Biochemical markers of bone turnover in girls during puberty

Circadian Regulation of Bone Remodeling

Adult bones are continuously remodeled by the balance between bone resorption by osteoclasts and subsequent bone formation by osteoblasts. Many studies have provided molecular evidence that bone remodeling is under the control of circadian rhythms. Circadian fluctuations have been reported in the serum and urine levels of bone turnover markers, such as digested collagen fragments and bone alkaline phosphatase. Additionally, the expressions of over a quarter of all transcripts in bones show circadian rhythmicity, including the genes encoding master transcription factors for osteoblastogenesis and osteoclastogenesis, osteogenic cytokines, and signaling pathway proteins. Serum levels of calcium, phosphate, parathyroid hormone, and calcitonin also display circadian rhythmicity. Finally, osteoblast- and osteoclast-specific knockout mice targeting the core circadian regulator gene Bmal1 show disrupted bone remodeling, although the results have not always been consistent. Despite these studies, however, establishing a direct link between circadian rhythms and bone remodeling in vivo remains a major challenge. It is nearly impossible to repeatedly collect bone materials from human subjects while following circadian changes. In addition, the differences in circadian gene regulation between diurnal humans and nocturnal mice, the main model organism, remain unclear. Filling the knowledge gap in the circadian regulation of bone remodeling could reveal novel regulatory mechanisms underlying many bone disorders including osteoporosis, genetic diseases, and fracture healing. This is also an important question for the basic understanding of how cell differentiation progresses under the influence of cyclically fluctuating environments.

Should we consider the sex when estimating bone age from hand bone biometrics?

BACKGROUND

Recently, it was proposed to estimate age from the biometric information of hand bones. We observed that these estimations became less precise as children get older, especially from the age of 13-15 years.

OBJECTIVE

This study aimed to evaluate the influence of considering sex for age estimation based on hand bones biometrics.

MATERIALS AND METHODS

The study sample consisted of metacarpals and proximal phalanges measurements collected on 1003 medical images performed at Nancy and Marseille Hospitals of individuals aged under 21 years. This sample was divided into two subgroups delineated by the age of 13, as it is a relevant legal threshold for most European countries. First, the influence of sex on the hand bones biometrics and on the estimated age was evaluated. Then, based on these results, new sex-specific age estimation formulas were constructed from linear models and their precision was assessed using residual analysis, in comparison with previous global formulas.

RESULTS

An influence of sex was only highlighted from the age of 13 and for the total study sample. Thus, new sex-specific age estimation formulas were built for the [1-21] global sample and the [13-21] subsample. Even though the differences with the previous formulas were minor, age was more accurately estimated when sex was considered.

CONCLUSION

Considering sex in age estimation is relevant when relying on hand bone biometrics. A new tool was proposed to select the most appropriate age estimation formula, based on the discriminant analysis result and the a priori knowledge of the sex.

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.

Earlier appearance of Risser sign on ultrasound versus radiograph in adolescent idiopathic scoliosis

Objective

The usefulness of ultrasound in the detailed assessment of the Risser sign is still unclear. The purpose of this study was to analyze the usefulness of ultrasound for determining the Risser sign compared with that determined by conventional radiography by each Risser grade.

Materials and Methods

Eighty-eight iliac crests from 44 adolescent patients who visited the scoliosis clinic with Risser grades 0-4 were evaluated. The ultrasound probe was placed vertically on the iliac crest and the point where iliac apophysis ossification ended was marked. The length of ossification relative to the length of the iliac crest was calculated.

Results

Agreement between radiographic and ultrasound images were found in 58/86 iliac crests (67%). Kappa value was 0.565. Agreement between the two methods with regard to Risser grade was 53% for grade 0, 43% for grade 1, 47% for grade 2, 88% for grade 3, and 90% for grade 4. With additional analysis by integrating grades into two groups, the agreement rate was 47.7% and the Kappa value was 0.288 in the grade 0-2 group, and 88% and 0.703 in grades 3-4 group, respectively. In cases of disagreements, 93% of the iliac crests were judged as having higher Risser grades by ultrasound than by radiograph.

Conclusion

Risser sign evaluation by ultrasound demonstrated a higher agreement rate in grades 3 and 4, whereas less agreement was found in grades 0-2. In the majority of cases with disagreement, ultrasound showed a higher grade than radiography, suggesting that ossification can be detected earlier with ultrasound than with radiography.

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.

