Bone mass and bone metabolism markers during adolescence: The HELENA Study

Reduced Bone Mineral Density in Middle-Aged Male Patients with Adult Growth Hormone Deficiency

The aim of the work was to investigate the bone mineral density (BMD) in middle-aged male patients with both childhood-onset (CO) and adulthood-onset (AO) adult growth hormone deficiency (AGHD). In this retrospective cross-sectional study in a major medical center in China, dual X-ray absorptiometry was performed in 50 male AGHD patients (average age was 35.2±9.8 years) and 50 age- and BMI-matched non-athletic healthy men. BMD was compared between AGHD patients and controls. Compared with healthy controls, AGHD group had significantly decreased IGF-1 (p1<0.001) and IGF-1 SDS (p1<0.001). Serum testosterone levels were significantly lower in AGHD patients (p1<0.001), mainly in AO AGHD patients (p3<0.001). The BMD of the femoral neck, trochanter, femoral shaft, total hip, and lumbar spine were significantly lower in all AGHD patients compared with healthy controls (all p1<0.05), especially in CO AGHD patients (all p2<0.05). Multiple stepwise linear regression indicated AGHD was negatively correlated with BMD at each site (β<0, p<0.05). Additionally, serum testosterone level was an independent influencing factor of BMD of the femoral neck (β=0.256, p=0.018) and lumbar spine (β=0.219, p=0.040). BMD was significantly reduced in AGHD patients, especially in CO AGHD patients. Our data suggested that the status of growth hormone deficiency and testosterone level were important for maintaining of bone mineral density in middle-aged male patients with AGHD.

The Benefits of Midmorning Snack to Combat Stunting: A Longitudinal Panel Study in the Riau Province of Indonesia

Aim:

The aim of this research was to help stunted adolescents improve their nutritional status.

Background:

Stunting is a leading global nutritional problem, especially in developing countries such as Indonesia. This was a longitudinal panel study in the SMP Negeri 3 Pekanbaru Riau Province Junior High School, Indonesia.

Objective:

The objective of this study was to determine the impact of calcium and phosphorus supplementation via additional midmorning snacks for adolescents with stunting conditions.

Methods:

We included 36 participants, aged 12–15 years with a height-for-age Z-score of <-2 Standard Deviation. They underwent a one-month nutritional intervention during which selected snacks and high-calcium milk were given for midmorning snacks. The midmorning snack menu was daily varied and included gado-gado (rice, boiled egg, potato, tempeh, tofu, long beans, cabbage & peanut sauce), fried vermicelli (vermicelli, omelet, cucumber & prawn crackers), batagor (tofu, cassava flour crackers, boiled egg & peanut sauce), lontong medan (rice, boiled egg, vermicelli, french fries, fried anchovy, green bean & carrots curry), sandwich (plain toast, omelet, cucumber, lettuce, tomato & chili sauce), chicken porridge (rice porridge, fried bread, shredded chicken & chicken broth), and fried rice teri (rice, anchovy, prawn crackers, cucumber, chili sauce & soy sauce). The total amount of energy of the meals and milk was 541.8 kcal (30% of RDA-Recommended Dietary Allowance), 25 g of protein (50% of RDA), 90 g of carbohydrate (30% of RDA), and 600 mg of calcium (35% of RDA). Meal and milk administration lasted 34 days in total. Data analysis and food intake consumption were conducted using the Pearson Product moments test.

Results:

The participants’ mean height-for-age Z-score before and after the nutritional intervention was -2.5 ± 0.4 (-3.2 — -2.0) and -2.3 ± 0.4 (-3.2 — -1.2), respectively. After the intervention, the rate of stunting was reduced up to 19.4%; the rate of calcium intake before the nutritional intervention was 50% below the recommended dietary allowance—27.3 ± 27.8 (3.3:100.0) %; the rate of phosphorus intake among the participants was sufficient. The rate of calcium intake after the nutritional intervention was 59.1 ± 19.0 (15.5 —100.0) % due to which the nutritional quality of food before the intervention was still lacking, namely 52.7 ± 15.5 (28.4 — 86.3) after the nutrition intervention increased to 84.8 ± 20.3 (30.9 — 100.0); (r value = 0.43; p value = 0.01).

Conclusion:

The nutritional intervention increased calcium intake. The outcome of the nutritional intervention led to the improvement of nutritional status from stunting to the normal category.

Other:

The midmorning snack that is given to teenagers is a snack meal available in the school canteen that they can buy with pocket money. It is necessary to create awareness about the importance of consuming high calcium midmorning snacks to teenagers. The activity of consuming high-calcium midmorning snacks by adolescents can be continued independently. So far, teenagers do not use pocket money to buy midmorning snacks that are high in calcium, but they buy other types of snacks that are low in calcium, consisting of pastel, noodles, tofu, fritters, pao, tempeh, rice cake, and eclairs. So far, no nutritional intervention has significantly increased the nutritional status of stunted children to normal levels; however, this type of intervention may become a viable option in the future.

Dental cementum virtual histology of Neanderthal teeth from Krapina (Croatia, 130-120 kyr): an informed estimate of age, sex and adult stressors

The evolution of modern human reproductive scheduling is an aspect of our life history that remains vastly uncomprehended. The present work aims to address this gap by validating a non-destructive cutting-edge methodology to infer adult life-history events on modern teeth with known life history and then applying it to fossil specimens. We use phase-contrast synchrotron X-ray microtomography to visualize the dental cementum of 21 specimens: nine contemporary humans; 10 Neanderthals from Krapina (Croatia, 130-120 kyr); one Neolithic Homo sapiens from Ajmana (Serbia); and one Mesolithic H. sapiens from Vlasac (Serbia). We were able to correctly detect and time (root mean square error = 2.1 years; R2 = 0.98) all reproductive (menarche, parturition, menopause) and other physiologically impactful events in the modern sample. Nonetheless, we could not distinguish between the causes of the events detected. For the fossil specimens, we estimated age at death and age at occurrence of biologically significant events. Finally, we performed an exploratory analysis regarding possible sexual dimorphism in dental cementum microstructure, which allowed us to correctly infer the sex of the Neolithic specimen, for which the true value was known via DNA analysis.

More than Sports Participation: The Role of Ground Reaction Force, Osteocalcin and Lean Soft Tissue on Bone Density Accrual in Adolescents: ABCD Growth Study

The objective of this study was to identify predictors of 12-mo areal bone density accrual in different body segments, lean soft tissue, and osteogenic characteristics attributed to sports participation among adolescent girls and boys. Adolescents (Girls [n = 64], [aged = 14.7]); Boys [n = 129], [aged = 14.6]) were stratified into three groups according to their engagement in different sports (Control [n = 68], Swimming [n = 25], and Weight-bearing sports [n = 100]). Areal bone density (aBMD [g/cm²]) and lean soft tissue (LST) [kg] were measured by dual-energy x-ray absorptiometry (DXA; Lunar DPX-NT; General Electric Healthcare, Little Chalfont, Buckinghamshire, United Kingdom). The ground reaction force (GRF) index attributed to sports participation (Sport-GRF) was created considering the GRF attributed to each sport, body weight of the adolescent, and the amount of time spent in sports participation. Osteocalcin levels (ng/mL) were estimated from a venous blood sample. Multiple regression analysis showed that after adjusting for covariates, the models involving sport-GRF, LST (Δ), and osteocalcin explained 15.8% to 76.2% of the aBMD gains. Specifically in girls, OC was only associated with lower limb aBMD accrual. In boys, however, sport ground reaction forces were positively associated with total spine aBMD accrual. Furthermore, the LST (Δ) was positively associated with aBMD accrual in all body sites (β = 0.003 to 0.011) in both sexes. Increases in LST contributed significantly to gains in aBMD accrual in both sexes, being a more important predictor of changes in bone outcomes than ground reaction forces and osteocalcin.

