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

Moderate-to-vigorous physical activity modulates the association between serum 25-hydroxyvitamin D and bone stiffness in European children and adolescents

It remains unclear how serum 25-hydroxyvitamin D (25(OH)D) concentrations relate to childhood bone health. We hypothesized that 25(OH)D was inversely associated with bone turnover biomarkers and positively associated with bone stiffness. Cross-sectional analyses were performed using data from participants (2-15-year-old, 51% boys) from the Identification and Prevention of Dietary- and Lifestyle-induced Health Effects in Children and Infants Study (IDEFICS)/I.Family cohort, comprising 3,638 serum 25(OH)D measurements collected in 2007-2008 and 2012-2013 across eight European countries. A biomarker of bone formation (serum osteocalcin), a biomarker of bone resorption (serum C-terminal telopeptides of type I collagen [CTx]), and stiffness index measured using calcaneal quantitative ultrasound were considered outcomes. Linear mixed-effects models were used to adjust for confounders (i.e., age, sex, parental education, time spent in sports club, dairy products consumption, sedentary behavior, height and weight z-scores), the cluster effect of country and repeated measurements. Interactions of calcium intake, moderate-to-vigorous physical activity (MVPA) and weight status with 25(OH)D on outcomes were tested. Only 1 in 3 participants reached the sufficient 25(OH) D concentration of 20 ng/mL. Sufficient 25(OH)D was associated with higher stiffness index if participants had MVPA ≥60 min/day (β = 12.14, P < .05). Moreover, 25(OH)D was inversely associated with CTx (β = -7.09, P < .05); this association was positive but not statistically significant among primary school children living with overweight/obesity. No interaction was observed for calcium intake. In conclusion, serum 25(OH)D and CTx were inversely associated. MVPA interacted with the positive association between 25(OH)D and bone stiffness, highlighting the importance of promoting MVPA guidelines in future vitamin D and bone health interventions.

Reference Intervals (RIs) of the Bone Turnover Markers (BTMs) in Children and Adolescents: A Proposal for Effective Use

BACKGROUND/OBJECTIVES

Bone turnover markers (BTMs) can provide information on the bone growth of apparently healthy children and adolescents or useful results in the diagnosis and monitoring of the disease condition, comparing them with appropriate reference intervals (RIs). The aim of this study was to establish the RI for the BTM [specific bone alkaline phosphatase (BALP), carboxy-terminal cross-linked collagen type I telopeptide (CTX), N-terminal propeptide pro-collagen type I (PINP), osteocalcin (OC), resistant to acid tartrate phosphatase isoform 5b (TRAcP-5b)] on serum samples from children and adolescents.

METHOD

202 samples from children and adolescents (ages 1-18 years) (51.48% male), considered apparently healthy. The biomarker was analyzed on automatic immunometric equipment (TGSTA Technogenetics) and the IDS-iSYS automated system kits The RI of the studied parameters was calculated according to CLSI Guideline C28-A3 with stratification by age and sex. Evaluation of the distribution of values and the meaning of the biomarker concentrations were used to calculate general and specific RI for an age group.

RESULTS

BTM concentrations vary with pubertal growth. The pattern of change differs for each bone marker. General and age-specific RI were calculated: 1-14 years, 15-18 years for BALP and CTX; 1-13 years, 14-18 years for Oc and PINP and 1-12 years, 13-18 years for TRAcP.

DISCUSSION AND CONCLUSIONS

Concentrations for biomarker studied vary with age and gender. The proof of concentrations with insignificant changes until puberty led to identification of two groups of RI relating to the covariables (age and sex) for each biomarker.

The vitamin D status in a Chinese osteogenesis imperfecta population and its correlation with bone metabolic markers and bone density

Objective

Studies on the baseline vitamin D levels in osteogenesis imperfecta (OI) patients before medication are scarce. This study assessed the vitamin D status of a population with OI at both the overall level and within different age groups. It correlated baseline 25-hydroxyvitamin D (25(OH)D) levels with other bone-related factors, biochemical markers, and bone density.

Patients and methods

We collected 25(OH)D levels from 95 OI patients in East China (59 under 18 years old and 36 over 18 years old). Postmenopausal women and men over 50 years old are excluded. Measurements included body indicators, biochemical markers, and bone mineral density (BMD) assessed by Dual-energy X-ray absorptiometry (DXA). Data analysis was performed using SPSS 26.0.

Results

In the overall population, among those under 18 years old, and among those over 18 years old, 87.4, 83.1, and 94.4%, respectively, were vitamin D deficient (<30 ng/mL), while 47.4, 40.7, and 58.3% had vitamin D deficiency (<20 ng/mL), respectively. In the overall population and among those under 18 years old, serum 25(OH)D levels were negatively correlated with age and parathyroid hormone (PTH) levels, and 25(OH)D levels (<10 ng/mL, 10-20 ng/mL, 20-30 ng/mL, >30 ng/mL) showed a negative correlation with BMI. In OI patients under 18 years old, serum 25(OH)D was negatively correlated with serum β-CTX levels. In adult male OI population, 25(OH)D levels were negatively correlated with OI severity (Type I, IV, III). No statistically significant correlation was found between 25(OH)D levels and BMD Z-scores.

Conclusion

This study on OI in East China reveals significant vitamin D insufficiency and deficiency in baseline levels among pediatric, adolescent and adult OI patients. It assesses the correlation of 25(OH)D levels with various influencing factors, providing crucial insights into understanding the impact of OI on vitamin D status across different age groups and aiding in better clinical management of OI patients.

Relationship Between Serum 25-Hydroxyvitamin D and Bone Mineral Density, Fracture Risk, and Bone Metabolism in Adults With Osteoporosis/Fractures

OBJECTIVE

To evaluate the association of serum 25-hydroxyvitamin D (25(OH) D) levels with bone mineral density (BMD), fracture risk, and bone metabolism.

METHODS

This multicenter cross-sectional study recruited menopausal females and males greater than or equal to 50 year old with osteoporosis/fractures between September 2016 and September 2021. Assessment included clinical data, 25(OH)D, intact parathyroid hormone (iPTH), procollagen type 1 amino-terminal propeptide (P1NP), carboxy-terminal collagen crosslinks (CTX), lateral thoracolumbar spine x-rays, and BMD.

