Sex- and age-specific reference curves for serum markers of bone turnover in healthy children from 2 months to 18 years

Osteoclast indices in osteogenesis imperfecta: systematic review and meta-analysis

Osteogenesis imperfecta (OI) is a rare bone fragility disorder caused by mutations in genes encoding collagen type I or that affect its processing. Alterations in osteoclasts were suggested to contribute to OI pathophysiology. We aimed to systematically identify studies reporting measures of osteoclast formation and function in patients and mouse models of OI, to quantify OI-induced changes. The systematic search of Medline, Ovid, and Web of Science identified 798 unique studies. After screening, we included 23 studies for meta-analysis, reporting osteoclast parameters in 310 patients with OI of 9 different types and 16 studies reporting osteoclast parameters in 406 animals of 11 different OI mouse models. The standardized mean difference with 95% confidence interval (CI) was used as the effect size, and random-effects meta-analysis was performed. In patients with OI, collagen degradation markers were significantly higher compared with age-matched controls, with an effect size of 1.23 (CI: 0.36, 2.10]. Collagen degradation markers were the most elevated in the 3- to 7-year-old age group and in patients with more severe forms of OI. Bone histomorphometry demonstrated the trends for higher osteoclast numbers (1.16; CI: -0.22, 2.55) and osteoclast surface (0.43; CI: -0.63, 1.49), and significantly higher eroded surface (3.24; CI: 0.51, 5.96) compared with age-matched controls. In OI mice, meta-analysis demonstrated significant increases in collagen degradation markers (1.59; CI: 1.07, 2.11), in osteoclast numbers (0.94; CI: 0.50, 1.39), osteoclast surface (0.73; CI: 0.22, 1.23), and eroded surface (1.31; CI: 0.54, 2.08). The largest differences were in OI mice with the mutations in Col1a1 and Col1a2 genes. There were no differences between males and females in clinical or animal studies. Quantitative estimates of changes in osteoclast indices and their variance for patients with OI are important for planning future studies. We confirmed that similar changes are observed in mice with OI, supporting their translational utility.

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.

Clinical features, treatment, and follow-up of OPPG and high-bone-mass disorders: LRP5 is a key regulator of bone mass

Osteoporosis-pseudoglioma syndrome (OPPG) and LRP5 high bone mass (LRP5-HBM) are two rare bone diseases with opposite clinical symptoms caused by loss-of-function and gain-of-function mutations in LRP5. Bisphosphonates are an effective treatment for OPPG patients. LRP5-HBM has a benign course, and age-related bone loss is found in one LRP5-HBM patient.

PURPOSE

Low-density lipoprotein receptor-related protein 5 (LRP5) is involved in the canonical Wnt signaling pathway. The gain-of-function mutation leads to high bone mass (LRP5-HBM), while the loss-of-function mutation leads to osteoporosis-pseudoglioma syndrome (OPPG). In this study, the clinical manifestations, disease-causing mutations, treatment, and follow-up were summarized to improve the understanding of these two diseases.

METHODS

Two OPPG patients and four LRP5-HBM patients were included in this study. The clinical characteristics, biochemical and radiological examinations, pathogenic mutations, and structural analysis were summarized. Furthermore, several patients were followed up to observe the treatment effect and disease progress.

RESULTS

Congenital blindness, persistent bone pain, low bone mineral density (BMD), and multiple brittle fractures were the main clinical manifestations of OPPG. Complex heterozygous mutations were detected in two OPPG patients. The c.1455G > T mutation in exon 7 was first reported. During the follow-up, BMD of two patients was significantly improved after bisphosphonate treatment. On the contrary, typical clinical features of LRP5-HBM included extremely high BMD without fractures, torus palatinus and normal vision. X-ray showed diffuse osteosclerosis. Two heterozygous missense mutations were detected in four patients. In addition, age-related bone loss was found in one LRP5-HBM patient after 12-year of follow-up.

CONCLUSION

This study deepened the understanding of the clinical characteristics, treatment, and follow-up of OPPG and LRP5-HBM; expanded the pathogenic gene spectrum of OPPG; and confirmed that bisphosphonates were effective for OPPG. Additionally, it was found that Ala242Thr mutation could not protect LRP5-HBM patients from age-related bone loss. This phenomenon deserves further study.

Discordant responses of bone formation and absorption markers in Japanese infants with vitamin D deficiency: a comprehensive matched case-control study

Vitamin D deficiency during infancy has been associated with increased bone turnover rate and bone mineral loss. However, few studies have examined bone turnover markers (BTMs) for both bone formation and resorption in infants with vitamin D deficiency. Here, we analyzed serum concentrations of 25OHD, intact parathormone (iPTH), and BTMs including total alkaline phosphatase (ALP), tartrate-resistant acid phosphatase isoform 5b (TRACP-5b), and serum type I collagen N-telopeptide (NTx) as well as basic clinical characteristics of 456 infants (626 samples) aged less than 12 mo born at Saitama City Hospital, Japan (latitude 35.9° North) between January 2021 and December 2022. One hundred sixteen infants (147 samples) were classified as having vitamin D deficiency (25OHD < 12.0 ng/mL), and 340 infants (479 samples) had sufficient vitamin D levels (25OHD ≥ 12.0 ng/mL). In addition to 25OHD and ALP, both TRACP-5b and sNTx were measured in 331 infants (418 samples), while 90 infants (105 samples) had only TRACP-5b measured and 101 infants (103 samples) had only sNTx measured. Statistical comparison of 104 subjects each in the vitamin D deficiency and sufficiency groups after matching for the background characteristics revealed that the vitamin D deficiency group had significantly higher levels of ALP and iPTH compared with the sufficiency group (P = <.0001, .0012, respectively). However, no significant differences were found in TRACP-5b and NTx levels between the 2 groups (P = .19, .08, respectively). Our findings suggest discordant responses between bone formation and resorption markers in subclinical vitamin D deficiency during infancy.

Demographic and disease-related factors impact bone turnover and vitamin D in children with hemato-oncological diseases

Children with hemato-oncological diseases may have significant skeletal morbidity, not only during and after treatment but also at the time of diagnosis before cancer treatment. This study was designed to evaluate the vitamin D status and circulating bone metabolic markers and their determinants in children at the time of diagnostic evaluation for hemato-oncological disease. This cross-sectional study included 165 children (91 males, median age 6.9 yr range 0.2-17.7 yr). Of them, 76 patients were diagnosed with extracranial or intracranial solid tumors, 83 with leukemia, and 6 with bone marrow failure. Bone metabolism was assessed by measuring serum 25OHD, PTH, bone alkaline phosphatase, intact N-terminal propeptide of type I procollagen, and C-terminal cross-linked telopeptide of type I collagen. Vitamin D deficiency was found in 30.9% of children. Lower 25OHD levels were associated with older age, lack of vitamin D supplementation, season outside summer, and a country of parental origin located between latitudes -45° and 45°. Children diagnosed with leukemia had lower levels of markers of bone formation and bone resorption than those who had solid tumors or bone marrow failure. In conclusion, vitamin D deficiency was observed in one-third of children with newly diagnosed cancer. Bone turnover markers were decreased in children with leukemia, possibly because of the suppression of osteoblasts and osteoclasts by leukemic cells. The identification of patients with suboptimal vitamin D status and compromised bone remodeling at cancer diagnosis may aid in the development of supportive treatment to reduce the adverse effects of cancer and its treatment.