Bone Metabolism, Bone Mineral Content, and Density in Elite Late Teen Female Sprinters

With intensive training, bone injuries are a major concern for athletes. To assess bone condition, we often measure bone turnover markers, bone mineral content and density; however, in junior athletes, it is not easy to distinguish changes caused by bone injuries from those caused by growth, because the metabolism is increased in both cases. Moreover, although some studies have examined female endurance athletes, knowledge regarding changes in static and dynamic bone conditions in late teen athletes is limited. In this study, we measured the bone mineral content and density, as well as bone turnover markers, in 40 elite female sprinters in their late teens. Whole body mode dual-energy X-ray absorptiometry was performed to measure bone mineral content and density. Blood samples were collected to determine bone resorption and formation markers at the end of track season in 2016 and during the same period of the following year. Body weight and bone mineral content significantly increased, and tartrate-resistant acid phosphatase type 5b, bone-type alkaline phosphatase, and osteocalcin significantly decreased after a year. Furthermore, the rate of change in bone mineral content was higher in younger athletes, indicating that bone growth approaches completion in the late teen years and that bone metabolism accordingly decreases.

3D DXA Hip Differences in Patients with Acromegaly or Adult Growth Hormone Deficiency

The skeleton is regulated by and responds to pituitary hormones, especially when the circulating levels are perturbed in disease. This study aims to analyse the between-group differences in 3D dual-energy X-ray absorptiometry (DXA) parameters at the hip site among patients with acromegaly or adult growth hormone deficiency (AGHD) and a healthy control group. The current cross-sectional study includes data for 67 adults, 20 with acromegaly, 14 with AGHD and 33 healthy controls. We obtained the areal bone mineral density (aBMD) outcomes using DXA and cortical and trabecular parameters using 3D-DXA software (3D-SHAPER). The mean-adjusted 3D-DXA parameters did not differ between acromegaly patients and the controls (p > 0.05); however, we found cortical bone impairment (−7.3% to −8.4%; effect size (ES) = 0.78) in AGHD patients (p < 0.05). Differences in the cortical bone parameters were more evident when comparing AGHD patients (−8.5% to −16.2%; ES = 1.22 to 1.24) with acromegaly patients (p < 0.05). In brief, the 3D mapping highlighted the trochanter as the site with greater cortical bone differences between acromegaly patients and the controls. Overall, AGHD patients displayed lower cortical parameters at the trochanter, femoral neck and intertrochanter compared to the controls and acromegaly patients. To sum up, 3D-DXA provided useful information about the characteristics of bone involvement in growth hormone (GH)-related disorders. Patients with AGHD showed distinct involvement of the cortical structure.

Screen Time and Bone Status in Children and Adolescents: A Systematic Review

Introduction: Technological advances over the last 2 decades have led to an increase in the time spent by children and youth engaged in screen-based activities, and growing recognition of deleterious effects on health. In this systematic review of cohort and cross-sectional studies, we assess current data on the relationship between screen time and bone status in children and teenagers. Methods: We searched PUBMED and SCOPUS databases for studies of children and adolescents that assessed screen time and bone status, determined by measuring bone mineral content or density, bone stiffness index, bone speed of sound, bone broadband ultrasound attenuation, or frame index. Searches were limited to studies published between 1900 and 2020, and performed in accordance with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. The studies included were evaluated using the Newcastle-Ottawa quality assessment scale. Results: Ten cohort and cross-sectional studies including pediatric population were selected. The combined study population was 20,420 children/adolescents, of whom 18,444 participated in cross-sectional studies. Four studies assessed the effects of total screen time, seven the consequences of TV viewing time, and six the effects of recreational computer use on bone health. Our findings indicate an inverse association between total and weekly screen time and bone health in children and adolescents. In 57% of the studies included also a negative correlation between television viewing time and bone status was observed, while recreational computer time did not have a significant impact on bone health. According to the only four studies that included dietetic factors, no relevant differences were found between calcium intake and screen time or bone broadband ultrasound attenuation and bone speed of sound. Conclusions: Review of the literature of the past three decades provides strong support for comprehensive education of screen time on bone status. The findings of this systematic review support a negative association between screen time and bone status in children and adolescents, with a different impact when considering the different technological devices. As peak bone mass in adolescents is the strongest predictor of osteoporosis risk, strategies aimed at improving bone health should incorporate conscious use of digital technology.

Effects of whole-body vibration training on bone density and turnover markers in adolescent swimmers

Background Whole-body vibration training has recently been proposed as a complementary training modality to improve the bone health of adolescent swimmers. However, there is no longitudinal study regarding the effects of this training combination on bone metabolism. Therefore, the main goal was to analyze the effects of swimming and vibration training on bone turnover markers during adolescence. Methods The present study included 68 adolescent swimmers and 41 normoactive controls (CON). Swimmers were randomly selected to either continue with their regular swimming training (SWI) or participate in an additional vibration protocol (VIB). Anthropometric measurements and serum level determinations of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide crosslaps (CTX) were performed before and after the 6-month intervention. Results Statistically significant group by time interactions were found for both bone formation markers. VIB showed a decrease over time in OC (baseline: 101.4 μg/mL, follow-up: 82.8 μg/mL, p < 0.05) and P1NP (baseline: 528.4 μg/mL, follow-up: 389.0 μg/mL, p < 0.05) and SWI had analogous reductions in P1NP (baseline: 685.8 μg/mL, follow-up: 542.0 μg/mL, p < 0.05), whereas CON experienced an increase in OC levels (baseline: 94.4 μg/mL, follow-up: 103.4 μg/mL, p < 0.05). After stratifying the sample according to the pubertal status, similar interactions were observed. Conclusions The combination of swimming training and this particular vibration protocol led to a decrease in bone formation markers, especially during early puberty. Whole-body vibration might not induce an osteogenic stimulus in adolescent swimmers.

Association Between Physical Fitness and Bone Strength and Structure in 3- to 5-Year-Old Children

BACKGROUND

The positive association between physical fitness and bone structure has been widely investigated in children and adolescents, yet no studies have evaluated this influence in young children (ie, preschoolers).

