Interpretation and application of bone turnover markers in children and adolescents

Associations of Serum Irisin and Fibroblast Growth Factor-21 Levels With Bone Mineral Characteristics in Eumenorrheic Adolescent Athletes With Different Training Activity Patterns

PURPOSE

To describe serum irisin and fibroblast growth factor-21 (FGF-21) concentrations in healthy female adolescents with different training activity patterns and their associations with bone mineral properties and metabolic markers.

METHODS

A total of 62 adolescent girls aged 14-18 years were recruited: 22 rhythmic gymnasts, 20 swimmers, and 20 untrained controls. Bone mineral characteristics by dual-energy X-ray absorptiometry, daily energy intake by dietary recall, serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen were measured in all girls.

RESULTS

Whole body and lumbar spine areal bone mineral density and lumbar spine bone mineral content were higher in the rhythmic gymnasts group compared with swimmers and untrained controls groups (P < .05). Serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen levels were not significantly different between the groups. In the rhythmic gymnasts group, serum FGF-21 concentration was positively correlated with lumbar spine areal bone mineral density independently of confounding factors (r = .51; P = .027).

CONCLUSIONS

Serum irisin and FGF-21 levels were not different between adolescent eumenorrheic girls with different training activity patterns. FGF-21 was positively associated with lumbar spine areal bone mineral density, which predominantly consists of trabecular bone in adolescent rhythmic gymnasts.

Abnormal Bone Turnover Observed in Obese Children based on Puberty Stage-Specific Bone Turnover Marker Reference

CONTEXT

Childhood and adolescence are critical periods for lifelong bone health. The impact of obesity on these phases is controversial, which may be due to the lack of standards for age-, sex-, and puberty-specific bone turnover markers (BTMs) that could sensitively reflect bone metabolism.

OBJECTIVE

To generate age-, sex, and puberty stage-specific BTM reference curves in children and adolescents and to explore the effect of obesity on bone metabolism in the Chinese population.

METHODS

Our study was part of the Evaluation and Monitoring on School-based Nutrition and Growth in Shenzhen study. A total of 800 participants aged 6∼18 years with normal body mass index (BMI) were selected to establish BTM reference curves for boys and girls at different ages under different pubertal development stages. Additionally, 200 participants with obesity (BMI > 95th percentile) were matched with healthy children from the original cohort at a 1:1 ratio. All participants underwent bone mineral density assessment, and serum levels of procollagen type 1 N-propeptide (P1NP) and β-C-telopeptide of type I collagen (CTX) were measured.

RESULTS

The BTM values presented significant age, sex, and puberty stage differences. Analysis of serum BTMs based on the established reference revealed a higher percentage of low-level P1NP in boys with obesity (P = .005); no significant difference was observed in girls. However, the obese group showed a significantly higher proportion of high β-CTX levels for girls, not boys (P = .022).

CONCLUSION

We provide age-, sex-, and puberty stage-specific P1NP and β-CTX reference curves. According to these, obesity appeared to be a negative factor for bone formation in boys and for bone resorption in girls.

Enhancing the contemporary human and water isotope reference database for the Netherlands: New insights from Sr-O-C-N-H isotope data

The determination of an individual's geographic origin is an essential aspect of forensic investigations. When primary identifiers cannot be used to make a positive identification, isotope analysis can be utilized to provide new leads. Modern reference data are essential for accurate interpretation of human isotopic data in terms of diet and origin. This article presents Sr-O-C-N-H isotope data of modern individuals (hair, dental enamel, and dentine collagen) and drinking water from the Netherlands. The δ15N values of human hair fall within the range of values observed worldwide and cannot be utilized to differentiate from other countries. Distinct disparities in the hair δ13C are evident between European countries and other regions, making it possible to exclude the Netherlands as a region of origin. Comparing Dutch dental isotope data to those of other nations has proven difficult due to the limited availability of reference data. The same limitation applies to tap water δ2H data.

Bone metabolism in children with normal weight and overweight/obesity in a northeastern region of Spain

Objectives

Bone mass progressively increases to peak during childhood and adolescence, which determines future bone health. Bone formation-resorption processes are assessed using bone markers. However, studies on the impact of obesity on bone turnover markers at this age are limited, and results are inconsistent. The objective of this study was to examine the potential impact of overweight/obesity on bone metabolism.

Methods

A study was performed to compare parameters of bone metabolism in 45 girls and boys with normal weight (controls) and in a group of 612 girls and boys with overweight/obesity (cases) from the Exergames study (University of Zaragoza). Ages ranged from 8 to 12 years.

Results

Higher values of phosphorus and IGFBP-3 were observed in children with overweight/obesity, as compared to children with normal weight, (p=0.042) and (p=0.042), respectively. BAP, osteocalcin, magnesium, vitamin D and IGF-I concentrations were lower in the group with overweight/obesity, whereas calcium concentrations were higher in this group, although differences were not statistically significant. A negative correlation was found (r=-0.193) (p=0.049) between BAP and BMI.

Conclusions

Although differences did not reach statistical significance, BAP and osteocalcin concentrations were lower in children with overweight/obesity. This added to the negative correlation found between BAP and MIC may demonstrate that overweight/obesity may negatively affect bone health already at a young age.

Metabolismo óseo en niños aragoneses con normopeso y niños con sobrepeso/obesidad

Objetivos

En la infancia y adolescencia se produce un aumento de masa ósea, hasta alcanzar un pico máximo, determinante para la salud ósea. Los marcadores óseos evalúan los procesos de formación-resorción ósea. Sin embargo, los estudios sobre la influencia de la obesidad en los marcadores de recambio óseo en esta edad, son escasos y los resultados contradictorios. El objetivo de nuestro estudio fue evaluar si el sobrepeso/obesidad influían en el metabolismo óseo.

Métodos

Se compararon parámetros relacionados con el metabolismo óseo, en 45 niños y niñas normopeso (controles) y en un grupo de 61 niños y niñas con sobrepeso/obesidad (casos), procedentes del estudio Exergames (Universidad de Zaragoza), de edades comprendidas, todos ellos, entre 8 y 12 años.

Resultados

La concentración de fósforo y la de IGFBP-3 fueron superiores en los niños con sobrepeso/obesidad, respecto a la de los niños normopeso, (p=0,042) y (p=0,042), respectivamente. Las concentraciones de BAP, osteocalcina, magnesio, vitamina D e IGF-I fueron más bajas en el grupo de los niños con sobrepeso/obesidad y la de calcio más elevada, pero las diferencias no fueron estadísticamente significativas. Existe correlación negativa (r=−0,193) (p=0,049) entre BAP e IMC.

Conclusiones

En los niños con sobrepeso/obesidad pese a que no se llegó a alcanzar significación estadística, la concentración de BAP y osteocalcina fue inferior a la de los niños normopeso, lo cual junto con la correlación negativa de BAP respecto al IMC encontrada, puede indicar que ya en edades tan tempranas el sobrepeso/obesidad puede afectar a la salud ósea.

Assessment of Biochemical Bone Turnover Markers in Polish Healthy Children and Adolescents

BACKGROUND

Assessing bone turnover in paediatric populations is crucial for understanding the physiological changes occurring during skeletal development and identifying potential abnormalities. The objective of this study was to assess osteocalcin (OC), bone alkaline phosphatase (BALP), and C-terminal telopeptide of type I collagen (CTX-I) levels reflecting bone formation and resorption for age and sex in Polish healthy children and adolescents.

MATERIALS AND METHODS

A total of 355 healthy normal-weight children and adolescents (46.5% girls) aged 1-18 years old were recruited. Total body less head (TBLH) and spine L1-L4 were used in children to assess bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA). Bone marker concentrations were determined by immunoenzymatic methods.

RESULTS

Bone marker levels in girls and boys started with higher values in the first year of life and subsequently decreased until reaching a nadir during the prepubertal period. The pubertal peak values of bone markers were reached at 11-13 years old in boys and at 9-11 years old in girls. After puberty, the adolescents showed a gradual decline in bone marker concentrations to the values observed in adults. We found positive correlations between OC level and TBLH-BMD (r = 0.329, p = 0.002), TBLH-BMD Z-score (r = 0.245, p = 0.023), and L1-L4 BMD (r = 0.280, p = 0.009) in the prepubertal group.

CONCLUSIONS

We showed serum levels of bone turnover markers-BALP, OC, and CTX-I-in relation to age and sex in healthy Polish children and adolescents. The age intervals of these markers for girls and boys aged 1-18 years old may be clinically useful in the assessment of bone metabolism in individuals with skeletal disorders.

Changes in bone turnover markers after discontinuing long-term glucocorticoid administration in children with idiopathic nephrotic syndrome: a multicenter retrospective observational study

BACKGROUND

Glucocorticoids affect bone turnover. Little is known about how bone turnover changes when glucocorticoids are discontinued following long-term administration.

METHODS

This retrospective observational study was conducted on the relationship between discontinuation of long-term administration of glucocorticoid and bone turnover markers (BTMs) in patients with childhood-onset idiopathic nephrotic syndrome. Serum bone alkaline phosphatase (BAP), intact procollagen type 1 N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase-5b (TRACP-5b) were evaluated as BTMs.

