Body composition in a cohort of Swedish adolescents aged 15, 17 and 20.5 years

Objective: To assess variables of body composition and identify their correlates in a group of individuals studied from adolescence to early adulthood. Methods: Cross‐sectional results were obtained from 203, 149 and 106 subjects at the respective ages. Sixty‐two subjects examined at all three ages constituted the longitudinal study group. A cohort of randomly selected 15‐year‐old adolescents from an industrial town in Sweden was studied by dual energy X‐ray absorptiometry (DXA) and followed up at 17 and 20.5 years. Lean body mass (LBM), fat mass (FM) and total body bone mineral content (TBMC) were measured by DXA. Total bone mineral density (TBMD) was calculated. Information of parental educational level, energy intake and food habits, energy expenditure (TEE) and physical activity level (PAL) was obtained by questionnaires and diaries. Results: LBM, TBMC and TBMD increased significantly more in males and FM more in females, from 15 to 20.5 years of age. Body weight, height, TEE, PAL and the fathers' educational level and, at age 15, also gender were identified as significant correlates of the body composition variables. Conclusion: New reference values for body composition at ages 15, 17 and 20.5 years are presented and also a finding about an association between the father's educational level and the adolescent's body composition.     

Growth hormone treatment enhances bone mineralisation in children with chronic renal failure

Dual energy X-ray absorptiometry of the whole body and the lumbar spine was performed to study bone mineralisation before and after 1 year of recombinant human growth hormone (rhGH) treatment in ten children with chronic renal failure. At the start, median age was 7.3 years (range 2.0–8.8 years) and median glomerular filtration rate 15 ml/min per 1.73 m² (range 7–41 ml/min per 1.73 m²). Total body mineral content (TBMC), lumbar spine mineral content (LBMC), total body bone mineral density (TBMD) and lumbar spine mineral density (LBMD) improved significantly (P < 0.05) after 1 year of treatment. Bone mineral data before and after treatment were compared with two groups of controls, i.e. ten healthy children matched for age and ten healthy children matched for height. Patients' TBMC, LBMC, TBMD and LBMD data before treatment were no different from those of height-matched controls; the same was true after 1 year of treatment except for the patients' significantly better LBMD (P < 0.05). When compared with age-matched controls, patients had significantly lower baseline TBMC and LBMC levels before treatment; after treatment LBMC was no longer different. However, there were no differences in TBMD or LBMD between patients and age-matched controls at baseline or after rhGH. Conclusion Recombinant human growth hormone treatment for 1 year results in a significant increase in both growth velocity and bone mineralisation. Comparison with height-matched controls shows a similar bone mineralisation at baseline and a better bone mineral density after treatment. Received: 10 August 2000 and in revised form 10 November 2000 and 5 January 2001 /  Accepted: 8 January 2001     

Familial and environmental influences on bone growth from 11-17 years

The influences on bone growth of familial factors, nutrition and physical activity are described in a cohort of 108 children (56M, 52F). Distal forearm bone width, mineral content and volumetric density, anthropometry, pubertal status, nutritional intake and physical activity were measured at ages 11, 13, 15 and 17 y. Parental forearm bone status was also determined. Both mothers' and fathers' bone variables were significant predictors of the respective children's bone variables, but heritability estimates were greater between mothers and their children than between fathers and their children. By age 17 y boys had attained 101%, 85% and 89% of their fathers' height, bone mineral content and volumetric density, respectively; girls had attained 103%, 95% and 98% of their mothers' height, bone mineral content and volumetric density, respectively. There were no consistent associations among nutrient variables and bone status or rate of change in bone status. However, there was a significantly greater increase in bone mineral content and density from 11-17 y in those girls with consistently high calcium intake. There were no significant correlations between physical activity and bone values or rate of change of bone values. Age, gender, pubertal status, height, weight and parental bone values accounted for 80%, 71% and 49% of the variance of bone mineral content, bone width and volumetric density, respectively and 52%, 55% and 58% respectively of the variance of change in these variables. After age, gender, sexual maturity and body size, heritability accounts for the greatest variance in bone values through adolescence.     

