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.     

Axial and peripheral bone mineral acquisition: a 3-year longitudinal study in Chinese adolescents

We performed a 3-year longitudinal study of a group of 179 healthy Chinese adolescents (92 boys and 87 girls) aged from 12 to 16 years to determine the effects of puberty, physical activity, physical fitness, and calcium intake on the acquisition of bone mass. At yearly intervals for 3 consecutive years we recorded nutrition, calcium intake and anthropometric measurements, and assessed pubertal status according to Tanner. Bone mass of the lumbar spine was determined by dual-energy X-ray absorptiometry and radial bone mass by single-photon absorptiometry. Physical fitness and level of physical activity were assessed and muscle strength and power determined by isokinetic testing. Peripheral bone mass correlated with axial skeleton bone mass. Age, pubertal staging, physical fitness and muscle strength were significantly associated with bone mass increments on cross-sectional univariate and regression analysis. Longitudinal regression analysis showed that the most important factor affecting bone mass accretion in adolescents in both sexes was their pubertal stage. In boys, bone mass increment throughout the study was greater in children who were already in the advanced pubertal stages on entering the study than in those who started puberty in year 2 or 3 of the study. The percentage change in bone mineral content of the forearm and in bone mineral density of the lumbar spine was greater than 25% in the advanced pubertal group as compared to around 20% in the less mature group. For girls, the reverse was true. The increment of bone mass during the study period was significantly greater in those who presented in the earlier pubertal stages than in those who were at the more advanced stage of puberty on entry into the study. There was no significant effect of calcium intake and physical activities on the bone mass accretion. Conclusion In Chinese adolescents, bone mineral accretion at adolescence is not influenced by exercise, level of physical fitness and calcium intake. In both sexes, and especially in girls, to optimally increase bone mass, regular physical exercise programmes should be instituted well before the onset of puberty rather than at or after it. Once puberty starts, these interventions may have no or only limited effect. Received: 23 September 1998 / Accepted in revised form: 11 January 1999     

Lean body mass and bone health in urban adolescents from northern India

Objective

To prepare percentile charts of lean body mass (LBM) among Indian urban children and adolescents; and to evaluate gender differences in LBM, and its relation with pubertal status.

Design

Secondary data analysis.

Setting

School in city of Delhi, India.

Participants

1403 apparently healthy children and adolescents (826 boys) with mean (SD) age 13.2 (2.7) years.

Outcome measures

Lean body mass assessed by dual energy absorptiometry.

Results

Total and regional lean mass were greater in older age groups in both sexes. LBM showed rising trends up to the age of 18 years in boys, whereas it plateaued after the age of 15 years in girls. The age-associated increase in LBM was significantly higher in boys (130%) compared to girls (83%) (P<0.001). Total and regional lean mass increased with progression of pubertal staging in both genders. During pubertal development, LBM almost doubled (100% increase) from stage-2 to stage-5 in boys, as opposed to a 73% rise in girls (P<0.001). Total and regional lean mass and Appendicular skeletal muscle mass index (ASMI) was positively correlated with age, body mass index (BMI), serum 25(OH)D, total fat mass, and bone mineral content (BMC). Relation between LBM and BMC remained significant even after adjusting for age, fat mass and various biochemical parameters.

Conclusion

Total and regional LBM rise with age and pubertal maturation in both genders, but more so in boys when compared to girls. LBM has direct bearing on BMC even after adjusting for age, fat mass and biochemical parameters.

     

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.     