RESULTS

A total of 3003 individuals were stratified by 25(OH) D levels: 720 individuals (24%) <20 ng/mL, 1338 individuals (44.5%) 20 to 29 ng/mL, and 945 individuals (31.5%) ≥30 ng/mL. In unadjusted and multivariable models, BMD T-score, except spine, was significantly and positively associated with 25(OH)D levels. 25(OH) D levels were inversely associated with Fracture Risk Assessment Tool scores. Patients with 25(OH)D <20 ng/mL had significantly higher iPTH and bone turnover markers (P1NP and CTX) than patients with 25(OH)D ≧20 ng/mL in all models. When analyzing bone-related markers and BMD, total hip and femoral neck BMD T-scores were positively correlated with 25(OH)D concentrations and BMI but negatively correlated with iPTH, P1NP, CTX, and age. In multivariate models with all bone-related markers, only 25(OH)D levels were significantly associated with total hip and femoral neck BMD.

CONCLUSION

Vitamin D deficiency is significantly associated with decreased total hip and femoral neck BMD and increased fracture risk as assessed by Fracture Risk Assessment Tool. In those with osteoporosis/fractures, vitamin D is implicated in the causal relationship between bone remodeling and BMD. Assessing vitamin D status is imperative for those at risk for osteoporosis/fractures.

Functional Assessment of Vitamin D Status by a Novel Metabolic Approach: The Low Vitamin D Profile Concept

BACKGROUND

Determining serum 25-hydroxyvitamin D [25(OH)D], 24,25-dihydroxyvitamin D [24,25(OH)2D] and the vitamin D metabolite ratio (VMR) allows the identification of individuals with a low vitamin D metabolite profile. Here, we evaluated if such a functional approach provides superior diagnostic information to serum 25(OH)D alone.

METHODS

25(OH)D, 24,25(OH)2D, and the VMR were determined in participants of the DESIRE (Desirable Vitamin D Concentrations, n = 2010) and the LURIC (Ludwigshafen Risk and Cardiovascular Health, n = 2456) studies. A low vitamin D metabolite profile (vitamin D insufficiency) was defined by a 24,25(OH)2D concentration <1.2 ng/mL (<3 nmol/L) and a VMR <4%. Parathyroid hormone (PTH) and bone turnover markers were measured in both cohorts, whereas 10-year mortality data was recorded in LURIC only.

RESULTS

The median age in DESIRE and LURIC was 43.3 and 63.8 years, respectively. Median 25(OH)D concentrations were 27.2 ng/mL (68.0 nmol/L) and 15.5 ng/mL (38.8 nmol/L), respectively. Serum 25(OH)D deficiency, defined as <20.2 ng/mL (<50 nmol/L), was present in 483 (24.0%) and 1701 (69.3%) participants of DESIRE and LURIC, respectively. In contrast, only 77 (3.8%) and 521 (21.2%) participants had a low vitamin D metabolite profile. Regardless of the serum 25(OH)D concentration, a low vitamin D metabolite profile was associated with a significantly higher PTH, accelerated bone metabolism, and higher all-cause mortality than an unremarkable vitamin D metabolite profile.

CONCLUSIONS

The personalized assessment of vitamin D status using a functional approach better identifies patients with accelerated bone metabolism and increased mortality than the use of a fixed 25(OH)D cutoff of 20 ng/mL (50 nmol/L).

Variation of Bone Turnover Markers in Childhood and Adolescence

Objectives

To determine the bone metabolic marker changes from childhood to adolescence and to provide reference values for monitoring bone development in children in Southwest China.

Methods

We surveyed 703 participants attending physical examinations from April 2019 and August 2021. Twenty-eight participants were excluded for lack of laboratory tests, and 14 people were excluded for diseases that might affect bone metabolism. A total of 661 children were selected for the study. According to the main developmental periods, the children were divided into preschool, preadolescence, and adolescence groups. Serum bone turnover markers including β-isomerized C-terminal telopeptide of type I collagen (β-CTx), N-terminal midfragment of osteocalcin (N-MID), and procollagen type 1 N-propeptide (P1NP) as well as growth and development indices such as serum calcium (Ca), phosphorus (Pi), alkaline phosphatase (ALP), and vitamin D were measured. The changes in bone metabolism-related markers and the correlations between the indices were analyzed.

Results

During the development in boys, the levels of β-CTx and N-MID increased with age from preschool to adolescence, while the levels of P1NP decreased and then increased. In girls, the levels of β-CTx and N-MID plateaued in early adolescence and showed little change in subsequent adolescence, while the levels of P1NP exhibited a downward trend. The correlations between bone metabolism markers and vitamin D were not significant.

Conclusions

The levels of bone metabolism markers differed between boys and girls. Reference intervals can be used as essential tools to examine the levels of bone metabolism markers reasonably.

Gene-environment interaction in the association of residential greenness and 25(OH) vitamin D

There is increasing awareness for beneficial health effects of green space surrounding the home, but the underlying mechanisms are not yet fully understood and challenging to study given the correlation with other exposures. Here, the association of residential greenness and vitamin D including a gene-environment interaction is investigated. 25-hydroxyvitamin D (25(OH)D) was measured by electrochemiluminescence at ages 10 and 15 years in participants of two German birth cohorts GINIplus and LISA. Greenness was measured using the Landsat-derived Normalized Difference Vegetation Index (NDVI) in a 500 m buffer surrounding the home. Linear and logistic regression models were applied at both time points adjusted for several covariates (N_10Y = 2,504, N_15Y = 2,613). In additional analyses vitamin D-related genes, physical activity, time spent outdoors, supplements, and measurement season were investigated as potential confounders or effect modifiers. A 1.5-SD increase in NDVI was significantly associated with increased 25(OH)D values at ages 10 and 15 years (β_10y = 2.41 nmol/l, p=<0.01; β_15y = 2.03 nmol/l, p = 0.02). In stratified analyses, the associations were not seen in participants spending more than 5 h/day outside in summer, having a high physical activity level, taking supplements, or being examined during the winter season. In a subset (n = 1,732) with genetic data, a significant gene-environment interaction of NDVI with CYP2R1, an upstream gene in 25(OH)D synthesis, was observed at age 10 years. When investigating 25(OH)D sufficiency, defined as values above 50 nmol/l, a 1.5-SD increase in NDVI was associated with significantly higher odds of having sufficient 25 (OH)D levels at age 10 years (OR = 1.48, 1.19-1.83). In conclusion, robust associations between residential greenness and 25 (OH)D levels were observed in children and adolescents independent of other confounders and additionally supported by the presence of a gene-environment interaction. Effects of NDVI were stronger in those having lower vitamin D levels at age 10 years due to their covariate profile or genetically lower 25(OH)D synthesis.

