) are needed to evaluate bone mineralisation during childhood. Whole body bone mineral content (BMC) and bone area (BA) were determined by dual energy x ray absorptiometry (Hologic 1000/W) with a one year interval in healthy girls (n = 192) and boys (n = 140) aged 6-19 years. Annual accretion in BMC (DeltaBMC (g/year)) and BA (DeltaBA (cm2/year)) according to sex and pubertal stages were calculated. DeltaBA and DeltaBMC were highly significantly associated with pubertal stages in girls and boys. Centile curves for DeltaBA and DeltaBMC according to sex and age were constructed using the LMS method. Peak DeltaBA and DeltaBMC values were reached earlier in girls (12.3 and 12.5 years, respectively) than in boys (13.4 and 14. 2 years, respectively). The DeltaBA peak was dissociated in time from the DeltaBMC peak, indicating that increase in bone size occurs before increase in bone mineral content. Assuming that 32.2% of BMC consist of calcium, the median (90th centile) annual bone calcium accretion in pubertal stage III was 220 mg/day (302) and 317 mg/day (386) for girls and boys, respectively. To obtain an average bone calcium accretion, a high calcium absorption is needed during puberty. This may have implications for dietary calcium requirements at this time.     

Whole body bone mineral content in healthy children and adolescents

Data from healthy children are needed to evaluate bone mineralisation during childhood. Whole body bone mineral content (BMC) and bone area were examined by dual energy x ray absorptiometry (Hologic 1000/W) in healthy girls (n = 201) and boys (n = 142) aged 5-19 years. Centile curves for bone area for age, BMC for age, bone area for height, and BMC for bone area were constructed using the LMS method. Bone mineral density calculated as BMC/bone area is not useful in children as it is significantly influenced by bone size. Instead, it is proposed that bone mineralisation is assessed in three steps: height for age, bone area for height, and BMC for bone area. These three steps correspond to three different causes of reduced bone mass: short bones, narrow bones, and light bones.     

Whole body bone mineral content in healthy children and adolescents

Accepted 23 July 1996
Data from healthy children are needed to evaluate bone mineralisation during childhood. Whole body bone mineral content (BMC) and bone area were examined by dual energy x ray absorptiometry (Hologic 1000/W) in healthy girls (n=201) and boys (n=142) aged 5-19 years. Centile curves for bone area for age, BMC for age, bone area for height, and BMC for bone area were constructed using the LMS method. Bone mineral density calculated as BMC/bone area is not useful in children as it is significantly influenced by bone size. Instead, it is proposed that bone mineralisation is assessed in three steps: height for age, bone area for height, and BMC for bone area. These three steps correspond to three different causes of reduced bone mass: short bones, narrow bones, and light bones.

     

Rate of radial bone mineral accretion in healthy children

Radial bone width and mineral content were measured in 392 healthy Cambridge children aged 6–12 years from a cohort of 420 children studied 2 years previously. The typical rate of bone mineral accretion was 0.044 g/cm/year for boys across the whole age range and 0.042 g/cm/year for girls up to a mean age of 9 years, rising rapidly thereafter in association with changes in body size. The factors best predicting bone mineral accretion rate were mean bone mineral content, mean height, height velocity, weight velocity and bone width velocity. After adjusting for anthropometry, age did not contribute to the model. These are the first available longitudinal reference data for the rate of radial bone mineral accretion in healthy children.     

Influence of weight, age and puberty on bone size and bone mineral content in healthy children and adolescents

The biology of bone mineralization during growth is important for peak bone mass. The aim of the study was to examine how body size, age and puberty influence bone size and bone mineral density. Whole body bone area (BA) and bone mineral content (BMC) were examined by dual-energy X-ray absorptiometry (Hologic 1000/W) in healthy girls ( n = 201) and boys ( n = 142) aged 5–19 y. The influence of height, weight, age and puberty on bone mineralization was examined by multiple regression. Main determinants of BA were height and weight. Bone width, approximated by BA corrected for height, increased highly significantly with weight and depended weakly significantly on pubertal stage. Main determinants of BMC were BA, height, age and pubertal stages. Bone mineral density, approximated by BMC corrected for BA and height, depended on age and pubertal stage, but not on weight. Thus skeletal size is mainly determined by body size, while bone density is determined by age and pubertal stage.     