RESULTS

Thirty-eight pairs of BTMs at glucocorticoid administration and after discontinuation were analyzed in 29 patients. The median age at baseline was 12.4 (interquartile range, 9.0-14.5) years, and the median time from the onset of nephrotic syndrome was 5.9 (3.3-9.7) years. The mean period from prednisolone discontinuation to the measurement of BTMs after glucocorticoid discontinuation was 3.5 ± 1.0 months. Changes in BTMs after glucocorticoid discontinuation were modest when the daily prednisolone dose was < 0.25 mg/kg/day (ln BAP standard deviation [SD] score, p = 0.19; log intact P1NP SD score, p = 0.70; TRACP-5b, p = 0.95). When the daily prednisolone dose was ≥ 0.25 mg/kg/day, all BTMs increased significantly after glucocorticoid discontinuation (ln BAP SD score, p < 0.01; log intact P1NP SD score, p < 0.01; TRACP-5b, p < 0.01).

CONCLUSIONS

Decreased BTMs can rise within a few months of discontinuing long-term glucocorticoid administration. When the administered glucocorticoid dose is low, changes in BTMs may be small. A higher resolution version of the Graphical abstract is available as Supplementary information.

The evolution of the adolescent growth spurt: Urinary biomarkers of bone turnover in wild chimpanzees (Pan troglodytes)

Life history theory addresses how organisms balance development and reproduction. Mammals usually invest considerable energy into growth in infancy, and they do so incrementally less until reaching adult body size, when they shift energy to reproduction. Humans are unusual in having a long adolescence when energy is invested in both reproduction and growth, including rapid skeletal growth around puberty. Although many primates, especially in captivity, experience accelerated growth in mass around puberty, it remains unclear whether this represents skeletal growth. Without data on skeletal growth in nonhuman primates, anthropologists have often assumed the adolescent growth spurt is uniquely human, and hypotheses for its evolution have focused on other uniquely human traits. The lack of data is largely due to methodological difficulties of assessing skeletal growth in wild primates. Here, we use two urinary markers of bone turnover-osteocalcin and collagen-to study skeletal growth in a large, cross-sectional sample of wild chimpanzees (Pan troglodytes) at Ngogo, Kibale National Park, Uganda. For both bone turnover markers, we found a nonlinear effect of age, which was largely driven by males. For male chimpanzees, values for osteocalcin and collagen peaked at age 9.4 years and 10.8 years, respectively, which corresponds to early and middle adolescence. Notably, collagen values increased from 4.5 to 9 years, suggesting faster growth during early adolescence compared to late infancy. Biomarker levels plateaued at 20 years in both sexes, suggesting skeletal growth continues until then. Additional data, notably on females and infants of both sexes, are needed, as are longitudinal samples. However, our cross-sectional analysis suggests an adolescent growth spurt in the skeleton of chimpanzees, especially for males. Biologists should avoid claiming that the adolescent growth spurt is uniquely human, and hypotheses for the patterns of human growth should consider variation in our primate relatives.

Bone Turnover Markers in Children: From Laboratory Challenges to Clinical Interpretation

Bone turnover markers (BTMs) have been developed many years ago to study, in combination with imaging techniques, bone remodeling in adults. In children and adolescents, bone metabolism differs from adults since it implies both growth and bone remodeling, suggesting an age- and gender-dependent BTM concentration. Therefore, specific studies have evaluated BTMs in not only physiological but also pathological conditions. However, in pediatrics, the use of BTMs in clinical practice is still limited due to these many children-related specificities. This review will discuss about physiological levels of BTMs as well as their modifications under pathological conditions in children and adolescents. A focus is also given on analytical and clinical challenges that restrain BTM usefulness in pediatrics.

Metabolomic Profiling of Samples from Pediatric Asthma Patients Unveils Deficient Nutrients in African Americans

Plasma metabolomics represents a potentially powerful approach to understand the biochemical mechanisms of nutrition and metabolism in asthma. This study aims to acquire knowledge on plasma metabolites in asthma, which may provide avenues for nutrition therapy, as well as explanations for the observed effects in existing therapies. This study investigated 249 metabolites from 18 metabolite groups in a large cohort of African American population, including 602 pediatric patients with asthma and 593 controls, using a nuclear magnetic resonance (NMR) metabolomics platform. Decreased levels of citrate, ketone bodies, and two amino acids histidine (His) and glutamine (Gln), were observed in asthma cases compared to controls. Metabolites for lipid metabolism lost significance after controlling for comorbid obesity. For the first time, this study depicts a broad panorama of lipid metabolism and nutrition in asthma. Supplementation or augmentation of nutrients that are deficient may be beneficial for asthma care.

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Asthma is a major health issue in African Americans

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Metabolomics represents a powerful approach to understand the metabolism in asthma

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We observed decreased citrate, ketone bodies, and amino acids in the plasma

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Supplementation of nutrients that are deficient may be beneficial for asthma care

Fluctuations in Metabolites and Bone Markers Across the Menstrual Cycle in Eumenorrheic Women and Oral Contraceptive Users

CONTEXT

Little is known about changes in circulating metabolites during the menstrual cycle and how use of oral contraceptives (OCs) affects these changes.

OBJECTIVES

To study fluctuations in circulating metabolite and bone marker levels during the menstrual/pill cycle in eumenorrheic women and OC users.

METHODS

Plasma samples were collected from 28 eumenorrheic women and 10 OC users at 7 to 9 time points across a menstrual/pill cycle. Longitudinal and cross-sectional analyses were performed to examine the cycle- and OC-induced variations in the plasma metabolite and bone turnover marker levels.

RESULTS

In eumenorrheic women, plasma levels of alanine, glutamine, threonine, and tyrosine varied significantly across the menstrual cycle, and all dropped to the lowest level around day 21 of the menstrual cycle. These amino acid concentrations were negatively correlated with fluctuations in progesterone and/or estrogen levels. A between-group analysis showed that plasma levels of alanine, glutamine, glycine, proline, and tyrosine were lower in OC users than in nonusers. Concomitantly, plasma C-terminal telopeptide of type I collagen (CTX) and N-terminal propeptide of type I procollagen (PINP) levels were lower in OC users. Intriguingly, when all data were pooled, variations in CTX and PINP levels were positively correlated with fluctuations in proline and glycine concentrations (r > 0.5 or 0.3 < r < 0.5, P < 0.05).

CONCLUSIONS

The menstrual cycle and the use of OCs alter plasma levels of metabolites and bone turnover markers in young women. While the impact of these findings remains to be established, the lower glycine level among OC users and the accompanying lower CTX level supports that the use of OCs lowers collagen turnover in young women and may thereby have long-term implications for bone health among OC users.

Decreased cortical bone density and mechanical strength with associated elevated bone turnover markers at peri-pubertal peak height velocity: a cross-sectional and longitudinal cohort study of 396 girls with adolescent idiopathic scoliosis

Decreased cortical bone density and bone strength at peak height velocity (PHV) were noted in girls with adolescent idiopathic scoliosis (AIS). These findings could provide the link to the previously reported observation that low bone mineral density (BMD) could contribute as one of the prognostic factors for curve progression that mostly occurs during PHV in AIS.

INTRODUCTION

As part of the studies related to aetiopathogenesis of AIS, we assessed bone qualities, bone mechanical strength and bone turnover markers (BTMs) focusing at the peri-pubertal period and PHV in AIS girls.

METHODS

396 AIS girls in two separate cohorts were studied. Skeletal maturity was assessed using the validated thumb ossification composite index (TOCI). Bone qualities and strength were evaluated with high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA).

RESULTS

Cohort-A included 179 girls (11.95 ± 0.95 years old). Girls at TOCI-4 had numerically the highest height velocity (0.71 ± 0.24 cm/month) corresponding to the PHV. Subjects at TOCI-4 had lower cortical volumetric BMD (672.36 ± 39.07 mg/mm³), cortical thickness (0.68 ± 0.08 mm) and apparent modulus (1601.54 ± 243.75 N/mm²) than: (a) those at TOCI-1-3 (724.99 ± 32.09 mg/mm³ (p < 0.001), 0.79 ± 0.11 mm (p < 0.001) and 1910.88 ± 374.75 N/mm² (p < 0.001), respectively) and (b) those at TOCI-8 (732.28 ± 53.75 mg/mm³ (p < 0.001), 0.84 ± 0.14 mm (p < 0.001), 1889.11 ± 419.37 N/mm² (p < 0.001), respectively). Cohort-B included 217 girls (12.22 ± 0.89 years old). Subjects at TOCI-4 had higher levels of C-terminal telopeptide of type 1 collagen (1524.70 ± 271.10 pg/L) and procollagen type 1 N-terminal propeptide (941.12 ± 161.39 µg/L) than those at TOCI-8 (845.71 ± 478.55 pg/L (p < 0.001) and 370.08 ± 197.04 µg/L (p < 0.001), respectively).

CONCLUSION

AIS girls had decreased cortical bone density and bone mechanical strength with elevated BTMs at PHV. Coupling of PHV with decreased cortical and FEA parameters could provide the link to the previously reported observation that low BMD could contribute as one of the prognostic factors for curve progression that mostly occurs during PHV in AIS.