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.

Ambient ozone exposure and bone turnover markers in children: Results from the GINIplus and LISA birth cohorts

BACKGROUND

Multiple environmental factors can regulate bone metabolism, and it is hypothesized that air pollution may be deleteriously involved in this regulation. However, only a few studies considered bone turnover markers (BTMs) - sensitive and specific markers of bone metabolism - as outcomes, and no study investigated the exposure to ambient ozone. Here, we intended to explore the associations between long-term exposure to ambient ozone and concentrations of two BTMs, osteocalcin and β-isomer of C-terminal telopeptide of type I collagen (CTx), amongst 10-year-old children.

METHODS

Based on the GINIplus and LISA birth cohorts, our cross-sectional analysis included 1848 children aged 10 years from Munich and Wesel. Serum osteocalcin and CTx concentrations were measured. We estimated ozone exposures by optimal interpolation, assessed nitrogen dioxide and particulate matter with an aerodynamic diameter <10 μm concentrations by land use regression models, and assigned the exposures to home addresses. Linear regression models were built and adjusted for covariates as well as co-pollutants.

RESULTS

The mean concentrations were 93.09 ng/mL and 663.66 ng/L for osteocalcin and CTx, respectively. In general, higher levels of ozone were associated with decreased concentrations of both BTMs. This held true for the two areas and different exposure metrics. The number of days per year with a maximum 8-h average concentration exceeding 120 μg/m³ showed consistent results across different models. Specifically, models adjusted for co-pollutants illustrated that the beta estimates and 95% confidence intervals on osteocalcin and CTx were -2.51 (-3.78, -1.14) and -44.53 (-57.12, -31.93), respectively, for an increase of 10 days.

CONCLUSIONS

We found that long-term exposure to ambient ozone was associated with decreased concentrations of BTMs in German children. This association might potentially affect bone metabolism. Nevertheless, unless other prospective studies confirm our results, the detrimental effects of ambient ozone on bone development in children should be interpreted cautiously.

[Serum vitamin K2 level and its association with bone metabolism markers in 1 732 children]

OBJECTIVES

To study the level of serum vitamin K2 (VitK2) and its association with bone metabolism markers osteocalcin (OC), type I procollagen amino-terminal peptide (PINP), and type I collagen carboxy-terminal peptide (CTX) in children.

METHODS

A prospective analysis was performed on 1 732 children who underwent routine physical examination from October 2020 to October 2021. The serum levels of VitK2 and 25-hydroxy vitamin D [25(OH)D] were measured. According to age, they were divided into four groups: <1 year, 1-3 years group, >3-6 years group, and >6-14 years. A total of 309 children with 25(OH)D≥50 nmol/L were screened out, and serum levels of OC, PINP, and CTX were measured to investigate the correlation of the serum levels of OC, PINP, and CTX with serum VitK2 levels in different age groups.

RESULTS

The prevalence rate of serum VitK2 deficiency was 52.31% (906/1 732). The VitK2 deficiency group had higher prevalence rates of overweight/obesity and growth pain (≥3 years of age) than the normal VitK2 group (P<0.05). There were differences in the prevalence rate of serum VitK2 deficiency (P<0.0083) and the serum level of VitK2 (P<0.05) between the 1-3 years group and the >6-14 years group. The <1 year group had a higher serum level of CTX and a lower serum level of PINP than the >3-6 years group and the >6-14 years group (P<0.05). The <1 year group had a lower serum level of OC than the >6-14 years group (P<0.05). Serum VitK2 level was positively correlated with OC level (rs=0.347, P<0.01), and CTX level was negatively correlated with PINP level (rs=-0.317, P<0.01).

CONCLUSIONS

Serum VitK2 deficiency may be associated with overweight/obesity. Serum VitK2 may affect the level of OC and even bone health.

Broad application prospects of bone turnover markers in pediatrics

BACKGROUND

Bone turnover markers (BTMs) have been studied for application in clinical medicine. However, BTMs in children are challenging, and few studies explore these BTMs in children. The application of BTMs is complicated mainly due to pre-analytical factors, variable reference intervals of age- and sex-related BTMs for adolescents and children in different regions and laboratories. Therefore, laboratory testing of BTMs is critical for understanding pediatric bone development and metabolism, which provides additional information about bone development and diseases.

METHODS

Literature search was conducted using the MeSH term "child" combined with the terms that bone turnover markers such as "osteocalcin," "Procollagen type I N-terminal propeptide," "procollagen type I C-terminal propeptide," "osteocalcin," "N-terminal cross-linked telopeptide," and "C-terminal cross-linked telopeptide," Several databases including Web of Science, Google Scholar, and PubMed were searched to obtain the relevant studies.

RESULTS

BTMs represent the combined effects of skeletal development, growth, and remodeling in children, which can be used in clinical pediatrics to assist in the diagnosis and prognosis of bone metabolic disorders.

CONCLUSION

BTMs are clearly helpful for diagnosis and monitoring of bone growth and development as well as bone metabolic disorders.

Bone markers and bone mineral density associates with periodontitis in females with poly-cystic ovarian syndrome

INTRODUCTION

Studies suggest an association between poly-cystic ovarian syndrome (PCOS) and chronic periodontitis (CP), both being inflammatory conditions. However, insufficient evidence assesses the impact of this inflammation on bone metabolism and bone turnover markers (BTMs). The present study aimed to determine the association between BTMs, bone mineral density (BMD), and clinical periodontal parameters in PCOS women with CP.

MATERIALS AND METHODS

Three groups, each with 40 newly diagnosed (1) PCOS+CP, (2) PCOS alone, (3) CP alone, and fourth group (n = 20) systemically and periodontally healthy females aged 18-30 years were included in the study. Full mouth clinical periodontal parameters, C-terminal telopeptides of type I collagen (CTX), bone alkaline phosphatase (ALP), BMD and 25-hydroxyvitamin D (VD) were recorded for all.