HYPOTHESIS

Fit children will present improved bone variables when compared with unfit children, and no sex-based differences will emerge in the sample.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Handgrip strength, standing long jump (SLJ), speed/agility, balance, and cardiorespiratory fitness (CRF) were assessed using the Assessing FITness levels in PREschoolers (PREFIT) test battery in 92 children (50 boys; age range, 3-5 years). A peripheral quantitative computed tomography scan was performed at 38% of the length of the nondominant tibia. Cluster analysis from handgrip strength, SLJ, speed/agility, and CRF was developed to identify fitness groups. Bone variables were compared between sexes and between cluster groups. The association between individual physical fitness components and different bone variables was also tested.

RESULTS

Three cluster groups emerged: fit (high values on all included physical fitness variables), strong (high strength values and low speed/agility and CRF), and unfit (low strength, speed/agility, and CRF). The fit group presented higher values than the strong and unfit groups for total and cortical bone mineral content, cortical area, and polar strength strain index (all P < 0.05). The fit group also presented a higher cortical thickness when compared with the unfit group (P < 0.05). Handgrip, SLJ, and speed/agility predicted all bone variables except for total and cortical volumetric bone mineral density. No differences were found for bone variables between sexes.

CONCLUSION

The results suggest that global fitness in preschoolers is a key determinant for bone structure and strength but not volumetric bone mineral density.

CLINICAL RELEVANCE

Physical fitness is a determinant for tibial bone mineral content, structure, and strength in very young children. Performing physical fitness tests could provide useful information related to bone health in preschoolers.

Body Composition as a Mediator between Cardiorespiratory Fitness and Bone Mass during Growth

INTRODUCTION AND PURPOSE

To examine the effect of cardiorespiratory fitness (CRF) and muscle power output (MPO) on bone mass of prepubertal and pubertal children using lean mass (LM) and percentage of fat mass (%FM) as mediator variables. The hypothesis was that both LM and %FM would be independent mediators of the relationships during the sexual maturation period.

METHODS

We analyzed 200 children (88 boys and 112 girls [11.5 ± 2.0 yr]). Body composition was analyzed by bone densitometry, and indirect calorimetry and cycle ergometer were used to calculate V˙O2peak (mL·kg·min) and MPO (W) during an incremental exercise test. Sample was divided by pubertal status.

RESULTS

In the prepubertal group, LM and %FM acted independently as mediators in the relationship between bone mass and CRF or MPO (22%-25% for LM and 37%-50% for %FM, respectively). In pubertal children, LM acted as mediator at 37%.

CONCLUSIONS

Although the independent mediator role of LM and %FM in the associations between CRF or MPO and bone mass was present during the prepubertal stage, only LM remain its mediator role in these associations during the postpubertal period. Therefore, with growth and sexual maturation, the full effect of LM seems to increase, whereas the influence of %FM seems to disappear.

One-year adolescent bone mineral density and bone formation marker changes through the use or lack of use of combined hormonal contraceptives

OBJECTIVE

The objective of this study was to evaluate the effects of two low-dose combined oral contraceptives on bone metabolism in adolescents for one year.

METHODS

This was a quasi-experimental study. The adolescents were divided into three groups: oral contraceptives 1 (n=42) (20μg EE/150μg desogestrel), oral contraceptives 2 (n=66) (30μg EE/3mg drospirenone), and a control group (n=70). Adolescents underwent anthropometric assessment and densitometry (dual-energy X-ray). Bone age and bone formation markers (osteocalcin and bone alkaline phosphatase) were evaluated. The oral contraceptives users were evaluated again after 12 months. Linear regression analysis was used to indirectly study the effect of each additional year of chronological age on anthropometric and densitometric variables as well as on bone markers in the control group.

RESULTS

At study entry, no significant differences were observed between the oral contraceptives 1, oral contraceptives 2, and controls in the analyzed variables. Linear regression analysis showed an increase in bone mineral density and bone mineral content for each additional year. There was a significant reduction in bone alkaline phosphatase levels; no significant difference was observed for osteocalcin in control individuals. Comparison of dual-energy X-ray variables at baseline and after one year showed no significant differences in the oral contraceptives 1 or oral contraceptives 2 groups. A significant reduction in bone alkaline phosphatase and osteocalcin levels was observed in both the oral contraceptives 1 and oral contraceptives 2 groups.

CONCLUSION

Adolescent women gain peak bone mass during this phase of life. Two low-dose combined oral hormonal contraceptives were associated with lower bone gain and lower bone formation markers than in untreated controls.

A 9-Month Jumping Intervention to Improve Bone Geometry in Adolescent Male Athletes

PURPOSE

Sports have different effects on bone development and effective interventions to improve bone health of adolescent athletes are needed. The purpose of the study was to investigate the effect of a 9-month jumping intervention on bone geometry and metabolism in adolescent male athletes.

METHODS

Ninety-three adolescent (14.1 yr old) male swimmers (SWI), footballers (FOO), and cyclists (CYC) were randomized to intervention and sport (INT-SWI = 19, INT-FOO = 15, and INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, and CON-CYC = 12) groups. Cross-sectional area, cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck were assessed using hip structural analysis and trabecular texture of the lumbar spine using trabecular bone score. Bone mineral content (BMC) at femoral neck and lumbar spine was assessed using dual-energy x-ray absorptiometry. Serum N-terminal propeptide of procollagen type I, isomer of the carboxy-terminal telopeptide of type 1 collagen, total serum calcium, and 25-hydroxyvitamin D were analyzed.

RESULTS

INT-CYC acquired significantly higher lumbar spine BMC (4.6%) and femoral neck BMC (9.8%) than CON-CYC. INT-CYC acquired significantly higher cross-sectional area (11.0%), CSMI (10.1%), and trabecular bone score (4.4%) than CON-CYC. INT-SWI acquired significantly higher femoral neck BMC (6.0%) and CSMI (10.9%) than CON-SWI. There were no significant differences between INT-FOO and CON-FOO in any bone outcomes. N-terminal propeptide of procollagen type I significantly decreased in CON-SWI, INT-FOO, CON-FOO, and CON-CYC. Carboxy-terminal telopeptide of type 1 collagen significantly decreased in CON-SWI and CON-CYC. The 25-hydroxyvitamin D significantly increased in INT-CYC, CON-CYC, INT-FOO, and CON-FOO.

CONCLUSIONS

A 9-month jumping intervention improved bone outcomes in adolescent swimmers and cyclists, but not in footballers. This intervention might be used by sports clubs to improve bone health of adolescent athletes.

May Young Elite Cyclists Have Less Efficient Bone Metabolism?

The purpose of this work was to describe changes in metabolic activity in the bones of young male competitive cyclists (CYC) as compared with age-matched controls (CON) over a one-year period of study. Eight adolescent male cyclists aged between fourteen and twenty, and eight age-matched controls participated in this longitudinal study. Serum osteocalcin (OC), amino-terminal propeptide of type I procollagen (PINP), beta-isomerized C-telopeptides (β-CTx) and plasma 25 hydroxyvitamin D [25(OH)D], were investigated by an electrogenerated chemiluminescence immunoassay. Analysis of variance revealed no significant differences in formation and resorption markers between cyclists and controls. Within the groups, both CYC and CON showed decreased OC at -30% and -24%, respectively, and PINP where the figures were -28% and -30% respectively (all p < 0.05). However, only the CYC group showed a decrease in [25(OH)D], lower by 11% (p < 0.05). The similarity in the concentrations of markers in cyclists and controls seems to indicate that cycling does not modify the process of bone remodeling. The decrease in vitamin D in cyclists might be detrimental to their future bone health.