Acquisition of peak bone mass

Peak bone mass (PBM) is a key determinant of bone mass and fragility fractures later in life. The increase in bone mass during childhood and adolescence is mainly related to an increase in bone size rather to changes in volumetric bone density. Race, gender, and genetic factors are the main determinants of PBM achievement. Nevertheless, environmental factors such as physical activity, calcium and protein intakes, weight and age at menarche, are also playing an important role in bone mass accrual during growth. Therefore, optimization of calcium and protein intakes and weight-bearing physical activity during growth is an important strategy for optimal acquisition of PBM and bone strength and for contributing to prevent fractures later in life.

Parathormone, bone alkaline phosphatase and 25-hydroxyvitamin D status in a large cohort of 1200 children and teenagers

Objectives: 25-Hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and bone alkaline phosphatase (BALP) are biomarkers of calcium/phosphate metabolism and bone turnover. Although vitamin D deficiency is a well-known cause of secondary hyperparathyroidism, few studies have considered vitamin D status when establishing reference ranges. In this study, we report PTH levels according to the vitamin D status and BALP levels in a large cohort of 1200 children. Additionally, we provide PTH pediatric reference values according to 25(OH)D status as well as BALP pediatric reference ranges.Methods: Serum samples from 1200 children (equally distributed from 5 months to 20 years old) who underwent blood sampling for allergy exploration were used to quantify 25(OH)D, PTH and BALP.Results: The percentage of vitamin D deficient children (<20 ng/ml) progressively increased during childhood starting from 7% in the 0 to 2 year-old subgroup to a mean of at least 50% among teenagers. PTH levels inversely mirrored 25(OH)D concentrations for all age and gender subgroups, and 25(OH)D deficient subgroups presented higher PTH levels than their non-deficient counterparts. In the non-deficient 25(OH)D population, PTH levels were the highest at 11 years old for girls and 14 years old for boys. BALP results were slightly increased during childhood and showed a constant decrease during teenage years starting from 12 years old for girls and 14 years old for boys.Conclusion: Our results highlight the inverse relationship between PTH and 25(OH)D in children and the need for a well characterized 25(OH)D population to establish pediatric reference ranges for PTH.

Application of bone metabolic parameters in the diagnosis of growing pains

Objective

The present study aimed to assess the diagnostic significance of serum bone metabolic parameters in children with growing pains (GPs).

Methods

All patients diagnosed with GP and healthy controls matched with age and gender were recruited at the outpatient clinic of Children's Hospital at Zhejiang University School of Medicine from August 2016 to August 2021. In all subjects, serum levels of calcium (Ca), phosphorus (P), procollagen type‐I N‐terminal (PINP), parathormone (PTH), 25‐hydroxyvitamin D (25‐(OH)D), osteocalcin (OC), N‐terminal cross‐linked telopeptides of type‐I collagen (CTX), and tartrate‐resistant acid phosphatase type 5b (TRACP5b) were investigated. The univariate analysis, multivariate logistic regression analysis, and receiver operating characteristic (ROC) curve were used to identify the bone metabolic parameters factors for diagnosing GP.

Results

We enrolled 386 children with GP and 399 healthy controls in present study. The mean age of GP group was 5.319 years, and, primarily, the subjects were preschool‐age children. The gender ratio (male‐to‐female) was 1.27 in GP group. After adjusting for age and gender, we identified that the serum levels of Ca (p < 0.001, OR: 25.039), P (p = 0.018, OR: 2.681), PINP (p < 0.001, OR: 1.002), and PTH (p = 0.036, OR: 0.988) were independent diagnostic factors associated with GP. Area under curve (AUC) of the ROC curves was in the order: PINP (0.612) > Ca (0.599) > P (0.583) > PTH (0.541). A combination of independent diagnostic factors and multivariable logistic regression analysis provided a refined logistic regression model to improve the diagnostic potential, of which the AUC had reached 0.655.

Conclusions

Serum levels of Ca, P, PINP, and PTH could be independent diagnostic factors associated with GP. The logistic model was significantly superior to bone metabolic parameters for diagnosing GP.

Long-Term Administration of Abacavir and Etravirine Impairs Semen Quality and Alters Redox System and Bone Metabolism in Growing Male Wistar Rats

Highly active antiretroviral therapy (HAART) is used in HIV-infected patients. Alongside the prolongation of patients' life, adverse side effects associated with long-term therapy are becoming an increasing problem. Therefore, optimizing of HAART is extremely important. The study is aimed at evaluating the toxicity of abacavir and etravirine in monotherapy on the reproductive system, liver, kidneys, and bones in young, sexually mature, male rats. Thirty-six 8-week-old male Wistar rats randomized into three 12-animal groups received either normal saline (control), abacavir 60 mg/kg (AB group), or etravirine 40 mg/kg (ET group) once daily for 16 weeks. Semen morphology, oxide-redox state parameters (MDA, SOD, catalase, GPx, glutathione, GSH/GSSG ratio) in tissue homogenates (testes, liver, kidneys), and serum samples were studied. In bones, microcomputed tomography and a four-point bending test were performed. Total sperm count, sperm concentration, motility, and sperm morphology did not differ significantly in AB or ET groups compared to the control. In the flow cytometry of semen, an increased percentage of cells with denatured DNA was noticed for both tested drugs. However, no significant changes of oxide-redox state in testicular homogenates were found, except of increased SOD activity in the AB-receiving group. Additionally, ET significantly altered catalase and GPx in the liver and SOD activity in kidneys. Abacavir decreased catalase in the liver and GSH levels in kidneys. AB caused significant changes to bone microarchitecture (bone volume fraction, trabecular number, connectivity density, total porosity) and increased Young's modulus. Etravirine had a greater impact on macrometric parameters of bones (tibial index, mid-tibial diameter, femur length). After 4 weeks in the ET group, a lower 1,25-dihydroxyvitamin D₃ serum concentration was found. The results showed that abacavir and etravirine disturb oxidative stress. An increase in the percentage of sperms with chromatin damage suggests decreased fertility in rats receiving the studied drugs. Both drugs affected bone formation in growing rats. Additionally, etravirine disturbed vitamin D metabolism.

Serum sclerostin concentration is associated with specific adipose, muscle and bone tissue markers in lean adolescent females with increased physical activity

OBJECTIVES

Sclerostin is an important regulator of bone mass involving the Wnt/β-catenin signalling pathway. Relatively few studies have investigated the relationships of circulating sclerostin levels with adiposity-related and muscle-related biochemical factors in individuals with increased energy metabolism. The aim of this study was to investigate the associations of circulating sclerostin with adipokines, myokines, osteokines and body composition values in lean adolescent females with increased physical activity.

METHODS

A total of 73 adolescent females who were physically active and aged 14-18 years old participated in the study. Sclerostin, leptin, resistin, tumour necrosis factor (TNF)-α, interleukin (IL)-6, irisin, osteocalcin, C-terminal telopeptide of type I collagen (CTx), insulin-like growth factor (IGF)-1 and insulin were obtained from fasting blood samples. Body composition was measured by dual-energy X-ray absorptiometry (DXA) and analyzed for body fat mass, lean body mass, bone mineral content and muscle mass.

RESULTS

Serum sclerostin (117.9 ± 60.3 pg/mL) was correlated with age, age at menarche, body fat, muscle mass, training activity, leptin, TNF-α, irisin, osteocalcin, CTx and IGF-1. Multivariate linear regression analysis demonstrated that fat mass (β = 0.434; p = 0.001), leptin (β = -0.308; p = 0.015), irisin (β = 0.227; p = 0.024) and CTx (β = 0.290; p = 0.031) were the most important predictors of serum sclerostin concentration.

CONCLUSIONS

Bone-derived sclerostin is associated with specific adipokine, myokine and osteokine values in lean adolescent females with increased physical activity. These results suggest that the interactions between bone, adipose and muscle tissues could also be associated with circulating sclerostin concentrations.

Relationships of Bone Mineral Variables with Body Composition, Blood Hormones and Training Volume in Adolescent Female Athletes with Different Loading Patterns

The aim of this investigation was to determine the relationships of areal bone mineral density (aBMD) and content (BMC) with body composition, blood hormone and training load variables in adolescent female athletes with different loading patterns. The participants were 73 healthy adolescent females (14–18 years), who were divided into three groups: rhythmic gymnasts (RG; n = 33), swimmers (SW; n = 20) and untrained controls (UC; n = 20). Bone mineral and body compositional variables were measured by dual-energy X-ray absorptiometry, and insulin-like growth factor-1 (IGF-1), estradiol and leptin were analyzed from blood samples. In addition, aerobic performance was assessed by a peak oxygen consumption test. No differences (p > 0.05) in weekly training volume were observed between rhythmic gymnasts (17.6 ± 5.3 h/week) and swimmers (16.1 ± 6.9 h/week). Measured areal bone mineral density and bone mineral content values were higher in rhythmic gymnasts compared with other groups (p < 0.05), while no differences (p > 0.05) in measured bone mineral values were seen between swimmers and untrained control groups. Multiple regression models indicated that IGF-1 alone explained 14% of the total variance (R² × 100) in lumbar spine aBMD, while appendicular muscle mass and training volume together explained 37% of the total variance in femoral neck BMC in the rhythmic gymnast group only. In swimmers, age at menarche, estradiol and appendicular muscle mass together explained 68% of the total variance in lumbar spine BMC, while appendicular muscle mass was the only predictor and explained 19 to 53% of the total variance in measured bone mineral values in untrained controls. In conclusion, adolescent rhythmic gymnasts with specific weight-bearing athletic activity present higher areal bone mineral values in comparison with swimmers and untrained controls. Specific training volume together with appendicular muscle mass influenced cortical bone development at the femoral neck site of the skeleton in rhythmic gymnasts, while hormonal values influenced trabecular bone development at the lumbar spine site in both athletic groups with different loading patterns.