Determinants of pregnancy in adolescents in Nepal

Objective : Social factors and prevalent norms in the community determine the proportion of teenage pregnancy in the community. In the light of high risk associated with teenage pregnancy, the socio-cultural determinants, which influence the conception among teenagers in Nepal, need to be understood. These determinants may be modified by suitable interventions to reduce teenage pregnancy. Aim of this study was to examine the socio-cultural determinants of teenage pregnancy in eastern Nepal.Methods : A case-control study design was selected for comparing the education, economic status, family support and freedom towards conception among teenagers as compared to higher age group women.Result : Seventy adolescent pregnant women were compared with seventy primigravida women in the 20 to 29 years age group. The teenage pregnant women were less educated, had poor economic background, more likely to have accidental pregnancies as compared to the other group and more likely to have love marriages. Husbands were more likely to decide about continuation of pregnancy. They had less psychological and social support from the family.Conclusion : Marriage at young age and pregnancy during teens are associated with less social acceptance and poor support in the family.     

青少年超重/肥胖与肠易激综合征相关性研究

目的初探青少年超重/肥胖与肠易激综合征(IBS)之间的相关性。方法随机选取初中及高中学生,测量身高、体质量,并填写IBS流行病学调查表。结果入选1 173名中学生,初中生700名,高中生473名;超重/肥胖的总检出率30.52%。男生中超重/肥胖检出率(28.40%)与女生(32.65%)的差异无统计学意义(P=0.114);初中生超重/肥胖检出率(30.57%)与高中生(30.44%)的差异也无统计学意义(P=0.963)。221名学生患有IBS,检出率为18.84%。男生IBS检出率(17.00%)与女生(20.68%)的差异无统计学意义(P=0.107);高中生IBS检出率(26.85%)高于初中生(13.43%),差异有统计学意义(P=0.000);超重/肥胖学生IBS检出率(22.07%)与正常体质量学生(17.42%)的差异无统计学意义(P=0.061);超重/肥胖与正常体质量学生之间IBS亚型的分布差异也无统计学意义(χ2=0.91,P=0.823)。结论超重/肥胖与IBS是青少年的常见病,但两者之间相关性还有待证实。     

Decreased lumbar spine bone mass and low bone turnover in children and adolescents with insulin dependent diabetes mellitus followed longitudinally

The effects of insulin dependent diabetes mellitus (IDDM) on bone metabolism are still not well defined. We evaluated total bone mineral content (TBMC) and bone mineral density (BMD) at the lumbar spine and femoral neck using dual X-ray absorptiometry in 26 IDDM children (15 M, 11 F) with a mean chronological age of 12.1+/-3.1 yr (range 7.1-14.2 yr). Duration of diabetes was 4.3+/-2.9 yr, with a mean glycosylated hemoglobin of 9.2+/-0.4%. BMD and TBMC standard deviation scores (Z-scores) were determined by comparing our results to controls matched for age, sex and pubertal status. BMD and bone formation and resorption markers were determined at the beginning of the study and after one year of follow up. Mean lumbar spine Z-score was -1.06+/-0.2, with negative values in 24 of 26 children (92.6%); 14/26 patients (53.8%) had a lumbar spine Z-score >1.0 SD below the mean. Mean lumbar spine Z-score remained unchanged after one year of follow up (-1.02+/-0.3). No significant differences were obtained in femoral neck BMD or TBMC between groups. No correlation was observed between lumbar spine BMD Z-scores and duration of IDDM or degree of diabetes control, as assessed by the mean glycosylated hemoglobin. Daily urinary calcium excretion was elevated in our patients initially and after one year of follow up; however, no correlation was obtained between lumbar spine BMD and 24 h urinary calcium excretion. Carboxy-terminal propeptide of type 1 collagen values and levels of urinary cross-linked N-telopeptides of type 1 collagen in the diabetic children were significantly lower than those of the matched controls. Osteoblastic activity as assessed by serum osteocalcin and by the carboxy-terminal propeptide of type I collagen and bone resorption as measured by cross-linked N-telopeptides of type 1 collagen did not correlate with the lumbar spine Z-scores. When IDDM patients were subdivided into males and females and into children with more than or less than 2 yr duration of diabetes since diagnosis, no differences between groups were found. These results suggest that insulin dependent diabetes in children is associated with low bone turnover resulting in a deficit in bone mass which may be manifested as osteopenia in the growing bone. This defect is already present in trabecular bone early on in the disease and seems not to be related to glycemic control.     