Association of Serum Total Osteocalcin Concentrations With Endogenous Glucocorticoids and Insulin Sensitivity Markers in 12-Year-Old Children: A Cross-Sectional Study

Background: Osteocalcin (OC) is an osteoblast-derived marker of bone turnover that has recently been linked to glucose metabolism, glucocorticoid action, and cardiovascular risk. Objective: We determined whether serum total OC (tOC) is associated with cardiometabolic factors, such as insulin sensitivity (IS) markers and endogenous glucocorticoids in 12-year-old children. In addition, we assessed whether low birth weight or exposure to maternal preeclampsia affect tOC concentrations. Methods: In this cross-sectional study, 192 children (109 girls) were studied at 12 years of age. Seventy of them had been born small (SGA), 78 appropriate for gestational age (AGA), and 44 from preeclamptic pregnancies (PRE) as AGA. Blood pressure was measured, and fasting blood samples were collected for markers of glucose metabolism, osteoblast, adipocyte, and adrenocortical function. IS was estimated by Quantitative Insulin Sensitivity Check Index (QUICKI). Free cortisol index (FCI) was calculated as serum cortisol/corticosteroid binding globulin. Results: The highest tOC concentrations were detected in midpubertal children (Tanner B/G stage 3). The children in the highest tOC quartile (n = 48) had lower body mass index (BMI), waist-to-height ratio, diastolic blood pressure, leptin, cortisol/cortisone ratio and FCI, and higher insulin-like growth factor I (IGF-I), IGF-binding protein-1 (IGFBP-1), IGFBP-3, and alkaline phosphatase (ALP) than those in the lower tOC quartiles (p < 0.02 for all). QUICKI was similar in these subgroups. In logistic regression analysis, pubertal developmental stages 2 and 3, high ALP, IGF-I, and low FCI and BMI (p < 0.02 for all) were associated independently with higher tOC. The means of serum tOC and IS markers were similar in the SGA, AGA, and PRE subgroups. Conclusions: In both sexes, the highest tOC levels were detected in midpubertal children reflecting the fast pubertal growth phase. Higher tOC levels were associated with lower BMI and FCI, whereas no association was found with IS. Birth weight or exposure to preeclampsia had no effect on tOC concentrations.

Physical Fitness, Adiposity, and Diets as Surrogate Measures of Bone Health in Schoolchildren: A Biochemical and Cross-Sectional Survey Analysis

This study aimed to investigate the associations between adiposity, muscular fitness (MF), diet, sun exposure, and physical activity profiles as surrogate measures with bone health status in a sample of schoolchildren aged 8-18 yr old. A total of 250 Egyptian schoolchildren aged 8-18 yr were randomly invited to participate in these cross-sectional survey analyses. Calcaneal broadband ultrasound attenuation (c-BUA), bone mineral density (BMD), and bone formation markers (total calcium, serum bone alkaline phosphatase, and osteocalcin) were measured as markers of bone health. Adiposity profile, MF, physical activity (PA), sun exposure, Ca, and vitamin D dietary intake as related cofactors of bone health were measured by using prevalidated questionnaires and standard analytical techniques. A total of 85% (n = 213) of the study population showed normal bone health and 14.8% (n = 37) had abnormal bone health; most of them are girls (67.6%) classified according to BMD and c-BUA Z-scores into osteopenia (9.6%) and osteoporosis (5.2%). Compared with boys, higher correlations between c-BUA, bone mineral content, and BMD measures in the femoral neck, lumbar spine, whole body, and bone markers were reported in girls with lower bone mass. There was a positive significant correlation between body mass index, adiposity, sun exposure, MF, PA status, Ca and vitamin D intake, and c-BUA and BMD score analyses. These parameters were shown to be associated with about ~57.3%-88.4% of bone health characteristics of children and adolescents with osteopenia and osteoporosis. In children and adolescents, sun exposure, Ca and vitamin D diets, adiposity, PA, and changes in the levels of Ca, osteocalcin, and serum bone alkaline phosphatase were shown to be associated with bone health. Also, a significant correlation was reported between c-BUA score, dual-energy X-ray absorptiometry-BMD measures, and bone markers at clinically important bone sites of girls and boys. However, further clinical trials should be studied to consider c-BUA and bone markers as the benchmark estimates of bone mass for diagnostic purposes in young ages.

Mediterranean diet, diet quality, and bone mineral content in adolescents: the HELENA study

Dietary scores, rather than individual nutrients, allow exploring associations between overall diet and bone health. The aim of the present study was to assess the associations between the Mediterranean Diet Score for Adolescents (MDS-A) and the Diet Quality Index for Adolescents (DQI-A) and bone mineral content (BMC) among Spanish adolescents. Our results do not support an association between dietary scores or indices and BMC in adolescents.

INTRODUCTION

To assess the associations between the MDS-A and a DQI-A with the BMC measured with dual-energy X-ray absorptiometry.

METHODS

The MDS-A and the DQI-A were calculated in 179 Spanish adolescents, based on two 24-h dietary recalls from the HELENA cross-sectional study. The associations between the diet scores and the BMC outcomes [total body less head (TBLH), femoral neck (FN), lumbar spine (LS), and hip] were analyzed using logistic regression models adjusting for several confounders.

RESULTS

Four hundred ninety-two models were included and only fruits and nuts and cereal and roots were found to provide significant ORs with regard to BMC. The risk of having low BMC reduced by 32% (OR 0.684; CI 0.473-0.988) for FN when following the ideal MDS-A, but this association lost significance when adjusting for lean mass and physical activity. For every 1-point increase in the cereal and root and the fruit and nut components, the risk of having low FN diminished by 56% (OR 0.442; CI 0.216-0.901) and by 67% (OR 0.332; CI 0.146-0.755), respectively.

CONCLUSION

An overall dietary score or index is not associated with BMC in our adolescent Spanish sample.

Bone metabolism markers and vitamin D in adolescent cyclists

This study aimed to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls. The main result is that younger subjects present a higher bone turnover than the older ones. Moreover, cyclists under the age of 17 have higher scores on all markers than age-matched controls.

PURPOSE

The purpose of this study was to describe bone metabolic activity in adolescent competitive cyclists compared to age-matched controls.

METHODS

Twenty-two male adolescent cyclists between 14 and 20 years (y) and 20 age-matched controls participated in this study. Serum osteocalcin (OC), aminoterminal propeptide of type I procollagen (PINP), and β-isomerized C-telopeptides (β-CTX) were analyzed by electrochemiluminescence immunoassay (ECLIA); plasma 25 hydroxyvitamin D [25(OH)D] was analyzed by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Analysis of variance revealed no significant differences in bone metabolism markers and vitamin D between cyclists and controls. Cyclists over 17 y had a significantly lower concentration in bone formation and resorption biochemical markers compared to cyclists under 17 y (all P < 0.05). Moreover, controls over 17 y presented lower concentration for PINP (P < 0.05) compared to their peers under 17 y. Comparisons between cyclists and controls under 17 y revealed higher concentrations of OC and PINP (P < 0.05) in cyclists. Group interaction by age was found for OC, PINP, and β-CTX (P < 0.01). Cyclists over 17 y had higher concentrations of [25(OH)D] (P < 0.05) than age-matched controls.