A Longitudinal Study of Bone Mineral Accrual during Growth in Competitive Premenarcheal Rhythmic Gymnasts

The purpose of this investigation was to study whether prolonged competitive rhythmic gymnastics training influenced bone mineral accrual in premenarcheal girls. Eighty-nine girls (45 rhythmic gymnasts [RG] and 44 untrained controls [UC]) between 7 and 9 years of age were recruited and measured annually for four years (not all participants were measured at every occasion). Dual energy x-ray absorptiometry was used to assess the development of whole body (WB), femoral neck (FN) and lumbar spine (LS) bone mineral content (BMC). In addition, body composition, blood adipokine and jumping performance characteristics were obtained. For longitudinal analyses, hierarchical mixed-effects models were constructed to predict differences in the development of WB, FN and LS BMC between RG and UC groups, while accounting for differences in body composition, blood adipokine and jumping performance values. It appeared that from 8 years of age, RG had lower (p < 0.05) fat mass and leptin values, and higher (p < 0.05) jumping performance measures in comparison with UC girls. Hierarchical mixed-effects models demonstrated that RG had 71.9 ± 12.0, 0.23 ± 0.11 and 1.39 ± 0.42 g more (p < 0.05) WB, FN and LS BMC, respectively, in comparison with UC girls. In addition, WB, FN and LS BMC increased more (p < 0.05) between 7 to 12 years of age in RG girls in comparison with UC. In conclusion, these findings suggest that the prolonged exposure to competitive rhythmic gymnastics trainings in premenarcheal girls is associated with greater bone mineral accrual despite lower body fat mass and leptin values.

Sclerostin, preadipocyte factor-1 and bone mineral values in eumenorrheic adolescent athletes with different training patterns

INTRODUCTION

The specific aims of the study were to compare possible differences in sclerostin and preadipocyte factor-1 (Pref-1) between rhythmic gymnasts (RG), swimmers (SW) and untrained controls (UC), and to investigate the relationships of sclerostin and Pref-1 with bone mineral characteristics in studied groups.

MATERIALS AND METHODS

This study included 62 eumenorrheic adolescents (RG = 22; SW = 20; UC = 20). Bone mineral and body composition characteristics were measured by dual-energy X-ray absorptiometry, and sclerostin, Pref-1, osteocalcin and C-terminal telopeptide of type I collagen (CTx) were measured.

RESULTS

Sclerostin was higher (P = 0.001) in RG (129.35 ± 51.01 pg/ml; by 74%) and SW (118.05 ± 40.05 pg/ml; by 59%) in comparison with UC (74.32 ± 45.41 pg/ml), while no differences (P = 0.896) were seen in Pref-1 (RG: 1.42 ± 0.16 ng/ml; SW: 1.41 ± 0.20 ng/ml; UC: 1.39 ± 0.26 ng/ml) between groups. Osteocalcin (RG: 7.74 ± 4.09 ng/ml; SW: 8.05 ± 4.18 ng/ml; UC: 7.04 ± 3.92 ng/ml; P = 0.843) and CTx (RG: 0.73 ± 0.22 ng/ml; SW: 0.64 ± 0.16 ng/ml; UC: 0.62 ± 0.20 ng/ml; P = 0.173) were not different between groups. Sclerostin correlated (P < 0.05) with whole-body bone mineral content (r = 0.61) and lumbar spine (LS) areal bone mineral density (aBMD) (r = 0.43) in RG, and femoral neck aBMD (r = 0.45) in UC. No correlation was found between sclerostin and bone mineral values in SW, and Pref-1 was not correlated with any bone mineral characteristics in studied groups. Sclerostin was the independent variable that explained 14% of the total variance (R² × 100) in LS aBMD value only in RG.

CONCLUSIONS

Adolescent athletes have higher sclerostin compared to UC. Sclerostin was correlated with bone mineral values and predicted areal bone mineral density in RG.

Association of higher bone turnover with risk of curve progression in adolescent idiopathic scoliosis

OBJECTIVE

Emerging evidence suggest abnormal bone metabolism and defective bone qualities are associated to etipathogenesis of Adolescent Idiopathic Scoliosis (AIS). Systemic low bone mass is important prognosticator to predict risk of curve progression in AIS. The underlying mechanism is still unclear. We hypothesize that aberrant bone turnover correlates with bone qualities in AIS and associates to risk of curve progression.

SUBJECTS AND METHODS

Two cohorts were included in this study. The case-control study recruited 161 AIS girls and 161 ethnic/age-matched healthy girls. The longitudinal cohort recruited 128 AIS girls with two-year follow-up. Areal bone mineral density (BMD) at femoral necks were measured with dual-energy x-ray absorptiometry (DXA), and bone qualities of distal radius by high-resolution peripheral quantitative computed tomography (HR-pQCT). Time-lapse analysis of registered HR-pQCT images estimated local bone remodeling quantitatively. Serum levels of CTX and P1NP were measured with ELISA kits.

RESULTS

AIS presented significantly higher serum level of P1NP. In both AIS and control, the negative correlations were consistently observed between serum CTX/P1NP levels and most cortical bone quality parameters after adjustment to age. Significant correlation between serum bone turnover markers and trabecular bone parameters have been observed only in control. Progressive AIS has significant increase of serum P1NP level at first clinic visit. Time lapse register analysis showed high bone resorption and low net bone gain was associated with risk of progression in AIS.

CONCLUSIONS

Our study characterized AIS with higher serum bone turnover markers, which may contribute to defective bone qualities in AIS. For the first time, we showed that progressive AIS had higher systemic bone turnover markers level and local bone remodeling. This fresh evidence indicated association between disrupted bone turnover and risk of progression of AIS, which set the foundation of new prognostic method and of novel treatment target to curve progression. This study demonstrated the importance of bone metabolism in developing disease management of AIS to achieve goal of early prediction and non-surgical modulation.

Promoting bone health in children and adolescents following solid organ transplantation

Solid organ transplantation in children and adolescents provides many benefits through improving critical organ function, including better growth, development, cardiovascular status, and quality of life. Unfortunately, bone status may be adversely affected even when overall status is improving, due to issues with pre-existing bone disease as well as medications and nutritional challenges inherent post-transplantation. For all children and adolescents, bone status entering adulthood is a critical determinant of bone health through adulthood. The overall health and bone status of transplant recipients benefits from attention to regular physical activity, good nutrition, adequate calcium, phosphorous, magnesium and vitamin D intake and avoidance/minimization of soda, extra sodium, and obesity. Many immunosuppressive agents, especially glucocorticoids, can adversely affect bone function and development. Minimizing exposure to "bone-toxic" medications is an important part of promoting bone health in children post-transplantation. Existing guidelines detail how regular monitoring of bone status and biochemical markers can help detect bone abnormalities early and facilitate valuable bone-directed interventions. Attention to calcium and vitamin D supplementation, as well as tapering and withdrawing glucocorticoids as early as possible after transplant, can provide best bone outcomes for these children. Dual-energy X-ray absorptiometry can be useful to detect abnormal bone mass and fracture risk in this population and newer bone assessment methods are being evaluated in children at risk for poor bone outcomes. Newer bone therapies being explored in adults with transplants, particularly bisphosphonates and the RANKL inhibitor denosumab, may offer promise for children with low bone mass post-transplantation.

Management of primary and secondary osteoporosis in children

Osteoporosis in children differs from adults in terms of definition, diagnosis, monitoring and treatment options. Primary osteoporosis comprises primarily of osteogenesis imperfecta (OI), but there are significant other causes of bone fragility in children that require treatment. Secondary osteoporosis can be a result of muscle disuse, iatrogenic causes, such as steroids, chronic inflammation, delayed or arrested puberty and thalassaemia major. Investigations involve bone biochemistry, dual-energy X-ray absorptiometry scan for bone densitometry and vertebral fracture assessment, radiographic assessment of the spine and, in some cases, quantitative computed tomography (QCT) or peripheral QCT. It is important that bone mineral density (BMD) results are adjusted based on age, gender and height, in order to reflect size corrections in children. Genetics are being used increasingly for the diagnosis and classification of various cases of primary osteoporosis. Bone turnover markers are used less frequently in children, but can be helpful in monitoring treatment and transiliac bone biopsy can assist in the diagnosis of atypical cases of osteoporosis. The management of children with osteoporosis requires a multidisciplinary team of health professionals with expertise in paediatric bone disease. The prevention and treatment of fragility fractures and improvement of the quality of life of patients are important aims of a specialised service. The drugs used most commonly in children are bisphosphonates, that, with timely treatment, can give good results in improving BMD and reshaping vertebral fractures. The data regarding their effect on reducing long bone fractures are equivocal. Denosumab is being used increasingly for various conditions with mixed results. There are more drugs trialled in adults, but these are not yet licenced for children. Increasing awareness of risk factors for paediatric osteoporosis, screening and referral to a specialist team for appropriate management can lead to early detection and treatment of asymptomatic fractures and prevention of further bone damage.

