Timing of peak bone mass in Caucasian females and its implication for the prevention of osteoporosis. Inference from a cross-sectional model

Calcium requirements for bone growth in Canadian boys and girls during adolescence

Adequate dietary intake during the growth period is critical for bone mineral accretion. In 1997, an adequate intake (AI) of 1300 mg/d Ca was set for North American adolescents aged 9-18 years based on best available data. We determined bone Ca accrual values from age 9 to 18 years taking into account sex and maturity. Furthermore, we used the accrual data to estimate adolescents' Ca requirements. Total body bone mineral content (TBBMC) of eighty-five boys and sixty-seven girls participating in the Saskatchewan Paediatric Bone Mineral Accrual Study were used to determine annual TBBMC accumulation over the pubertal growth period. Using a similar factorial approach as the AI, we estimated Ca requirements of adolescent boys and girls for two age groups: 9-13 and 14-18 years. Between 9 and 18 years, boys accrued 198.8 (SD 74.5) g bone mineral content (BMC) per year, equivalent to 175.4 (SD 65.7) mg Ca per d with the maximum BMC accrual of 335.9 g from age 13 to 14 years. Girls had 138.1 (SD 64.2) g BMC per year, equalling121.8 (SD 56.6) mg Ca per d with the maximum annual BMC accrual of 266.0 g from age 12 to 13 years. Differences were observed between both sex and age groups with respect to Ca needs: boys and girls aged 9-13 years would require 1000-1100 mg/d Ca, and from age 14 to 18 years, the mean Ca requirements would be relatively stable at 1000 mg/d for girls but would rise to 1200 mg/d for boys.

Bone density in cerebral palsy

This article discusses the problem of osteoporosis in cerebral palsy. Osteoporosis remains a major health problem worldwide. Cerebral palsy is the most prevalent childhood condition associated with osteoporosis. Bone density is significantly decreased. Children with cerebral palsy often sustain painful fractures with minimal trauma that impair their function and quality of life. This article addresses the anatomy and structure of bone and bone metabolism, the clinical assessment of bone mass, the causes of osteoporosis and its evaluation and treatment in children with cerebral palsy.

Long-term therapy in COPD: any evidence of adverse effect on bone?

Patients with COPD have high risk for osteoporosis and fractures. Hip and vertebral fractures might impair mobility, and vertebral fractures further reduce lung function. This review discusses the evidence of bone loss due to medical treatment opposed to disease severity and risk factors for COPD, and therapeutic options for the prevention and treatment of osteoporosis in these patients. A review of the English-language literature was conducted using the MEDLINE database until June 2009. Currently used bronchodilators probably lack adverse effect on bone. Oral corticosteroids (OCS) increase bone resorption and decrease bone formation in a dose response relationship, but the fracture risk is increased more than reflected by bone densitometry. Inhaled corticosteroids (ICS) have been associated with both increased bone loss and fracture risk. This might be a result of confounding by disease severity, but high doses of ICS have similar effects as equipotent doses of OCS. The life-style factors should be modified, use of regular OCS avoided and use of ICS restricted to those with evidenced effect and probably kept at moderate doses. The health care should actively reveal risk factors, include bone densitometry in fracture risk evaluation, and give adequate prevention and treatment for osteoporosis.

The interrelationships between abdominal adiposity, leptin and bone mineral content in overweight Latino children

BACKGROUND/AIMS

The link between abdominal fat and bone mineral content (BMC), independent of weight, has not been extensively studied. In Latino children, the contributions of abdominal subcutaneous and visceral fat to BMC have not been examined. Research on the effect of leptin on BMC has also been inconclusive.

METHODS

The present study included 256 overweight Latino children (111 girls, 145 boys; mean BMI 28.2; age 11.1 +/- 1.7 years) from Los Angeles, California. Subcutaneous abdominal adipose tissue (SAAT) and intra-abdominal adipose tissue (IAAT) were determined by single-slice magnetic resonance imaging. BMC was measured using dual-energy X-ray absorptiometry.

RESULTS

Independent of age, Tanner stage and weight, abdominal adipose tissue (SAAT + IAAT) was inversely correlated with BMC (r = -0.46, p < 0.0001; n = 256). In girls, there was an inverse correlation between SAAT and BMC (r = -0.38, p < 0.05), between IAAT and BMC (r = -0.32, p < 0.05) and between leptin and BMC (r = -0.39, p < 0.05). In boys, SAAT and BMC were inversely correlated (r = -0.26, p < 0.05), but the correlation between IAAT and BMC was not significant (p = 0.22). Leptin was also inversely correlated with BMC (r = -0.38, p < 0.05) in boys and contributed to the variances in BMC in both girls and boys.

CONCLUSION

Total abdominal adipose fat and leptin are negatively associated with BMC in Latino children. The correlation between SAAT and BMC is stronger in girls than boys. IAAT and BMC are negatively associated in girls but not correlated in boys.

Decreased bone mineral density in adults born with very low birth weight: a cohort study

BACKGROUND

Very-low-birth-weight (VLBW, <1,500 g) infants have compromised bone mass accrual during childhood, but it is unclear whether this results in subnormal peak bone mass and increased risk of impaired skeletal health in adulthood. We hypothesized that VLBW is associated with reduced bone mineral density (BMD) in adulthood.

METHODS AND FINDINGS

The Helsinki Study of Very Low Birth Weight Adults is a multidisciplinary cohort study representative of all VLBW births within the larger Helsinki area from 1978 to 1985. This study evaluated skeletal health in 144 such participants (all born preterm, mean gestational age 29.3 wk, birth weight 1,127 g, birth weight Z score 1.3), and in 139 comparison participants born at term, matched for sex, age, and birth hospital. BMD was measured by dual energy X-ray absorptiometry at age 18.5 to 27.1 y. Adults born with VLBW had, in comparison to participants born at term, a 0.51-unit (95% confidence interval [CI] 0.28-0.75) lower lumbar spine Z score and a 0.56-unit (95% CI 0.34-0.78) lower femoral neck Z score for areal BMD. These differences remained statistically significant after adjustment for the VLBW adults' shorter height and lower self-reported exercise intensity.

CONCLUSIONS

Young adults born with VLBW, when studied close to the age of peak bone mass, have significantly lower BMD than do their term-born peers. This suggests that compromised childhood bone mass accrual in preterm VLBW children translates into increased risk for osteoporosis in adulthood, warranting vigilance in osteoporosis prevention.

Treatment for 24 months with recombinant human GH has a beneficial effect on bone mineral density in young adults with childhood-onset GH deficiency

OBJECTIVE

Discontinuation of growth hormone (GH) therapy on completion of linear growth may adversely affect bone mineral density (BMD) in young adults with childhood-onset GH-deficiency (GHD). In the present study, we analyzed the impact of GH treatment on bone in young adults with GHD.