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.

Risk Factors Associated with Incident Vertebral Fractures in Steroid-treated Males with Duchenne Muscular Dystrophy

PURPOSE

Prevention of fractures is an unmet need in glucocorticoid (GC)-treated Duchenne muscular dystrophy. This study explored factors associated with incident vertebral fractures (VFs) to inform future fracture prevention efforts.

METHODS

VFs were evaluated prospectively at study baseline and 12 months on lateral spine radiographs in participants aged 4 to 25 years with Duchenne muscular dystrophy. Clinical factors were analyzed for their association with the change in Spinal Deformity Index (sum of the Genant-defined VF grades from T4 to L4) between baseline and 12 months.

RESULTS

Thirty-eight males were evaluated (mean ± SD age at baseline 11.0 ± 3.6 years; mean ± SD GC duration at baseline 4.1 ± 3.1 years; 74% ambulatory). Nine of 38 participants (24%) had 17 incident VFs, of which 3/17 VFs (18%) were moderate/severe. Participants with 12-month incident VF had lower mean ± SD baseline lumbar spine areal bone mineral density Z-scores (-2.9 ± 1.0 vs -1.9 ± 1.1; P = .049) and lower total body less head areal bone mineral density Z-scores (-3.1 ± 1.2 vs -1.6 ± 1.7; P = .036). Multivariable linear regression showed that at least 1 VF at baseline (P < .001), a higher number of antecedent non-VF (P < .001), and greater bone age delay at baseline (P = .027) were significant predictors of an increase in the Spinal Deformity Index from baseline to 12 months.

CONCLUSION

The observation that ≥ 1 prevalent VF and/or non-VF were the strongest predictors of incident VFs at 12 months supports the need for prevention of first fractures in this high-risk setting. Bone age delay, a marker of GC exposure, may assist in the prioritization of patients in efforts to prevent first fractures.

Low bone mineral density and reduced bone-specific alkaline phosphatase in 5q spinal muscular atrophy type 2 and type 3: A 2-year prospective study of bone health

AIM

Individuals with spinal muscular atrophy (SMA) are at risk of developing skeletal problems. This study investigated bone mineral density (BMD), bone turnover markers and motor function in children and adolescents with SMA type 2 and type 3 over a two-year period. The effect of nusinersen was studied in a subgroup.

METHODS

Single-centre study, including 20 patients, 2-18 years, of whom ten patients received nusinersen treatment. BMD was measured by dual-energy X-ray absorptiometry.

RESULTS

All patients had low BMD levels at baseline; mean Z-score -2.3 for total body less head (TBLH) and -2.9 for total hip left (THL). Significant correlations were found both at baseline and for the follow-up change for motor function and Z-scores (TBLH and THL). For the whole study group, reduced bone formation and unchanged bone resorption, assessed by bone-specific alkaline phosphatase (BALP) (p = 0.0006, ES = -0.83) and C-terminal cross-linking telopeptide of type I collagen (CTX), respectively, were found over the study period. However, BALP decreased less in the nusinersen treatment group, which suggests a positive development on bone mass in these patients.

CONCLUSION

Bone health evaluation is important in follow-up programmes for SMA patients. Further investigations are warranted for individuals on survival motor neuron-targeted treatments.

Early Castration in Horses Does Not Impact Osteoarticular Metabolism

The castration of stallions is traditionally performed after puberty, at around the age of 2 years old. No studies have focused on the effects of early castration on osteoarticular metabolism. Thus, we aimed to compare early castration (3 days after birth) with traditional castration (18 months of age) in horses. Testosterone and estradiol levels were monitored from birth to 33 months in both groups. We quantified the levels of biomarkers of cartilage and bone anabolism (CPII and N-MID) and catabolism (CTX-I and CTX-II), as well as of osteoarthritis (HA and COMP) and inflammation (IL-6 and PGE2). We observed a lack of parallelism between testosterone and estradiol synthesis after birth and during puberty in both groups. The extra-gonadal synthesis of steroids was observed around the 28-month mark, regardless of the castration age. We found the expression of estrogen receptor (ESR1) in cartilage and bone, whereas androgen receptor (AR) expression appeared to be restricted to bone. Nevertheless, with respect to osteoarticular metabolism, steroid hormone deprivation resulting from early castration had no discernable impact on the levels of biomarkers related to bone and cartilage metabolism, nor on those associated with OA and inflammation. Consequently, our research demonstrated that early castration does not disrupt bone and cartilage homeostasis.

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 C-Terminal Cross-linked Telopeptide of Type I Collagen (CTX-I) as a Potential Cardiomyopathy Biomarker in Friedreich Ataxia Patients

Friedreich's ataxia (FRDA) is the most common inherited recessive ataxia. Cardiomyopathy (CM) with myocardial hypertrophy is the predominant cause of death. The presence of CM is variable and the risk factors for cardiac involvement are not entirely clear. Markers of collagen degradation, such as C-terminal cross-linked telopeptide of type I collagen (CTX-I), seem to be associated with unfavorable cardiovascular outcomes. The aim of our study was to measure serum CTX-I as a marker of cardiac fibrosis in FRDA patients. We measured serum CTX value in twenty-five FRDA patients (mean age, 31.3 ± 14.7 years) and nineteen healthy controls (mean age, 34.0 ± 13.5 years). Patients underwent echocardiography and SARA scale evaluation. CTX values were significantly higher in the patients than in the control group (31.82 ± 2.27 vs 16.44 ± 1.6 μg/L; p = 0.006). CTX-I was inversely correlated with age (R =  - 0,535; n = 44; p < 0.001). The regression model identified disease duration and TT3 levels to be independent predictors of CTX-I (model R2 = 0.938; intercept - 64.0, p = 0.071; disease duration coefficient =  - 2.34, p = 0.005; TT3 coefficient = 127.17, p = 0.011). CTX-I, a biomarkers of collagen turnover, is elevated in FRDA and should provide complementary information to identify patients with high cardiological risk even if longitudinal studies are needed to define the role of this serologic marker of collagen metabolism in the natural history of cardiomyopathy in FRDA patients.

Alkaline Phosphatase and Hyperphosphatasemia in Vitamin D Trial in Healthy Infants and Toddlers

CONTEXT

Childhood hyperphosphatasemia is usually transient and may be associated with infections. It remains less well known how hyperphosphatasemia is related to growth and bone mineralization.

OBJECTIVE

We explored alkaline phosphatase (ALP) concentrations and prevalence of hyperphosphatasemia, and their association with vitamin D, growth, infections, and bone parameters in healthy children.

METHODS

The study was a secondary analysis of a vitamin D intervention trial. Participants received vitamin D3 10 or 30 µg daily from age 2 weeks to 2 years. Children with data on ALP at 12 and/or 24 months (n = 813, girls 51.9%) were included. Anthropometrics and bone parameters were measured at 12 and 24 months. Infections were recorded prospectively by the parents.