Childhood bone mass acquisition and peak bone mass may not be important determinants of bone mass in late adulthood

During childhood and adolescence, bone mass acquisition occurs primarily through skeletal growth. It is widely assumed that bone mass acquisition throughout childhood is an important determinant of the risk of osteoporosis in late adulthood; bone mass is thought to resemble a bank account in which deposits persist indefinitely. However, several well-controlled clinical studies suggest that increasing bone mass acquisition during childhood will have only transient effects. A likely explanation is that bone mass is governed by a homeostatic system that tends to return to a set point after any perturbation and, therefore, bone mass depends primarily on recent conditions, not those in the distant past. Indeed, in an animal model, we have shown evidence that bone mass acquisition in early life has no effect on bone mass in adulthood, in part because many areas of the juvenile skeleton are replaced in toto through skeletal growth. Therefore, it should not be assumed that alterations in childhood bone mass acquisition will affect bone mass many decades later in late adulthood. This issue remains open and the solution may depend on the type of childhood condition (for example calcium intake versus exercise) and its magnitude, timing, and duration. To date, both animal studies and clinical studies suggest that much of the effect of early bone mass acquisition does not persist.     

Reference centile curves for body fat percentage,fat-free mass,muscle mass and bone mass measured by bioelectrical impedance in Asian Indian children and adolescents

Objectives

To create gender-specific percentile curves for percent body fat (%BF) by Bio electrical Impedance Analysis (BIA) for screening adiposity and risk of hypertension in Indian children and generate reference curves for percent fat-free mass (%FFM), muscle mass (%LM) and bone mineral content (BMC) by using bioelectrical impedance.

Design

Secondary analysis of data from previous multicenter cross-sectional studies.

Setting

Private schools from five regions of India.

Participants

A random sample of 3850 healthy school children (2067 boys) (5-17 yr) from private schools in five major Indian cities.

Methods

Anthropometry, blood pressure (BP) and body composition were measured by bioelectrical impedance. Reference curves were generated by the LMS method.

Main outcome measures

%BF, %FFM, %LM, BMC and BP

Results

Median %BF increased by 6% from 5 to 13 years of age and declined (around 2%) up to 17 years in boys. In girls, %BF increased by 8% from 5 to 14 years and thereafter declined by 3%. Based upon the risk of hypertension, the new cut-offs of 75th and 85th percentile of %BF were proposed for detecting over fatness and excess fatness in children. Median %FFM was 90% at 5 yrs and decreased till 12 years, and then showed a slight increase to 84% at 17 yrs in boys. In girls, it was 86% at 5 yrs and decreased till 15 yrs, and plateaued at 71.8% at 17 yrs.

Conclusions

Reference curves for percent body fat for Indian children would be useful to screen children for health risk in clinical set up.

     

Body mass index in Bengali adolescents

We describe a mixed longitudinal analysis of body mass index (BMI) in a group of Bengali adolescents (age 11-17 years) from a middle income family background and compare this against existing national and international data. Healthy school children, comprising of 416 boys and 343 girls were consented for annual repeat measurements of weight, height and pubertal staging between the years 1998 and 2001. The LMS method was used to construct smoothed BMI mean and standard deviation (SD) curves. Bengali adolescents have lower BMI than affluent Indian children and are -1 to -2 SD below US children. BMI increases in adolescence (boys: r = 0.49, p < 0.001, girls: r = 0.54, P < 0.001) with age but SMR does not have an independent effect on BMI.     