Decreased trabecular bone mineral density in patients with phenylketonuria measured by peripheral quantitative computed tomography

The bone mineral density (BMD) of 14 children, adolescents, and adults with phenylketonuria (PKU) on dietary treatment (age 5-28 y; 6F, 8M) was investigated using peripheral quantitative computed tomography (pQCT) of the distal radius. BMD of total (TBMD) and spongy bone (SBMD) were compared to those of healthy gender-, age-, weight- and height-matched controls. We found a significant decrease of SBMD in patients with PKU while TBMD was only slightly decreased, reaching no statistical significance. These results indicate minor changes of BMD in patients with PKU under treatment, which are more accentuated in the trabecular bone compartment. One additional patient who was untreated until the pQCT investigation at the age of 10 y also showed markedly decreased SBMD and TBMD.     

Physical activity positively predicts bone architecture and bone strength in adolescent males and females

Aims: Physical activity (PA) has positive effects on bone accrual and geometry in children during growth. However, we do not know how PA influences adaptations in bone architecture during growth. We evaluated the contribution of PA to bone density, architecture and strength in adolescents. Methods: We used HR‐pQCT (XtremeCT, Scanco Medical) to assess cross‐sectional moments of inertia [Imin, Imax (mm⁴)], total bone density (Tt.Dn, mg HA/cm³), total bone area (Tt.Ar, mm²), cortical bone density (Ct.Dn, mg HA/cm³), cortical thickness (Ct.Th, μm), trabecular bone density (Tb.Dn, mg HA/cm³), trabecular number (Tb.N, mm^?1) and trabecular thickness (Tb.Th, μm) at the distal tibia in 146 male and 132 female participants (15–20 years). We evaluated the contribution of impact loading PA (ImpactPA) and non‐impact loading PA (NoimpactPA) on bone (p < 0.05). Results: ImpactPA explained 10% of variance in Imin (p = 0.000), and 12% of variance in Imax (p = 0.000) in male participants. In male participants, ImpactPA explained 6% of variance in Tt.Ar (p = 0.003). In female participants, ImpactPA explained 4% of variance in Tt.Dn (p = 0.011), 5% of variance in Tb.Dn (p = 0.004) and 8% of variance in Tb.N (p = 0.001). Conclusion: Our findings suggest that ImpactPA is significantly associated with bone architecture and bone strength in adolescent males and females.     

Is paediatric assessment of motor development of very preterm and low‐birthweight children appropriate?

Aim: To determine whether paediatricians that examine, in regular clinical practice, very preterm and very-low-birthweight children at 5 y of age detect neurological impairments and functional motor problems in these children.

Methods: We compared a paediatric judgement, a standardized neurological examination (Touwen examination) and a screening of motor development (Denver Developmental Screening Test; DDST) with the Movement ABC in 396 5-y-old very preterm and low-birthweight children.

Results: The Movement ABC detected clinically important motor disorders in 20.5% and borderline disturbances in 22.5% of the children. Compared to the Movement ABC, the sensitivity of the paediatric judgement was 0.19, Touwen examination 0.62 and DDST 0.52; the negative predictive values were 0.61, 0.74 and 0.69, respectively.

Conclusion: Paediatric assessment of motor development in 5-y-old very preterm and low-birthweight children generally is not sensitive enough to detect functional motor problems. The Movement ABC should be added to the assessment of the motor development of very preterm and low-birthweight children at 5 y of age.     

Bone and joint infection after traumatic implantation of Scedosporium prolificans treated with voriconazole and surgery

Scedosporium prolificans is an environmental mould that may cause local infection in bone and joints after traumatic implantation, or generalized infection in immunocompromised patients. The fungus is highly drug resistant, both in vitro and in vivo. We present a case of osteomyelitis and arthritis caused by S. prolificans in a 9-y-old boy whose knee had been punctured by a hawthorn spike. Treatment with different drugs was difficult and arthrodesis was necessary. Concomitantly, voriconazole was given, and after three months bone biopsies were sterile despite a high in vitro MIC-value of the fungus against voriconazole. Reversible skin depigmentation and fingernail oncholysis appeared toward the end of 17 months of voriconazole treatment. Twelve months after discontinuation of treatment, no signs of relapse were detected.