RESULTS

Boys had higher ALP than girls at 12 months (median [IQR] 287 [241-345] U/L vs 266 [218-341] U/L; P = .02). At 24 months concentrations were lower than at 12 months (240 [202-284]; P < .001) but without sex difference. The prevalence of hyperphosphatasemia (ALP > 1000 U/L) at 12 months was 5.3% and at 24 months 0.6%. Body size, growth rate, and bone mineral content associated positively with ALP, while vitamin D intervention had no effect. Infants with hyperphosphatasemia were smaller than infants with ALP ≤ 1000 U/L. Hyperphosphatasemia was not associated with previous infections.

CONCLUSION

Approximately 5% of infants had hyperphosphatasemia at 12 months, but <1% at 24 months. ALP concentrations and hyperphosphatasemia were associated with sex, anthropometry, and bone mineralization. Infections did not contribute to hyperphosphatasemia.

Children with severe acute malnutrition have high rates of bone resorption: A cross-sectional comparative study

Malnutrition in under-5 children (i.e., children younger than age 5 years) remains a major public health problem. Because of the reductive adaptation in children with severe acute malnutrition (SAM), changes in bone health are often subtle. We hypothesized that children with SAM have higher rates of bone resorption than bone formation, which can be assessed using bone turnover markers. In this cross-sectional comparative study, we evaluated the status of bone turnover markers, serum osteocalcin and serum tartrate-resistant acid phosphatase-5b (TRAP-5b) in under-5 children with SAM. Thirty children (6-59 months) with SAM (defined as per World Health Organization criteria) were enrolled as cases and another 30 children (age and sex matched) with normal nutritional status (weight for height -1 standard deviation [SD] to +1 SD) were enrolled for comparison of bone turnover markers. Serum TRAP-5b concentrations were significantly higher in children with SAM compared with children with normal nutritional status (mean [SD] 22.6 [15.3] vs. 11.3 [9.6], P = .009), whereas serum osteocalcin concentrations were comparable between the 2 groups (mean [SD] 40.6 [17.9] vs. 36.0 [12.5], P = .344). Frequency of hypocalcemia and vitamin D deficiency were also significantly high in children with SAM (P < .05). An inverse correlation was found between serum calcium and serum osteocalcin (r = -0.383, P < .05). Our results indicate that children with SAM have a higher bone resorption rate than children with normal nutrition status indicating compromised bone health.

Evaluation of bone mineral density and bone turnover in children on anticoagulation

Background

Childhood and adolescence are critical periods of bone mineral acquisition. Children on anticoagulation (AC) might have an increased risk for reduced bone mineral density (BMD). Risk factors for impaired bone accumulation include chronic diseases, immobility, and medication. Vitamin K (VK) deficiency reflected by undercarboxylated osteocalcin levels (ucOC) has been identified as a predictor of osteoporosis and fractures. Data on bone health in children under AC are sparse.

Aims

To evaluate BMD in children on AC and characterize the risk factors of low BMD, including VK and Vitamin D (VD) status.

Methods

Single-center cross-sectional study of clinical, biochemical, and densitometric parameters. Assessment of VK surrogate parameters included ucOC and matrix gla protein (MGP).

Results

A total of 39 children (4-18 years; 12 females) receiving AC were included, 31 (79%) on VK antagonists and 8 (21%) on direct oral anticoagulants. Overall, BMD was decreased for both the lumbar spine (LS; -0.7SDS) and total body less head (TBLH; -1.32SDS) compared with pediatric reference data. Significant associations were found between early pubertal development and TBLH-BMD, and between BMI and LS-BMD. VK surrogate parameters were highly related to patients' age and pubertal development. Neither serum parameters nor AC-related factors predicted BMD. VD was detected in 10/39 patients with lower values during puberty.

Conclusion

Our data indicate BMD reduction in pediatric patients on AC. Although AC-related factors did not predict reduced BMD, low BMI and pubertal stages represented important risk factors. Awareness of risk factors for low BMD and high prevalence of VD deficiency during puberty could contribute to the improvement of bone health in this vulnerable patient group.

Pediatric reference values of alkaline phosphatase: Analysis from a German population-based cohort and influence of anthropometric and blood parameters

BACKGROUND

Due to different growth and metabolic processes, reference values of alkaline phosphatase (AP) for children aged 3 month to 18 years are dependent on age and sex. They are not constant and differ from those of adults due to the growth processes taking place. Accordingly, reference levels of AP continuous across these ages were generated for boys and girls based on of a large German health- and population-based study, LIFE Child. We considered AP at different growth and Tanner stages and additionally its association with other anthropometric parameters. The association between AP and BMI was of particulary great interest due to controversial literature on this topic. The role of AP in liver metabolism was investigated by examining ALAT, ASAT, and GGT.

METHODS

3976 healthy children (12,093 visits) were included from the LIFE Child study from 2011 to 2020. The subjects´ age ranged from 3 months to 18 years. Serum samples from 3704 subjects (10,272 cases, 1952 boys and 1753 girls) were analysed for AP after applying specific exclusion criteria. After calculating of reference percentiles, associations between AP and height-SDS, growth velocity, BMI-SDS, Tanner stage and the liver enzymes ALAT, ASAT and GGT were examined via linear regression models.

RESULTS

In the continuous reference levels, AP showed a first peak during the first year of life, followed by a plateau at a lower level until the start of puberty. In girls, AP increased beginning at the age 8, with a peak around 11 years, in boys beginning at the age 9, with a peak around age 13. Afterwards, AP values decreased continuously until age 18. In Tanner stages 1 and 2, AP levels did not differ between the two sexes. We found a strong positive association between AP-SDS and BMI-SDS. We also observed a significantly positive association between AP-SDS and height-SDS, which was stronger in boys than in girls. We found different intensities in the associations of AP with growth velocity depending on age group and sex. Furthermore, we found a significantly positive association between ALAT and AP in girls but not in boys, whereas ASAT-SDS and GGT-SDS were significantly positively associated with AP-SDS in both sexes.

CONCLUSION

Sex and age, but also BMI may act as confounding factors for AP reference ranges. Our data confirm the remarkable association between AP and growth velocity (or height-SDS, respectively) during infancy and puberty. In addition, we were able to specify the associations between AP and ALAT, ASAT, and GGT and their differences in both sexes. These relations should be considered when evaluating liver and bone metabolism markers, especially in infancy.

Bone Mineral Density and Serum Bone Turnover Markers among Post-Menarchal Girls from Rural South India

Background

The data on the bone mineral density (BMD) and bone turnover markers (BTMs) in Indian adolescents are limited.

Objectives

To assess BMD at lumbar spine (LS, L1-L4) and femoral neck (FN) in South Indian post-menarchal girls and correlate it with dietary calcium intake (mg/day), physical activity score and post-menarchal years. The study also assessed serum BTMs and their correlation with chronological age in the study population.

