Evaluation of cortical thickness and bone density by roentgen microdensitometry in growing males and females

The bone mineral content (BMC) and the cortical thickness at the distal radius and at the II metacarpal were assessed in growing individuals (167 females and 158 males) by radiometric and quantitative roentgen microdensitometric methods. BMC adjusted for age and pubertal status was significantly higher in males than in females. However, the BMC corrected for bone volume (volumetric bone density, g/cm³) and the metacarpal cortical index (cortical area/total area) were identical in males and females. BMC rose progressively with age, approaching a plateau by the end of puberty. Lower but still significant increases with age were also observed for volumetric bone density of the metacarpus and the metacarpal index. These increases were also most marked by the end of pubertal maturation and might be related to diminution of bone turnover.Conclusion This study provides the normative data of bone mass in growing individuals by making use of a reasonably accurate and easily available technique. The results obtained indicate that most of the differences between males and females and the changes with age are related to changes in skeletal dimension rather than density.     

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.     

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 (ΔBMC (g/year)) and BA (ΔBA (cm²/year)) according to sex and pubertal stages were calculated. ΔBA and ΔBMC were highly significantly associated with pubertal stages in girls and boys. Centile curves for ΔBA and ΔBMC according to sex and age were constructed using the LMS method. Peak ΔBA and ΔBMC values were reached earlier in girls (12.3 and 12.5 years, respectively) than in boys (13.4 and 14.2 years, respectively). The ΔBA peak was dissociated in time from the ΔBMC 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.     

Insulin-like growth factors and bone mineral density in African American and White girls

OBJECTIVES: African American children have greater bone mineral density (BMD) and bone mineral content (BMC) than white children. We examined the hypothesis that differences in insulin-like growth factors (IGFs) are important determinants of BMD during childhood. METHODS: We measured IGFs and IGF binding proteins in 59 African American and 59 white girls matched for age, body mass index, socioeconomic status, and pubertal stage. BMD and BMC were determined by dual emission x-ray absorptiometry. RESULTS: African American girls had greater total BMD (P <.001), BMC (P <.01), total IGF-1 (P <.001), and free IGF-1 (P <.01) than white girls. IGFBP-1, IGFBP-2, and IGFBP-3 were similar in both groups or lower in African Americans. IGF-1 was positively correlated with IGF-2 in white girls (P =.012) but was negatively correlated with IGF-2 in African Americans (P =.015). IGF-1 and free IGF-1 were positively correlated with BMD/BMC. Multiple regression analyses showed 80% of the variance in BMC could be accounted for by the use of body weight, height, and IGF-1 in the model. When IGF-1 was included as a factor, race did not add to the model's predictive power. CONCLUSION: IGF-1 and free IGF-1 are greater in African American than in white girls and may contribute to the greater BMD of African Americans.     

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.     

Relationship between local and total bone mineral in normal pubertal boys

The bone mineral content of the distal forearm (BMC) using single-photon absorptiometry and total body bone mineral (TBBM) using dual-photon absorptiometry were determined in 19 normal boys at different pubertal stages. A highly significant correlation between BMC and TBBM was seen (r=0.78, P<0.001) with a standard error of estimate (SEE) of 13%. Subgroups of early and late pubertal stages did not show any significant differences in the regression lines indicating an identical relationship between BMC and TBBM at various stages of pubertal development although great changes in bone mineral content take place. Due to high accuracy and reproducibility of both methods, which are non-invasive and harmless, measurement of BMC is suitable to estimate changes in total mineral content of the body. This may be of importance in various diseases with disturbance in growth and bone metabolism.Abbreviations BMC bone mineral content of the distal forearm - TBBM total body bone material - SEE standard error of estimate - PH pubic hair development     

Correlation of sex steroids with IGF-1 and IGFBP-3 during different pubertal stages

Insulin-like growth factor 1 (IGF-1) is the major factor that affects linear bone growth. Also, androgens and estrogens are necessary for increasing longitudinal bone growth during sexual maturation. The aim of this study was to investigate the relationships among IGF-1 axis and sex steroids during pubertal development in healthy adolescents. In this cross-sectional study, IGF-1, IGF binding protein-3 (IGFBP-3) and sex steroid levels (estradiol in girls, testosterone in boys) of 205 healthy adolescents (101 female, 104 male) aged 9-17 years were measured. All subjects were apparently healthy, with no growth retardation and with skeletal ages appropriate for chronological ages, and none were taking medications known to influence calcium homeostasis. Greulich and Pyle's Radiographic Atlas of Skeletal Development of the Hand and Wrist was used for determination of skeletal ages. Tanner's classification was used to determine the pubertal developmental stage. Fasting blood samples were obtained from subjects between 09:00-10:00 h. Serum IGF-1 and IGFBP-3 levels differed significantly between pubertal developmental stages. Serum IGF-1 levels and IGF-1/IGFBP-3 ratios increased with proceeding stages and maximum mean values were found at stages III-IV in girls and at stage IV in boys. Estradiol levels of girls and testosterone levels of boys differed significantly between stages, and in both sexes, serum IGF-1 levels and IGF-1/IGFBP-3 ratios were significantly correlated with sex steroid levels. Increase in growth hormone secretion increases IGF-1 levels. Furthermore, increasing sex steroids with pubertal development increase the IGF-1 levels and IGF-1/IGFBP-3 ratios that affect bone growth.     