Conclusion: Voriconazole may be a valuable adjunct to surgical treatment of bone and joint infection by Scedosporium prolificans.     

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.     

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.     

Determinants of bone mineral density in prematurely born children aged 6–7 years

The aim of this study was to assess the long-term effects of prematurity and growth during the first year on bone mineralization in prematurely born children. The study group consisted of 38 prematurely born Finnish children (17M, 21F) examined at the age of 6-7 y. After birth, all children were fed with banked human milk until discharge from hospital. Thereafter, 27 children were partially breastfed until the age of 5–7 months. Infants with gestational age (GA) <33 weeks ( n = 25) received calcium 45-50 mg/100 kcal, phosphorus 40-45 mg/100 kcal, vitamin A 1000 IU/d, vitamin C 2 mg/d and vitamin D 400 IU/d until 2.5 kg. Infants born > 33 weeks received only vitamin D 400 IU/d. Bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry (DXA) of the lumbar spine (L2-L4) at 6-7 y of age. At examination, all children had normal height and weight. BMD values were within the confidence interval of the Finnish reference values. In regression analysis bone area, present weight, GA and weight at 1 y were the most significant factors explaining 77.1% of the variance of BMC. After adjusting for other independent variables the prematurely born children who were thinner at 1 y of age subsequently had higher BMC values when examined at the age of 6-7 y. This study shows that growth patterns during the first year of life have long-term effects on bone mineralization.     

Gender-specific effects of apolipoprotein E genotype on plasma lipid levels in a population-based sample of 6-7-year-old children in Spain

Aim: The effects of gender on the association between apolipoprotein E genotype and plasma lipid levels remain unclear in children. The aim of the present work was to evaluate these gender differences in a large population-based sample of 6-7-y-old children, free of the effects of sex hormones.

Methods: Lipid levels and apo E genotypes were studied in a sample of 1255 (631 M, 624 F) Caucasian schoolchildren, aged 6-7 (mean age, 6.7) y in Spain.

Results: A significant effect of the apo E genotype on plasma total cholesterol, LDL-C (low-density lipoprotein cholesterol) and apo B levels was observed. Taking the homozygous ε3 ε3 genotype as reference, the presence of the ε2 and ε4 alleles is associated with substantially lower and higher plasma levels, respectively, of these variables. It was found that the effect of the apo E polymorphism on total cholesterol, LDL-C and particularly on apo B levels was greater in girls than in boys.

Conclusion : At this prepubertal age, the influence of the apo E genotype on total cholesterol, LDL-C and apo B levels is more evident in girls than in boys. This difference in effect is not due to sex hormones. In our opinion, the earlier increase in adrenal androgens in girls than in boys at this age related to pubertal maturation could be responsible for these differences.     

Bone density in the Asian thalassaemic population: a cross-sectional review

As survival improves in β-thalassaemia, osteoporosis is emerging as a significant problem. This study examines bone mineral density (BMD) of thalassaemic patients of Asian origin (age range 9.5-24 y) to evaluate the extent of problems in this group and identify potential risk factors. Eleven patients were scanned using dual-energy X-ray absorptiometry. BMD z -scores and the bone mineral apparent density (BMAD) z -scores were calculated, to correct for short stature. All but three patients had lumbar spine BMD and BMAD z -scores below the mean. Three patients had BMAD z -scores more than 2.5 standard deviations below the mean. A negative correlation between age and BMAD was seen, as was an association between endocrine disorders and decreased bone density.

Conclusion: The data confirm significant reductions in BMD in the Asian thalassaemic population, even after correcting for body size. Further research is needed to identify risk factors and means of prevention.     

Thyroxine unmasks Addison's disease

Patients with primary hypothyroidism may also have other underlying associated endocrinopathies, which are important to exclude. A 15-y-old girl presented with clinical and biochemical evidence of hypothyroidism.