Methods

This cross-sectional study included apparently healthy post-menarchal adolescent girls aged 12-16 years randomly selected from the community. Participants with vitamin D deficiency were excluded. The data on calcium intake and physical activity were obtained using validated questionnaires. All participants were evaluated with serum calcium, 25-hydroxy vitamin D, parathyroid hormone, N-terminal propeptide of type 1 collagen (P1NP) and Beta-CrossLaps (CTx) and BMD at LS and FN using dual X-ray absorptiometry (DXA).

Statistical Analysis

EpiData version 3.1 was used for the data entry. The data analysis was done using Statistical Package for Social Sciences (SPSS) version 21. Continuous variables were expressed as mean ± SD. Pearson's correlation coefficient (r) was calculated, and two-tailed Kendall's tau-b test was used for assessing correlation of all nonparametric measures.

Results

A total of 103 participants were screened, and data from 77 were analysed. There was a significant positive correlation of BMD at LS with chronological age (r: +0.235, P = 0.036), but not at FN. Positive correlation of BMD with increase in post-menarchal years was also noted at LS (r: +0.276, P = 0.015). There was no significant association of BMD with calcium intake and physical activity scores at both sites. There was a significant negative correlation of serum BTMs with age CTx (r: -0.596, P = 0.0001) and P1NP (r: -0.505, P = 0.0001).

Conclusion

This study provides insight into the reference BMD range at LS spine and FN in South Indian rural post-menarchal adolescent girls. BMD positively correlated, whereas BTMs negatively correlated with age. The study also provides the first Indian reference range for serum BTMs in this age group.

Bone Turnover Marker for the Evaluation of Skeletal Remodelling in Autosomal Recessive Osteopetrosis after Haematopoietic Stem Cell Transplantation: A Case Report

Background: Autosomal recessive osteopetrosis (ARO) is a rare genetic disorder of bone metabolism, primarily affecting the remodelling function of osteoclasts. Haematopoietic stem cell transplantation (HSCT) is the first-line treatment for ARO. Traditional tools for the assessment of therapeutic response, such as measuring donor chimerism, do not provide information on bone remodelling. The use of bone turnover markers (BTMs) might be ideal. Here, we report a case of a paediatric ARO patient undergoing successful HSCT. Methods: For the evaluation of donor-derived osteoclast activity and skeletal remodelling throughout the transplantation, the bone resorption marker β-CTX (β-C-terminal telopeptide) was used. Results: The low baseline level of β-CTX markedly increased after transplantation and remained in the elevated range even after 3 months. Donor-derived osteoclast activity reached its new baseline level around the 50th percentile range after 5 months and proved to be stable during the 15-month follow-up time. The apparent increase of the baseline osteoclast activity after HSCT was in consonance with the radiographic improvement of the disease phenotype and the correction of bone metabolic parameters. Despite the successful donor-derived osteoclast recovery, craniosynostosis developed, and reconstructive surgery had to be performed. Conclusions: The use of β-CTX may be of aid in assessing osteoclast activity throughout the transplantation. Further studies could help to establish the extended BTM profile of ARO patients using the available osteoclast- and osteoblast-specific markers.

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.

Muscle and bone characteristics of a Chinese family with spinal muscular atrophy, lower extremity predominant 1 (SMALED1) caused by a novel missense DYNC1H1 mutation

BACKGROUND

Spinal muscular atrophy, lower extremity predominant (SMALED) is a type of non-5q spinal muscular atrophy characterised by weakness and atrophy of lower limb muscles without sensory abnormalities. SMALED1 can be caused by dynein cytoplasmic 1 heavy chain 1 (DYNC1H1) gene variants. However, the phenotype and genotype of SMALED1 may overlap with those of other neuromuscular diseases, making it difficult to diagnose clinically. Additionally, bone metabolism and bone mineral density (BMD) in patients with SMALED1 have never been reported.

METHODS

We investigated a Chinese family in which 5 individuals from 3 generations had lower limb muscle atrophy and foot deformities. Clinical manifestations and biochemical and radiographic indices were analysed, and mutational analysis was performed by whole-exome sequencing (WES) and Sanger sequencing.

RESULTS

A novel mutation in exon 4 of the DYNC1H1 gene (c.587T > C, p.Leu196Ser) was identified in the proband and his affected mother by WES. Sanger sequencing confirmed that the proband and 3 affected family members were carriers of this mutation. As leucine is a hydrophobic amino acid and serine is hydrophilic, the hydrophobic interaction resulting from mutation of amino acid residue 196 could influence the stability of the DYNC1H1 protein. Leg muscle magnetic resonance imaging of the proband revealed severe atrophy and fatty infiltration, and electromyographic recordings showed chronic neurogenic impairment of the lower extremities. Bone metabolism markers and BMD of the proband were all within normal ranges. None of the 4 patients had experienced fragility fractures.

CONCLUSION

This study identified a novel DYNC1H1 mutation and expands the spectrum of phenotypes and genotypes of DYNC1H1-related disorders. This is the first report of bone metabolism and BMD in patients with SMALED1.

Establishment of Reference Intervals for Bone Turnover Markers in Healthy Chinese Older Adults

BACKGROUND

Reference ranges for bone turnover markers (BTMs) are still lacking in the healthy Chinese population.

AIM

To establish reference intervals for BTMs and to investigate the correlations between BTMs and BMD in Chinese older adults.

SUBJECTS AND METHODS

A community-based cross-sectional study was conducted among 2,511 Chinese subjects aged over 50 yrs residing in Zhenjiang, Southeast China. Reference intervals for BTMs (i.e., procollagen type I N-terminal propeptide, P1NP; β cross-linked C-terminal telopeptide of type I collagen, β-CTX) were calculated as the central 95% range of all measurements in Chinese older adults.

RESULTS

The reference intervals of P1NP, β-CTX and P1NP/β-CTX were 15.8-119.9 ng/mL, 0.041-0.675 ng/mL and 49.9-1261.5 for females and 13.6-111.4 ng/mL, 0.038-0.627 ng/mL and 41.0-1269.1 for males, respectively. In the multiple linear regression analysis, only β-CTX was negatively associated with BMD after adjusting for age and body mass index (BMI) in both sex-stratified groups (all P < 0.05).

CONCLUSION

This study established age- and sex-specific reference intervals for BTMs in a large sample of healthy Chinese participants ≥ 50 and < 80 years of age and explored the correlations between BTMs and BMD, which provides an effective reference for the assessment of bone turnover in the clinical practice of osteoporosis.

Bone Turnover Markers and Osteokines in Adolescent Female Athletes of High- and Low-Impact Sports Compared With Nonathletic Controls

This study examined differences in resting concentrations of markers of bone formation and resorption, and osteokines between female adolescent (12-16 y) swimmers, soccer players, and nonathletic controls. Resting, morning blood samples were obtained after an overnight fast from 20 swimmers, 20 soccer players, and 20 nonathletic controls, matched for age. carboxyl-terminal cross-linking telopeptide of type I collagen (CTX), amino-terminal propeptide of type I collagen (P1NP), total osteocalcin (OC), sclerostin, osteoprotegerin (OPG), and receptor activator of nuclear factor kappa B ligand (RANKL) were analyzed in serum. After controlling for percent body fat, there were no significant differences between swimmers and nonathletic controls in any of the measured markers. In contrast, soccer players had significantly higher P1NP (89.5 [25.6] ng·mL-1), OC (57.6 [22.9] ng·mL-1), and OPG (1052.5 [612.6] pg·mL-1) compared with both swimmers (P1NP: 66.5 [20.9] ng·mL-1; OC: 24.9 [12.5] ng·mL-1; OPG: 275.2 [83.8] pg·mL-1) and controls (P1NP: 58.5 [16.2] ng·mL-1; OC: 23.2 [11.9] ng·mL-1; OPG: 265.4 [97.6] pg·mL-1), with no differences in CTX, sclerostin, and RANKL. These results suggest that bone formation is higher in adolescent females engaged in high-impact sports like soccer compared with swimmers and controls.