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.

The Important Role of Adiponectin and Orexin-A, Two Key Proteins Improving Healthy Status: Focus on Physical Activity

Exercise represents the most important integrative therapy in metabolic, immunologic and chronic diseases; it represents a valid strategy in the non-pharmacological intervention of lifestyle linked diseases. A large body of evidence indicates physical exercise as an effective measure against chronic non-communicable diseases. The worldwide general evidence for health benefits are both for all ages and skill levels. In a dysregulated lifestyle such as in the obesity, there is an imbalance in the production of different cytokines. In particular, we focused on Adiponectin, an adipokine producted by adipose tissue, and on Orexin-A, a neuropeptide synthesized in the lateral hypothalamus. The production of both Adiponectin and Orexin-A increases following regular and structured physical activity and both these hormones have similar actions. Indeed, they improve energy and glucose metabolism, and also modulate energy expenditure and thermogenesis. In addition, a relevant biological role of Adiponectin and Orexin A has been recently highlighted in the immune system, where they function as immune-suppressor factors. The strong connection between these two cytokines and healthy status is mediated by physical activity and candidates these hormones as potential biomarkers of the beneficial effects induced by physical activity. For these reasons, this review aims to underly the interconnections among Adiponectin, Orexin-A, physical activity and healthy status. Furthermore, it is analyzed the involvement of Adiponectin and Orexin-A in physical activity as physiological factors improving healthy status through physical exercise.

Effects of post exercise protein supplementation on markers of bone turnover in adolescent swimmers

BACKGROUND

This study examined the effects of whey protein supplementation, compared with an isocaloric carbohydrate beverage and water, consumed immediately following an intense swimming trial on bone turnover in adolescent swimmers.

METHODS

Fifty-eight (31 female, 27 male) swimmers (14.1 ± 0.4 years) were stratified into three groups matched for age, sex and body mass. The protein and carbohydrate groups consumed two isocaloric post-exercise beverages each containing 0.3 g.kg- 1 of whey protein (with ~ 6 mg of calcium) or maltodextrin while the control group consumed water. Participants provided a morning, fasted, resting blood sample, then performed an intense swimming trial consisting of a maximal 200 m swim followed by a high intensity interval swimming protocol (5x100m, 5x50m and 5x25m; 1:1 work-to-rest ratio). Following swimming, they consumed their first respective post-exercise beverage, and 2 h later, they performed a second maximal swim immediately followed by the second beverage. Approximately 3 h after the second beverage, two post-consumption blood samples were collected at 8 h and 24 h from baseline. Procollagen type 1 intact N-terminal propeptide (PINP) and carboxy-terminal collagen crosslinks (CTXI) were measured in serum. The multiples of medians of PINP and CTXI were also used to calculate bone turnover rate and balance.

RESULTS

No significant changes were observed in PINP. CTXI increased (+ 11%) at 8 h in all groups, but then significantly decreased (- 22%) at 24 h in the protein group only. The protein group also had a significantly higher calculated rate of bone turnover at 8 h and 24 h compared to baseline, which was not observed in the other groups.

CONCLUSIONS

These results shed light on the potential importance of protein consumed shortly after intense swimming in promoting positive bone turnover responses up to 24 h following exercise in adolescent athletes.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov PRS; NCT04114045. Registered 1 October 2019 - Retrospectively registered.

Expert panel consensus recommendations for diagnosis and treatment of secondary osteoporosis in children

BACKGROUND

Osteoporosis incidence in children is increasing due to the increased survival rate of patients suffering from chronic diseases and the increased use of drugs that can damage bones. Recent changes made to the definition of childhood osteoporosis, along with the lack of guidelines or national consensuses regarding its diagnosis and treatment, have resulted in a wide variability in the approaches used to treat this disease. For these reasons, the Osteogenesis Imperfecta and Childhood Osteoporosis Working Group of the Spanish Society of Pediatric Rheumatology has sounded the need for developing guidelines to standardize clinical practice with regard to this pathology.

METHODS

An expert panel comprised of 6 pediatricians and 5 rheumatologists carried out a qualitative literature review and provided recommendations based on evidence, when that was available, or on their own experience. The level of evidence was determined for each section using the Oxford Centre for Evidence-based Medicine (CEBM) system. A Delphi survey was conducted for those recommendations with an evidence level of IV or V. This survey was sent to all members of the SERPE. All recommendations that had a level of agreement higher or equal to 70% were included.

RESULTS

Fifty-one recommendations, categorized into eight sections, were obtained. Twenty-four of them presented an evidence level 4 or 5, and therefore a Delphi survey was conducted. This was submitted electronically and received a response rate of 40%. All recommendations submitted to the Delphi round obtained a level of agreement of 70% or higher and were therefore accepted.

CONCLUSION

In summary, we present herein guidelines for the prevention, diagnosis and treatment of secondary childhood osteoporosis based on the available evidence and expert clinical experience. We believe it can serve as a useful tool that will contribute to the standardization of clinical practice for this pathology. Prophylactic measures, early diagnosis and a proper therapeutic approach are essential to improving bone health, not only in children and adolescents, but also in the adults they will become in the future.

Relationship between bone mineral content and bone turnover markers, sex hormones and calciotropic hormones in pre- and early pubertal children

We investigated associations between bone mineral content (BMC) and bone-related biomarkers (BM) in pre-and early pubertal children of both sexes. In this population, we found that bone turnover markers explain a small part of BMC variance.

INTRODUCTION

It is still debated whether BM including bone turnover markers (BTM), sex hormones and calciotropic (including cortisol) hormones provide information on BMC changes during growth.

METHODS

Three hundred fifty-seven girls and boys aged 6 to 13 years were included in this study. BM was measured at baseline and BMC twice at 9 months and 4 years using DXA. Relationship between BMs was assessed using principal component analysis (PCA). BM was tested in its ability to explain BMC variation by using structural equation modelling (SEM) on cross-sectional data. Longitudinal data were used to further assess the association between BM and BMC variables.

RESULTS

BMC and all BMs, except calciotropic hormones, increased with age. PCA in BM revealed a three-factor solution (BTM, sex hormones and calciotropic hormones). In the SEM, age accounted for 61% and BTM for 1.2% of variance in BMC (cross-sectional). Neither sex nor calciotropic hormones were BMC explanatory variables. In the longitudinal models (with single BM as explanatory variables), BMC, age and sex at baseline accounted for 79-81% and 70-75% in BMC variance at 9 months and 4 years later, respectively. P1NP was consistently associated with BMC.

CONCLUSION

BMC strongly tracks in pre- and early pubertal children. In this study, only a small part of BMC variance was explained by single BTM at the beginning of pubertal growth.

Serum Procollagen Type I N-Terminal Propeptide and Osteocalcin Levels in Korean Children and Adolescents

PURPOSE

Bone markers can be useful for the diagnosis and treatment of skeletal diseases in children and adolescents. Owing to high skeletal growth velocity and rapid bone turnover, children and adolescents have higher bone marker levels than adults. Thus, a valid age- and sex-specific reference should be established for pediatric populations living in similar environments. We aimed to assess the associations of procollagen type I N-terminal propeptide (P1NP) and osteocalcin with age and sex in a group of healthy Korean children and adolescents.

MATERIALS AND METHODS

The participants (290 boys and 290 girls, age range 0-18 years) were Korean outpatients. Serum P1NP and osteocalcin levels were measured in control materials and patient samples by electrochemiluminescence immunoassay using an automated Cobas e411 analyzer.

RESULTS

Significant age-dependent variations in bone marker levels were observed in both sexes (p<0.001). The highest P1NP levels were observed during the first year of life; thereafter, levels decreased until puberty. There was no postnatal peak for osteocalcin; however, its levels remained higher than the adult reference range throughout childhood. Significant differences were observed between boys and girls (p<0.05), especially between the ages of 12 and 17 years. Cobas e411 results for P1NP showed satisfactory precision and linearity.

CONCLUSION

We established reference data for P1NP and osteocalcin levels in healthy Korean children and adolescents, as the first and only study of these parameters in pre-adulthood in Korea. Cobas e411-quantified bone markers may be useful for determining bone metabolism indices.

Impacts of lead exposure and chelation therapy on bone metabolism during different developmental stages of rats

OBJECTIVE

To explore the impacts of Pb exposure and the dimercaptosuccinic acid (DMSA) chelation therapy on bone metabolisms in young rats of different ages, as well as the potential mechanisms.

METHOD

Young rats were exposed to 0.05%-0.1% Pb acetate for 19 days, during infanthood (postnatal day, PND2-20), childhood (PND21-39) and adolescenthood (PND40-58) respectively. In each developmental stage, rats were further divided into three subgroups: lead-exposed, one-course and two-course DMSA chelation therapy subgroups. Blood/bone lead concentrations, serum calciotropic hormones concentrations, and mRNA and protein expressions of bone turnover markers in the serum and bones were measured. Bone microstructures were analyzed using Micro-CT.