RESULTS

Low BMD (0.89 ± 0.11 g/cm²), increased CTX levels (2.76 ± 4.64 ng/ml), decreased bone ALP levels (11.09 ± 6.86 ng/ml), higher VD levels (289.02 ± 168.28 nmol/l) and poor clinical periodontal status were observed in PCOS + CP females. BMD-spine showed weak positive correlation with CTX, bone ALP, VD (r = 0.02, r = 0.07, r = 0.15, respectively) in PCOS + CP group. ANCOVA depicted covariates had no confounding effect. Multiple regression model explained 21.0% for BMD-spine and 12.7% for BMD-femur of total variability signifying association with all measured parameters among all groups.

CONCLUSION

Enhanced inflammatory thrust by periodontitis increases CTX levels and decreases bone ALP and BMD levels in women with PCOS. Screening PCOS women for periodontal disease and vice versa may have a direct bearing on overall bone health.

Advances in bone turnover markers

Bone fragility fractures remain an important worldwide health and economic problem due to increased morbidity and mortality. The current methods for predicting fractures are largely based on the measurement of bone mineral density and the utilization of mathematical risk calculators based on clinical risk factors for bone fragility. Despite these approaches, many bone fractures remain undiagnosed. Therefore, current research is focused on the identification of new factors such as bone turnover markers (BTM) for risk calculation. BTM are a group of proteins and peptides released during bone remodeling that can be found in serum or urine. They derive from bone resorptive and formative processes mediated by osteoclasts and osteoblasts, respectively. Potential use of BTM in monitoring these phenomenon and therefore bone fracture risk is limited by physiologic and pathophysiologic factors that influence BTM. These limitations in predicting fractures explain why their inclusion in clinical guidelines remains limited despite the large number of studies examining BTM.

Bone turnover in pregnancy, measured by urinary CTX, is influenced by vitamin D supplementation and is associated with maternal bone health: findings from the Maternal Vitamin D Osteoporosis Study (MAVIDOS) trial

BACKGROUND

The pattern of change in maternal bone turnover throughout pregnancy is poorly characterized.

OBJECTIVES

We investigated changes across pregnancy in a marker of maternal bone resorption, urinary C-terminal telopeptide of type I collagen (CTX), the influence of gestational vitamin D supplementation, and associations between CTX and maternal postnatal bone indices.

METHODS

MAVIDOS (the Maternal Vitamin D Osteoporosis Study) is a randomized, double-blind, placebo-controlled trial of 1000 IU cholecalciferol/d compared with placebo from 14 weeks of gestation to birth. Maternal second-void urinary α- and β-CTX were measured (ELISA) at 14 and 34 weeks of gestation; DXA was performed within 2 wk postpartum. The Mann-Whitney Rank Sum test, Spearman's rank correlation, and linear regression were used to compare median CTX values within and between groups from early to late pregnancy, and associations with maternal bone outcomes.

RESULTS

In total, 372 women had CTX and 25-hydroxyvitamin D [25(OH)D] measured in early and late pregnancy. CTX at 14 and 34 weeks of gestation were correlated in both placebo (r = 0.31) and cholecalciferol (r = 0.45) groups (P < 0.0001). Median CTX increased from 14 to 34 weeks of gestation in both groups (n = 372 total) [placebo (n = 188): from 223.6 to 449.7 μg/mmol creatinine; cholecalciferol (n = 184): from 222.3 to 419.3 μg/mmol creatinine; P = 0.03 for placebo compared with cholecalciferol difference in CTX at 34 weeks of gestation]. The conditional mean ± SD increase in CTX [z-score (SD)] from early to late pregnancy was greater in the placebo group (n = 188) than in the cholecalciferol group (n = 184) (placebo: 0.16 ± 0.92; cholecalciferol: -0.16 ± 1.06; P-difference < 0.01). Higher CTX at 34 weeks of gestation was associated, similarly in both groups, with lower maternal total hip and lumbar spine bone mineral content and bone mineral density (BMD) (e.g., lumbar spine BMD: β = -0.02 g · cm-2 · SD-1 increase in CTX; 95% CI: -0.027, -0.002 g · cm-2 · SD-1; P = 0.02, n = 283).

CONCLUSIONS

Maternal urinary CTX, a bone resorption marker, rises through pregnancy, although to a lesser degree with gestational cholecalciferol supplementation, and is inversely associated with maternal bone mass postpartum.This trial was registered at www.isrctn.com as ISRCTN 82927713 and eudract.ema.europa.eu as EudraCT 2007-001716-23.

Mycophenolic Acid Exposure Optimization Based on Vitamin D Status in Children with Systemic Lupus Erythematosus: A Single-Center Retrospective Study

Introduction

Systemic lupus erythematosus (SLE) can affect bone metabolism and homeostasis of serum electrolytes that are associated with abnormal levels of vitamin D. Mycophenolate mofetil (MMF) is a commonly used immunosuppressant with the active metabolite mycophenolic acid (MPA). The area under the plasma concentration–time curve (AUC) of MPA is often monitored during the treatment to assess the exposure levels. This study aims to explore the association between exposure levels of MPA and 25-hydroxyvitamin D [25(OH)D] levels in children with SLE.

Methods

Repeated measured data of children with SLE who were treated with MMF and under therapeutic drug monitoring (TDM) were retrospectively collected from the electronic medical records. MPA exposure levels were reflected by the area under the concentration–time curve over 24 h (AUC_0–24h). Univariate and multivariate linear regression models were employed to analyze factors associated with 25(OH)D levels. Hierarchical linear models were developed to analyze the intra- and inter-individual effects of AUC_0–24h on the variance of 25(OH)D levels.

Results

Data from 184 children with SLE (142 female and 42 male) with 518 follow-ups were collected. The median age was 14 years (range 3–18 years) at TDM. Children with normal 25(OH)D levels had significantly higher AUC_0–24h than children with low 25(OH)D levels (98.71 vs. 84.05 mg·h/L, P = 0.004). Intra- and inter-individual effects of AUC_0–24h on 25(OH)D levels were similar (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\gamma }_{10}$$\end{document}γ10 = 0.034 vs. \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\gamma }_{01}$$\end{document}γ01 = 0.037) but only the intra-individual effect was significant (P = 0.001) in hierarchical models. Other associated factors include age, sex, season at measurement, glucocorticoid daily dose, and external vitamin D₃ supplements.