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.

Risk factors associated with prevalent vertebral fractures in Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy (DMD) have a high fracture burden due to progressive myopathy and steroid-induced osteoporosis. This study in males with DMD showed that markers of systemic glucocorticoid exposure including shorter stature, greater bone age delay, and lower lumbar spine bone mineral density were associated with spine fragility.

INTRODUCTION

Fragility  fractures are frequent in DMD. The purpose of this study was to identify clinical factors associated with prevalent vertebral fractures (VF) in boys, teens/young adults with Duchenne muscular dystrophy (DMD).

METHODS

This was a cross-sectional study of males aged 4-25 years with DMD. VF were evaluated using the modified Genant semi-quantitative method on T4-L4 lateral spine radiographs. Areal bone mineral density (aBMD) was measured at the lumbar spine (LS) and used to estimate volumetric BMD (vBMD). Clinical factors were analyzed for their association with the Spinal Deformity Index (SDI, the sum of the Genant grades).

RESULTS

Sixty participants were enrolled (mean age 11.5 years, range 5.4-19.5). Nineteen participants (32%) had a total of 67 VF; 23/67 VF (34%) were moderate or severe. Participants with VF were shorter (mean height Z-score ± standard deviation: - 3.1 ± 1.4 vs. - 1.8 ± 1.4, p = 0.001), had longer glucocorticoid exposure (mean duration 6.0 ± 3.3 vs. 3.9 ± 3.3 years, p = 0.027), greater bone age (BA) delay (mean BA to chronological age difference - 3.2 ± 3.4 vs. - 1.3 ± 1.2 years, p = 0.035), and lower LSaBMD Z-scores (mean - 3.0 ± 1.0 vs. - 2.2 ± 1.2, p = 0.023). There was no difference in LSvBMD Z-scores. Multivariable Poisson regression showed that every 0.1 mg/kg/day increment in average glucocorticoid daily dose was associated with a 1.4-fold SDI increase (95% confidence interval: 1.1-1.7, p = 0.013). Greater BA delay (p < 0.001), higher weight Z-score (p = 0.004), decreased height Z-score (p = 0.025), and lower LSvBMD Z-score (p = 0.025) were also associated with SDI increase.

CONCLUSION

Readily measurable clinical variables were associated with prevalent VF in males with glucocorticoid-treated DMD. These variables may be useful to identify candidates for primary osteoporosis prevention after glucocorticoid initiation.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

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.

Effect of emicizumab prophylaxis on bone and joint health markers in people with haemophilia A without factor VIII inhibitors in the HAVEN 3 study

INTRODUCTION

Emicizumab prophylaxis significantly reduces bleeding events; however, the associated impact on bone/joint health is unknown.

AIM

To explore the effect of emicizumab prophylaxis on bone/joint health in people with haemophilia A (PwHA) without FVIII inhibitors enrolled in HAVEN 3 (NCT02847637).

METHODS

Haemophilia joint health scores (HJHS; v2.1) were evaluated at baseline and Weeks 49 and 97 in PwHA receiving emicizumab (n = 134), and at baseline and Weeks 49, 73 and 97 in PwHA who switched to emicizumab after 24 weeks of no prophylaxis (n = 17). Bone and joint biomarkers were measured in 117 PwHA at baseline and at Weeks 13, 25, 49 and 73.

RESULTS

HJHS was lower for PwHA who were previously on FVIII prophylaxis, aged <40 years or had no target joints at baseline compared with PwHA who were receiving no prophylaxis, aged ≥40 years or with target joints. Clinically significant mean (95% confidence interval) improvements from baseline of -2.13 (-3.96, -.29) in HJHS joint-specific domains were observed at Week 49 in PwHA with at least one target joint at study entry (n = 71); these changes were maintained through Week 97. Improvements in HJHS from baseline were also observed for PwHA aged 12-39 years. Biomarkers of bone resorption/formation, cartilage degradation/synthesis, and inflammation did not change significantly during emicizumab prophylaxis.

CONCLUSIONS

Clinically relevant improvements in HJHS were observed in younger PwHA and those with target joints after 48 weeks of emicizumab in HAVEN 3. Biomarkers of bone/joint health did not show significant changes during 72 weeks of emicizumab prophylaxis.

Minimally invasive biomarkers in human and non-human primate evolutionary biology: Tools for understanding variation and adaptation

BACKGROUND

The use of minimally invasive biomarkers (MIBs - physiological biomarkers obtained from minimally invasive sample types) has expanded rapidly in science and medicine over the past several decades. The MIB approach is a methodological strength in the field of human and non-human primate evolutionary biology (HEB). Among humans and our closest relatives, MIBs provide unique opportunities to document phenotypic variation and to operationalize evolutionary hypotheses.

AIMS

This paper overviews the use of MIBs in HEB. Our objectives are to (1) highlight key research topics which successfully implement MIBs, (2) identify promising yet under-investigated areas of MIB application, and (3) discuss current challenges in MIB research, with suggestions for advancing the field.

DISCUSSION AND CONCLUSIONS

A range of MIBs are used to investigate focal topics in HEB, including energetics and life history variation/evolution, developmental plasticity, and social status and dominance relationships. Nonetheless, we identify gaps in existing MIB research on traits such as physical growth and gut function that are central to the field. Several challenges remain for HEB research using MIBs, including the need for additional biomarkers and methods of assessment, robust validations, and approaches that are standardized across labs and research groups. Importantly, researchers must provide better support for adaptation and fitness effects in hypothesis testing (e.g., by obtaining complementary measures of energy expenditure, demonstrating redundancy of function, and performing lifetime/longitudinal analyses). We point to continued progress in the use of MIBs in HEB to better understand the past, present, and future of humans and our closest primate relatives.

Associations between physical physique/fitness in children and bone development during puberty: a 4-year longitudinal study

Bone growth is most remarkable during puberty. This study aimed to clarify the effects of physique and physical strength on bone mineral density and bone metabolism markers during puberty to help improve bone growth during puberty and prevent future osteoporosis. There were 277 pubertal participants (125 boys and 152 girls) in this survey from 2009 to 2015, all aged 10/11 and 14/15 years. The measures included physical fitness/physique indices (such as muscle ratio etc.), grip strength, bone density (osteo sono-assessment index, OSI), and bone metabolism markers (bone-type alkaline phosphatase and type I collagen cross-linked N-telopeptide). At 10/11-years-old for girls, a positive correlation was found between body size/grip strength and OSI. At 14/15-year-old for boys, all body size factors/grip strength were positively correlated with OSI. The change in body muscle ratio was positively correlated with change in OSI for both sexes. The height, body muscle ratio and grip strength at 10/11-year-old were significantly associated with OSI (positively) and bone metabolism markers (negatively) at 14/15-year-old for both sexes. Adequate physique building after 10/11 years for boys and before 10/11 years for girls may be effective in increasing peak bone mass.