RESULTS

Compared with lead-exposed during childhood and adolescenthood, increases in blood/bone lead levels, and the changes of blood/bone lead and trabecular bone microstructures after one-course DMSA chelation were most significant in rats lead-exposed during infanthood (P < .05). The serum osteocalcin (OC) concentrations, mRNA/protein expressions of OC and runt-related transcription factor 2 (RUNX2) in bones all decreased after Pb exposure, along with significant increases in serum C-terminal telopeptide of type I collagen (CTX) concentrations (P < .05). These effects were accompanied by changes of serum parathormone (PTH) and 1,25-dihydroxyvitamin D₃ (1,25-(OH₂)-D₃) concentrations. DMSA chelation partially reversed the changes of bone microarchitectures, bone formation and resorption markers, and calciotropic-hormones, and the efficiency was greatest when the therapy was provided during infanthood.

CONCLUSION

Developmental Pb exposure impaired bone microstructures and interfered bone metabolism, and the exposure effect was more obvious during infanthood than during childhood and adolescenthood. Lead effects were partially reversed by chelation therapy, and the efficacy may be most significant when the therapy was provided at younger ages.

Bone formation and resorption markers at 7 years of age: Relations with growth and bone mineralization

Purpose

We aimed to describe bone formation and resorption markers in generally healthy prepubertal children using total alkaline phosphatase (tALP), osteocalcin (OC) and β-isomerized C-terminal telopeptides of type I collagen (β-CTx) serum concentrations and to estimate markers’ correlations with anthropometric growth (height, weight, body mass index and trajectories of weight gain) as well as bone mineral content (BMC) and areal density (aBMD).

Methods

We assessed 395 7-year-old children from the Generation XXI cohort with tALP, OC and β-CTx concentrations determined from a fasting venous blood sample and BMC/aBMD measured by dual-energy X-ray absorptiometry. Gender-specific reference intervals for tALP, OC and β-CTx in 7-year-old children were established by calculating the 2.5^th and 97.5^th percentiles. Pearson and partial correlation coefficients (controlling for sex, age, body size and season) between bone markers and growth measures were computed.

Results

tALP increased with height (r_partial controlled for sex = 0.26, 95%CI: 0.17, 0.35), was higher in overweight than in healthy weight children, and in children who gained weight above average during infancy. No correlations were found between OC or β-CTx and growth. In girls, OC was slightly correlated with subtotal BMC (r_partial = 0.22, 95%CI: 0.08, 0.35), subtotal aBMD (r_partial = 0.20, 95%CI: 0.06, 0.33) and lumbar spine aBMD (r_partial = 0.23, 95%CI: 0.09, 0.36). tALP and β-CTx were not correlated with any of the DXA-derived bone measures.

Conclusion

This study contributed to the description of bone turnover at 7 years of age and suggested that bone metabolism markers measured in a single point in time have limited ability to describe anthropometric growth and overall bone status in generally healthy prepubertal children.

Phenotype and response to growth hormone therapy in siblings with B4GALT7 deficiency

B4GALT7 encodes beta-1,4-galactosyltransferase which links glycosaminoglycans to proteoglycans in connective tissues. Rare, biallelic variants in B4GALT7 have been associated with spondylodysplastic Ehlers-Danlos and Larsen of Reunion Island syndromes. Thirty patients with B4GALT7-related disorders have been reported to date with phenotypic variability. Using whole exome sequencing, we identified male and female siblings with biallelic, pathogenic B4GALT7 variants and phenotypic features of spondylodysplastic Ehlers-Danlos syndrome as well as previously unreported skeletal characteristics. We also provide detailed radiological characterization and describe the siblings' responses to growth hormone treatment. Our report extends the phenotypic spectrum of B4GALT7-associated spondylodysplastic Ehlers-Danlos syndrome and reports results of growth hormone treatment for patients with this rare disorder.

Daily oligofructose-enriched inulin intake impacts bone turnover markers but not the cytokine profile in pediatric patients with celiac disease on a gluten-free diet: Results of a randomised, placebo-controlled pilot study

BACKGROUND

Bone metabolism disturbances are commonly observed in patients with newly diagnosed celiac disease (CD). The only available treatment for CD-the intake of a gluten-free diet (GFD)-has been found to be insufficient in effectively improving bone health in some patients. Therefore, there is an urgent need to modify the GFD so as to allow for the provision of all the necessary nutrients and improved absorption. Prebiotics intake reportedly improves the absorption of bone-related vitamin D and calcium as well as bone metabolism. The effect of prebiotic intake on bone health in CD patients has not been studied yet. This study aimed to evaluate the effect of oligofructose-enriched inulin intake on bone metabolism and immune response in children with CD on a GFD.

METHODS

A total of 34 children with CD were randomised into two groups receiving 10 g of oligofructose-enriched inulin (Synergy 1) or a placebo (maltodextrin) for three months, together with a strict GFD. The children's bone metabolism marker levels and cytokine profiles were analysed before and after the intervention.

RESULTS

After supplementation, the concentration of osteocalcin increased significantly in children receiving Synergy 1, while the concentration of bone alkaline phosphatase increased in both groups, independent of supplementation. After the intervention, the level of pyridinoline increased significantly in the placebo group, resulting in a concentration that was two times higher than that in the Synergy 1 group, in which it remained stable. Moreover, the plasma concentrations of N-terminal telopeptides of type I collagen decreased in both the groups, whereas the tartrate-resistant acid phosphatase 5b level increased particularly in the Synergy 1 group. The intervention did not lead to immunological response changes.

CONCLUSIONS

The proposed supplementation beneficially altered bone metabolism, through increased bone formation rates and decreased bone resorption process rates. Supplementation of GFD with prebiotic oligofructose-enriched inulin may be a promising auxiliary therapy for bone metabolism improvements in children with CD.

Early-Life Cadmium Exposure and Bone-Related Biomarkers: A Longitudinal Study in Children

BACKGROUND

Chronic cadmium exposure has been associated with osteotoxicity in adults, but little is known concerning its effects on early growth, which has been shown to be impaired by cadmium.

OBJECTIVES

Our objective was to assess the impact of early-life cadmium exposure on bone-related biomarkers and anthropometry at 9 y of age.

METHODS

For 504 children in a mother-child cohort in Bangladesh, cadmium exposure was assessed by concentrations in urine (U-Cd, long-term exposure) and erythrocytes (Ery-Cd, ongoing exposure) at 9 and 4.5 y of age, and in their mothers during pregnancy. Biomarkers of bone remodeling [urinary deoxypyridinoline (DPD), urinary calcium, plasma parathyroid hormone, osteocalcin, vitamin D3, insulin-like growth factor (IGF) 1, IGF binding protein 3, thyroid stimulating hormone] were measured at 9 y of age.

RESULTS

In multivariable-adjusted linear models, a doubling of concurrent U-Cd was associated with a mean increase in osteocalcin of [Formula: see text] (95% CI: 0.042, 5.9) and in urinary DPD of [Formula: see text] (95% CI: 12, 32). In a combined exposure model, a doubling of maternal Ery-Cd was associated with a mean increase in urinary DPD of [Formula: see text] (95% CI: [Formula: see text], 30). Stratifying the osteocalcin model by gender ([Formula: see text] 0.001), a doubling of concurrent U-Cd was associated with a mean decrease in osteocalcin of [Formula: see text] (95% CI: [Formula: see text], [Formula: see text]) in boys and a mean increase of [Formula: see text] (95% CI: 5.4, 13) in girls. The same pattern was seen with U-Cd at 4.5 y of age ([Formula: see text] 0.016). Children's U-Cd and Ery-Cd, concurrent and at 4.5 y of age, were inversely associated with vitamin D3.

CONCLUSIONS

Childhood cadmium exposure was associated with several bone-related biomarkers and some of the associations differed by gender. https://doi.org/10.1289/EHP3655.