CONCLUSIONS

The present results support the idea that cycling during adolescence may be associated to a decrease in bone turnover that may affect bone health later in life.

Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: The PRO-BONE Study

Adolescence is a crucial period for bone development, and exercise can enhance bone acquisition during this period of life. However, it is not known how the different loading sports practiced can affect bone acquisition in adolescent male athletes. Therefore, the purpose of the present study was to determine the 1-year longitudinal bone acquisition among adolescent males involved in osteogenic (football) and non-osteogenic (swimming and cycling) sports and to compare with active controls. A total of 116 adolescent males aged 12 to 14 years at baseline were followed for 1 year: 37 swimmers, 37 footballers, 28 cyclists, and 14 active controls. Bone mineral content (BMC) was assessed using dual-energy X-ray absorptiometry (DXA); cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck was assessed using hip structural analysis (HSA); and bone texture of the lumbar spine was assessed using trabecular bone score (TBS). Serum N-terminal propeptide of procollagen type I (PINP), isomer of the Carboxi-terminal telopeptide of type 1 collagen (CTX-I), total serum calcium, and 25 hydroxyvitamin D [25(OH)D] were analyzed. Footballers had significantly higher adjusted BMC at the lumbar spine (7.0%) and femoral neck (5.0%) compared with cyclists, and significantly greater BMC at the lumbar spine (6.9%) compared with swimmers. Footballers presented significantly greater TBS (4.3%) compared with swimmers, and greater CSMI (10.2%), CSA (7.1%), Z (8.9%) and TBS (4.2%) compared with cyclists. No differences were noted between cyclists and swimmers, both groups had similar bone acquisition compared with controls. PINP was significantly higher in footballers and controls compared with cyclists and swimmers (3.3% to 6.0%), and 25(OH)D was significantly higher in footballers and cyclists compared with swimmers and controls (9.9% to 13.1%). These findings suggest that bone acquisition is higher in adolescent male footballers compared with swimmers and cyclists at the femoral neck and lumbar spine sites of the skeleton. © 2017 American Society for Bone and Mineral Research.

Use of CTX-I and PINP as bone turnover markers: National Bone Health Alliance recommendations to standardize sample handling and patient preparation to reduce pre-analytical variability

The National Bone Health Alliance (NBHA) recommends standardized sample handling and patient preparation for C-terminal telopeptide of type I collagen (CTX-I) and N-terminal propeptide of type I procollagen (PINP) measurements to reduce pre-analytical variability. Controllable and uncontrollable patient-related factors are reviewed to facilitate interpretation and minimize pre-analytical variability.

INTRODUCTION

The IOF and the International Federation of Clinical Chemistry (IFCC) Bone Marker Standards Working Group have identified PINP and CTX-I in blood to be the reference markers of bone turnover for the fracture risk prediction and monitoring of osteoporosis treatment. Although used in clinical research for many years, bone turnover markers (BTM) have not been widely adopted in clinical practice primarily due to their poor within-subject and between-lab reproducibility. The NBHA Bone Turnover Marker Project team aim to reduce pre-analytical variability of CTX-I and PINP measurements through standardized sample handling and patient preparation.

METHODS

Recommendations for sample handling and patient preparations were made based on review of available publications and pragmatic considerations to reduce pre-analytical variability. Controllable and un-controllable patient-related factors were reviewed to facilitate interpretation and sample collection.

RESULTS

Samples for CTX-I must be collected consistently in the morning hours in the fasted state. EDTA plasma is preferred for CTX-I for its greater sample stability. Sample collection conditions for PINP are less critical as PINP has minimal circadian variability and is not affected by food intake. Sample stability limits should be observed. The uncontrollable aspects (age, sex, pregnancy, immobility, recent fracture, co-morbidities, anti-osteoporotic drugs, other medications) should be considered in BTM interpretation.

CONCLUSION

Adopting standardized sample handling and patient preparation procedures will significantly reduce controllable pre-analytical variability. The successful adoption of such recommendations necessitates the close collaboration of various stakeholders at the global stage, including the laboratories, the medical community, the reagent manufacturers and the regulatory agencies.

Plasma concentrations of osteocalcin are associated with the timing of pubertal progress in boys

BACKGROUND

Animal models have shown that the skeletal hormone osteocalcin stimulates testicular testosterone synthesis. To assess whether osteocalcin might be a useful marker to detect pubertal development disorders, we examined osteocalcin plasma concentrations in children and adolescents with and without disorders of pubertal development.

METHODS

Osteocalcin concentrations were investigated in a total of 244 patients with endocrine disorders (122 males, mean age: 11.87+3.77 years), including patients with precocious puberty and constitutional delay of puberty.

RESULTS

Osteocalcin concentrations were highest among adolescents with precocious puberty and advanced pubertal development (120.60±45.22 ng/mL), while the concentrations were lowest among patients with constitutional delay of puberty (102.20±37.13 ng/mL). Overall, osteocalcin concentrations were strongly correlated with markers of bone metabolism.

CONCLUSIONS

Although plasma osteocalcin concentrations are associated with pubertal development in boys, it does not appear to be a useful diagnostic marker for altered pubertal development.

Longitudinal associations between bone and adipose tissue biochemical markers with bone mineralization in boys during puberty

Background

We investigated longitudinal relationships between the biochemical markers of bone and adipose tissue with bone mineral content (BMC), bone mineral density (BMD), moderate-to-vigorous physical activity (MVPA) and sedentary time (SED) in pubertal boys.

Methods

Ninety-six boys (11.9 ± 0.6 years old) were measured at baseline, after 12 and 24 months. Body composition (fat mass [FM], lean body mass [LBM]), and whole body (WB), lumbar spine (LS) and femoral neck (FN) BMD and BMC were assessed. Additionally, serum leptin, adiponectin, osteocalcin (OC) and C-terminal telopeptide of type I collagen (CTX) were measured.

Results

OC had a strong longitudinal inverse effect on changes in WB_BMD (p < 0.001) and LS_BMD (p = 0.021), while CTX had an inverse effect only on changes in FN_BMD (p = 0.011). Leptin had an inverse effect on changes in WB_BMC/WB_BMD (p = 0.001), FN_BMD (p = 0.002) and LS_BMD (p = 0.001). MVPA showed a longitudinal inverse effect on changes in leptin (p = 0.030), however no longitudinal effect of SED to biochemical markers of bone and adipose tissue was found.

Conclusions

Bone metabolism markers have negative effect on bone mineral accrual during puberty. Increases in MVPA affect leptin, suggesting a positive link of MVPA through leptin metabolism on increases in bone mineralization during puberty.