Gender-Affirming Hormone Treatment Decreases Bone Turnover in Transwomen and Older Transmen

Sex steroids play a key role in bone turnover and preserving BMD; hence, gender-affirming hormone treatment (HT) in transgender people affects bone metabolism. Most studies have looked into the effect of HT on changes in BMD; however, they do not provide insights into changes in bone metabolism caused by HT. This study investigated changes in bone turnover markers (BTMs) and sclerostin, as well as their correlations with change in BMD in transwomen and transmen during the first year of HT. Transwomen received estradiol and antiandrogens; transmen received testosterone. Sclerostin; P1NP; alkaline phosphatase (ALP); CTx; and BMD of the total hip, the femoral neck, and the lumbar spine were evaluated at baseline and after 1 year of HT. There were 121 transwomen (median age 30 years, interquartile range [IQR] 24 to 41 years) and 132 transmen (median age 24 years, IQR 21 to 33 years) included in the study. In transwomen, ALP decreased in 19% (95% CI, -21 to-16), CTx in 11% (95% CI, -18 to-4), and sclerostin in 8% (95%CI, -13 to-4) of study participants after 1 year of HT. In contrast, in transmen P1NP, ALP, and sclerostin increased in 33% (95% CI, 24 to 42), 16% (95% CI, 12 to 20), and 15% (95% CI, 10 to 20) of study participants, respectively, after 1 year of HT. No age differences were seen in transwomen, whereas in transmen aged ≥50 years a decrease in all BTMs was found in contrast with the other age groups. These transmen had low estrogen concentration at the start of HT based on their postmenopausal state before the start of HT; their estradiol concentrations increased during testosterone treatment. Changes in BTMs and BMD were weakly correlated (correlation coefficient all <0.30). To conclude, 1 year of HT resulted in decreased bone turnover in transwomen and older transmen, whereas it increased in younger transmen. The decrease in bone resorption in older transmen shows the importance of estrogen as a key regulator of bone turnover. © 2019 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc.

The Effect of Clothing on Vitamin D Status, Bone Turnover Markers, and Bone Mineral Density in Young Kuwaiti Females

Many Arab women in the Gulf region cover their bodies for cultural and religious reasons, limiting the skin's exposure to sunlight and therefore its ability to synthesize vitamin D. The aim of this study is to determine whether the clothing style of Kuwaiti premenopausal women affects their vitamin D status, bone marker expression, and bone density. Three groups of healthy unmarried single Kuwaiti females (20-35 years old; n=30 per group) were recruited randomly from the general community: a control group who wear Western-style clothing (unveiled group), a group who wear a hejab that covers the whole body except for the face and hands (hejab group), and a group who wear a black veil with the entire body covered (veiled group). Bone mineral density (BMD), bone markers (procollagen type 1 N-terminal propeptide [P1NP], osteocalcin, and β-CrossLaps), 25-hydroxy vitamin D, intact parathyroid hormone [iPTH], and calcitonin were measured. The bone marker osteocalcin was significantly higher in the hejab group compared to the control group, whereas P1NP and β-CrossLaps were significantly higher in the veiled group compared to the control group. 25-hydroxy vitamin D, iPTH, calcitonin, and BMD were not significantly different across the three groups despite the observed elevation in bone turnover markers. The majority of participants in all three groups exhibited vitamin D deficiency; however, the lowest vitamin D levels were observed among the hejab and veiled participants. These findings suggest that clothing style may contribute to vitamin D deficiency in young Kuwaiti women.

Comparison of two bone markers with growth evolution in 74 girls with central precocious puberty

Background

The bone markers bone alkaline phosphatase (BAP) and C-terminal telopeptide of type I collagen crosslinks (CTX) are correlated with growth rate during normal puberty. The objective of this study was to evaluate the relationship between the serum concentrations of BAP and CTX and growth evolution in girls with idiopathic central precocious puberty (CPP) to help predict adult height.

Methods

A retrospective single-center study was conducted in 74 girls with CPP for whom a serum sample at initial evaluation was available to retrospectively measure BAP and CTX concentrations; 66.2% of them were untreated.

Results

The serum BAP concentrations showed significant positive correlations with height in standard deviations (SDS) at the initial evaluation (n = 62; r = 0.31; p = 0.015) and with the difference between bone and chronological ages (n = 61; r = 0.39; p = 0.002). BAP was also positively correlated with adult height as measured in both cm and SDS in untreated patients (n = 19; r = 0.58; p = 0.009).

The serum CTX concentrations showed significant positive correlations with growth rate the year before the initial evaluation as measured in both cm and SDS (n = 65; r = 0.34; p = 0.006).

Conclusions

This study revealed significant correlations of serum BAP and CTX concentrations with growth evolution in girls with CPP. The high positive correlation between serum BAP and adult height in untreated girls suggests that BAP can possibly be used to optimize models of adult height prediction in girls with CPP.