Bone biochemical markers for assessment of bone responses to differentiated phosphorus supply in growing-finishing pigs

Phosphorus (P) is essential for building and maintaining a healthy and strong skeleton. Moreover, dietary P supply may play a role for bone turnover, and the excretion of bone turnover metabolites may be useful as markers for sufficient dietary P supply. The objective was to study the long-term effects of low, medium, and high dietary P supply on bone metabolism in terms of serum concentration and urinary excretion of bone turnover components and metabolites in healthy growing-finishing pigs compared with bone mineral content (BMC) and bone mineral density (BMD) of humerus and femur. Pigs were fed diets containing low [LP; 4.1 g/kg dry matter (DM)], medium (MP; 6.2 g/kg DM), or high dietary P (HP; 8.9 g/kg DM) from 39.7 kg body weight (BW) until slaughter at 110 kg BW. Urine and blood were collected at 40, 70, and 110 kg BW while bones were collected at slaughter. Serum was analyzed for osteocalcin (OC), bone alkaline phosphatase (BAP), and C-terminal telopeptides of type I collagen (CTX-I), whereas urine was analyzed for pyridinoline (PYD), deoxypyridinoline (DPD), CTX-I, hydroxylysine (HYL), galactosyl-hydroxylysine (GAL-HYL), glycosyl-galactosyl-hydroxylysine (GLC-GAL-HYL), and hydroxyproline (HYP). Humerus and femur were analyzed for BMC and BMD. The LP diet caused reduced OC and increased BAP and CTX-I concentrations in serum. Furthermore, BAP was increased in response to the HP diet. Urine metabolites of bone resorption were all increased in pigs fed the LP diet, but only a few responses were obtained in response to the HP diet. Furthermore, age-related decreases were identified for BAP, HYL, GAL-HYL, and GLC-GAL-HYL. Bone mineral content and BMD were markedly lowered in pigs fed the LP diet but were not affected in pigs fed the HP diet. In conclusion, OC, BAP, and CTX-I in serum have proved useful for P adequacy in growing-finishing pigs. In addition, urine bone resorption metabolites have also proved useful for P adequacy and analysis of PYD, DPD, and CTX-I was considered to be the most relevant markers due to their specificity for bone and their negative correlation with BMD, BMC, ash, calcium (Ca), and P contents. Finally, DPD may be the preferred marker in long-term P feeding assessments.

Assessment of Biochemical Bone Turnover Markers and Bone Mineral Density in Thin and Normal-Weight Children

Objective There is scant research examining the prevalence of thinness in early childhood, despite its potential negative consequences for health and development across the life course. The objective of this study was to assess bone status through measurement of bone mineral density and biochemical bone turnover markers, with special attention paid to carboxylated (c-OC) as well as undercarboxylated (uc-OC) forms of osteocalcin, in the groups of thin and normal-weight children. Design The study included 80 healthy prepubertal children (median age 7.0 years), who were divided (according to Cole's international cutoffs) into 2 subgroups: thin children ( n = 40, body mass index [BMI] = 13.5 kg/m²) and normal-weight children ( n = 40, BMI = 16.1 kg/m²). Bone mineral density (BMD) and bone mineral content (BMC) were assessed by dual-energy x-ray absorptiometry method. Serum concentrations of C-terminal telopeptide of collagen type I (CTX), total osteocalcin (OC), and c-OC, and uc-OC forms of osteocalcin were determined using enzyme-linked immunosorbent assays. Results In thin children, we observed higher levels of bone resorption marker CTX compared with normal-weight peers. Total osteocalcin concentrations were comparable in both groups of children; however, in thin children we observed higher median values of uc-OC (34.40 vs. 29.30 ng/mL, P < 0.05) and similar c-OC levels (25.65 vs. 28.80 ng/mL). The ratio of c-OC to uc-OC was significantly lower ( P < 0.05) in thin than in normal-weight children. Total BMD and BMC were significantly decreased ( P < 0.0001) in thin children compared with normal-weight peers (0.724 ± 0.092 vs. 0.815 ± 0.060 g/cm² and 602.7 ± 159.2 vs. 818.2 ± 220.1 g, respectively). Conclusion Increased concentrations of CTX and uc-OC might lead to disturbances in bone turnover and a decrease in bone mineral density in thin children.

Bone status and adipokine levels in children on vegetarian and omnivorous diets

BACKGROUND & AIMS

Measurements of bone mineral density (BMD) reflect bone status but not the dynamics of bone turnover. Biochemical markers, which show global skeletal activity, were validated for the assessment of bone formation and resorption processes. Adipokines also play a significant role in the regulation of bone metabolism.

OBJECTIVE

To assess body composition, bone mineral density, bone turnover markers and adipokine levels in relation to vegetarian and omnivorous diets.

METHODS

The study included 53 vegetarian and 53 omnivorous prepubertal healthy children matched for age and sex (median age 7.0 years). Body composition and BMD were assessed by dual-energy X-ray absorptiometry. 25-hydroxyvitamin D and parathormone levels were measured by chemiluminescence method. Serum carboxy-terminal propeptide of type I collagen (CICP), total osteocalcin (OC) and its forms carboxylated (c-OC) and undercarboxylated (uc-OC), C-terminal cross-linking telopeptide of collagen type I (CTX), leptin and adiponectin levels were determined using immunoenzymatic assays.

RESULTS

Both groups of children were comparable in terms of body composition, except for the percentage of fat mass, which was lower (19.24 vs. 21.77%, p = 0.018) in vegetarians. Mean values of total BMD z-score and lumbar spine BMD z-score were lower (-0.583 vs. -0.194, p = 0.009 and -0.877 vs. -0.496, p = 0.019, respectively) in vegetarians compared with omnivores. Serum leptin level was about 2-fold lower (1.39 vs. 2.94 ng/mL, p < 0.001) in vegetarians, however, adiponectin concentration was similar in both groups. Vegetarians had similar concentration of 25-hydroxyvitamin D, but higher parathormone (40.8 vs. 32.1 pg/mL, p = 0.015) and CTX (1.94 vs. 1.76 ng/mL, p = 0.077) levels than omnivores. Total osteocalcin and CICP concentrations were comparable in both groups, however, c-OC/uc-OC ratio was higher (1.43 vs. 1.04 ng/mL, p < 0.05) in vegetarians. We found positive correlation between c-OC and nutritional parameters adjusted for total energy intake (plant protein, phosphorus, magnesium and fiber intakes) in vegetarian children.

CONCLUSIONS

Prepubertal children on a vegetarian diet had significantly lower total and lumbar spine BMD z-scores, but absolute values of bone mineral density did not differ. BMD z-scores did not correlate with bone metabolism markers and nutritional variables, but were positively associated with anthropometric parameters. Lower leptin levels in vegetarian children reflect lower body fat. Longitudinal studies are necessary to evaluate the impact of the observed association on bone health at adulthood.

Longitudinal changes in bone-testis axis and their associations with insulin resistance in 11- to 12-year-old boys

PURPOSE

Associations between osteocalcin (OCN), an osteoblast-specific hormone, and different markers of energy metabolism and insulin resistance have been reported in adults, but few studies have investigated this in children. The aim of the current study was to investigate serum OCN levels during pubertal development in normal weight (NW) and overweight (OW) boys, and to evaluate possible associations of OCN with body composition, testosterone, insulin resistance and adipocytokine values during puberty.

METHODS

Ninety 11- to 12-year-old boys were investigated at 12-month intervals over the next 2years. Boys were divided by their BMI into NW (n=60) and OW (n=30) groups. Serum OCN, testosterone, leptin, adiponectin, insulin, HOMA-IR score, and body composition were measured.

RESULTS

Pubertal development over the 2-year period was similar in both groups. Serum OCN was not different at the beginning of the study and increased similarly in both groups. However, at the end of the study, NW had higher OCN than OW (142.9±5.2 vs. 124.0±7.4ng/ml; p<0.05). OW had higher leptin, insulin and HOMA-IR compared to NW, and these differences remained significant through the 2-year period. Testosterone, insulin and HOMA-IR increased through the study period in both groups. In multiple regression analyses increment in OCN was associated with the increase in testosterone in NW (p<0.001) and OW (p=0.049) boys. Increment in OCN was also associated with the increase in insulin (p=0.019) and HOMA-IR (p=0.012) over the 2-year period in NW boys.

CONCLUSION

Serum OCN concentration increases in puberty and the increment is positively associated with the rise in testosterone level in both NW and OW boys. The positive association between the rise in OCN and insulin in NW boys would suggest that OCN may have a role in the development of insulin resistance.

Inhibition of bone resorption by bisphosphonates interferes with orthodontically induced midpalatal suture expansion in mice

OBJECTIVES

Craniofacial sutures are important growth sites for skull development and are sensitive to mechanical stress. In order to determine the role of bone resorption in stress-mediated sutural bone growth, midpalatal suture expansion was performed in mice receiving alendronate, an anti-resorptive bisphosphonate.

MATERIALS AND METHODS

The midpalatal sutures of 8-week-old C57BL/6 mice were expanded by orthodontic wires over the period of 2 weeks. Mice with maxillary expansion without drug treatment as well as untreated animals served as controls. Skulls were analyzed with micro-computed tomography (micro-CT), immunohistochemistry and histology.

RESULTS

Maxillary expansion in mice without drug treatment resulted in an increase of TRAP-positive osteoclasts. In contrast, no increase in osteoclasts was observed in expanded sutures of mice with bisphosphonate treatment. Double calcein labeling demonstrated rapid bone formation on the oral edges of the expanded sutures in mice without bisphosphonate treatment. Less bone formation was observed in bisphosphonate-treated mice after expansion. Histology revealed that the sutural architecture was reestablished in expanded sutures of mice without bisphosphonate treatment. In contrast, the sutural architecture was disorganized and the cartilage had an irregular form, following expansion in bisphosphonate-treated mice. Finally, micro-CT imaging demonstrated that the total amount of maxillary expansion was significantly lower in mice with bisphosphonate treatment as compared to those of mice without drug treatment.

CONCLUSIONS

In conclusion, our results indicate that osteoclast-mediated bone resorption is needed for maxillary suture expansion and reorganization of sutural architecture.

CLINICAL SIGNIFICANCE

Orthodontic palatal expansion can be complicated in patients with inherited or drug-induced diseases of osteoclast dysfunction.