Adipocytokines and bone metabolism markers in relation to bone mineral values in early pubertal boys with different physical activity

BACKGROUND

We aimed to examine the associations of adipocytokines and circulating bone metabolism markers with bone mineral parameters in early pubertal boys with different physical activity level.

METHODS

Eighty-six early pubertal boys were divided into active and non-active boys according to the accumulated moderate-to-vigorous physical activity (MVPA) level. Body composition and bone mineral parameters were assessed and testosterone, leptin, adiponectin, osteocalcin (OC), and C-terminal telopeptide of type I collagen (CTX) were measured.

RESULTS

Active subjects had significantly lower (p<0.05) body mass, body mass index (BMI), fat mass (FM), leptin, and sedentary time values, while non-active subjects had lower (p<0.05) vigorous physical activity level and femoral neck bone mineral density (FN-BMD). OC contributed to the models in physically active group and explained 6.6% and 9.7% of variance in whole body (WB) [F(5,44)=10.847; p<0.001] and lumbar spine bone mineral content (LS-BMC) [F(5,44)=4.158; p=0.004], respectively. No other biochemical parameters were found to be related to bone mineral parameters in either the active or non-active group.

CONCLUSIONS

Bone metabolism markers were positively correlated with bone mineral values only in active pubertal boys. Leptin and adiponectin were not related to bone mineral parameters in active and non-active pubertal boys.

Associations between serum 25-hydroxyvitamin D and bone turnover markers in a population based sample of German children

Severe vitamin D deficiency is known to cause rickets, however epidemiological studies and RCTs did not reveal conclusive associations for other parameters of bone health. In our study, we aimed to investigate the association between serum levels of 25(OH) vitamin D and bone turnover markers in a population-based sample of children. 25(OH)D, calcium (Ca), osteocalcin (OC), and β-Crosslaps (β-CTx) were measured in 2798 ten-year-old children from the German birth cohorts GINIplus and LISAplus. Linear regression was used to determine the association between bone turnover markers and 25(OH)D levels. 25(OH)D, OC, and β-CTx showed a clear seasonal variation. A 10 nmol/l increase in 25(OH)D was significantly associated with a 10.5 ng/l decrease (p < 0.001) in β-CTx after adjustment for design, sex, fasting status, time of blood drawn, BMI, growth rate, and detectable testosterone/estradiol. For OC alone no significant association with 25(OH)D was observed, whereas the β-CTx-to-OC ratio was inversely associated with 25(OH)D (−1.7% change, p < 0.001). When stratifying the analyses by serum calcium levels, associations were stronger in children with Ca levels below the median. This study in school-aged children showed a seasonal variation of 25(OH)D and the bone turnover markers OC and β-CTx. Furthermore a negative association between 25(OH)D and the bone resorption marker β-CTx was observed.

Bone structure of adolescent swimmers; a peripheral quantitative computed tomography (pQCT) study

OBJECTIVES

The aims of the present study were: (1) to characterize vBMD, bone structure and strength with peripheral quantitative computerized tomography (pQCT) in adolescent swimmers and compare it to normo-active controls (CG); and (2) to evaluate the possible interaction that weight-bearing sports might have on swimmers bone.

DESIGN

Cross-sectional.

METHODS

The non-dominant radius and tibia of 79 (32 females) swimmers and 49 (22 females) CG (both 11-18 years old) were evaluated at proximal and distal sites with a pQCT scanner. Values of total, trabecular and cortical volumetric bone mineral density (vBMD) were obtained from each scan. Cortical thickness, endosteal and periosteal circumferences were also measured and bone strength indexes were calculated. Analyses of covariance were used to compare variables between groups adjusting for age, tanner stage and bone length. Three different analyses were performed according to present and past sport participation in addition to swimming in order to determine differences among swimmers who had performed or were performing other sports (OTHER-SP) (10 females/17 males) and swimmers who had not performed other sports (NO-OTHER-SP) (22 females/22 males). Both of these groups were compared to each other and to a CG (22 females/27 males).

RESULTS

No differences were found between swimmers and CG for bone strength indexes, structure or vBMD (independently of the compared sample).

CONCLUSIONS

These results indicate that swimmers present similar bone strength and structure than CG who did not present high physical activity levels.

Association between bone mineralization, body composition, and cardiorespiratory fitness level in young Australian men

The critical age for attainment of peak bone mineralization is however 20-30 yr, but few studies have investigated bone mineralization and its association with body composition and cardiorespiratory fitness level in young men. This study aimed to investigate relationships between age, bone mineral measurements, body composition measurements, and cardiorespiratory fitness level in a group of young healthy Australian men. Thirty-five healthy men aged 18-25 yr had anthropometric measures, body composition, and cardiorespiratory fitness level assessed. Bone mineral content was significantly associated with height, body mass and lean mass, and bone mineral density positively correlated with lean mass and body mass. Bone mineral measurements did not correlate with fat mass, percentage of fat mass, or cardiorespiratory fitness level. Age was directly correlated with total body mass, body fat, and percentage of fat mass. Body mineral measurements correlated with lean mass but not with fat mass or with cardiorespiratory fitness in this group of young healthy men. Positive association between body fat and age in such young group suggests that more studies with young men are warranted and may help inform strategies to optimize increase in bone mineral measurements.

Bleeding and non-bleeding phenotypes in patients with GGCX gene mutations

Functional limitations for the vitamin K cycle, caused either by mutations in gamma-glutamyl carboxylase or vitamin K epoxide reductase genes, result in hereditary deficiency of vitamin K-dependent coagulation factors (VKCFD1 and VKCFD2, respectively). Patients suffering from VKCFD often share several other anatomical irregularities which are not related to haemostasis. Here we report on nine patients, eight of them previously unreported, who presented with VKCFD1. All were examined with special attention to vitamin K-dependent coagulation factors as well as to bone and heart development and to other anatomical signs of embryonal vitamin K deficiency. In total, we detected ten mutations in the gamma-glutamyl carboxylase gene of which seven have not been previously reported. Most interestingly, additional non-bleeding phenotypes were observed in all patients including midfacial hypoplasia, premature osteoporosis, cochlear hearing loss, heart valve defects, pulmonary stenosis, or pseudoxanthoma elasticum-like phenotype. Undercarboxylated matrix Gla protein, osteocalcin, and periostin appear to be responsible for these defects which are also observed in cases of fetal warfarin syndrome.

The Tromsø Study: Fit Futures: a study of Norwegian adolescents' lifestyle and bone health

Bone mass achievement predicts later fracture risk. This population-based study describes bone mineral density (BMD) levels and associated factors in Norwegian adolescents. Compared with international reference ranges, BMD levels appear higher and physical activity levels are positively associated with BMD.

PURPOSE

Norway has one of the highest reported incidences of osteoporotic fractures. Maximisation of peak bone mass may prevent later fractures. This population-based study compared BMD levels of Norwegian adolescents with international reference ranges and explored associated factors.