Filipino Children with High Usual Vitamin A Intakes and Exposure to Multiple Sources of Vitamin A Have Elevated Total Body Stores of Vitamin A But Do Not Show Clear Evidence of Vitamin A Toxicity

Background

Young children exposed to high-dose vitamin A supplements (VAS) and vitamin A (VA)-fortified foods may be at risk of high VA intake and high VA total body stores (TBS).

Objectives

TBS and estimated liver VA concentration were compared among children with adequate or high VA intake and different timing of exposure to VAS, and associations between estimated liver VA concentrations and biomarkers of VA toxicity were examined.

Methods

Children 12-18 mo of age (n = 123) were selected for 3 groups: 1) retinol intake >600 µg/d and VAS within the past mo, 2) retinol intake >600 µg/d and VAS in the past 3-6 mo, and 3) VA intake 200-500 µg retinol activity equivalents (RAE)/d and VAS in the past 3-6 mo. Dietary intake data were collected to measure VA intakes from complementary foods, breast milk, and low-dose, over-the-counter supplements. TBS were assessed by retinol isotope dilution, and VA toxicity biomarkers were measured. Main outcomes were compared by group.

Results

Mean (95% CI) VA intakes excluding VAS were 1184 (942, 1426), 980 (772, 1187), and 627 (530, 724) µg RAE/d, in groups 1-3, respectively; mean VA intake was higher in groups 1 and 2 compared with group 3 (P < 0.05). Geometric mean (GM) (95% CI) TBS were 589 (525, 661), 493 (435, 559), and 466 (411, 528) µmol, respectively. GM TBS and GM liver VA concentrations were higher in group 1 compared with group 3 (liver VA concentration: 1.62 vs. 1.33 µmol/g; P < 0.05). Plasma retinyl ester and 4-oxo-retinoic acid concentrations and serum markers of bone turnover and liver damage did not indicate VA toxicity.

Conclusions

In this sample, most children had retinol intakes above the Tolerable Upper Intake Level (UL) and liver VA concentrations above the proposed cutoff for "hypervitaminosis A" (>1 µmol/g liver). There was no evidence of chronic VA toxicity, suggesting that the liver VA cutoff value should be re-evaluated. This trial was registered at www.clinicaltrials.gov as NCT03030339.

An in vitro model for discovery of osteoclast specific biomarkers towards identification of racehorses at risk for catastrophic fractures

BACKGROUND

Focal bone microcracks with osteoclast recruitment and bone lysis, may reduce fracture resistance in racehorses. As current imaging does not detect all horses at risk for fracture, the discovery of novel serum biomarkers of bone resorption or osteoclast activity could potentially address this unmet clinical need. The biology of equine osteoclasts on their natural substrate, equine bone, has never been studied in vitro and may permit identification of specific biomarkers of their activity.

OBJECTIVES

1) Establish osteoclast cultures on equine bone, 2) Measure biomarkers (tartrate resistant acid phosphatase isoform 5b (TRACP-5b) and C-terminal telopeptide of type I collagen (CTX-I)) in vitro and 3) Study the effects of inflammation.

STUDY DESIGN

In vitro experiments.

METHODS

Haematopoietic stem cells, from 5 equine sternal bone marrow aspirates, were differentiated into osteoclasts and cultured either alone or on equine bone slices, with or without pro-inflammatory stimulus (IL-1β or LPS). CTX-I and TRACP-5b were immunoassayed in the media. Osteoclast numbers and bone resorption area were assessed.

RESULTS

TRACP-5b increased over time without bone (p < 0.0001) and correlated with osteoclast number (r = 0.63, p < 0.001). CTX-I and TRACP-5b increased with time for cultures with bone (p = 0.002; p = 0.02 respectively), correlated with each other (r = 0.64, p < 0.002) and correlated with bone resorption (r = 0.85, p < 0.001; r = 0.82, p < 0.001 respectively). Inflammation had no measurable effects.

MAIN LIMITATIONS

Specimen numbers limited.

CONCLUSIONS

Equine osteoclasts were successfully cultured on equine bone slices and their bone resorption quantified. TRACP-5b was shown to be a biomarker of equine osteoclast number and bone resorption for the first time; CTX-I was also confirmed to be a biomarker of equine bone resorption in vitro. This robust equine specific in vitro assay will help the study of osteoclast biology.

Osteoporosis and Bone Health in Transgender Individuals

This review discusses the changes in bone mass, structure, and metabolism that occur upon gender-affirming hormonal treatment (GAHT) in transgender adults and adolescents, as well as their clinical relevance. In general, available evidence shows that GAHT in transgender adults is not associated with major bone loss. In transgender adolescents, pubertal suppression with gonadotropin-releasing hormone agonist monotherapy impairs bone development, but at least partial recovery is observed after GAHT initiation. Nevertheless, a research gap remains concerning fracture risk and determinants of bone strength other than bone mineral density. Attention for bone health is warranted especially in adult as well as adolescent trans women, given the relatively high prevalence of low bone mass both before the start of treatment and after long-term GAHT in this population. Strategies to optimize bone health include monitoring of treatment compliance and ensuring adequate exposure to administered sex steroids, in addition to general bone health measures such as adequate physical activity, adequate vitamin D and calcium intake, and a healthy lifestyle. When risk factors for osteoporosis exist the threshold to perform DXA should be low, and treatment decisions should be based on the same guidelines as the general population.

The relationship between circulating hormone levels, bone turnover markers and skeletal development in healthy boys differs according to maturation stage

INTRODUCTION

This study investigates peri-pubertal changes in bone turnover markers, Wnt-signalling markers, insulin-like growth factor-1 (IGF-1) and sex steroid levels, and how they reflect skeletal development in peri-pubertal boys.

MATERIALS AND METHODS

Population-based study in 118 peri-pubertal boys from the NINIOS cohort (age range at baseline 5.1-17.3 years) with repeated measurements at baseline and after two years. Serum levels of the classical bone turnover markers (BTM) procollagen type 1 N-terminal propeptide and carboxy-terminal collagen crosslinks, as well as sex-hormone binding globulin, IGF-1, osteoprotegerin, sclerostin and dickkopf-1 were measured using immunoassays. Sex steroids (estradiol, testosterone, and androstenedione) were measured using mass spectrometry and free fractions calculated. Dual energy x-ray absorptiometry was used for bone measurements at the lumbar spine and whole body. Volumetric bone parameters and bone geometry at the proximal and distal radius were assessed by peripheral QCT. Pubertal development was categorized based on Tanner staging.

RESULTS

During puberty, sex steroid and IGF-1-levels along with most parameters of bone mass and bone size increased every next Tanner stage. In contrast, classical bone turnover markers and sclerostin peaked around mid-puberty, with subsequent declines towards adult values in late puberty. Especially classical BTM and sex steroid levels showed consistent associations with areal and volumetric bone parameters and bone geometry. However, observed associations differed markedly according to pubertal stage and skeletal site.