A school-based exercise intervention augments bone mineral accrual in early pubertal girls

OBJECTIVE: To evaluate the effects of an elementary school-based physical education exercise intervention program on bone mineral accrual in prepubertal and early pubertal girls. STUDY DESIGN: A total of 14 schools were randomly assigned to control (C) and intervention (I) groups. Girls in the I group completed a 10-minute, 3 times per week circuit of varied jumping activities over 7 months. We measured total body, lumbar spine, proximal femur, femoral neck, and trochanteric bone mineral content and areal bone mineral density and estimated femoral neck volumetric bone mineral density at baseline and final measurement in 87 girls in the I group and 90 girls in the C group. Girls were between 8.7 and 11.7 years at baseline. Tanner stage 1 girls were considered prepubertal; Tanner stages 2 and 3 girls were considered early pubertal. We used analysis of covariance (adjusting for baseline bone values, change in size, age, and maturity) to compare 7-month change in bone mineral content, areal bone mineral density, and volumetric bone mineral density between C and I groups within prepubertal and early pubertal girls. RESULTS: There was no difference in 7-month change in bone parameters between prepubertal I and C groups. Early pubertal girls in the I group gained 1.5% to 3.1% more bone at the femoral neck and lumbar spine than early pubertal girls in the C group (P <.05); gain at other sites did not differ. CONCLUSIONS: In girls, early puberty may be a particularly opportune time during growth for simple exercise interventions to have a positive effect on bone health.     

Measured and predicted bone mineral content in healthy boys and girls aged 6–18 years: adjustment for body size and puberty

Dual-energy X-ray absorptiometry (DEXA) is a rapid and precise technique for the assessment of bone mineralization in children. Interpretation of the results in growing children is complex as results are influenced by age, body size (height and weight) and puberty. Conventionally, bone mineral data derived from DEXA have been presented as an areal density [BMD; bone mineral content (BMC, g)/projected bone area (BA, cm²)], yet this fails to account for changes in BMC that result from changes in age, body size or pubertal development. Measurement of BMC and BA of the whole body, lumbar spine and left hip were made in 58 healthy boys and girls using DEXA. The relationship between BMC and BA was curvilinear, with the best fit being that of a power model (BMD = BMC/BA^λ, where λ is the exponent to which BA is raised in order to remove its influence on BMC). The value of λ changed when measures of body size and puberty were taken into account (e.g. for lumbar spine from 1.66 to 1.49). Predictive formulae for BMC were produced using regression analysis and based on the variables of age, body size and pubertal development. This provides a method for interpreting the measured BMC which is independent of such variables and a constant reference range for children aged 6-18 y.     

Serum gonadotropins and estradiol levels in Turkish pubertal girls

Serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E₂) levels were measured by radioimmunoassay in the sera of 37 healthy Turkish pubertal girls. The data show that FSH levels significantly increased from stage 2 to 3, and tented to plateau during stages 3,4 and 5, and LH and estradiol levels constantly rises with advances in sexual development and significantly correlates with pubertal stages. When the serum FSH level was compared in pre and postmenarcheal girls of the same age the level was almost identical. Adversely, LH and estradiol levels were higher in postmenarcheal girls than in premenarcheal girls.     

Bone mineral content and bone mineral density are lower in older than in younger females with Rett syndrome

Although bone mineral deficits have been identified in Rett syndrome (RTT), the prevalence of low bone mineral density (BMD) and its association with skeletal fractures and scoliosis has not been characterized fully in girls and women with RTT. Accordingly, we measured total body bone mineral content (BMC) and BMD using dual energy x-ray absorptiometry in a cross-sectional group of 50 females, aged 2-38 y, with RTT. Methyl-CpG-binding 2 (MECP2) mutations, skeletal fractures, and scoliosis were documented. The prevalence of BMC and BMD z scores < or-2 SD was 59 and 45%, respectively. Although absolute BMC and BMD increased significantly with increasing age, BMC, and BMD z scores were significantly lower in older than in younger females. The prevalence of fractures and scoliosis was 28 and 64%, respectively. Low BMD z scores were positively associated with fractures and scoliosis. Deficits in BMD were identified across a broad range of MECP2 mutations. This study identified associations among low BMD, fractures, and scoliosis, and underscored the need for better understanding of the molecular mechanisms of MECP2 in the regulation of bone mineral metabolism.     