METHODS

All first-year upper-secondary school students, aged 15-19 years in the Tromsø region were invited to the Fit Futures study in 2010-2011. Over 90 % of the invited participants attended, 508 girls and 530 boys. BMD was measured at total hip, femoral neck and total body by dual X-ray absorptiometry. Lifestyle variables were collected by self-administered questionnaires and interviews. All analyses were performed sex stratified, using linear regression models.

RESULTS

In girls, mean BMD (SD) was 1.060 g/cm(2) (0.124), 1.066 g/cm(2) (0.123) and 1.142 g/cm(2) (0.077) at the total hip, femoral neck and total body, respectively. In boys, corresponding values were 1.116 (0.147), 1.103 (0.150) and 1.182 (0.097), with significant higher values than the Lunar pediatric reference at 16 years of age. In girls, height and self-reported intensive physical activity of more than 4 h a week and early sexual maturation were positively associated with BMD at both femoral sites (p < 0.047). Among boys age, height, body mass index, physical activity and alcohol intake were positively (p < 0.038), whereas early stages of sexual maturation and smoking was negatively (p < 0.047) related to BMD.

CONCLUSIONS

Despite the heavy fracture burden, Norwegian adolescents' BMD levels are higher than age-matched Caucasians. Physical activity is associated with 1 SD increased BMD levels in those involved in competition or hard training.

Does bone resorption stimulate periosteal expansion? A cross-sectional analysis of β-C-telopeptides of type I collagen (CTX), genetic markers of the RANKL pathway, and periosteal circumference as measured by pQCT

We hypothesized that bone resorption acts to increase bone strength through stimulation of periosteal expansion. Hence, we examined whether bone resorption, as reflected by serum β-C-telopeptides of type I collagen (CTX), is positively associated with periosteal circumference (PC), in contrast to inverse associations with parameters related to bone remodeling such as cortical bone mineral density (BMDC ). CTX and mid-tibial peripheral quantitative computed tomography (pQCT) scans were available in 1130 adolescents (mean age 15.5 years) from the Avon Longitudinal Study of Parents and Children (ALSPAC). Analyses were adjusted for age, gender, time of sampling, tanner stage, lean mass, fat mass, and height. CTX was positively related to PC (β=0.19 [0.13, 0.24]) (coefficient=SD change per SD increase in CTX, 95% confidence interval)] but inversely associated with BMDC (β=-0.46 [-0.52,-0.40]) and cortical thickness [β=-0.11 (-0.18, -0.03)]. CTX was positively related to bone strength as reflected by the strength-strain index (SSI) (β=0.09 [0.03, 0.14]). To examine the causal nature of this relationship, we then analyzed whether single-nucleotide polymorphisms (SNPs) within key osteoclast regulatory genes, known to reduce areal/cortical BMD, conversely increase PC. Fifteen such genetic variants within or proximal to genes encoding receptor activator of NF-κB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) were identified by literature search. Six of the 15 alleles that were inversely related to BMD were positively related to CTX (p<0.05 cut-off) (n=2379). Subsequently, we performed a meta-analysis of associations between these SNPs and PC in ALSPAC (n=3382), Gothenburg Osteoporosis and Obesity Determinants (GOOD) (n=938), and the Young Finns Study (YFS) (n=1558). Five of the 15 alleles that were inversely related to BMD were positively related to PC (p<0.05 cut-off). We conclude that despite having lower BMD, individuals with a genetic predisposition to higher bone resorption have greater bone size, suggesting that higher bone resorption is permissive for greater periosteal expansion.

Sedentary behaviours and its association with bone mass in adolescents: the HELENA Cross-Sectional Study

Background

We aimed to examine whether time spent on different sedentary behaviours is associated with bone mineral content (BMC) in adolescents, after controlling for relevant confounders such as lean mass and objectively measured physical activity (PA), and if so, whether extra-curricular participation in osteogenic sports could have a role in this association.

Methods

Participants were 359 Spanish adolescents (12.5-17.5 yr, 178 boys,) from the HELENA-CSS (2006–07). Relationships of sedentary behaviours with bone variables were analysed by linear regression. The prevalence of low BMC (at least 1SD below the mean) and time spent on sedentary behaviours according to extracurricular sport participation was analysed by Chi-square tests.

Results

In boys, the use of internet for non-study was negatively associated with whole body BMC after adjustment for lean mass and moderate to vigorous PA (MVPA). In girls, the time spent studying was negatively associated with femoral neck BMC. Additional adjustment for lean mass slightly reduced the negative association between time spent studying and femoral neck BMC. The additional adjustment for MVPA did not change the results at this site. The percentage of girls having low femoral neck BMC was significantly smaller in those participating in osteogenic sports (≥ 3 h/week) than in the rest, independently of the cut-off selected for the time spent studying.

Conclusions

The use of internet for non-study (in boys) and the time spent studying (in girls) are negatively associated with whole body and femoral neck BMC, respectively. In addition, at least 3 h/week of extra-curricular osteogenic sports may help to counteract the negative association of time spent studying on bone health in girls.

Vitamin D status and physical activity interact to improve bone mass in adolescents. The HELENA Study

The effects of vitamin D concentrations on bone mineral content in adolescents are still unclear. Vitamin D and physical activity (PA) may interact to determine bone mineral content (BMC) in two possible directions; 25(OH)D sufficiency levels improve BMC only in active adolescents, or PA increases BMC in individuals with replete vitamin D levels.

INTRODUCTION

The effects of suboptimal 25-hydroxycholecalciferol (25(OH)D) concentrations on BMC in adolescents are still unclear. The main aim of this study was to evaluate the influence of 25(OH)D on BMC in adolescents, considering the effect of body composition, sex, age, Tanner stage, season, calcium and vitamin D intakes, physical fitness and PA.

METHODS

Serum 25(OH)D concentrations, anthropometric measurements, dual energy X-ray absorptiometry measurements, calcium and vitamin D intakes, PA and physical fitness were obtained in 100 Spanish adolescents (47 males), aged 12.5-17.5 years, within the framework of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. Relations were examined using ANCOVA and regression analyses including BMC as dependent variable.

RESULTS

Linear regression of BMC suggested that 25(OH)D concentrations independently influenced total and leg BMC after controlling for age, sex, lean mass, seasonality and calcium intake (B = 0.328, p < 0.05, and B = 0.221, p < 0.05, respectively) in the physically active group. No significant influence of 25(OH)D concentrations on BMC was observed in the inactive group. Significant effect was shown between the interaction of 25(OH)D and PA on BMC for the total body and legs (both p < 0.05).

CONCLUSIONS

Vitamin D and PA may interact to determine BMC. 25(OH)D sufficiency levels improve bone mass only in active adolescents, or PA has a positive influence on BMC in individuals with replete vitamin D levels.

Socioeconomic status and bone mass in Spanish adolescents. The HELENA Study

PURPOSE

Socioeconomic status (SES) has been frequently associated with body composition, particularly fat mass and obesity. However, the SES-bone mass association is not clear. We aimed to evaluate the associations between different SES indicators (Family Affluence Scale, parental education, and occupation) and bone mineral content in Spanish adolescents.