METHODS

BMD at the lumbar spine (L2-L4), total hip, and total body was measured at baseline and after 24 months in a cohort of young adults (18-25 years; n=160) with severe GHD treated with GH during childhood who were randomized to GH (n=109) or no treatment (n=51) in a multicenter, multinational, open-label study. GH starting doses (0.2 mg/day (males), 0.4 mg/day (females)) were increased after 1 month to 0.6 mg/day (males) and 0.9 mg/day (females) and then to 1.0 mg/day (males) and 1.4 mg/day (females) at 3 months for the remainder of the study.

RESULTS

After 24 months, lumbar spine BMD had increased significantly more in GH-treated patients than in controls (6 vs 2%; estimated treatment difference; 3.5% (95% confidence interval, 1.52-5.51) P<0.001). GH also had a significant positive effect on total hip BMD (P=0.015). Total body BMD was unchanged from baseline (P=0.315).

CONCLUSIONS

In young adults treated for childhood-onset GHD, there is a beneficial effect of continued GH treatment on BMD in adult life. Twenty-four months of GH treatment in these young adults was associated with an estimated 3.5% greater increase in BMD of the lumbar spine compared with controls.

Bone mineral density in healthy Tunisian women

Interpretation of densitometric results requires a comparison with reference bone mineral density (BMD) values of normal age and sex-matched persons. Thus the aim of this study was to determine these values for healthy Tunisian women, to estimate the prevalence of osteoporosis and to compare our findings with other populations. A cross-sectional study of 1378 Tunisian women aged between 20 and 96 years was carried out using DXA (GE-Lunar Prodigy). Subjects with suspected conditions affecting bone metabolism were excluded. Measurements were taken at the lumbar spine and femoral neck. These values were expressed at T-scores, with reference to the mean BMD values of the group aged 20-40 years. The peak bone mass, estimated in this age group was 1.174+0.127 g/cm(2) at the lumbar spine and 1.016+/-0.118 g/cm(2) at the femoral site. It was attained respectively within the age of 25 years and 36 years. For both sites, the expected decline in BMD was shown when the successive age groups [40-49 years] and [50-59 years] were compared. Bone loss was rapid during the first 5 years after menopause. Thereafter BMD declined slowly but continually. The prevalence of osteoporosis in the women over 50 years of age, taking account of peak bone mass observed in our cohort, was 23.3% at the spine and 17.3% at the femoral neck with a combined prevalence of 23.4%. These rates attained respectively 30.4%, 11.8% and 32.9% when we considered the Italian values, which demonstrate the variability of osteodensitometric depending to the reference population adopted.

Postpartum bone status in teenage mothers assessed using peripheral quantitative computed tomography

Teenage pregnancy occurs during a time when the maternal skeleton may still be accruing mineral. We hypothesized that teenage mothers would have reduced amounts of bone mineral and altered bone geometry compared with controls. This cross-sectional, observational compared teenage mothers (n=18) to age- and ethnicity-matched controls (n=52). The main outcomes were peripheral quantitative computed tomography and dual-energy X-ray absorptiometry to measure bone geometry, bone mineral density (BMD) at radius, lumbar spine and hip, and whole body bone mineral content (WBBMC). In teenage mothers, cortical BMD was reduced at the radial diaphysis (mean difference: -1.3%; p=0.03). Size-adjusted WBBMC was reduced (mean difference: -4.0%; p=0.004) and was lower for a given amount of lean mass (mean difference: -5.8%; p=0.02). No other significant differences between groups were found. The recruitment and retention of participants to this study were extremely difficult and disappointing. Teenage mothers had lower BMD at cortical sites compared with age-matched controls. These data suggest that pregnancy might have a detrimental effect on teenage mothers' future skeletal health. The results of this study require confirmation and provide pilot data for further investigations.

Lumbar spine peak bone mass and bone turnover in men and women: a longitudinal study

Peak bone mass is an important determinant of bone mass in later life, but the age of peak bone mass is still unclear. We found that bone size and density increase and bone turnover decreases until age 25. It may be possible to influence bone accrual into the third decade.

INTRODUCTION

Peak bone mass is a major determinant of bone mass in later life. Bone growth and maturation is site-specific, and the age of peak bone mass is still unclear. It is important to know the age to which bone accrual continues so strategies to maximise bone mass can be targeted appropriately. This study aims to ascertain the age of lumbar spine peak bone mass.

METHODS

We measured lumbar spine BMC, estimated volume and BMAD by DXA and biochemical markers of bone turnover in 116 healthy males and females ages 11 to 40, followed up at an interval of five to nine years.

RESULTS

The majority of peak bone mass was attained by the mid-twenties. Increases in BMC in adolescents and young adults were mostly due to increases in bone size. Bone turnover markers decreased through adolescence and the third decade and the decreasing rate of change in bone turnover corresponded with the decreasing rate of change in lumbar spine measurements.

CONCLUSIONS

Skeletal maturation and bone mineral accrual at the lumbar spine continues into the third decade.

Lean body mass, not estrogen or progesterone, predicts peak bone mineral density in premenopausal women

Estrogen and body fat content are important predictors of bone mineral density (BMD) in postmenopausal women, but their association with BMD in premenopausal women is less clear. Mounting evidence suggests that dietary fats can have detrimental effects on bone health. In a cross-sectional sample of healthy 30- to 40-y-old women (n = 242), we investigated the predictors of BMD at the hip and spine by multilevel multiple regression analyses. Predictor variables in the models included dietary intake of various fats, serum concentrations of sex steroids, blood chemistries and markers of metabolic syndrome, anthropometric variables, and ethnicity. Among these premenopausal women, lean body mass was the strongest independent predictor (P < 0.0001) and African-American ethnicity (P < 0.05) was another positive independent predictor of BMD at the hip and spine. Dietary fats were not independent predictors of BMD of hip and spine. Lean body mass and being African-American explained 33% of the variance in hip BMD. Lean body mass, African-American ethnicity, and serum concentrations of triglycerides (a negative predictor, P = 0.0001) explained 28% of the variance in spine BMD. In contrast, luteal phase serum concentrations of estradiol, progesterone, and testosterone were not predictors of BMD. It remains to be determined whether efforts to increase lean body mass in premenopausal women with normal levels of endogenous estrogen may be an effective preventive strategy to preserve bone health.

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/cm(3)) 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.

[Body composition and bone mineral density of prepubertal boys involved in different kinesiologic treatments]

INTRODUCTION

It is well known that physical activity has an anabolic effect on the bone tissue. But there is a lack of information about the effect of intensive physical activity in childhood, particularly at the prepubertal stage. The type, frequency, intensity, and duration of activity that best produce the desired increases in mass and strength of human bones have not yet been well determined.

MATERIAL AND METHODS

To examine the influence of different kinesiological treatments on body composition and bone mineral density we studied a group of prepubertal boys at the starting phase of their peak bone mass acquisition. 90 healthy prepubertal boys took part in this study. The sport group consisted of 28 swimmers (aged 10.80.8) and 32 soccer players (aged 10.70.5), who had been training their chosen high-level sport activity for at least 1 year (8-12 h per week for swimmers, 10-15 h per week for soccer players). 30 boys (aged 11.2 +/- 0.7) doing 1.5 h per week of physical activity in school served as a control group. Bone mineral density measurements of the left and right calcaneus were done by ultrasound densitometer "Sahara". The body composition was assessed by Body Fat Analyser "BES 200 Z".