Determinants of blood glucose variability in adolescents with insulin-dependent diabetes mellitus

Metabolic control and blood glucose variability in children with insulin-dependent diabetes mellitus (IDDM) during and after puberty were studied. Seventy-two children (43M, 29F), aged 10-19 years, with a 2-16-year duration of IDDM participated in the study. Fourteen of the patients were prepubertal (Tanner stage 1), 27 pubertal (Tanner 2-4) and 31 postpubertal (Tanner 5). They performed self-monitoring of blood glucose (SMBG) five times daily, every 2 days for 4 weeks. The SD (SDbg) for all values in each patient was calculated as a measure of blood glucose variability. Weight-length index, linear growth velocity and Tanner stage were recorded. Hemoglobin (Hb)A_Ic, alkaline phosphatase and sex hormone levels in serum were analyzed. Subjectively experienced hypoglycemic episodes were recorded. HbA_Ic levels showed no relation to Tanner stage. SDbg was lower in stage 5 than in stages 2-4 ( p = 0.02). There was no significant correlation between HbA _lc and SDbg, but the variability was significantly lower in individuals with mean blood glucose in the lower quartile compared with those in the upper three quartiles ( p < 0.001). Alkaline phosphatase concentration, as a measure of growth velocity, was the main independent determinant of SDbg ( r = 0.35, p < 0.005). There was an inverse correlation between levels of sex hormones and SDbg. We conclude that blood glucose variability is lower after than during puberty. This variability seems to be related to linear growth velocity or its biochemical marker.     

中国0～18岁儿童、青少年体块指数的生长曲线

目的 研究制定0～18岁中国儿童的体块指数(BMI)生长参照值及生长曲线.方法 根据"2005年中国九市7岁以下儿童体格发育调查"及"2005年中国学生体质与健康调研"所获得的资料,采用九省市93 702名0～19岁(差1天未满19岁)城区健康儿童青少年的身高(3岁以下测量身长)、体重测量数据,计算BMI值并应用LMS方法对数据进行拟合修匀,通过L、M、S三个参数计算产生所需要的百分位和标准差单位(Z分值)数值并绘制相应的曲线图.采用与中国成人BMI界值点接轨的方法探讨中国儿童超重肥胖的筛查界值点.结果 制定出0～18岁儿童的BMI百分位数及标准差单位生长参照值及曲线图,并计算出了筛查2～18岁儿童超重肥胖的参考界值点.本参照曲线与世界卫生组织(WHO)BMI曲线及美国疾病预防控制中心2000年(CDC2000)曲线进行比较,三者之间存在明显的差异,尤其是在青春期、第97百分位(P97)上.总体上中国男童BMI在p97处于三者之间,而女童最低.与日本比较,在P97也有明显差异.结论 使用BMI生长曲线图有利于儿童青少年的生长与营养监测,早期识别童的超重和肥胖,建议在临床工作及预防保健服务领域推广使用.     

中国0～18岁儿童、青少年体块指数的生长曲线

Objective To construct the body mass index(BMI)reference data and curves for Chinese children and adolescents from birth to 18 years of age.Methods Data from two national representative cross-sectional surveys which were The National Growth Survey of Children under 7 years in the Nine Cities of China in 2005 and The Physical Fimess and Health Surveillance of Chinese School Students in 2005,Height(length was measured for children under 3 years)and weight data of 93 702 urban healthy children from nilie cities/prodnces used to calculate tlle BMI.The LMS method was used to smooth the BMI,with estimates of L,M.and S parameters,values of percentile and Z-score curves which were required were calculated,and then standardized growth charts were generated.Adult cut-offs for overweisht and obesity at 18 years was used to study the cut-offs for children 2 to 18 years of age.Results The smoothed percentiles and Z-scores reference data and curves of BMI-for-age for boys and girls aged 0.18 years were made out respectively.BMI cut-off values for overweight and obesity for children from 2 to 18 years of age were also deftned.At 18 years,the BMI values are equivalent to the overweight cut-off (≥24 kg/rn2)and obesity cut-off(≥28 kg/m2)for Chinese adults.Comparison with the reference of the WHO and 2000 CDC for the United States,there were some difference among them,at the 97th percentile curve therewas a big difference between Chinese and U.S.adolescents.On the whole,the China BMI curve for boys was higherthan the WHO curve and lower than 2000 CDC at 97 percentile curve,but the China BMI curve for girls was lowest among the three curves.There was also significant difierence between China and Japan BMI values at 97 percentile curve.Conclusion BMI growth curves are very useful in child growth monitoring and nutritional surveillance,discovering overweight and obesity.The BMI growth charts are recommended for use in pediatric clinic and public health service.     