Decreased bone turnover in HIV-infected children on antiretroviral therapy

In this study, we evaluated the relationships between immune activation, bone turnover, and bone mass in virally suppressed HIV-infected children and HIV-uninfected children in South Africa. We found that decreased bone mass may occur or persist independent of immune activation and altered bone turnover.

PURPOSE

HIV-infected children and adolescents have deficits in skeletal growth which include decreases in bone mass and alterations in bone microarchitecture. However, the mechanism by which HIV infection compromises bone accrual in children and adolescents is unclear. The goal of this study was to evaluate the relationships between immune activation, bone turnover, and bone mass in a group of pre-pubertal HIV-infected children randomized to remain on ritonavir-boosted lopinavir (LPV/r)-based antiretroviral therapy (ART) or switch to efavirenz-based ART in South Africa virally suppressed at the time of this study.

METHODS

This cross-sectional analysis included 219 HIV-infected and 180 HIV-uninfected children enrolled in the CHANGES Bone Study conducted in Johannesburg, South Africa. Whole body (WB) bone mineral content (BMC) was assessed by dual x-ray absorptiometry and WB BMC Z-scores adjusted for sex, age, and height were generated. Bone turnover markers, including C-telopeptide of type 1 collagen (CTx) and procollagen type I N-terminal propeptide (P1NP), were analyzed. Markers of immune activation were also measured, including cytokines IL-6 and TNF-alpha, as well as soluble CD14 and high-sensitivity C-reactive protein (CRP).

RESULTS

Compared to uninfected controls, HIV-infected children had lower WB BMC Z-scores, similar IL-6 and TNF-alpha, higher soluble CD14 and high-sensitivity CRP, and lower markers of bone resorption (CTX) and bone formation (P1NP). Bone turnover markers were not different in those remaining on LPV/r or switched to efavirenz.

CONCLUSIONS

Our findings suggest that in HIV-infected children with viral suppression, decreased bone accrual may occur or persist independent of immune activation and altered bone turnover.

Bone-specific alkaline phosphatase - a potential biomarker for skeletal growth assessment

OBJECTIVE

The present study was aimed to assess levels of serum Bone-specific alkaline phosphatase (BALP) and serum Insulin-like growth factor-1 (IGF-1) and comparing with cervical vertebral maturation index (CVMI) stages.

DESIGN

Cross-sectional study.

SETTING

Maulana Azad Institute of Dental Sciences, New Delhi, India.

PARTICIPANTS

150 subjects (75 males and 75 females) in the age group of 8-20 years.

METHODS

Subjects were divided into six CVMI stages. Enzyme-linked immunosorbant assay was performed for the estimation of serum BALP and serum IGF-1 levels. Mann-Whitney U test was performed to compare mean ranks of serum BALP and serum IGF-1 with different CVMI stages. Spearman correlation between serum BALP and serum IGF-1 was done across 6 CVMI stages.

RESULTS

Peak serum IGF-1 levels were found at CVMI stages 4 and 3 for males and females respectively. Peak levels for serum BALP were found at stage 3 for both genders with significant differences from other stages. A statistically significant correlation was seen between serum IGF-1 and serum BALP from CVMI stages 1 to 3 and 4 to 6 (p < .01).

CONCLUSIONS

BALP showed promising results and can be employed as a potential biomarker for the estimation of growth status.

Reference and Influential Factors of Serum Bone Markers in Chinese Adolescents

This study aimed to establish reference ranges of bone markers in Chinese adolescents between the age of 12 and 16, and to search these markers’ characteristics and influential factors. Personal information and fasting blood samples were collected from 174 healthy adolescents in Northeast China. Serum levels of PINP, ALP, β-CrossLaps, calcium, phosphate, PTH, 25(OH)D and TSH were measured. Reference ranges were established for PINP [(85.55–2,028.75)ng/ml], ALP [(53.88–463.63)U/L], β-CrossLaps [(0.16–1.19)ng/ml], calcium [(2.35–2.70)mmol/L], phosphate [(1.17–2.06)mmol/L] and PTH [(2.64–43.36)μg/L] in this population. We observed that bone formation markers PINP and ALP levels were evidently higher when compared to kit references for adults. Reference ranges for calcium, phosphate and PTH also differed from those provided by kit manuals. Serum ALP, PINP, phosphate and PTH changed with age (all P < 0.005), and were significantly higher in boys than in girls (all P < 0.05). Serum 25(OH)D and TSH levels didn’t correlate with PINP, ALP and β-CrossLaps (all P > 0.05). In conclusion, unique reference ranges should be provided for adolescents. BMI, sex and age independently influence certain serum bone markers in adolescents. Vitamin D deficiency is widespread. Serum levels of vitamin D and TSH may not influence bone turnover markers in this population.

Congenital Hypothyroidism and Bone Remodeling Cycle

OBJECTIVE

The present study aimed to evaluate the biochemical markers of bone turnover in children with congenital hypothyroidism during the course of treatment as compared to healthy children selected as controls.

METHODS

The study included 31 children with congenital hypothyroidism and 29 healthy children. In both groups, we evaluated serum procollagen type-1 N-terminal propeptide (PINP) and tartrate-resistant acid phosphatase type 5b isoform (TRACP 5b) levels as bone turnover markers.

RESULTS

In both groups, thyroid hormone levels were within normal limits. The levels of vitamin D were significantly higher in the cases with congenital hypothyroidism. Although PINP levels were not found to be different, TRACP 5b levels which are related to osteoclastic activities were significantly higher in the control group.

CONCLUSION

We did not detect an increase in bone resorption in patients with congenital hypothyroidism, despite long-term treatment with LT4. Our results suggest that with effective vitamin D treatment and thyroxin replacement, congenital hypothyroidism is not a deleterious factor for bone turnover.

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.

Biochemical markers of bone turnover in children with clinical bone fragility

BACKGROUND

The role of biochemical bone turnover markers (BTMs) in assessing low bone mass and monitoring bisphosphonate treatment in pediatric patients with clinical bone fragility is not well established. The aim of the study was to examine the correlations of BTMs and the bone mineral density (BMD), and evaluate the effects of bisphosphonates therapy on BTMs in children with clinical bone fragility.

METHODS

Clinical data of 115 patients with clinical bone fragility (mean age 9.7±5.8 years), 102 of whom received bisphosphonates, were studied. Serum alkaline phosphatase (ALP), osteocalcin (OC), urine pyridinoline (PD) and deoxypyridinoline (DPD), BMD at baseline and subsequent years were analyzed.

RESULTS

There was a significant negative correlation between urine PD and lumbar BMD (slope=-0.29, p<0.001). There were no correlations between BTMs and lumbar BMD Z-score. There was a significant positive correlation between serum OC and serum ALP, urine PD and DPD (p<0.001). Serum OC, urine PD and DPD index, as expressed as measured value/upper limit of normal value for age, decreased during the first 3 years of bisphosphonate therapy.

CONCLUSIONS

In children with clinical bone fragility, BTMs correlated with each other, but not with lumbar BMD Z-score. While they were not reliable predictors of degree of low BMD, the bone markers showed suppression during bisphosphonate therapy and may be helpful in monitoring the response to therapy.

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.

Increased sclerostin and preadipocyte factor-1 levels in prepubertal rhythmic gymnasts: associations with bone mineral density, body composition, and adipocytokine values

SUMMARY

Rhythmic gymnastics as high-impact bone loading sport has positive effects on bone mineralization in prepubertal years. Sclerostin and preadipocyte factor-1 (Pref-1) are hormones that inhibit bone formation. The present study demonstrates that these hormones are higher in gymnasts, and gymnasts present higher bone mineral density (BMD) as compared to controls.

INTRODUCTION

Rhythmic gymnasts (RG) start their heavy trainings already in prepuberty and despite of low body fat mass (FM) and hypoleptinemia, their BMD is higher than in non-trained normal girls. The specific role of sclerostin and Pref-1, which are the inhibitors of bone formation, in bone development is not well understood. The impact of sclerostin and Pref-1 levels on BMD, body composition, and adipocytokine values was studied in prepubertal RG and untrained controls (UC).

METHODS

Sixty-four 9-10-year-old girls were divided into RG (n = 32) and UC (n = 32) groups. Bone mineral and body composition values were measured by dual-energy X-ray absorptiometry and bone age by X-ray. Sclerostin, Pref-1, leptin, and adiponectin levels were measured from fasting blood samples.

RESULTS

Sclerostin (RG 19.8 ± 6.3 pmol/l; UC 15.8 ± 5.4 pmol/l) and Pref-1 (RG 1.6 ± 1.0 ng/ml; UC 1.1 ± 0.5 ng/ml) were higher (p < 0.05) in RG compared with UC. Sclerostin was related to adiponectin (r = 0.41; p < 0.05) in UC. No relationship was found between sclerostin and Pref-1 with BMD values in prepubertal RG and age-matched UC groups.

CONCLUSIONS

Sclerostin and Pref-1 levels are higher in RG compared to UC girls. Specific physical activity pattern seen in prepubertal RG has a beneficial effect on bone mineralization despite increased levels of hormones that inhibit bone formation.