Conclusion

25(OH)D levels are associated with MPA exposure levels, and may serve as a potential indicator to optimize the exposure level of MPA during treatment. AUC_0–24h of 98.71 mg·h/L or AUC_0–12h of 49.36 mg·h/L could be the targeted exposure level for children with SLE.

Role of Bone Turnover Markers in Osteoporosis Therapy

Bone turnover markers fill a clinical need that improves comprehensive care of metabolic bone health and osteoporosis. Creating a standard process for drawing them that reduces modifiable variability improves their precision and clinical usefulness. Creating a standard process for interpreting them by applying statistical significance improves their clinical applicability. Understanding what causes them to increase and decrease can help elucidate secondary causes of osteoporosis. Monitoring them can assess patient adherence to therapy for a silent disease that will progressively become louder with an aging global population.

The importance of maternal pregnancy vitamin D for offspring bone health: learnings from the MAVIDOS trial

Optimisation of skeletal mineralisation in childhood is important to reduce childhood fracture and the long-term risk of osteoporosis and fracture in later life. One approach to achieving this is antenatal vitamin D supplementation. The Maternal Vitamin D Osteoporosis Study is a randomised placebo-controlled trial, the aim of which was to assess the effect of antenatal vitamin D supplementation (1000 IU/day cholecalciferol) on offspring bone mass at birth. The study has since extended the follow up into childhood and diversified to assess demographic, lifestyle and genetic factors that determine the biochemical response to antenatal vitamin D supplementation, and to understand the mechanisms underpinning the effects of vitamin D supplementation on offspring bone development, including epigenetics. The demonstration of positive effects of maternal pregnancy vitamin D supplementation on offspring bone development and the delineation of underlying biological mechanisms inform clinical care and future public-health policies.

Physical Determinants of Vitamin D Photosynthesis: A Review

Vitamin D synthesis by exposure of skin to solar ultraviolet radiation (UVR) provides the majority of this hormone that is essential for bone development and maintenance but may be important for many other health outcomes. This process, which is the only well-established benefit of solar UVR exposure, depends on many factors including genetics, age, health, and behavior. However, the most important factor is the quantity and quality of UVR reaching the skin. Vitamin D synthesis specifically requires ultraviolet B (UVB) radiation that is the minority component (<5%) of solar UVR. This waveband is also the most important for the adverse effects of solar exposure. The most obvious of which is sunburn (erythema), but UVB is also the main cause of DNA damage to the skin that is a prerequisite for most skin cancers. UVB at the Earth's surface depends on many physical and temporal factors such as latitude, altitude, season, and weather. Personal, cultural, and behavioral factors are also important. These include skin melanin, clothing, body surface area exposed, holiday habits, and sunscreen use. There is considerable disagreement in the literature about the role of some of these factors, possibly because some studies have been done by researchers with little understanding of photobiology. It can be argued that vitamin D supplementation obviates the need for solar exposure, but many studies have shown little benefit from this approach for a wide range of health outcomes. There is also increasing evidence that such exposure offers health benefits independently of vitamin D: the most important of which is blood-pressure reduction. In any case, public health advice must optimize risk versus benefit for solar exposure. It is fortunate that the individual UVB doses necessary for maintaining optimal vitamin D status are lower than those for sunburn, irrespective of skin melanin. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.

Serum and Urinary Osteocalcin in Healthy 7- to 19-Year-Old Finnish Children and Adolescents

Children and adolescents have high bone turnover marker (BTM) levels due to high growth velocity and rapid bone turnover. Pediatric normative values for BTMs reflecting bone formation and resorption are vital for timely assessment of healthy bone turnover, investigating skeletal diseases, or monitoring treatment outcomes. Optimally, clinically feasible measurement protocols for BTMs would be validated and measurable in both urine and serum. We aimed to (a) establish sex- and age-specific reference intervals for urinary and serum total and carboxylated osteocalcin (OC) in 7- to 19-year-old healthy Finnish children and adolescents (n = 172), (b) validate these against standardized serum and urinary BTMs, and (c) assess the impact of anthropometry, pubertal status, and body composition on the OC values. All OC values in addition to other BTMs increased with puberty and correlated with pubertal growth, which occurred and declined earlier in girls than in boys. The mean serum total and carboxylated OC and urinary OC values and percentiles for sex-specific age categories and pubertal stages were established. Correlation between serum and urinary OC was weak, especially in younger boys, but improved with increasing age. The independent determinants for OC varied, the urinary OC being the most robust while age, height, weight, and plasma parathyroid hormone (PTH) influenced serum total and carboxylated OC values. Body composition parameters had no influence on any of the OC values. In children and adolescents, circulating and urinary OC reflect more accurately growth status than bone mineral density (BMD) or body composition. Thus, validity of OC, similar to other BTMs, as a single marker of bone turnover, remains limited. Yet, serum and urinary OC similarly to other BTMs provide a valuable supplementary tool when assessing longitudinal changes in bone health with repeat measurements, in combination with other clinically relevant parameters.

Effect of Vitamin D Levels on Bone Remodeling in Healthy Women

BACKGROUND

Vitamin D deficiency is prevalent among Indian women. Subclinical vitamin D deficiency is a significant risk factor for osteopenia and fractures. However, its effect on bone metabolism and bone mineral density (BMD) is still debatable.

OBJECTIVES

This study aimed to determine relationships of the vitamin D status with bone turnover markers, carboxy-terminal telopeptide of type-I collagen (CTX), N-terminal propeptide of type I procollagen (PINP), and BMD in healthy Indian women.

METHODS

In this cross-sectional study, we determined serum levels of 25-hydroxy vitamin D (25(OH)D), parathyroid hormone, serum CTX, and PINP using commercial ELISA kits in 310 healthy Indian women aged 25 - 65 years who underwent BMD measurements with DXA scan.

RESULTS

The prevalence of vitamin D deficiency was 53.87% and vitamin D insufficiency 31.29%. A direct correlation of BMD with vitamin D levels was not observed. PINP negatively correlated with vitamin D in both premenopausal (Spearman's r = -0.169, P < 0.05) and postmenopausal (Spearman's r = -0.241, P < 0.05) women. However, CTX positively correlated with vitamin D in both premenopausal (Spearman's r = 0.228, P < 0.01) and postmenopausal (Spearman's r = 0.244, P < 0.05) women.