Determinants of axial and peripheral bone mass in Chinese adolescents

OBJECTIVE—To determine the relation of puberty, physical activity, physical fitness, and calcium intake with bone mineral content (BMC) of the distal radius, and on bone mineral density (BMD) of the L2 to L4 vertebrae in a group of healthy Chinese adolescents.DESIGN—Cross sectional survey.SUBJECTS—A group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged 12 to 13 years enrolled in the first year of the Tii Junior High School in Shatin, Hong Kong. Ninety four of the pupils enrolled were in the physical education major class (PE), and the other 85 were in the art major class (ARTS).MAIN OUTCOME MEASURES—Correlation of BMC of the distal radius and BMD of the L2 to L4 vertebrae with level of physical activity, physical fitness (isometric and isokinetic), muscle strength of the upper and lower limb, and calcium intake.RESULTS—BMC of the distal radius and BMD of the L2 to L4 vertebrae were significantly positively correlated. Univariate and regression analysis showed that age, pubertal staging, physical fitness, and muscle strength were significantly associated with bone mass in a positive way. Calcium intake and type of sport practised did not exert a significant influence on BMC of the distal radius and BMD of the L2 to L4 vertebrae in boys. The results for the BMD of the L2 to L4 vertebrae were similar in girls and boys; however, in girls, the BMC of the distal radius had a negative correlation with calcium intake. Physical fitness was a significant positive predictor of BMD of the L2 to L4 vertebrae.CONCLUSIONS—Among Chinese adolescents bone mass was positively influenced by certain measures of physical fitness as well as by age, weight, and pubertal stage.     

Markers of bone turnover are associated with growth and development in young subjects with sickle cell anemia

Children with sickle cell anemia (SCA) have low bone mass though bone turnover has not been well described. In this study, growth and pubertal development were assessed twice, 1 year apart, in 80 young subjects with type-SS SCA, while whole body bone mineral content (BMC) and density where measured in a subset (n = 46). Markers of bone turnover were measured at the second visit. Bone formation (alkaline phosphatase) was elevated, whereas bone resorption (deoxypyridinoline) was decreased compared to published data in healthy children. Markers of bone turnover correlated with growth velocity and pubertal development but not with changes in bone mass.     

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.     

Role of estrogen and androgen in pubertal skeletal physiology

Since both estrogen and androgen are present in each sex, it has been difficult to discern the exact role that each sex steroid plays in skeletal physiology. However, studying clinical syndromes in which there is either only estrogen or androgen action has allowed us to gain insight into the unique role that each sex steroid plays in the growing skeleton. In complete androgen insensitivity syndrome (AIS) the only functional sex steroid receptor is that for estrogen. Effected XY females have a pubertal growth spurt that is typical of normal females, both in magnitude and timing. Individuals with AIS have a mild reduction in bone density but it is difficult to distinguish whether this is the result of androgen resistance or estrogen deficiency. These observations suggest that estrogen action only is sufficient to induce a normal pubertal growth spurt, epiphyseal maturation, and near normal bone mineral accretion in women. Until recently, the skeletal effects of estrogen were not thought to be of importance in the male. Conventional wisdom dictated that, in the male, testosterone mediated these skeletal changes. The notion that estrogen is of little importance in the male has been challenged by the recent discovery of two human syndromes in which estrogen action is lacking. In males with either estrogen resistance (inability to respond to circulating estrogen) or aromatase deficiency (inability to synthesize estradiol), as a result of the lack of estrogen action, a pubertal growth spurt does not appear to occur. Furthermore, complete epiphyseal maturation does not take place allowing for continued growth in adulthood and resultant tall stature. Finally normal bone mineral accretion does not take place resulting in severe osteoporosis. These findings indicate that estrogen plays a critical role in skeletal physiology of males as well as females.     

Bone growth from 11 to 17 years: relationship to growth, gender and changes with pubertal status including timing of menarche

The tempo and change in bone growth during puberty in relation to physical growth is described in a cohort of 56 boys and 52 girls. Distal forearm bone width, mineral content and volumetric density, anthropometry and pubertal status were measured at ages 11, 13, 15 and 17 y, and bone age at 17 y. Bone width and mineral content increased independently with age for each pubertal stage. Volumetric density fell during early puberty and then increased rapidly. Maximal increase of all bone variables occurred earlier in girls than in boys and earliest for bone width, then mineral content, then density. In girls most change occurred in the 12 mo before and after menarche. The degree of tracking was similar to that for height. Bone growth followed physical growth but at a slower tempo. By age 17 y boys had attained 86% of the reference adult bone mineral content and volumetric density; girls had attained 93% of the reference adult bone mineral content and 94% of volumetric density. Those skeletally mature at 17 y had greater mineral content and volumetric density. To maximize peak bone mass, modifiable environmental factors should be optimized before the onset of puberty and be maintained throughout this period of rapid growth and beyond attainment of sexual maturity.     