评价儿童青少年骨体重负荷的意义及指标选择(英文)

目的　探讨儿童青少年骨体重负荷对腰椎和髋部骨矿含量 (BMC)、骨密度 (BMD)的影响 ,并比较两指标的优次。方法　应用DXAQDR - 4 5 0 0A型扇形束骨密度仪测量长沙地区 5 4 7例 6～ 15岁儿童青少年腰椎前后位 ,仰卧侧位及髋部股骨近端的骨量。结果　不论男女 ,儿童青少年体重、体块指数 (BMI)、腰椎及髋部BMC和BMD随年龄增加而增加 (P <0 .0 5或 0 .0 1) ;体重与BMC的相关性较体重与BMD的相关性更密切 ;髋部及腰椎各部位体重标准化BMC随年龄增加而增大 ,而髋部和腰椎各部位体重标准化BMD随年龄增加反而减小。结论　 6～ 15岁儿童青少年腰椎及髋部BMC指标判断骨强度优于BMD ,尤以髋部及腰椎侧位BMC为佳。     

Bone mineral content and body composition in overweight children and adolescents

The aim of this study was to analyze the bone mineral content (BMC) of the skeleton and the body composition in lean and fat masses in a population of young overweight subjects, before diet or medical intervention. A total of 496 white youths (298 females, 198 males) were studied. Their body mass index (BMI) values were 29.2+/-5.5 kg/m2 in females and 28.3+/-5.1 kg/m2 in males, corresponding to relative weights (wts) [actual wt, W, divided by the mean wt normal for height (ht), Wi] of 1.55+/-0.24 and 1.53+/-0.24, respectively. Whole-body dual-energy x-ray absorptiometry (DXA) scans were performed (Norland XR36 DXA system) to obtain the total BMC (BMCt), lean tissue mass (LTMt) and fat mass (FMt), as well as the values of the corresponding parameters in arms (a), legs (l), and abdomen (ab). The measured data were compared with theoretical values calculated for Wi. The differences with reference values in LTMt and FMt were sex dependent, and the accretion in FMt, greater in males than in females, yielded a similar FMt/LTMt ratio in both sexes. The wt corresponding to the BMC of the bearing skeleton, lower than the actual wt by about 20%, seemed a reasonable first step to consider in the wt management of these youths.     

Dietary calcium and bone mineral status of children and adolescents

We studied 164 healthy, white children aged 2 to 16 years; there were 88 boys and 76 girls. By the method of single photon absorptiometry, we found that age, height, and weight correlated positively with bone mineral content of the radius bone. In the children's diet, most of those aged 2 to 11 years met the recommended dietary allowance (800 mg daily) for calcium. Children older than 11 years had low dietary calcium intake; only 15% met the recommended dietary allowance for calcium (1200 mg daily). Dietary calcium intake was associated with bone mineral status. Children ingesting more than 1000 mg of calcium daily had higher bone mineral content than those ingesting less. Almost all serum determinations of calcium, phosphate, magnesium, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were within normal limits and had no correlation with children's bone mineral status.     

Vertebra and femur neck bone mineral density values in healthy Turkish children

The bone mineral density (BMD) of the lumbar spine and femoral neck was measured by dual energy X-ray absorptiometry (DEXA) in 102 healthy Turkish children, aged 3-15, and values were correlated with age, height, weight and pubertal status. BMD increased with age in children of both sexes. The increase was steeper at the time of puberty. There were no significant differences between boys and girls until the age of 10. After the age of 10, lumbar BMD was higher in girls than in boys, probably because of the earlier onset of puberty in females. BMD was also highly correlated with height and weight. Because of low irradiation exposure, rapid scanning and high precision, DEXA is a non-invasive method, which is well adapted to children with diseases impairing bone metabolism.     