Urinary levels of pyridinoline and deoxypyridinoline and bone mineral density in children with type 1 diabetes mellitus

OBJECTIVE

There is still controversy over the impact of diabetes mellitus (DM) on bone mass in children. Pyridinoline (Pyr) and deoxypyridinoline (DPyr), which stabilize the collagen chains within the extracellular matrix, are known as specific bone turnover markers. The aim of this study was to investigate the relationship between urinary Pyr and DPyr excretions and bone mineral density (BMD) in children with type 1 DM.

METHODS

Serum levels of Ca, phosphorus (P), magnesium (Mg), and parathormone (PTH), alkaline phosphatase (ALP) activity, and urinary excretions of Pyr and DPyr were evaluated in 50 diabetic and 130 healthy control subjects aged between 7 and 15 years. The BMD was measured using DEXA at the lumbar vertebrae 2-4.

RESULTS

Serum levels of Ca, P and PTH, and BMD were similar between the two groups (p > 0.05). The serum ALP activity was significantly higher in diabetics than in healthy subjects (257.7 ± 86.5 vs. 188.2 ± 61.8, p < 0.05, respectively). Both urinary Pyr and DPyr excretions were significantly higher in diabetic subjects compared to control subjects (127.4 ± 95.5 vs. 88.7 ± 63.7, p < 0.05, respectively, and 23.6 ± 12.7 vs. 17.2 ± 9.6, p < 0.05, respectively). The urinary excretions of Pyr and DPyr were similar in male and female subjects within both groups.

CONCLUSION

The urinary excretions of Pyr and DPyr are higher in diabetic subjects than in healthy controls, suggesting the presence of increased bone turnover in diabetic patients, but we could not observe any negative effect of childhood diabetes on BMD. These results may suggest that diabetic patients are at risk for a decreased peak bone mass.

Osteocalcin and serum insulin-like growth factor-1 as biochemical skeletal maturity indicators

Background

With change in concepts of growth determination methods, there is a surge in the measurement of biomarkers for appraisal of growth status. Osteocalcin is a bone-specific protein and was observed to parallel the normal growth curve. Hence, the present study was intended to assess the levels of serum osteocalcin and serum insulin-like growth factor-1 (IGF-1) and compare them with cervical vertebral maturation index (CVMI) stages.

Methods

The cross-sectional study was performed on 150 subjects (75 males and 75 females) in the age group of 8–20 years and segregated into six CVMI stages. Serum osteocalcin and IGF-1 were estimated by ELISA. Mann-Whitney U test was used to compare the mean ranks of serum osteocalcin and serum IGF-1 with different CVMI stages. Spearman correlation was performed to find association between serum osteocalcin and serum IGF-1 across six CVMI stages.

Results

Peak serum IGF-1 levels were obtained at CVMI stages 4 and 3 for males and females, respectively, with insignificant difference between stages 3 and 4 in females. Peak serum osteocalcin levels were found at stage 5 and 3 for males and females with insignificant difference from other stages except stages 5 and 6 in males. A statistically significant correlation was seen between serum IGF-1 and serum osteocalcin across six CVMI stages (P < 0.01).

Conclusions

Osteocalcin followed IGF-1 across all CVMI stages but showed insignificant interstage differences.

Effect of pubertal suppression and cross-sex hormone therapy on bone turnover markers and bone mineral apparent density (BMAD) in transgender adolescents

Puberty is highly important for the accumulation of bone mass. Bone turnover and bone mineral density (BMD) can be affected in transgender adolescents when puberty is suppressed by gonadotropin-releasing hormone analogues (GnRHa), followed by treatment with cross-sex hormone therapy (CSHT). We aimed to investigate the effect of GnRHa and CSHT on bone turnover markers (BTMs) and bone mineral apparent density (BMAD) in transgender adolescents. Gender dysphoria was diagnosed based on diagnostic criteria according to the DSM-IV (TR). Thirty four female-to-male persons (transmen) and 22 male-to-female persons (transwomen)were included. Patients were allocated to a young (bone age of <15years in transwomen or <14 in transmen) or old group (bone age of ≥15years in transwomen or ≥14years in transmen). All were treated with GnRHa triptorelin and CSHT was added in incremental doses from the age of 16years. Transmen received testosterone esters (Sustanon, MSD) and transwomen received 17-β estradiol. P1NP, osteocalcin, ICTP and BMD of lumbar spine (LS) and femoral neck (FN) were measured at three time points. In addition, BMAD and Z-scores were calculated. We found a decrease of P1NP and 1CTP during GnRHa treatment, indicating decreased bone turnover (young transmen 95% CI -74 to -50%, p=0.02, young transwomen 95% CI -73 to -43, p=0.008). The decrease in bone turnover upon GnRHa treatment was accompanied by an unchanged BMAD of FN and LS, whereas BMAD Z-scores of predominantly the LS decreased especially in the young transwomen. Twenty-four months after CSHT the BTMs P1NP and ICTP were even more decreased in all groups except for the old transmen. During CSHT BMAD increased and Z-scores returned towards normal, especially of the LS (young transwomen CI 95% 0.1 to 0.6, p=0.01, old transwomen 95% CI 0.3 to 0.8, p=0.04). To conclude, suppressing puberty by GnRHa leads to a decrease of BTMs in both transwomen and transmen transgender adolescents. The increase of BMAD and BMAD Z-scores predominantly in the LS as a result of treatment with CSHT is accompanied by decreasing BTM concentrations after 24months of CSHT. Therefore, the added value of evaluating BTMs seems to be limited and DXA-scans remain important in follow-up of bone health of transgender adolescents.