CONCLUSIONS

Vitamin D deficiency is more prevalent in premenopausal women than in postmenopausal ones. Although vitamin D does not show any association with BMD, it affects bone remodeling, which is reflected by changes in the bone formation marker PINP and the bone resorption marker CTX.

The Associations of Vitamin D Status with Athletic Performance and Blood-borne Markers in Adolescent Athletes: A Cross-Sectional Study

The purpose of this study was to examine the associations of vitamin D status with athletic performance and blood-borne markers in adolescent athletes. This cross-sectional study included forty-seven Taekwondo athletes, aged 15–18 years old. Athletic performance was assessed using maximal oxygen consumption (VO_2max), Wingate anaerobic power test, vertical jump, agility T-test, lower limb muscle strength, and fatigue resistance. Blood samples were collected to assess serum 25-hydroxyvitamin D [25(OH)D], free-testosterone, cortisol, creatine kinase, and urea. One-way ANOVAs were applied using Bonferroni adjusted alpha levels, which was 0.02 (i.e., 0.05/3). Multiple linear regressions analyses as well as Pearson and partial correlation analyses were used to examine the relationship among 25(OH)D concentration, athletic performance, and blood-borne markers. The participants 25(OH)D concentration were ranged from 16 to 73.25 nmol/L, indicating that 74.5% of the adolescent athletes have vitamin D insufficiency or deficiency. The vitamin D status did not show any significant effects on the performance factors or blood-borne markers. Serum 25(OH)D concentration was positively correlated with mean power output (r = 0.359, p < 0.05) and relative mean power output (r = 0.325, p < 0.05) after adjusting for bone age, height, weight, training experience, lean body mass, and fat mass. However, 25(OH)D concentration was not associated with other performance-related factors and blood-borne markers. In addition, multiple linear regressions analyses revealed that serum 25(OH)D concentration were not significant predictors of athletic performance in adolescent athletes. In conclusion, vitamin D status is weakly correlated with anaerobic capacity; moreover, the underlying mechanisms of how vitamin D influence anaerobic performance is unclear in the present study. Nevertheless, the importance of vitamin D on health benefits should not be underestimated, especially during growth periods.

The Paradoxical Role of Uric Acid in Osteoporosis

Because of its high prevalence worldwide, osteoporosis is considered a serious public health concern. Many known risk factors for developing osteoporosis have been identified and are crucial if planning health care needs. Recently, an association between uric acid (UA) and bone fractures had been explored. Extracellular UA exhibits antioxidant properties by effectively scavenging free radicals in human plasma, but this benefit might be disturbed by the hydrophobic lipid layer of the cell membrane. In contrast, intracellular free oxygen radicals are produced during UA degradation, and superoxide is further enhanced by interacting with NADPH oxidase. This intracellular oxidative stress, together with inflammatory cytokines induced by UA, stimulates osteoclast bone resorption and inhibits osteoblast bone formation. UA also inhibits vitamin D production and thereby results in hyper-parathyroidism, which causes less UA excretion in the intestines and renal proximal tubules by inhibiting the urate transporter ATP-binding cassette subfamily G member 2 (ABCG2). At normal or high levels, UA is associated with a reduction in bone mineral density and protects against bone fracture. However, in hyperuricemia or gout arthritis, UA increases bone fracture risk because oxidative stress and inflammatory cytokines can increase bone resorption and decrease bone formation. Vitamin D deficiency, and consequent secondary hyperparathyroidism, can further increase bone resorption and aggravated bone loss in UA-induced osteoporosis.

The Role of Nutrients in Reducing the Risk for Noncommunicable Diseases during Aging

An increasing aging population worldwide accounts for a growing share of noncommunicable diseases (NCDs) of the overall social and economic burden. Dietary and nutritional approaches are of paramount importance in the management of NCDs. As a result, nutrition programs are increasingly integrated into public health policies. At present, programs aimed at reducing the burden of NCDs have focused mostly on the excess of unhealthy nutrient intakes whereas the importance of optimizing adequate essential and semi-essential nutrient intakes and nutrient-rich diets has received less attention. Surveys indicate that nutrient intakes of the aging population are insufficient to optimally support healthy aging. Vitamin and mineral deficiencies in older adults are related to increased risk of NCDs including fatigue, cardiovascular disease, and cognitive and neuromuscular function impairments. Reviewed literature demonstrates that improving intake for certain nutrients may be important in reducing progress of NCDs such as musculoskeletal disorders, dementia, loss of vision, and cardiometabolic diseases during aging. Current knowledge concerning improving individual nutrient intakes to reduce progression of chronic disease is still emerging with varying effect sizes and levels of evidence. Most pronounced benefits of nutrients were found in participants who had low nutrient intake or status at baseline or who had increased genetic and metabolic needs for that nutrient. Authorities should implement ways to optimize essential nutrient intake as an integral part of their strategies to address NCDs.

Effect of Vitamin D Supplementation on Bone Turnover Markers in Children and Adolescents from North India

OBJECTIVES

Vitamin D is known to play an important role in bone mineral metabolism. Its deficiency may affect growth and status of bone markers in children. Hence, we undertook to study the status of bone markers in children with vitamin D deficiency (VDD) and impact of vitamin D3 supplementation on them.

MATERIALS AND METHODS

Total 468 out of 615 children and adolescents with VDD, who were given either of the three doses (600, 1000, and 2000) of vitamin D supplementation, were included in the study. These 468 children with pre- and postsupplementation preserved samples with available anthropometry, serum biochemistry, 25-hydroxy-vitamin D, and parathormone were evaluated for bone formation (procollagen type 1 amino-terminal propeptide [P1NP]) and resorption (β-cross laps [CTx]) markers.

RESULTS

The mean age and body mass index of these children were 11.3 ± 2.3 years (boys: 11.5 ± 2.4; girls: 12.2 ± 1.2 years; P = 0.03) and 18.1 ± 3.8 kg/m² (boys: 18.2 ± 3.9; girls: 17.6 ± 3.2 kg/m²; P = 0.208), respectively. There were 8.8% subjects with severe, 42.7% with moderate, and 48.5% with mild VDD. There was a significant decline in serum P1NP (from 691 ± 233 ng/ml to 640 ± 259 ng/ml, P < 0.001) and CTx (from 1.67 ± 0.53 ng/ml to 1.39 ± 0.51 ng/ml, P < 0.001) following supplementation. Though decline in serum P1NP and CTx levels was observed in both boys and girls, among all three supplementation groups and VDD categories, the effect was more marked in serum CTx than P1NP levels.