CONCLUSION

Serum levels of sex steroids, IGF-1 and bone metabolism markers reflect skeletal development in peri-pubertal boys. However, skeletal development during puberty is nonlinear, and the relations between skeletal indices and hormonal parameters are nonlinear as well, and dependent on the respective maturation stage and skeletal site.

Clinical, Biochemical, Radiological, Genetic and Therapeutic Analysis of Patients with COMP Gene Variants

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia type 1 (MED1) are two rare skeletal disorders caused by cartilage oligomeric matrix protein (COMP) variants. This study aims to analyze the genotype and phenotype of patients with COMP variants. Clinical information for 14 probands was collected; DNA was extracted from blood for COMP variant detection. Clinical manifestations and radiology scoring systems were established to evaluate the severity of each patient's condition. Serum COMP levels in PSACH patients and healthy subjects were measured. Thirty-nine patients were included, along with 12 PSACH probands and two MED1 probands. Disproportionate short stature, waddling gait, early-onset osteoarthritis and skeletal deformities were the most common features. The height Z-score of PSACH patients correlated negatively with age at evaluation (r =  - 0.603, p = 0.01) and the clinical manifestation score (r =  - 0.556, p = 0.039). Over 50% of the PSACH patients were overweight/obese. The median serum COMP level in PSACH patients was 16.75 ng/ml, which was significantly lower than that in healthy controls (98.53 ng/ml; p < 0.001). The condition of MED1 patients was better than that of PSACH patients. Four novel variants of COMP were detected: c.874T>C, c.1123_1134del, c.1531G>A, and c.1576G>T. Height Z-scores and serum COMP levels were significantly lower in patients carrying mutations located in calmodulin-like domains 6, 7, and 8. As the two phenotypes overlap to different degrees, PSACH and MED1 are suggested to combine to produce "spondyloepiphyseal dysplasia, COMP type". Clinical manifestations and radiology scoring systems, serum COMP levels and genotype are important for evaluating patient condition severity.

Reference Standards for Newborn Screening of Metabolic Disorders by Tandem Mass Spectrometry: A Nationwide Study on Millions of Chinese Neonatal Populations

Introduction: The major clinical problem presently confronting the Chinese newborn screening (NBS) programs by tandem mass spectrometry (MS/MS) is the lack of comprehensive reference intervals (RIs) for disease biomarkers. To close this gap, the Chinese National Center for Clinical Laboratories (NCCL) launched a nationwide study to investigate the dynamic pattern of 35 MS/MS NBS biomarkers and establish accurate and robust RIs.

Methods: Blood spot samples from 4,714,089 Chinese neonates were tested in participating centers/laboratories and used for study analysis. MS/MS NBS biomarker trends were visually assessed by their concentrations over age. Specific partitions were determined arbitrarily by each day and sex or by the statistical method of Harris and Boyd. RIs, corresponding to the 2.5th and 97.5th percentiles, as well as the 1th, 25th, 75th and 99th percentiles were calculated for each reference partition using a non-parametric rank approach.

Results: Most MS/MS NBS biomarkers fluctuated during the first week of life, followed by a relatively stable concentration. Age and sex-specific RIs were established and presented an improved specificity over the RIs used in participating centers/laboratories. Females demonstrated higher 2.5th and 97.5th percentiles in all amino acids except arginine and ornithine than males, whereas males showed higher 2.5th and 97.5th percentiles in most acylcarnitines.

Conclusion: The present study determined the dynamic trends of 35 MS/MS biomarkers and established age and sex-specific RIs, valuably contributing to the current literature and timely evaluation of neonatal health and disease.

Bone Phenotyping Approaches in Human, Mice and Zebrafish - Expert Overview of the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal traits TranslatiOnal NEtwork")

A synoptic overview of scientific methods applied in bone and associated research fields across species has yet to be published. Experts from the EU Cost Action GEMSTONE ("GEnomics of MusculoSkeletal Traits translational Network") Working Group 2 present an overview of the routine techniques as well as clinical and research approaches employed to characterize bone phenotypes in humans and selected animal models (mice and zebrafish) of health and disease. The goal is consolidation of knowledge and a map for future research. This expert paper provides a comprehensive overview of state-of-the-art technologies to investigate bone properties in humans and animals - including their strengths and weaknesses. New research methodologies are outlined and future strategies are discussed to combine phenotypic with rapidly developing -omics data in order to advance musculoskeletal research and move towards "personalised medicine".

Height adjustment reduces occurrence of low bone mineral density in children and adolescents with HIV

OBJECTIVE

The aim of this study was to quantify the reduction of bone mineral density with and without height adjustment.

METHODS

A cross-sectional study was performed with 69 Brazilian children and adolescents vertically infected by HIV. Bone mineral density was measured by dual-energy absorptiometry in the lumbar spine. Anthropometric, demographic, and clinical variables were analyzed. A specific calculator was used for height adjustment.

RESULTS

The majority of participants (52.2%) were adolescents and did not present with immunological alterations (61%). Reduced bone mineral density (Z-score <-1) was present in 23.2% and low bone mass (Z-score <-2) in 5.8%. After height adjustment, these occurrences decreased to 11.6% and 0%, respectively. Patients with reduced bone mineral density had a higher mean age and lower body mass index than patients with normal bone mineral density.

CONCLUSION

The occurrence of reduced bone mineral density decreased after adjustment for height.

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.

Clinical Phenotype and Bone Biopsy Characteristics in a Child with Proteus Syndrome

Proteus syndrome is a rare genetic disorder, which is characterized by progressive, segmental, or patchy overgrowth of diverse tissues of all germ layers, including the skeleton. Here, we present a 9-year-old girl with a somatic-activating mutation (c.49G > A; p.Glu17Lys) in AKT1 gene in a mosaic status typical for Proteus syndrome. She presented with hemihypertrophy of the right lower limb and a "moccasin" lesion among others. A transiliac bone biopsy was analyzed for bone histology/histomorphometry as well as bone mineralization density distribution (BMDD) and osteocyte lacunae sections (OLS) characteristics based on quantitative backscattered electron imaging. Bone histomorphometry revealed highly increased mineralizing surface (Z-score + 2.3) and mineral apposition rate (Z-score + 19.3), no osteoclasts (Z-score - 2.1), and an increased amount of primary bone in the external cortex. BMDD abnormalities included a decreased mode calcium concentration in cancellous bone (Z-score - 1.7) and an increased percentage of highly mineralized cortical bone area (Z-score + 2.4) compared to reference. OLS characteristics showed several differences compared to reference data; among them, there were the highly increased OLS-porosity, OLS-area, and OLS-perimeter on the external cortex (Z-scores + 6.8, + 4.4 and 5.4, respectively). Our findings suggest that increased bone formation reduced matrix mineralization in cancellous bone while the enhanced amount of primary bone in the external cortex increased the portion of highly mineralized cortical bone and caused OLS-characteristics abnormalities. Our results indicate further that remodeling of primary bone might be disturbed or delayed in agreement with the decreased number of osteoclasts observed in this child with Proteus syndrome.