RESULTS

There were significant differences between soccer players and control group as regards fat mass and bone mineral density (p<.01). Besides, significant differences were determined between a group of swimmers and control group as regads fat mass (p<.03), while the differences in bone mineral density were not very obvious (p<.67).

Previous sport activity during childhood and adolescence is associated with increased cortical bone size in young adult men

Physical activity during growth has been associated with altered cortical bone geometry, but it remains uncertain if the physical activity-induced increments in cortical bone size remain when the level of physical activity is diminished or ceased. The aim of this study was to investigate if physical activity during growth is associated with cortical bone geometry in currently inactive young men. In this study, 1068 men (18.9 +/- 0.6 [SD] yr) were included. Cortical bone geometry at the tibia and radius were measured using pQCT. A standardized questionnaire was used to collect information about current and previous sport activity. Subjects who continued to be active (n = 678) and who had been previously active (n = 285) in sports had a wider cortical bone (periosteal circumference [PC], 4.5% and 3.2%, respectively) with increased cross-sectional area (CSA; 12.5% and 6.9%) of the tibia than the always inactive subjects (n = 82). In the currently inactive men (n = 367), regression analysis (including covariates age, height, weight, calcium intake, smoking, and duration of inactivity) showed that previous sport activity was independently associated with cortical bone size of the tibia (CSA and PC). Amount of previous sport activity explained 7.3% of the total variation in cortical CSA. Subjects, who ceased their sport activity for up to 6.5 yr previously, still had greater cortical PC and CSA of the tibia than always inactive subjects. The results from this study indicate that sport activity during growth confers positive effects on bone geometry even though sport activity is ceased.

Lower bone mineral density in children with type 1 diabetes is associated with poor glycemic control and higher serum ICAM-1 and urinary isoprostane levels

The purpose of the study was to investigate bone mineral density (BMD) in children with type 1 diabetes (DM1) and to establish the relationships between BMD, physical activity, glycemic control, and markers of systemic oxidative stress and inflammation. We studied 30 children with DM1, aged 4.7-18.6 years, and 30 healthy subjects, matched by sex, age, and body mass index (BMI). Mean duration of DM1 was 5.4 +/- 3.4 years and mean glycosylated hemoglobin (HbA(1c)) level over 12 months was 9.8 +/- 1.5%. Lumbar and total bone mineral density (BMD, g/cm(2)) were measured by dual-energy X-ray absorptiometry (DXA). We calculated the apparent volumetric lumbar BMD (BMDvol, g/cm(3)) and total mineral content adjusted for age and height (BMCadj), and measured plasma intercellular adhesion molecule-1 (ICAM-1), high sensitivity C-reactive protein (hs-CRP), and urinary 8-iso-prostaglandin F(2a) (F(2)-IsoPs). Calcium (Ca) intake was assessed by questionnaire and physical activity by questionnaire and accelerometer (ActiGraph, count/h). Total BMCadj and lumbar BMDvol were significantly lower in children with DM1 than in controls (101.8 +/- 7.7 vs. 107 +/- 5.7%, P = 0.005; 0.32 +/- 0.08 vs. 0.36 +/- 0.09 g/cm(3), P = 0.05, respectively). These differences were mostly caused by the differences in boys. Plasma ICAM-1 and hs-CRP levels were significantly higher in the DM1 group compared to the controls. Ca intake and urine F(2)-IsoPs levels were similar between the groups. Diabetic boys were less active than controls (18231 +/- 6613 vs. 24145 +/- 7449 count/h, P = 0.04). In the DM1 group, lumbar BMDvol correlated inversely with urinary F(2)-IsoPs (r = -0.5; P = 0.005) and plasma ICAM-1 levels (r = -0.4; P = 0.02), and also with HbA(1c) levels after adjustment for age (r = -0.45; P < 0.05). Total BMCadj correlated inversely with HbA(1c) levels (r = -0.4; P = 0.02). We conclude that children with DM1, particularly boys, have lower BMD. Poor glycemic control, elevated markers of oxidative stress, and inflammation are associated with lower BMD.

Peak bone mineral density in Vietnamese women

SUMMARY: This cross-sectional study showed that peak bone mineral density in Vietnamese women is comparable to that in Caucasian women; however, the prevalence of osteoporosis in post-menopausal Vietnamese women was slightly higher than in Caucasian women. The age of achieving peak bone mass in Vietnamese women was between 26 and 30 years. INTRODUCTION: While peak bone mass and its determinants have been well-documented in Caucasian populations, little has been studied in Asian populations. The present study was designed to estimate the peak bone mineral density (BMD), age of its attainment, and to examine the prevalence of osteoporosis in Vietnamese women aged 50+. METHODS: The study was designed as a cross-sectional study with 328 women aged between 10 and 65 years (average age: 41) who were randomly selected from two districts around Hanoi city according to a stratified sampling scheme. BMD at the lumbar spine, femoral neck and total hip was measured by a DXA instrument (GE Lunar Prodigy, WI, USA). BMD was modeled as a cubic function of age, from which peak BMD and age at peak BMD were estimated. Bootstrap method was utilized to estimate the 95% confidence interval of peak BMD and age at peak BMD. From the peak BMD, T-score was calculated for each woman, and using the World Health Organization criteria, any woman with femoral neck BMD T-score </= -2.5 was classified as having osteoporosis. RESULTS: Peak BMD was estimated at 1.16 g/cm(2) (standard deviation [SD]: 0.13 g/cm(2)) at the lumbar spine, 1.02 g/cm(2) (SD 0.12) at the total hip, and 0.94 g/cm(2) (SD 0.11) at the femoral neck. In the cubic polynomial model, the age at peak BMD was estimated to range between 27 and 29 years. The prevalence of osteoporosis among those aged between 50 and 65 years was 23%. This prevalence was higher than in Chinese, Japanese, Korean and Caucasian populations. CONCLUSION: These data suggest that although the peak BMD in Vietnamese women is comparable to, the prevalence of osteoporosis is higher than, in some other Asian and Caucasian women. It seems that osteoporosis is an important public health burden in Vietnam.

Age-related distribution of bone and skeletal parameters in 1,322 Japanese young women

We explored factors that could serve as indices for therapeutic intervention aimed at prevention of osteoporosis. In this cross-sectional study, we investigated the timing of peak bone mass (PBM) in 1,322 Japanese women aged 12-30 years old. We measured height, body weight, bone mineral density (BMD), bone mineral content (BMC), and bone area at the lumbar spine and total hip, as well as the blood markers calcium, phosphorus, and the bone metabolic markers bone alkaline phosphatase (BAP) and type I collagen cross-linked N-telopeptide (NTX). All measurements were standardized with the mean at age 18 defined as 100% to identify age-related differences. In the total hip, BMD peaked at age 18, while, in the lumbar spine, BMD peaked at age 29, of which 99.8% was attained at age 18, suggesting that peak BMD was attained at age 18 at both the total hip and lumbar spine. No age difference was observed in serum calcium, while there was a 15.1% decrease between ages 12 and 18 in serum phosphorus. There were 273.8% and 208.5% decreases in serum BAP and NTX, respectively, between ages 12 and 18, while these levels remained constant thereafter, suggesting that bone and calcium metabolism are constant between ages 19 and 30. Factors that had stronger correlations with BMD, BMC, and bone area from 12 years to 18 years were height and body weight. PBM was reached at age 18. Control of body weight by using total hip BMD as an index for intervention should be reasonable.