METHODS

Participants were 322 adolescents (164 boys and 158 girls, 12.5-17.5 years) from the Healthy Lifestyle in Europe by Nutrition in Adolescence study. The social background of the adolescents was self-reported using an SES questionnaire, and the bone variables were measured using dual-energy x-ray absorptiometry. Physical activity was measured using accelerometers. Calcium intake was estimated from two nonconsecutive 24 hours recalls. One-way analysis of covariance was performed to examine the relationships between SES indicators and bone mass using different sets of confounders: basic model (sex + sexual maturation), model 1 (basic model + height), model 2 (basic model + lean mass), and model 3 (basic model + calcium intake + average physical activity).

RESULTS

Adjusted results showed no association between SES indicators and whole-body or total hip bone mineral content. Additional analyses were performed in lumbar spine, pelvis, and hip subregions (femoral neck, trochanter, and intertrochanter), and no significant associations were observed at these sites either.

CONCLUSIONS

Our data do not support a link between different SES indicators (Family Affluence Scale, parental education, and occupation) and bone mass in adolescents.

Vitamin D, osteocalcin, and risk for adiposity as comorbidities in middle school children

Nonclassic actions of vitamin D include potential regulation of immune function and glucose homeostasis. The bone-metabolism loop has recently been expanded to include osteocalcin, which appears to play a more direct role in pancreatic beta cell function and energy metabolism. We hypothesized that both vitamin D and osteocalcin would correlate negatively with indices of adiposity-related comorbidity risk in periadolescents, varying by ethnic group. We analyzed anthropometric, metabolic, and inflammatory markers from a multiethnic population of 106 school children 11 to 14 years of age studied as part of the Reduce Obesity and Diabetes (ROAD) consortium. As expected, 25-hydroxyvitamin D (25-OH vitamin D) was inversely correlated with intact parathyroid hormone (iPTH); total osteocalcin (OCN) and uncarboxylated osteocalcin (uOCN) were directly correlated with each other. OCN and uOCN concentrations correlated inversely with age. Vitamin D deficiency was most prevalent among East Asians (EA) and African Americans (AA). The highest lipid risk scores and homeostatic model for assessment of insulin resistance (HOMA-IR) values were seen in the South Asian (SA) group. Overall, adiposity measures were inversely correlated with OCN and iPTH, whereas such relationships were not observed for vitamin D. Acute insulin response to glucose challenge correlated negatively with uOCN in all subjects; however, lipid risk score correlated negatively with uOCN only in whites. The relationships between markers of calcium metabolism and body composition, glucose homeostasis, lipids, and inflammation all showed racial and ethnic differences. No consistent relationship was found between vitamin D and adiposity or vitamin D and glucose metabolism; instead vitamin D levels varied by race and ethnicity in this school-based group. These findings are consistent with the hypothesis that markers of calcium and bone metabolism may reflect risk for adiposity-related comorbidities in children.

Factors associated with bone turnover and speed of sound in early and late-pubertal females

This cross-sectional study examines whether maturity, body composition, physical activity, dietary intake, and hormonal concentrations are related to markers of bone turnover and tibial speed of sound (tSOS) in premenarcheal (n = 20, 10.1 ± 1.1 years) and postmenarcheal girls (n = 28, aged 15.0 ± 1.4 years). Somatic maturity was evaluated using years from age of peak height velocity (aPHV). Daily dietary intake was assessed with a 24-h recall interview, and moderate to very vigorous physical activity (MVPA) was measured using accelerometry. Plasma levels of 25-OH vitamin D, serum levels of insulin-like growth-factor 1 (IGF-1) and leptin, and serum levels of bone turnover markers including osteocalcin (OC), bone-specific alkaline phosphatase (BAP) and cross-linked N-teleopeptide of type I collagen (NTX) were measured using ELISA. OC, BAP, and NTX were significantly higher while IGF-1 and tSOS were lower in the premenarcheal group. The premenarcheal girls were more active and had higher daily energy intake relative to their body mass but there were no group differences in body mass index percentile. Maturity predicted 40%-57% of the variance in bone turnover markers. Additionally, daily energy intake was a significant predictor of OC, especially in the postmenarcheal group. IGF-1 and MVPA were significant predictors of BAP in the group as a whole. However, examined separately, IGF-1 was a predictor of BAP in the premenarcheal group while MVPA was a predictor in the postmenarcheal group. Adiposity and leptin were both negative predictors of tSOS, with leptin being specifically predictive in the postmenarcheal group. In conclusion, while maturity was the strongest predictor of bone markers and tSOS, dietary intake, physical activity, body composition, and hormonal factors further contribute to the variance in bone turnover and bone SOS in young Caucasian females. Further, the predicting factors of bone turnover and tSOS were different within each maturity group.

Levels of physical activity that predict optimal bone mass in adolescents: the HELENA study

BACKGROUND

Physical activity is necessary for bone mass development in adolescence. There are few studies quantifying the associations between physical activity and bone mass in adolescents.

PURPOSE

To assess the relationship between moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) and bone mass in adolescents.

METHODS

Bone mass was measured by dual-energy X-ray absorptiometry and physical activity by accelerometers in 380 healthy Spanish adolescents (189 boys, aged 12.5-17.5 years) from the HELENA-CSS (2006-2007). Subjects were classified according to the recommended amount of MVPA (<60 minutes or ≥60 minutes of MVPA/day). Receiver operating characteristic curve analysis was applied to calculate the relationship between physical activity and bone mass.

RESULTS

Less than 41 and 45 minutes of MVPA/day are associated with reduced bone mass at the trochanter and femoral neck. More than 78 minutes of MVPA/day is associated with increased bone mineral density (BMD) at the femoral neck. Regarding VPA, more than 28 minutes/day for the hip and intertrochanter and more than 32 minutes/day for the femoral neck are associated with increased BMD.

CONCLUSIONS

The recommended amount of physical activity (minutes/day) seems insufficient to guarantee increased bone mass. With some minutes of VPA/day, bone adaptations could be obtained at different bone sites.

Contribution of bone turnover markers to bone mass in pubertal boys and girls

BACKGROUND AND AIMS

The association between bone turnover markers and bone mass in adolescence is not clear. We aimed to evaluate the associations between bone turnover markers and bone mineral content (BMC), density (BMD) and area (BMA).

SUBJECTS

A total of 56 adolescents (25 boys, 12.5-17.5 years) participated in the study.

METHODS

Bone mass and physical activity (PA) were measured using dual energy X-ray absorptiometry and accelerometers. Osteocalcin and amino-terminal propeptide of type I procollagen (PINP), as markers of bone formation, and beta-isomer of the C-terminal telopeptide of type I collagen, as marker of bone resorption were also measured. Sexual maturation, weight, height and average PA were considered as confounders.

RESULTS

Positive correlations (Pearson) were observed among the three bone turnover markers (r = 0.7-0.9). Stepwise multiple linear regression analyses showed that PINP was strong and negatively associated with BMC, BMD and BMA in girls, explaining 24.9% of the variance in BMC, 25.6% in BMD and 16.3% in BMA.

CONCLUSION

PINP is a strong predictor of bone related variables in pubertal girls.