Bone mineral density in the cortical and trabecular distal forearm in healthy children and adolescents

Gunnes M. Bone mineral density in the cortical and trabecular distal forearm in healthy children and adolescents. Acta Pædiatr 1994;83:463–7. Stockholm. ISSN 0803–5253
Bone mineral density in cortical (BMDd) and trabecular parts (BMDud) of the distal forearm was studied in 494 healthy subjects ranging from 8 to 17 years with single photon absorptiometry. Mean BMDd was 6.8% higher ( p < 0.0001) in boys than in girls in the < 11 years age group ( n = 163). Mean BMDud was 8.2% higher ( p < 0.0001) in boys than in girls in the adolescent age group (<11 years, n = 331). While BMDd increased from 11 years of age in girls and was delayed by 2 years in boys, BMDud increased from 10 years of age in boys and was delayed by 1 year in girls. By multiple regression analysis, age, weight and height were variably related to bone density depending on measuring site, sex and age. At 14 years of age, postmenarcheal girls had obtained BMDud values similar to those of an adult premenopausal group. Cortical bone density in girls was very close to corresponding BMDd values of the adult premenopausal group at 16 years of age. In conclusion, this cross-sectional study indicates sex and age variability in forearm bone mineralization at trabecular and cortical sites. The substantial mineralization taking place between 11 and 16 years of age, with achievement of adult premenopausal bone density values, makes this 5–year period crucial for bone development.     

Total body mineral mass measured with dual photon absorptiometry in healthy children

Using dual photon absorptiometry, bone mineral content (BMC) and bone mineral density (BMD) of the total body and the lumbar spine were assessed in 97 healthy, Caucasian children aged 3–14 years. Excellent correlations were found between BMC and BMD on the one hand and age, body height and body weight on the other. No differences were found between boys and girls. There was a strong correlation between lumbar spine measurement as compared to those of the total body. Regression equations for total body and the different parts of the skeleton were calculated with either BMC or BMD as the dependent variable, and age, body height and body weight as independent variables. High variation coefficients were obtained in these multiple regressions, except for the head. For total body BMC and total body BMD, growth charts were constructed using Tanner and Whitehouse data on body height and body height and body weight.The increase in total body mineral content is an important feature of normal growth. Normal data for BMC and BMD in childhood are essential for bone mineralistation abnormalities in paediatric patients.     

Value of physical activity for proper bone mass and bone mineral density attaining in children and adolescents

Physical activity is an important factor for healthy life of the humans. Its significance regards mostly the developmental age, when natural mobility of the youth prones to the proper growing of the skeleton and is important in the prevention and therapy of many diseases. The advantageous effect of regular physical activity and different sport disciplines on bone mass and density is described. In the young age, puberty is an ideal moment for attaining the maximal bone mass and density gain due to physical exercising. The possible harmful effect of exaggerated physical activity has been shown. It is connected with hormonal disorders - secondary amenorrhea, delay of menarche, increased injuries and BMD loss together with significant body mass reduction.     

Volumetric bone mineral density is an important tool when interpreting bone mineralization in healthy children

In adults, it is well known that gender influences bone mass, but studies in children have shown contradictory results. Also, conflicting results have been reported regarding bone mineral density in obese children.
Objective: To investigate bone parameters in healthy 8-year-old children and relate them to anthropometry and self-reported physical activity (PA).
Design: Bone measurements were performed with dual X-ray absorptiometry in 96 children, and questionnaires were used to assess self-reported PA.
Results: Bone mineral content and density differed by gender. Eighteen percent of the children were overweight/obese and they had higher bone mineral content and density than children with normal weight. Bone mineral apparent density (g/cm³) of the lumbar spine did not differ, since the vertebral size differed, as was also the case between genders. Self-reported weight-bearing PA influenced bone mass in the hip.
Conclusion: PA influenced bone mineralization at this age. The differences in bone mineral content and density in healthy children would mainly be explained by the differences in bone size, reflected in body height and the width of the vertebrae. This indicates the importance of determining volumetric bone mineralization in children.     