Factors associated with bone density in young women with karyotypically normal spontaneous premature ovarian failure

OBJECTIVE

To evaluate bone density and associated factors in women with premature ovarian failure (POF) compared to age-matched women with normal ovarian function.

METHODS

A cross-sectional study of 50 patients with POF undergoing bone mineral densitometry was conducted, compared to 50 women paired by age who menstruated regularly.

RESULTS

In women with POF, the mean bone mineral density measured was 1.22 g/cm(2) at the spine and 0.92 g/cm(2) at the femur, values which were significantly lower than in the control group (P < 0.0001). Factors directly associated with bone density of the lumbar spine were age and with bone density of the femur were BMI and reproductive age.

CONCLUSION

Young women with POF have a decrease in lumbar spine and femoral bone density. Age, reproductive age and BMI were the factors associated with BMD. These women need early investigation and treatment to prevent bone loss and minimize fracture risk in the future.

Eight-year clinical outcomes of long-term enzyme replacement therapy for 884 children with Gaucher disease type 1

OBJECTIVE

The goal was to analyze the clinical responses to enzyme replacement therapy with alglucerase or imiglucerase in a large international cohort of children with Gaucher disease type 1.

METHODS

Anonymized data from 884 children in the International Collaborative Gaucher Group Gaucher Registry were analyzed to determine the effects of long-term enzyme replacement therapy with alglucerase or imiglucerase on hematologic and visceral manifestations, linear growth, and skeletal disease. The parameters measured were hemoglobin levels, platelet counts, spleen and liver volumes, z scores for height and bone mineral density, and reports of bone pain and bone crises.

RESULTS

The median height z score for the study population was -1.4 at baseline. After 8 years of treatment, the median height approximated the median value for the normal population. Anemia, although not severe, was present in >50% of patients at baseline and resolved for all patients after 8 years of treatment. More than 50% of patients had platelet counts of <100000 platelets per mm3 at baseline, but >95% had platelet counts above this level after 8 years of treatment. Liver and spleen volumes decreased over 8 years of treatment. The mean bone mineral density z score was -0.34 at baseline, and values normalized within 6.6 years of treatment. Seventeen percent of patients reported a bone crisis before treatment and in the first 2 years of treatment, but no bone crises were reported after 2 years of enzyme replacement therapy. Few patients (2.5%) without bone crises before enzyme replacement therapy had a crisis after the start of treatment.

CONCLUSIONS

These longitudinal data quantitate the benefits of continuous enzyme replacement therapy with alglucerase/imiglucerase for children with Gaucher disease type 1. Within 8 years of enzyme replacement therapy, most clinical parameters studied became normal or nearly normal.

Canadian Society for Exercise Physiology position paper: resistance training in children and adolescents

Many position stands and review papers have refuted the myths associated with resistance training (RT) in children and adolescents. With proper training methods, RT for children and adolescents can be relatively safe and improve overall health. The objective of this position paper and review is to highlight research and provide recommendations in aspects of RT that have not been extensively reported in the pediatric literature. In addition to the well-documented increases in muscular strength and endurance, RT has been used to improve function in pediatric patients with cystic fibrosis and cerebral palsy, as well as pediatric burn victims. Increases in children's muscular strength have been attributed primarily to neurological adaptations due to the disproportionately higher increase in muscle strength than in muscle size. Although most studies using anthropometric measures have not shown significant muscle hypertrophy in children, more sensitive measures such as magnetic resonance imaging and ultrasound have suggested hypertrophy may occur. There is no minimum age for RT for children. However, the training and instruction must be appropriate for children and adolescents, involving a proper warm-up, cool-down, and appropriate choice of exercises. It is recommended that low- to moderate-intensity resistance exercise should be done 2-3 times/week on non-consecutive days, with 1-2 sets initially, progressing to 4 sets of 8-15 repetitions for 8-12 exercises. These exercises can include more advanced movements such as Olympic-style lifting, plyometrics, and balance training, which can enhance strength, power, co-ordination, and balance. However, specific guidelines for these more advanced techniques need to be established for youth. In conclusion, an RT program that is within a child's or adolescent's capacity and involves gradual progression under qualified instruction and supervision with appropriately sized equipment can involve more advanced or intense RT exercises, which can lead to functional (i.e., muscular strength, endurance, power, balance, and co-ordination) and health benefits.

Relationship between grip strength and bone mineral density in healthy Hong Kong adolescents

This study evaluated the magnitude of the correlations among grip strength, bone mineral density (BMD) and bone mineral content (BMC), after controlling for weight, height, pubertal development, weight-bearing activities and calcium intake. The results lead to the conclusion that grip strength is an independent predictor of bone mass in both sexes. The relationship between muscle strength and bone mass is systemic.

INTRODUCTION

Previous studies had shown a site-specific relationship between muscle strength and bone in pubertal children. This study evaluated the magnitude of the correlations among grip strength, bone mineral density (BMD) and bone mineral content (BMC) at distant bone.

METHODS

Cross-sectional data of 169 11- to 12-year-old boys and 173 10- to 11-year-old girls came from the baseline result of a cohort study. Grip strength, BMD, BMC, weight, height, pubertal development, weight-bearing activities and calcium intake were measured. Pearson correlations and multiple regressions were used to calculate univariate and adjusted associations among grip strength and bone mass at distant bone.

RESULTS

Significant correlations were shown between grip strength and bone mass at hip, spine and whole body (boys: BMC:0.72-0.74, BMD:0.38-0.60; girls: BMC:0.71-0.72, BMD:0.44-0.63; p<0.0001). Multiple regressions with all covariates showed that about 70% and 50%, respectively, of the variations in BMC and BMD could be explained but not for whole body BMD. Grip strength was an independent predictor of bone mass, except hip BMD in boys and whole body BMD in girls. Stepwise regression showed that grip strength was a robust predictor in both sexes. Prediction models by grip strength and weight explained about 60% and 40% of the variations in BMC of different sites and in BMD of hip and spine, respectively.

CONCLUSIONS

We found that grip strength is an independent predictor of bone mass in both sexes. The relationship between muscle strength and bone mass is systemic.