CONCLUSIONS

Vitamin D supplementation in VDD children resulted in decrease in both bone formation (P1NP) and resorption (CTx). The impact, however, was more marked on bone resorption than bone formation.

Vitamin D Deficiency: The Missing Etiological Factor in the Development of Juvenile Osteochondrosis Dissecans?

BACKGROUND

Vitamin D deficiency can result in rickets and hypocalcemia during infant and childhood growth. There is an increasing interest in the role of vitamin D with regards to childhood bone health. Osteochondrosis dissecans (OD) is a common disease affecting different joints. To date, the exact etiology of OD still remains unclear. The aim of this study was to evaluate a possible association of vitamin D deficiency and juvenile OD.

METHODS

A retrospective chart review of the years 2010 to 2015 of all orthopaedic patients with an initial diagnosis of juvenile OD admitted to undergo operative treatment of the OD was performed. Patient demographics, medical history, information on sports activity (if available) and serum vitamin D (25-OH-D) level on admission date were obtained. For statistical comparison, we measured baseline prevalence of vitamin D insufficiency in age-matched orthopaedic patients presenting at the department of pediatric orthopaedics.

RESULTS

A total of 80 patients were included in this study. Overall, 97.5% (n=78) of tested patients in the OD group had serum vitamin D levels below the recommended threshold of 30 ng/mL (mean value of 10.1 ng/mL (±6.7 ng/mL)). Over 60% (n=49) were vitamin D deficient, 29 patients (37%) showed serum levels below 10 ng/mL corresponding to a severe vitamin D deficiency. Of note, only 2 patients (2.5%) reached serum vitamin D levels above the recommended threshold of 30 ng/mL. No statistical difference was found in respect to sports activity level before onset of the symptoms (P=0.09). Statistical analysis found a significant difference in vitamin D levels between patients with OD and patients without an OD (P=0.026).

CONCLUSIONS

We found an unexpected high prevalence of vitamin D deficiency in juveniles diagnosed with OD presenting with significant lower mean 25-OH-D level compared with a control group. These results suggest that vitamin D deficiency is potentially associated with the development of OD. Thus, vitamin D deficiency might be an important cofactor in the multifactorial development of juvenile OD. For this reason, supplementation of vitamin D might not only be a potential additional therapy but also be a possible preventative factor in patients with juvenile OD. However, future prospective studies are needed to confirm this preliminary data.

LEVEL OF EVIDENCE

Level III-this is a case-control study.

Use of bone turnover markers in the management of osteoporosis

PURPOSE OF REVIEW

Osteoporosis is a common public health problem that is often undertreated and underdiagnosed. The clinical management of osteoporosis is often reactionary to devastating fracture events. Bone turnover markers may improve the ease and rapidity at which osteoporosis is monitored and treated. Bone turnover markers are biochemical byproducts of bone formation or bone resorption. The clinical use of bone turnover markers is limited by significant preanalytical variability. Effective interpretation of bone turnover markers requires a detailed understanding of the variables that can affect their responses to osteoporosis treatment and monitoring.

RECENT FINDINGS

Progress is continuously being made on the standardization of bone turnover markers. The literature on the response of bone turnover markers to unique clinical situations is expanding. Data for evidence-based reference intervals for bone turnover markers has increased. Variables that affect the appropriate timing of lab draws like diurnal variation, postprandial status, exercise and alcohol use have been described. Studies examining the expected response of bone turnover markers to treatments of osteoporosis and other medications that affect bone health continue to increase.

SUMMARY

Bone turnover markers have clinical utility in the comprehensive evaluation of osteoporosis. When interpreted with caution and with a good understanding of their natural variability, bone turnover markers provide information that supplements osteoporosis management and provides useful clinical information about conditions that alter bone turnover.

Association Between Vitamin D and Carboxy-Terminal Cross-Linked Telopeptide of Type I Collagen in Children During Growth Hormone Replacement Therapy

Growth hormone and insulin-like growth factor-1 (IGF-1) play a crucial role in the regulation of bone turnover. Adequate vitamin D status supports proper bone remodeling, leading to normal longitudinal bone growth and normal peak bone mass. The aim of this study was to evaluate the association between serum 25-hydroxyvitamin D [25(OH)D] and carboxy-terminal cross-linked telopeptide of type I collagen (ICTP) in children and adolescents with growth hormone deficiency at baseline and during recombinant human growth hormone (rhGH) replacement therapy. The study was prospective and included 30 children and adolescents aged 5 to 17 years. Concentrations of 25(OH)D, ICTP, and IGF-1 were measured at baseline and during the first year of rhGH therapy. Baseline serum 25(OH)D concentration correlated with ICTP concentrations during the first trimester of rhGH therapy (r = 0.38, p < 0.050); the correlation was stronger in the second trimester of therapy (r = 0.6, p = 0.002). We conclude that proper vitamin D status is important in reaching the adequate dynamics of bone remodeling during growth, which is essential to achieve a catch-up growth during rhGH therapy.

Children sustain high levels of skin DNA photodamage, with a modest increase of serum 25-hydroxyvitamin D3 , after a summer holiday in Northern Europe

BACKGROUND

Childhood solar ultraviolet radiation (UVR) exposure increases the risk of skin cancer in adulthood, which is associated with mutations caused by UVR-induced cyclobutane pyrimidine dimers (CPD). Solar UVR is also the main source of vitamin D, essential for healthy bone development in children.

OBJECTIVES

To assess the impact of a 12-day Baltic Sea (54° N) beach holiday on serum 25-hydroxyvitamin D₃ [25(OH)D₃ ] and CPD in 32 healthy Polish children (skin types I-IV).

METHODS

Blood and urine were collected before and after the holiday and assessed for 25(OH)D₃ and excreted CPD, respectively, and personal UVR exposure was measured. Diaries were used to record sunbathing, sunburn and sunscreen use. Before- and after-holiday skin redness and pigmentation were measured by reflectance spectroscopy.