Reproducibility of DXA measurements of bone mineral density and body composition in children

Background  The technique of X-ray-based dual photon absorptiometry (DXA) is frequently used in children for the detection of changes in bone mass or body composition. Such changes can only be considered real if the uncertainties arising from the measurement technique are exceeded. Objective  Our objectives were twofold: (1) to determine the reproducibility of bone mineral density (BMD) measurements in children at the spine and the hip and from the whole body, as well as of whole-body measurements of mineral mass, lean body mass and fat mass in children; and (2) to estimate, from the measured precision, the time interval that needs to elapse before a statistically significant change in a DXA variable can be detected. Materials and methods  The reproducibility of techniques for the measurement of BMD and body composition using DXA was measured in 15 young children (9 girls and 6 boys) and 17 older children (9 girls and 8 boys). Results  Reproducibility was derived from the standard deviation of three repeated measurements of spine BMD, total hip BMD, whole-body BMD (WBBMD), whole-body bone mineral content (WBBMC), lean mass and fat mass. Technique precision was better than 0.01 g cm⁻² for spine BMD and for WBBMD. Hip BMD measurements were slightly less precise, particularly in younger children (0.013 g cm⁻²). For body composition variables, technique precision was 13 g for WBBMC, 201 g for lean body mass and 172 g for fat mass in younger children. Technique precision for older children was 18 g, 251 g and 189 g for the corresponding variables. Predictions showed that the absence of a normal increase in WBBMC in a small-for-age girl could be established after 12 months. For spine BMD, a significant increase should be observable after 6 months for boys over the age of 11 years. For younger boys, more than 12 months has to elapse before anticipated changes can be detected with confidence. Conclusion  The time intervals required to elapse before decisions can be made concerning the significance of observed differences between successive measurements of BMD or body composition in children depend upon the age of the child.     

Bone metabolism biomarkers, body weight, and bone age in healthy Brazilian male adolescents

Eighty-seven male volunteers were grouped according to bone age (BA): 10-12 years (n=25), 13-15 years (n=36), and 16-18 years (n=26), and the following were recorded for each: weight (kg), height (m), BMI (kg/m(2)), calcium intake from three 24-h food recalls (mg/day), puberty evaluation by Tanner stages, bone biomarker (BB) evaluation, serum osteocalcin (OC), bone alkaline phosphatase (BAP), carboxyterminal telopeptide (S-CTx), and bone mineral density (BMD) evaluations by dual-energy X-ray absorptiometry (g x cm(2)) in the lumbar spine, proximal femur, and the whole body. BBs showed similar behaviors, and very high median values were observed for individuals aged 13-15 years (BAP = 155.50 IU/L, OC = 41.63 ng/mL, S-CT x =2.09 ng/mL). Lower median BB values were observed with advancing BA between 16 and 18 years (BA P =79.80 IU/L, O C =27.80 ng/mL, S-CT x =1.65 ng/mL). Stepwise multiple regression analysis showed body weight associated with BA as independent variables with greater determination power for S-CTx (r(2) = 0.40) and OC (r(2)=0.21). For BAP, stepwise analysis showed body weight and whole-body BMD (r(2) = 0.34). All predictive models showed significance ( p < 0.01). A high turnover for both bone formation and resorption biomarkers, particularly from 13 to 15 years of BA, were observed along with very low values in the 16-18 age range. Weight and BA were significant in determining predictive equations of OC and of S-CTx, whereas for BAP, weight and BMD of full body were selected.     

Whole body protein synthesis in relation to basal energy expenditure in healthy children and in children recovering from burn injury

Dynamic aspects of whole body nitrogen metabolism in children recovering from burn injury have been examined in relation to basal metabolic rate (BMR). A continuous administration of [15N]glycine was used to estimate the rates of whole body protein synthesis (S) and breakdown (C) in five acutely burned children (ages 5-16 years) and in nine healthy subjects (ages 9-18 years). S (grams of protein per kg body wt per day) and BMR were significantly correlated (r = +0.73; P less than 0.01). There was no significant correlation of C with BMR. The ratio of S (grams of protein per day) to BMR (kilocalories per day) was the same in burned and healthy children; the mean value for all children was 0.10 +/- 0.03 g protein synthesis/basal kcal. Calorie intake and S were significantly correlated (r = +0.70; P less than 0.01). There were significant correlations between BMR and percentage of total body surface area burned (r = +0.66; P less than 0.01), and BMR and age (r = -0.57; P less than 0.05). Age did not correlate significantly with percent of total body surface burned.