中国0～18岁儿童、青少年体块指数的生长曲线

Objective To construct the body mass index(BMI)reference data and curves for Chinese children and adolescents from birth to 18 years of age.Methods Data from two national representative cross-sectional surveys which were The National Growth Survey of Children under 7 years in the Nine Cities of China in 2005 and The Physical Fimess and Health Surveillance of Chinese School Students in 2005,Height(length was measured for children under 3 years)and weight data of 93 702 urban healthy children from nilie cities/prodnces used to calculate tlle BMI.The LMS method was used to smooth the BMI,with estimates of L,M.and S parameters,values of percentile and Z-score curves which were required were calculated,and then standardized growth charts were generated.Adult cut-offs for overweisht and obesity at 18 years was used to study the cut-offs for children 2 to 18 years of age.Results The smoothed percentiles and Z-scores reference data and curves of BMI-for-age for boys and girls aged 0.18 years were made out respectively.BMI cut-off values for overweight and obesity for children from 2 to 18 years of age were also deftned.At 18 years,the BMI values are equivalent to the overweight cut-off (≥24 kg/rn2)and obesity cut-off(≥28 kg/m2)for Chinese adults.Comparison with the reference of the WHO and 2000 CDC for the United States,there were some difference among them,at the 97th percentile curve therewas a big difference between Chinese and U.S.adolescents.On the whole,the China BMI curve for boys was higherthan the WHO curve and lower than 2000 CDC at 97 percentile curve,but the China BMI curve for girls was lowest among the three curves.There was also significant difierence between China and Japan BMI values at 97 percentile curve.Conclusion BMI growth curves are very useful in child growth monitoring and nutritional surveillance,discovering overweight and obesity.The BMI growth charts are recommended for use in pediatric clinic and public health service.     

中国0～18岁儿童、青少年体块指数的生长曲线

Objective To construct the body mass index(BMI)reference data and curves for Chinese children and adolescents from birth to 18 years of age.Methods Data from two national representative cross-sectional surveys which were The National Growth Survey of Children under 7 years in the Nine Cities of China in 2005 and The Physical Fimess and Health Surveillance of Chinese School Students in 2005,Height(length was measured for children under 3 years)and weight data of 93 702 urban healthy children from nilie cities/prodnces used to calculate tlle BMI.The LMS method was used to smooth the BMI,with estimates of L,M.and S parameters,values of percentile and Z-score curves which were required were calculated,and then standardized growth charts were generated.Adult cut-offs for overweisht and obesity at 18 years was used to study the cut-offs for children 2 to 18 years of age.Results The smoothed percentiles and Z-scores reference data and curves of BMI-for-age for boys and girls aged 0.18 years were made out respectively.BMI cut-off values for overweight and obesity for children from 2 to 18 years of age were also deftned.At 18 years,the BMI values are equivalent to the overweight cut-off (≥24 kg/rn2)and obesity cut-off(≥28 kg/m2)for Chinese adults.Comparison with the reference of the WHO and 2000 CDC for the United States,there were some difference among them,at the 97th percentile curve therewas a big difference between Chinese and U.S.adolescents.On the whole,the China BMI curve for boys was higherthan the WHO curve and lower than 2000 CDC at 97 percentile curve,but the China BMI curve for girls was lowest among the three curves.There was also significant difierence between China and Japan BMI values at 97 percentile curve.Conclusion BMI growth curves are very useful in child growth monitoring and nutritional surveillance,discovering overweight and obesity.The BMI growth charts are recommended for use in pediatric clinic and public health service.