A Three-Year Longitudinal Study Comparing Bone Mass, Density, and Geometry Measured by DXA, pQCT, and Bone Turnover Markers in Children with PKU Taking L-Amino Acid or Glycomacropeptide Protein Substitutes

In patients with phenylketonuria (PKU), treated by diet therapy only, evidence suggests that areal bone mineral density (BMDa) is within the normal clinical reference range but is below the population norm. Aims: To study longitudinal bone density, mass, and geometry over 36 months in children with PKU taking either amino acid (L-AA) or casein glycomacropeptide substitutes (CGMP-AA) as their main protein source. Methodology: A total of 48 subjects completed the study, 19 subjects in the L-AA group (median age 11.1, range 5–16 years) and 29 subjects in the CGMP-AA group (median age 8.3, range 5–16 years). The CGMP-AA was further divided into two groups, CGMP100 (median age 9.2, range 5–16 years) (n = 13), children taking CGMP-AA only and CGMP50 (median age 7.3, range 5–15 years) (n = 16), children taking a combination of CGMP-AA and L-AA. Dual X-ray absorptiometry (DXA) was measured at enrolment and 36 months, peripheral quantitative computer tomography (pQCT) at 36 months only, and serum blood and urine bone turnover markers (BTM) and blood bone biochemistry at enrolment, 6, 12, and 36 months. Results: No statistically significant differences were found between the three groups for DXA outcome parameters, i.e., BMDa (L2–L4 BMDa g/cm²), bone mineral apparent density (L2–L4 BMAD g/cm³) and total body less head BMDa (TBLH g/cm²). All blood biochemistry markers were within the reference ranges, and BTM showed active bone turnover with a trend for BTM to decrease with increasing age. Conclusions: Bone density was clinically normal, although the median z scores were below the population mean. BTM showed active bone turnover and blood biochemistry was within the reference ranges. There appeared to be no advantage to bone density, mass, or geometry from taking a macropeptide-based protein substitute as compared with L-AAs.

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.

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.

Monthly intravenous alendronate treatment can maintain bone strength in osteogenesis imperfecta patients following cyclical pamidronate treatment

Objectives Osteogenesis imperfecta (OI) is a skeletal dysplasia characterized by recurrent fractures due to congenital bone fragility. The only bisphosphonate approved for OI in Japan is pamidronate (PAM). To investigate whether monthly intravenous alendronate (ALN) infusions can maintain bone strength in OI children following cyclical PAM treatment. Methods A prospective and non-inferiority study was conducted. Eight school-age OI patients aged 8.5±2.0 years who were treated with cyclical PAM for 6.0±2.3 years were enrolled and switched to monthly intravenous ALN (0.030 mg/kg/month). Changes in L1-4 bone mineral density (BMD) Z-scores, fracture rates, and bone turnover markers for 12 months were analyzed. Results Average BMD Z-scores were -3.0±1.9, -2.9±2.0, and -2.2±2.0 in 12 months before enrollment, at enrollment, and after 12 months of ALN treatment, respectively. BMD Z-scores increased significantly during treatment with both PAM and ALN (p=0.012), and the effect of ALN was not inferior to that of PAM (p=0.67). There was no change in fracture rates (p=0.86) and bone turnover markers during the 12 months before and after enrollment. Additionally, ALN showed no remarkable side effects. Conclusions Our results suggest that monthly intravenous ALN can maintain bone strength after primary usage of cyclical PAM. We concluded that monthly intravenous ALN as a maintenance treatment following cyclical PAM administration can be an option for OI children.

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.

Glucocorticoid effects on bone strength in children with renal diseases

AIM

Glucocorticoids (GC) are essential medicines for idiopathic steroid-sensitive nephrotic syndrome (ISSNS) and IgA nephropathy (IgAN), with good clinical results. However, they cause bone fragility. The aim of this study was to elucidate GC effects on bone strength assessed as bone mineral density (BMD) and bone quality, using bone turnover markers (BTM), in children with ISSNS or IgAN.

METHODS

Eleven children with ISSNS and 13 with IgAN were included. All the patients received GC treatment according to each protocol. The BMD and BTM-serum alkaline phosphatase (S-ALP), tartrate-resistant acid phosphatase 5b (S-TRACP-5b), and undercarboxylated osteocalcin (S-ucOC)-were measured from the initiation of steroid treatment (STx) to the end of STx in both groups.

RESULTS

In ISSNS, S-ALP and S-ucOC levels were decreased significantly at 1 month. BMD and S-TRACP-5b levels showed no significant change through this observation period. In IgAN, BMD and S-ALP levels were decreased significantly at 1 and 3 months, respectively, and recovered to baseline at 10 months after the initiation of GC dosage reduction. S-TRACP-5b levels were decreased significantly at 3 months and remained lower than at baseline through the observation period. In both groups, S-ucOC levels did not directly reflect bone strength.

CONCLUSION

This study clarified the following three points regarding GC effects on bone strength in children with ISSNS or IgAN: first, S-ALP is a more sensitive bone quality marker than S-TRACP-5b; second, BMD loss was observed only when both S-ALP and S-TRACP-5b levels decreased, and third, S-ucOC levels do not directly reflect bone strength.

Bone turnover markers in children living with HIV remaining on ritonavir-boosted lopinavir or switching to efavirenz

INTRODUCTION

We previously found lower bone mass but similar bone turnover in pre-pubertal children living with HIV (CLWH) on a ritonavir-boosted lopinavir (LPV/r)-based vs. efavirenz-based antiretroviral therapy regimen 2 years after switch. Here, we evaluate if bone turnover differed between the groups close to the time of switch.

METHODS

Samples from 108 children remaining on LPV/r and 104 children switched to efavirenz were available for analysis 8 weeks post-randomization. Bone turnover markers, including C-telopeptide of type 1 collagen (CTx), procollagen type-I N-terminal propeptide (P1NP), and osteocalcin were measured. Markers of immune activation were also measured, including IL-6, TNF-alpha, soluble CD14 and high-sensitivity C-reactive protein (CRP).

RESULTS

Eight weeks post-randomization, we did not detect differences in CTx (1.42 vs. 1.44 ng/mL, p = 0.85) or P1NP concentrations (622 vs. 513 ng/mL, p = 0.68) between treatment groups. At 8 weeks, the treatment groups also had similar levels of IL-6, TNF-alpha, soluble CD14 and high-sensitivity CRP. Osteocalcin (ng/mL) was higher in the LPV/r than efavirenz group both at 8 weeks (88.6 vs. 67.3, p = 0.001) and 2 years (67.6 vs. 49.8, p = 0.001).

CONCLUSIONS

Overall, we failed to detect difference in bone turnover by P1NP and CTx in virologically-suppressed CLWH on different regimens at a time point close to the switch. We did observe higher levels of total osteocalcin in children remaining on LPV/r compared to children switched to efavirenz. Future studies should focus on uncovering the mechanism and determining whether perturbation in undercarboxylated osteocalcin could explain some of the bone side effects noted with protease inhibitors.