Conclusion: Thyroxine replacement unmasked Addison's disease and precipitated an acute adrenal crisis. On physiological steroid replacement therapy, her "hypothyroidism" resolved.     

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.     

Alterations in bone characteristics associated with glycemic control in adolescents with type 1 diabetes mellitus

OBJECTIVE: To determine whether bone characteristics in adolescents with type 1 diabetes mellitus (DM) are influenced by blood glucose regulation and disease duration. The subjects were adolescents with type 1 DM (n=55) recruited from the University of Utah's Primary Children's Pediatric Diabetes Treatment Center. A reference database consisting of 95 healthy adolescents from the same geographic area was used for comparison.Study design Measurements of the tibia by peripheral quantitative computed tomography were made to assess cortical and trabecular bone characteristics. Hip, spine, and whole body characteristics were measured by dual-energy x-ray absorptiometry. Height, weight, health histories, Tanner stage, disease duration, insulin regimen, and glycosylated hemoglobin values were recorded. RESULTS: Age, maturation, and body size and composition values were similar between the subjects with type 1 DM and reference. Subjects with type 1 DM had lower tibia trabecular and femoral neck density and whole body mineral content and density. The mean glycosylated hemoglobin value was inversely related to tibia trabecular bone density (R(2)=-0.30) and whole body bone mineral content (R(2)=-0.25) and accounted for 3.0% to 8.9% of the variance. CONCLUSIONS: Altered bone mineral acquisition in adolescents with type 1 DM may limit peak bone mass acquisition and increase the risk of osteoporosis in later life.     

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     

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。     

Age and gender differences in VO2max in Swedish obese children and adolescents

AIM: To describe age and gender differences in estimated maximum oxygen uptake (VO2max) and participation in organized physical activity in Swedish obese children and adolescents, and compare the results with an age-matched reference group representative of the general population. METHODS: Two hundred and nineteen obese children (102 boys, 117 girls, aged 8-16 years, Body Mass Index (BMI) 24.3-57.0 kg.m-2) performed a submaximal bicycle ergometry test and an interview concerning participation in organized physical activity. RESULTS: The obese children had lower relative VO2max (p<0.001) than the reference group. In contrast to the reference group no age or gender differences were detected in the obese children aged 11-13 years and 14-16 years. With increased age (after 11 years) the obese children participated less in organized physical activity than the reference group (p<0.001). In obese adolescents, participation in organized physical activity in leisure time explained 7% and BMI 45% of the variance in relative VO2max. CONCLUSION: The obese children had lower relative VO2max, and participated less in organized physical activity than the reference group. The variance in relative VO2max was primarily explained by BMI. Obese adolescents, especially boys, were found to be at risk of physical inactivity.     

Body composition in Prader-Willi syndrome compared with nonsyndromal obesity: Relationship to physical activity and growth hormone function.

OBJECTIVE: To study the relationship of fat mass, extracellular-to-intracellular-water ratio, and bone mineral density with growth hormone function and physical activity in Prader-Willi syndrome. STUDY DESIGN: There were 17 patients with PWS (10 women, ages 7.5-19.8 years) and 17 obese control patients, matched for gender and bone age. FM and extracellular-to-intracellular-water ratio were measured by bromide-deuterium dilution, BMD by dual-energy x-ray absorptiometry, GH function by fasted serum insulin-like growth factor-I concentration, and physical activity by doubly-labeled water in combination with basal metabolic rate by a ventilated hood. RESULTS: The PWS group had a similar fat mass, but a lower fat-free mass, whereas the extracellular-to-intracellular-water ratio was higher compared with the control group (0.87 +/- 0.07 l/l and 0.80 +/- 0.06 l/l, respectively [P <.01]). Fat mass was inversely related with PA in the PWS group, whereas IGF-I was positively correlated with FFM, ICW, and BMD of the limbs. BMD tended to be lower in patients with PWS. CONCLUSIONS: In children and adolescents with PWS, adiposity is associated with a reduced fat-free mass and extracellular-to-intracellular-water ratio is increased. Both findings are related to GH function and physical activity. BMD, especially in the limbs, tends to be reduced in patients with PWS and is related to GH function.