Vitamin D: a growing perspective

Vitamin D deficiency has been widely reported in all age groups in recent years. Rickets has never been eradicated in developed countries, and it most commonly affects children from recent immigrant groups. There is much evidence that current vitamin D guidelines for the neonatal period, 5-10 microg (200-400 IU)/day, prevent rickets at the typical calcium intakes in developed countries. The annual incidence of vitamin D-deficiency rickets in developed countries ranges between 2.9 and 7.5 cases per 100,000 children. The prevalence of vitamin D deficiency in mothers and their neonates is remarkable, and the results of one study suggest that third-trimester 25-hydroxyvitamin D (25(OH)D) is associated with fetal bone mineral accrual that may affect prepubertal bone mass accumulation. Beyond infancy, the evidence indicates that 5 microg (200 IU)/day of vitamin D has little effect on vitamin D status as measured by the serum 25(OH)D concentration. Two randomized clinical trials show that higher vitamin D intake improves one-year gain in bone density in adolescent girls. The functions of vitamin D extend beyond bone to include immune system regulation and anti-proliferative effects on cells. Early life vitamin D inadequacy is implicated in the risk of bone disease, autoimmune disease, and certain cancers later in life; however, long-term interventional studies do not exist to validate the widespread implementation of greater vitamin D consumption. Here we review the available data concerning vitamin D status and health effects of vitamin D in pregnancy through to and including adolescence.

Associations of oral contraceptive use and dietary restraint with bone speed of sound and bone turnover in university-aged women

The associations of oral contraceptive use and cognitive dietary restraint with bone speed of sound (SOS) and bone turnover were investigated in 100 Canadian university-aged women (18–25 years old). Dietary restraint was assessed using the Dutch Eating Behavior Questionnaire (DEBQ) and daily calcium intake (Ca++) was assessed by the rapid assessment method. Quantitative ultrasound was used to measure SOS at the tibia and radius. Bone formation was estimated from plasma osteocalcin (OC), 25-OH vitamin D, and serum bone-specific alkaline phosphatase (BAP). Bone resorption was determined from serum cross-linked N-teleopeptide of type I collagen (NTx) and plasma C-terminal telopeptide of type I collagen (CTx). Weekly physical activity energy expenditure (WAeq) was assessed using a standardized questionnaire, and height, body mass, relative body fat (%BF), and chest, waist, and hip circumferences were also measured. Participants were divided into low and moderate to high dietary restrainers (LDRs and MDRs, respectively). These groups were further sub-divided into users and non-users of oral contraceptives. All groups had similar age at menarche, body composition, WAeq, and equally low levels of Ca++and vitamin D. Within the non-users of oral contraceptives, MDR exhibited a lower tibial SOS (p ≤ 0.024) and OC (p ≤ 0.009) than LDR. Moreover, amongst the LDR, the oral contraceptive users had a lower tibial SOS (p ≤ 0.015) and BAP (p ≤ 0.002) than non-users. These results show that bone SOS and bone turnover were influenced by oral contraceptives and cognitive dietary restraint among this population of young women independent of body composition and physical activity.

Growth hormone, insulin-like growth factors, and the skeleton

GH and IGF-I are important regulators of bone homeostasis and are central to the achievement of normal longitudinal bone growth and bone mass. Although GH may act directly on skeletal cells, most of its effects are mediated by IGF-I, which is present in the systemic circulation and is synthesized by peripheral tissues. The availability of IGF-I is regulated by IGF binding proteins. IGF-I enhances the differentiated function of the osteoblast and bone formation. Adult GH deficiency causes low bone turnover osteoporosis with high risk of vertebral and nonvertebral fractures, and the low bone mass can be partially reversed by GH replacement. Acromegaly is characterized by high bone turnover, which can lead to bone loss and vertebral fractures, particularly in patients with coexistent hypogonadism. GH and IGF-I secretion are decreased in aging individuals, and abnormalities in the GH/IGF-I axis play a role in the pathogenesis of the osteoporosis of anorexia nervosa and after glucocorticoid exposure.

Effects of low-dose parathyroid hormone on bone mass, turnover, and ectopic osteoinduction in a rat model for chronic alcohol abuse

Parathyroid hormone (PTH) is used clinically in osteoporotic patients to increase bone mass by enhancing bone formation. PTH therapy is not uniformly effective at all skeletal sites and "life-style" factors may modulate the skeletal response to PTH. Alcohol may represent one of these factors. Chronic alcohol abuse is associated with osteoporosis and impaired fracture healing. Therefore, the present study investigated the effects of alcohol on the bone anabolic response to a dose of PTH similar to a human therapeutic dose 1) during normal cancellous and cortical bone growth and turnover, and 2) in a model of demineralized allogeneic bone matrix (DABM)-induced osteoinduction. Three-month-old male Sprague Dawley rats were fed a Lieber-DeCarli liquid diet with 35% of the calories derived from ethanol. The controls were pair-fed an alcohol-free isocaloric diet containing maltose-dextran. Following adaptation to the liquid diets, the rats were implanted subcutaneously with DABM cylinders prepared from cortical bone of rats fed normal chow. The rats were subsequently treated daily with PTH (1 microg/kg/d sc, 5 d/week) or vehicle and measurements on bone and DABM implants performed 6 weeks later. Total bone mass was evaluated on the day of necropsy using DXA. Tibiae were processed for histomorphometry. Bone mass and architecture in tibial diaphysis and DABM implants were evaluated by muCT. PTH treatment increased whole body bone mineral content (BMC) and bone mineral density (BMD). The hormone also increased bone formation and bone area/tissue area in the proximal tibial metaphysis. In contrast, PTH treatment had no effect on periosteal bone formation and minimal effects on DABM-induced osteoinduction. Alcohol consumption decreased whole body BMC. Alcohol also decreased cancellous as well as cortical bone formation and bone mass in tibia and impaired DABM-mediated osteoinduction. There was no interaction between PTH treatment and alcohol consumption for any of the endpoints evaluated. Our results indicate that the bone anabolic response to a therapeutic dose of PTH in the rat is largely confined to cancellous bone. In contrast, alcohol consumption inhibits bone formation at all sites. Furthermore, alcohol inhibits osteoinduction and reduces periosteal and cancellous bone formation, irrespective of therapeutic PTH administration. Based on the animal model, our findings suggest that alcohol consumption could impair the beneficial effects of PTH therapy in osteoporosis.

Peak bone density in Croatian women: variations at different skeletal sites

It is known that different skeletal sites have different peak bone mass at different times and lose bone at different rates. The purpose of the study was to assess bone mineral density (BMD) in healthy female student population (N=220), aged 18-25 yr and to analyze whether young women of that age have already started to lose the bone mass at the trabecular and cortical parts of skeleton. The influence of dietary intake and physical activity on their bone mass was also assessed. BMD was measured, using dual-energy X-ray absorptiometry technique, in spine, proximal femur, and distal third of the radius and in total body. Significant negative correlation between age and bone mass was found in all skeletal regions (p<0.05 spine; p<0.0001 total femur; and p<0.01 total body) except in cortical part of the radius. Peak bone mass in young Croatian women was achieved before the age of 20, but later in the long-bone cortical skeleton, where BMD continued to increase after mid-20s. The BMD values are comparable with those from National Health and Nutrition Examination Survey study, except for the cortical part of the radius, where it is significantly lower. Body weight and physical activity were the most significant positive predictors of bone density in all measured sites.