RESULTS

The average ± SD daily exposure UVR dose was 2·4 ± 1·5 standard erythema doses (SEDs), which is borderline erythemal. The mean concentration of 25(OH)D₃ increased (× 1·24 ± 0·19) from 64·7 ± 13·3 to 79·3 ± 18·7 nmol L^-1 (P < 0·001). Mean CPD increased 12·6 ± 10·0-fold from 26·9 ± 17·9 to 248·9 ± 113·4 fmol μmol^-1 creatinine (P < 0·001). Increased 25(OH)D₃ was accompanied by a very much greater increase in DNA damage associated with carcinogenic potential. Overall, skin type had no significant effects on behavioural, clinical or analytical outcomes, but skin types I/II had more CPD (unadjusted P = 0·0496) than skin types III/IV at the end of the holiday.

CONCLUSIONS

Careful consideration must be given to the health outcomes of childhood solar exposure, and a much better understanding of the risk-benefit relationships of such exposure is required. Rigorous photoprotection is necessary for children, even in Northern Europe.

The Effect of Vitamin D Supplementation on Bone Metabolic Markers in Chronic Kidney Disease

Use of active forms of vitamin D is advocated in patients with chronic kidney disease (CKD) for treatment of mineral bone disease because of the presumption that native forms of vitamin D would not undergo significant activation to calcitriol, the most active biological form of vitamin D. We present secondary analysis looking at bone turnover in subjects who completed the randomized, double blind, placebo-controlled trial investigating the effect of cholecalciferol supplementation on vascular function in nondiabetic CKD stage G3-G4 and vitamin D ≤20 ng/mL (Clinical Trials Registry of India: CTRI/2013/05/003648). Patients were randomized (1:1) to receive either two directly observed oral doses of 300,000 IU of cholecalciferol or matching placebo at baseline and 8 weeks. Of the 120 subjects enrolled, 58 in the cholecalciferol group and 59 in the placebo group completed the study. At 16 weeks, the serum 25(OH)D and 1,25(OH)₂ D levels increased in the cholecalciferol group but not in the placebo group (between-group difference in mean change: 23.40 ng/mL; 95% CI, 19.76 to 27.06; p < 0.001, and 14.98 pg/mL; 95% CI, 4.48 to 27.18; p = 0.007, respectively). Intact parathyroid hormone (iPTH) decreased in the cholecalciferol group (between-group difference in mean change -100.73 pg/mL (95% CI, -150.50 to -50.95; p < 0.001). Serum total and bone-specific alkaline phosphatase (SAP, BAP) and serum C-terminal cross-linked collagen type I telopeptides (CTX-1) were significantly reduced in cholecalciferol group (between group difference for change in mean: -20.25 U/L; 95% CI, -35.14 to -5.38 U/L; p = 0.008 for SAP; -12.54 U/L; 95% CI, -22.09 to -2.98 U/L; p = 0.013 for BAP; and -0.21 ng/mL; 95% CI, -0.38 to -0.05 ng/mL; p = 0.05 for CTX-1). Correlation analysis showed significant correlation of Δ25(OH)D with ΔiPTH (r = -0.409, p < 0.0001), Δ1,25(OH)₂ D (r = 0.305, p = 0.001), ΔSAP (r = -0.301, p = 0.002), ΔBAP (r = -0.264, p = 0.004), and ΔCTX-1 (r = -0.210, p = 0.0230). Cholecalciferol supplementation corrects vitamin D deficiency and is effective in lowering serum intact parathyroid hormone and bone turnover markers in early stages of CKD. © 2017 American Society for Bone and Mineral Research.

Higher serum 25(OH)D concentrations are associated with improved FEV1 and FVC in adolescence

Vitamin D plays a role in the development of the immune system and the lung, as well as in airway remodelling. Therefore, this study investigated the association between serum 25-hydroxyvitamin D (25(OH)D) concentrations and spirometric lung function parameters at age 15 years.

In the German birth cohorts GINIplus and LISAplus, lung function testing by spirometry and 25(OH)D measurements were performed during the 15-year follow-up examinations. Valid lung function measurements pre- and/or post-bronchodilation and serum 25(OH)D concentrations, which were adjusted for the date of blood sampling to account for seasonal variability, were available for 2607 adolescents. Associations between 25(OH)D concentrations and spirometric parameters were analysed using generalised additive models adjusted for confounding factors.

Serum 25(OH)D concentrations were significantly associated with forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC measured before bronchodilation after adjustment for potential confounders: FEV1 increased by 10 mL (95% CI 2–17), FVC by 20 mL (95% CI 12–28) and FEV1/FVC decreased by 0.177% (95% CI −0.286 to −0.067) per 10 nmol·L−1 increase in 25(OH)D concentrations. Flow rates (forced expiratory flow rates at 25, 50 and 75% of exhaled FVC (FEF25, FEF50, FEF75) and mean flow rate between 25 and 75% of FVC (FEF25–75)) were not associated with vitamin D. Similar associations were observed for lung function parameters measured after bronchodilation.

Vitamin D concentrations are positively associated with volume-related lung function parameters pre- and post-bronchodilation, suggesting structural changes in peripheral airways.

Bone Turnover Markers in the Diagnosis and Monitoring of Metabolic Bone Disease

BACKGROUND

Disorders of bone metabolism, most notably osteoporosis, are highly prevalent and predispose to fractures, causing high patient morbidity and mortality. Diagnosis and monitoring of bone metabolic defects can present a major challenge as these disorders are largely asymptomatic and radiographic measures of bone mass respond slowly to changes in bone physiology.

CONTENT

Bone turnover markers (BTMs) are a series of protein or protein derivative biomarkers released during bone remodeling by osteoblasts or osteoclasts. BTMs can offer prognostic information on fracture risk that supplements radiographic measures of bone mass, but testing using BTMs has to take into account the large number of preanalytic factors and comorbid clinical conditions influencing BTM levels. BTMs respond rapidly to changes in bone physiology, therefore, they have utility in determining patient response to and compliance with therapies for osteoporosis.

SUMMARY

BTMs are a useful adjunct for the diagnosis and therapeutic monitoring of bone metabolic disorders, but their use has to be tempered by the known limitations in their clinical utility and preanalytic variables complicating interpretation.