青春期骨矿物含量与血清骨钙素及碱性磷酸酶的关系

目的：　了解青少年骨矿物含量(BMC)增长的特点及与性发育、体格发育的相关性。方法：　选取9～20岁健康青少年 ,采用单光子骨密度仪检测桡骨BMC ,放射免疫法测定血清骨钙素(骨谷氨酸蛋白)、雌二醇及睾酮水平,总碱性磷酸酶水平测定采用生化法 ,常规测定体格发育指标并评价性发育程度。结果：　男、女性身高和体重增加最快的年龄分别为11.5～13.7岁和9.7～11.3岁。BMC增长最快的年龄男性为13.7～16.2岁,女性为11.3～13.7岁。骨量增长与性发育水平关系密切 ,不同性发育阶段BMC差异有显著性(P<0.01)。血清骨钙素水平和总碱性磷酸酶随年龄增长的变化趋势一致(r =0 .59,0 .63 ,P <0.01) ,其高峰出现时间与身高增长速度高峰时间基本一致。结论：　男、女性骨量在青春期出现明显的增长,与性发育关系密切。骨量增长与体格发育具有不同步性     

Fractional calcium absorption is increased in girls with Rett syndrome

BACKGROUND: Rett syndrome (RTT), an X-linked neurodevelopmental disorder primarilyaffecting girls, is characterized in part by osteopenia and increased risk of skeletal fractures. We hypothesized that decreased intestinal calcium (Ca) absorption relative to dietary Ca intake and increased renal Ca excretion might cause these problems in RTT. OBJECTIVE: We measured fractional Ca absorption, urinary Ca loss, dietary Ca intake, and the hormonal factors regulating Ca metabolism to determine whether abnormalities in Ca balance might relate to poor bone mineralization in RTT girls and to evaluate the contribution of these factors to the overall dietary Ca needs of RTT girls. STUDY DESIGN: Ten RTT girls and 10 controls, matched for age, sex, and pubertal status, were given a 3 day constant Ca diet that mimicked their habitual intakes. At the end of each dietary period, girls received single doses of Ca (intravenous) and Ca (oral). Fractional urinary excretion of Ca, Ca, 24 hour urinary Ca, and urinary cortisol excretion were determined. Serum Ca, phosphorous, alkaline phosphatase, vitamin D metabolites, parathyroid hormone (PTH), and osteocalcin were measured in the postabsorptive state. Bone mineral content (BMC) was measured by dual-energy x-ray absorptiometry. RESULTS: Fractional Ca absorption was significantly higher in RTT than in control girls (mean +/- SDp, 52 vs. 33 +/- 13%). Dietary Ca intake (mean +/- SDp, 1,100 vs. 1,446 +/- 440 g/d) and net Ca absorption (mean +/- SDp, 513 vs. 362 +/- 306 mg/d) did not differ significantly between RTT and controls, respectively. Although urinary Ca excretion did not differ between groups, the increased urinary Ca:creatinine ratio (mean +/- SDp, 0.39 vs. 0.23 +/- 0.38) was consistent with clinical hypercalcuria and paralleled the significantly increased urinary cortisol excretion (mean +/- SDp, 3.1 vs. 1.7 +/- 1.1 mg/kg lean body mass per day) in the RTT girls. BMC was significantly lower in RTT than in controls (mean +/- SDp, 527 vs. 860 +/- 275 g). Serum Ca, P, alkaline phosphatase, vitamin D metabolites, PTH, and osteocalcin concentrations did not differ between the groups. CONCLUSION: Fractional Ca absorption showed a compensatory increase in the presence of adequate dietary Ca intakes, mild hypercalcuria, and pronounced bone mineral deficits in RTT girls. Whether supplemental dietary Ca could enhance fractional Ca absorption and improve bone mineralization in RTT girls is unknown.     

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.     

Estrogen receptor alpha polymorphism modifies the association between childhood exercise and bone mass: follow-up study

This follow-up study confirms our previous findings that the ER-alpha PvuII polymorphism (Pp) modulates the association between exercise and bone mass. The differences in bone properties of girls with consistently low physical activity (LLPA) and consistently high physical activity (HHPA) were evident only in those bearing the heterozygote ER-alpha genotype (Pp). In particular, areal bone mineral density of the total femur, bone mineral content and areal bone mineral density of the femoral neck, and bone mineral content and cortical thickness of the tibia shaft were significantly (p < .05) lower in the Pp girls with LLPA than in their HHPA counterparts. These findings might partly explain the genetic basis of human variation associated with exercise training.