Current concepts in bone and reproductive health in adolescents with anorexia nervosa

Anorexia nervosa (AN) initiates an adaptive response at the level of the hypothalamus, which results in a complex interplay involving most elements of the neuroendocrine axis. Consequences of onset of disease in adolescence include amenorrhoea, pubertal arrest with potential loss of target height, and osteoporosis with reduced capacity for future attainment of peak bone mass. With recovery, delay in restoration of menses is common. Hormonal therapies for restoration of bone mineral density (BMD) in adolescents have shown limited efficacy. This review will discuss the reproductive endocrine effects of AN in adolescence, and discuss new investigative tools for monitoring restoration of reproductive function and BMD in this population.

Serum leptin in systemic lupus erythematosus

Leptin, a peptide hormone, plays an essential role in the regulation of body weight, the endocrine function, reproduction, the immune response and inflammation. The immune system, in turn, modifies leptin's production. Systemic lupus erythematosus (SLE) is an autoimmunological disease characterized by widespread inflammation with possible involvement of each body organ and system. In this study, we assessed serum leptin levels in SLE patients and the control group in search for correlations between leptin concentrations and other markers' level, the activity of the disease, its duration, the age of the patients and their bone mineral density. Blood samples were collected from 30 SLE and 30 control group women. Each SLE patient was matched with one from the control for age (+/-1 year) and the body mass index (BMI; +/-1). Serum leptin levels were determined using the DRG Leptin ELISA Kit. Serum leptin levels in SLE patients ranged from 1.8 to 66.3 ng/ml (median value 7.5), and in control group it was 8.8 ng/ml (0.7-39.2) (NS). In SLE, serum leptin levels (after the logarithmic transformation) correlated with BMI (r = 0.89, P < 0.0001), the age (r = 0.34, P < 0.01) and the patients' disease duration (r = 0.59, P < 0.0005). Serum leptin levels in SLE patients with arthritis (P < 0.05) and central nervous system (CNS) involvement (P = 0.05) were significantly lower in comparison with serum leptin levels in SLE patients without arthritis and CNS involvement. No correlation was found between serum leptin levels and the T-score. In the control group, the logarithmic transformation of serum leptin levels positively correlated with BMI (r = 0.52, P < 0.05). No differences in serum leptin levels were shown between SLE patients and the control group. However, we found correlation between BMI and serum leptin levels in both groups. Furthermore, serum leptin levels in SLE patients with arthritis and CNS involvement were significantly lower in comparison with SLE patients without arthritis and CNS involvement, which suggests that active chronic inflammation may lower plasma leptin concentrations.

Bone health knowledge, self-efficacy, and behaviors in adolescent females

PURPOSE

To determine whether an educational program about osteoporosis will improve knowledge and confidence about osteoporosis prevention, self-efficacy, and self-reported bone-health lifestyle behaviors in adolescent girls.

METHODS

Tests of knowledge, self-efficacy, calcium intake, and physical activity were compared before and after an osteoporosis educational in-service program. The differential effects of intervention, an osteoporosis in-service program versus no intervention, were determined using 2 x 2 analyses of variance.

RESULTS

The intervention group showed a significant increase in knowledge (p < 0.01) as well as self-efficacy (p < 0.03) whereas the control group results did not (p > 0.05). Results for calcium intake and exercise were also statistically significant; however, unusual performance trends raise questions related to clinical interpretation of the lifestyle behavior variables.

CONCLUSION

An osteoporosis educational in-service can significantly improve knowledge, self-efficacy, and reported calcium consumption in adolescent girls; however, it may not be an adequate intervention to change lifestyle behaviors.

High prevalence of asymptomatic vitamin D and iron deficiency in East African immigrant children and adolescents living in a temperate climate

OBJECTIVES

Vitamin D deficiency (VDD) is common in immigrant children with increased skin pigmentation living in higher latitudes. We assessed the pattern of and risk factors for VDD in immigrant East African children living in Melbourne (latitude 37 degrees 49' South).

STUDY DESIGN

A prospective survey of 232 East African children attending a clinic in Melbourne. Data were collected by questionnaire, medical assessment and laboratory tests.

RESULTS

Low 25-hydroxyvitamin D (25-OHD) levels (<50 nmol/l) occurred in 87% of children, and VDD (25-OHD <25 nmol/l) in 44%. Risk factors included age <5 years, female gender, increased time in Australia, decreased daylight exposure and winter/spring season. Anaemia (20%), vitamin A deficiency (20%) and iron deficiency (19%) were also identified.

CONCLUSIONS

Asymptomatic VDD is common in East African immigrant children residing at a temperate latitude. Risk factors for VDD limit endogenous vitamin D production. Screening of immigrant children with increased skin pigmentation for VDD, anaemia, iron and vitamin A deficiency is appropriate. VDD in adolescent females identifies an increased risk of future infants with VDD.

Role of hemoglobin A(1c), duration and puberty on bone mineral density in diabetic children

BACKGROUND

The aim of the present was to determine bone mineral density (BMD) in type 1 diabetic children and the roles of hemoglobin A(1c), disease duration and pubertal stage on BMD changes.

METHODS

Fifty-eight patients were investigated: 16 had been newly diagnosed (Diabetes(New)) and 42 were already on follow up (Diabetes(Follow up)). BMD of the lumbar vertebrae, HbA1c(HbA1c(last)), Ca, P, Mg were measured. Mean HbA1c of the previous year (HbA1c(1year)), the whole duration of diabetes (HbA1c(whole)), and diabetic impact index (HbA1c(whole) x diabetes duration) were calculated in the Diabetes(Follow up) group.

RESULTS

Mean BMD-Z score (-0.61 +/- 0.99 g/cm(2)) of the whole group was significantly lower than zero. Osteopenia was present in 14 (24.1%), and osteoporosis in three (5.2%). HbA1c(whole) was the most important determinant effecting BMD-Z (r = -0.35, P < 0.05) with the cut-off for osteopenia and osteoporosis being 9.8% and 12.1%, respectively. The cut-off of diabetes duration for osteopenia was 3.6 years and it was more predictive for osteopenia compared to HbA1c(whole). In the Diabetes(New) group, the BMD-Z score of the early pubertal group was significantly lower than those in other pubertal groups.

CONCLUSION

BMD is affected in diabetic children, and HbA1c(whole) and diabetes duration are the most important determinants. Pubertal stage is another determinant of BMD, especially in newly diagnosed patients.

Bone density in adolescents treated with a GnRH agonist and add-back therapy for endometriosis

STUDY OBJECTIVE

To evaluate the bone density of adolescents with endometriosis treated with a GnRH-agonist and "add-back" therapy with norethindrone acetate.

DESIGN

Retrospective chart review.

SETTING

Pediatric gynecology clinic at a tertiary care center.

PARTICIPANTS

36 adolescents, ages 13 to 21 years, with endometriosis.

MAIN OUTCOME MEASURES

Bone mineral density (BMD, g/cm(2)) by dual energy x-ray absorptiometry (DXA); BMD Z-scores of hip and spine.

RESULTS

The mean BMD Z-score at the total hip was -0.24 +/- 1.0, with a range of -2.4 to 1.7. At this site, 6 subjects had a BMD Z-score between -1.0 and -2.0 SD, while 2 had a Z-score < or = -2.0 SD. The mean BMD Z-score at the lumbar spine was 0.55 +/- 1.1, with a range of -2.8 to 1.4. At the spine, 11 subjects had a BMD Z-score between -1.0 and -2.0 SD, while 3 had a Z-score < or = -2.0 SD. There was no correlation noted between duration of therapy with the GnRH-agonist plus add-back and BMD at the hip or spine.

CONCLUSION

BMD at the hip was normal in most adolescents with endometriosis who were receiving a GnRH-agonist plus add-back therapy with norethindrone acetate. Almost one third of subjects exhibited skeletal deficits at the spine. These data suggest that BMD should be carefully monitored in adolescents receiving treatment with GnRH agonists.

Growth hormone replacement throughout life: insights into age-related responses to treatment

The adult growth hormone deficiency (GHD) syndrome is a well-defined clinical entity. Although the symptoms of GHD are not age specific, their relative importance differs depending on the patient's age, and the impact of GHD varies throughout adult life. Ceasing growth hormone (GH) therapy soon after final height in patients with severe GHD potentially limits somatic development by reducing accrual of bone and muscle mass. It is now recognized that the continuation of GH therapy in the transition years is required to achieve adult levels of somatic development. In middle age, the most worrying feature of GHD is the increase in cardiovascular risk, an important component of which is GHD-related dyslipidemia. One of the most profound effects of GH therapy in this age group is the durable reduction in cholesterol levels. Elderly GH-deficient patients experience the symptoms of GHD over and above the signs of normal aging. Perhaps most importantly, these patients have impaired quality of life, with fatigue as a major component. Evidence is growing for improved quality of life with GH therapy in the elderly. This review describes the diagnosis, symptoms and treatment of GHD specific to the different age groups.

Supplemental Escherichia coli phytase and strontium enhance bone strength of young pigs fed a phosphorus-adequate diet

Young pigs represent an excellent model of youth to assess potentials of dietary factors for improving bone structure and function. We conducted 2 experiments to determine whether adding microbial phytase (2,000 U/kg, OptiPhos, JBS United) and Sr (50 mg/kg, SrCO3 Alfa Aesar) into a P-adequate diet further improved bone strength of young pigs. In Expt. 1, 24 gilts (8.6 +/- 0.1 kg body wt) were divided into 2 groups (n = 12), and fed a corn-soybean-meal basal diet (BD, 0.33% available P) or BD + phytase for 6 wk. In Expt. 2, 32 pigs (11.4 +/- 0.2 kg) were divided into 4 groups (n = 8), and fed BD, BD + phytase, BD + Sr, or BD + phytase and Sr for 5 wk. Both supplemental phytase and Sr enhanced (P < 0.05) breaking strengths (11-20%), mineral content (6-15%), and mineral density (6-11%) of metatarsals and femurs. Supplemental phytase also resulted in larger total bone areas (P < 0.05) and a larger cross-sectional area of femur (P = 0.06). Concentrations of Sr were elevated 4-fold (P < 0.001) in both bones by Sr, and moderately increased (P = 0.05-0.07) in metatarsal by phytase. In conclusion, supplemental phytase at 2000 U/kg of P-adequate diets enhanced bone mechanical function of weanling pigs by modulating both geometrical and chemical properties of bone. The similar benefit of supplemental Sr was mainly due to an effect on bone chemical properties.

Age-related bone mineral density, bone loss rate, prevalence of osteoporosis, and reference database of women at multiple centers in China

Our study surveyed age-related bone mineral density (BMD), bone loss rate, and prevalence of osteoporosis in women at multiple research centers in China. Survey results were used to establish a BMD reference database for the diagnosis of osteoporosis in Chinese women nationwide. We used dual-energy X-ray absorptiometry bone densitometers to measure BMD at posteroanterior (PA) lumbar spine (L1-L4; n=8142) and proximal femur (n=7290) in female subjects of age 20-89 yr from Beijing, Shanghai, Guangzhou, Chengdu, Nanjing, and Jiaxing. A cubic regression-fitting model was used to describe the change of BMD with age at various skeletal sites. Peak BMD occurred between 30 and 34 yr of age for femur neck and total femur, and between 40 and 44 yr for spine and trochanter measurement sites. Young adult (YA) BMD values (mean and standard deviation [SD], calculated as the average BMD in the age range of 20-39, were 1.116+/-0.12, 0.927+/-0.12, 0.756+/-0.11, and 0.963+/-0.13 g/cm2 at PA spine, femoral neck, trochanter, and total femur, respectively. The BMD of 85-yr-old women reflected a loss of 32% at the spine and 30-35% at femur measurement sites. The prevalence of osteoporosis, defined as a BMD of <or=-2.5 SDs from YA values established in this study, in female subjects of age 50 yr or older, was 28% for the spine, 15% for any femur site, and 31% for any spine or femur site. This study provides important information for formulating osteoporosis prevention and treatment strategies in Chinese women, and it establishes a reliable BMD reference database for the diagnosis of osteoporosis of Chinese women nationwide.

Vitamin-D nutrition and bone mass in adolescent black girls

OBJECTIVE

To examine the relationship between bone mass and serum levels of 25-hydroxyvitamin D and parathyroid hormone in African-American adolescent girls.

STUDY DESIGN

A cross-sectional sample at a suburban research center.

METHODS

Twenty-one adolescent black girls 12-14 years of age, were studied during winter with biochemical measurements of serum 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH). Bone mass assessment was done with dual energy x-ray absorbsiometry (DXA) and peripheral quantitative computed tomography of the radius (p-QCT). Anthropometric, physical activity and nutritional data were collected.

RESULTS

All participants were vitamin-D deficient (serum 25-OHD level <50 nmol/L), of whom nine (43%) were severely vitamin-D deficient (serum 25-OHD level <20 nmol/L). Mean daily intake of dietary calcium was 540 mg/d and vitamin D was 195 IU/d. There was a positive correlation, although statistically not significant, between serum 25-OHD and various bone mass measurements. Serum PTH was inversely correlated to total body BMD (r = -0.51, p = 0.02) and other bone mineral density at the lumbar spine, total femur and mid-radius.

CONCLUSION

Vitamin-D insufficiency is a widely prevalent problem among adolescent African-American girls. Our data implies that enhancing vitamin-D nutrition resulting in lower serum PTH levels could potentially influence their peak bone mass.

Milk Supplementation and Bone Health in Young Adult Chinese Women

BACKGROUND

Milk is potentially beneficial for bone health, particularly for Chinese populations where consumption of dairy products is low. There are few data about milk consumption by Chinese women aged 20-35 years. This study examines whether milk supplement over 2 years caused increased bone mineral density (BMD) in Chinese women aged 20-35 years.

METHODS

Four hundred forty-one community-living women living in Hong Kong SAR (221) and Beijing (220) China were randomized to receive milk supplement or nothing. The supplement consisted of two sachets of milk powder (1000 mg calcium, 80 microg vitamin K(1)), for 24 months. BMD at total hip, total spine, and whole body was measured at baseline and at 6, 12, 18, and 24 months; blood specimens were analyzed at baseline and at 3 and 24 months for biochemical indices of bone turnover and vitamin K. Urine samples also were collected. Analysis was by intention to treat as well as per protocol. Differences in change from baseline between the milk and control groups were analyzed using the mixed models approach to repeated measures, including the baseline value as a covariate.

RESULTS

Both groups had an increase in BMD and a decrease in bone turnover markers over time, as an indicator of the process of attainment of peak bone mass during this period. Apart from a higher total spine BMD at 6 months in the milk group using per protocol analysis, there was little significant difference observed between the milk group and the control group.

CONCLUSIONS

Age-related bone metabolism and lack of compliance most likely explain the lack of consistent changes in BMD or bone biochemical measures in response to milk supplementation for 2 years in Chinese women aged 20-35 years.

Impact of depression and its treatment on the bones of growing children

Depression in adults has been linked to reduced bone mineral density (BMD), osteoporosis, and increased incidence of fractures. Physiologic factors, such as hypothalamic-pituitary-adrenal axis dysfunction and increased circulation of inflammatory cytokines, may adversely impact bone metabolism. In addition, behavioral factors, such as reduced physical activity and altered dietary intake (especially of bone-related nutrients such as calcium and vitamin D), may be implicated. Antidepressant medications also may have an impact on BMD. Childhood and adolescence may be times of particular vulnerability to the adverse effects of depression due to the rapid bone mineral accrual that occurs during periods of growth. This article will review potential contributing factors and resulting consequences of depression on BMD in these populations and also explore areas of needed research.

Ultrasound bone densitometry of the calcaneus in healthy Chinese children and adolescents

INTRODUCTION

We evaluate reference data to examine whether there are sex-, age-, height-, weight- and BMI-related differences of quantitative ultrasound parameters (QUS) for healthy Chinese children and adolescents.

METHODS

A total of 726 healthy children and adolescents (360 male and 366 female) aged from 10-21 years were examined with a Lunar Achilles Express densitometer. The measurements on the right heel included speed of sound (SOS), broadband ultrasound attenuation (BUA), and a calculated stiffness index (SI).

RESULTS

Our results found that there were no significant differences for BUA, SOS and SI between males and females, except in the age range of 12 to 13 years. The values of all parameters were significantly higher in the 12-year-old females compared to males, and BUA values were significantly higher in 13-year-old females compared to males. A spurt in QUS parameters were observed at 12 years in females and at 14 years in males. A steady increase of BUA, SOS, and SI was seen with increasing body height and weight in both sexes.

CONCLUSION

In conclusion, the present results can be used as reference data for children and adolescents in China.

The A1330V polymorphism of the low-density lipoprotein receptor-related protein 5 gene (LRP5) associates with low peak bone mass in young healthy men

INTRODUCTION

Polymorphisms in the gene coding for low-density lipoprotein receptor-related protein 5 (LRP5) contribute to variation in bone mass in the general population. Whether this is due to influence on bone mass acquisition or on bone loss thereafter has not been established.

METHODS

We studied the association of LRP5 polymorphisms with peak bone mass in young men. The study included 235 Finnish men, aged 18.3 to 20.6 years. Lifestyle factors and fracture history were recorded. Bone mineral content (BMC), density (BMD) and scan area were measured for the lumbar spine and proximal femur by dual energy X-ray absorptiometry (DXA). Blood and urine were collected for determination of bone turnover markers, serum 25-OHD and PTH. Genomic DNA was extracted from peripheral blood for genetic analysis of LRP5. Ten single nucleotide polymorphisms in LRP5 were analyzed and correlated with bone parameters.

RESULTS

Only the A1330V polymorphism of LRP5 significantly associated with bone parameters. In comparison with subjects with the AlaAla genotype (n=215), those with AlaVal genotype (n=20) had lower femoral neck BMC (P=0.029) and BMD (P=0.012), trochanter BMC (P=0.0067) and BMD (P=0.015), and total hip BMC (P=0.0044) and BMD (P=0.0089). Fracture history was similar for the genotypes.

CONCLUSION

The polymorphic valine variant at position 1330 of LRP5 was significantly associated with reduced BMC and BMD values in healthy young Finnish men. The results provide evidence for the crucial role of LRP5 in peak bone mass acquisition.

The effect of short-term calcium supplementation on biochemical markers of bone metabolism in healthy young adults

The influence of Ca supplementation of the usual diet for 14d on biochemical markers of bone turnover was investigated in healthy young adults aged 21–26 years. In a crossover study, eighteen subjects (five male and thirteen female) were randomly assigned to their self-selected diet (about 22 mmol Ca/d) or their self-selected diet with a 20 mmol/d Ca supplement (about 40 mmol Ca/d) for 14d followed by crossover to the alternative diet for a further 14d. During each dietary period fasting morning first void urine samples (last 3d) and fasting blood serum samples (morning of twelfth day) were collected. Ca supplementation reduced urinary excretion of pyridinoline (14%) and deoxypyridinoline (16%) (biochemical markers of bone resorption) but had no effect on biochemical markers of bone formation (serum osteocalcin and bone-specific alkaline phosphatase;EC3.1.3.1). It is concluded that Ca supplementation of the usual diet in young adults suppresses bone resorption over a 2-week period. If sustained, this could result in suppression of the bone remodelling rate and an increase in bone mass over time. The findings of this short-term study with a relatively small number of young adults highlight the need for a longer-term intervention study of the effect of increased Ca intake on bone mass in this age group.

A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls – a cross-sectional study

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.

Bone mineral content and bone mineral density at lumbar spine and forearm in Chinese girls aged 6-18 years

We investigated the age-related bone mineral content (BMC), bone mineral density (BMD) and the tempo of growth in BMC and BMD at lumbar spine and forearm in 455 Chinese girls aged 6-18 yr. BMC and BMD at the anteroposterior lumbar spine (LS), the left forearm (radius+ulna ultradistal, R+UUD) and one-third region (R+U1/3) were measured using a dual-energy X-ray bone densitometer (DXA). BMC and BMD exhibited different change patterns with the age changes. There were significant correlations between age, height, weight and BMC and BMD at LS, R+UUD and R+U1/3 sites. BMC and BMD increased significantly with increments in pubertal stages at LS, R+UUD and R+U1/3 sites. In conclusion, our study showed that Tanner stage had a significant positive association with BMC and BMD of the lumbar spine and forearm. The differences were found in the growth tempo of BMC and BMD within a region and between the spine and forearm. Both BMD and BMC were recommended to evaluate the bone health in children and adolescents.