The Gingival Crevicular Fluid as a Source of Biomarkers to Enhance Efficiency of Orthodontic and Functional Treatment of Growing Patients

Gingival crevicular fluid (GCF) is a biological exudate and quantification of its constituents is a current method to identify specific biomarkers with reasonable sensitivity for several biological events. Studies are being performed to evaluate whether the GCF biomarkers in growing subjects reflect both the stages of individual skeletal maturation and the local tissue remodeling triggered by orthodontic force. Present evidence is still little regarding whether and which GCF biomarkers are correlated with the growth phase (mainly pubertal growth spurt), while huge investigations have been reported on several GCF biomarkers (for inflammation, tissue damage, bone deposition and resorption, and other biological processes) in relation to the orthodontic tooth movement. In spite of these investigations, the clinical applicability of the method is still limited with further data needed to reach a full diagnostic utility of specific GCF biomarkers in orthodontics. Future studies are warranted to elucidate the role of main GCF biomarkers and how they can be used to enhance functional treatment, optimize orthodontic force intensity, or prevent major tissue damage consequent to orthodontic treatment.

Participation of sex hormones in multifactorial pathogenesis of adolescent idiopathic scoliosis

PURPOSE

In order to verify the potential association between the aetiopathogenesis of adolescent idiopathic scoliosis (AIS) and the process of sexual maturation, we determined the concentrations of oestrogens in pre- and postmenarcheal girls affected by this condition. AIS, occurring mostly in pubescent girls, is one of the most frequent forms of faulty posture. Therefore, it was assumed that the multifactorial pathomechanism of AIS involves significant deficiency of oestrogens.

METHODS

The diagnosis of AIS was established on the basis of physical examination and analyses of radiograms. Concentrations of FSH, LH, oestrogens, progesterone, osteocalcin and RANKL were determined by ELISA. The activity of alkaline phosphatase (AP) was measured by kinetic method. The study included pre- and postmenarcheal girls with AIS and corresponding groups of scoliosis-free controls.

RESULTS

In premenarcheal scoliotic girls, the levels of FSH, LH and oestradiol were lower; the levels of progesterone, oestrone and oestriol were higher; and the concentrations of oestrone and oestriol were similar compared to premenarcheal controls. Higher levels of RANKL, osteocalcin and AP were observed in premenarcheal adolescents with AIS compared to controls. The concentrations of FSH, LH, oestradiol, and progesterone in postmenarcheal girls with scoliosis were lower, oestrone were slightly lower and oestriol did not differ compared with the control group. Significantly higher levels of RANKL, osteocalcin and AP were observed in postmenarcheal scoliotic adolescents compared with controls.

CONCLUSIONS

There is an interdependence between the concentration of oestradiol and development of scoliosis. Determination of estradiol may have diagnostic value in the screening of spinal pathologies associated with AIS.

Age and gender specific biokinetic model for strontium in humans

A biokinetic model for strontium in humans is necessary for quantification of internal doses due to strontium radioisotopes. The ICRP-recommended biokinetic model for strontium has limitations for use in a population study, because it is not gender specific and does not cover all age ranges. The extensive Techa River data set on (90)Sr in humans (tens of thousands of measurements) is a unique source of data on long-term strontium retention for men and women of all ages at intake. These, as well as published data, were used for evaluation of age- and gender-specific parameters for a new compartment biokinetic model for strontium (Sr-AGe model). The Sr-AGe model has a similar structure to the ICRP model for the alkaline earth elements. The following parameters were mainly re-evaluated: gastrointestinal absorption and parameters related to the processes of bone formation and resorption defining calcium and strontium transfers in skeletal compartments. The Sr-AGe model satisfactorily describes available data sets on strontium retention for different kinds of intake (dietary and intravenous) at different ages (0-80 years old) and demonstrates good agreement with data sets for different ethnic groups. The Sr-AGe model can be used for dose assessment in epidemiological studies of general populations exposed to ingested strontium radioisotopes.

Measurement of urinary N-telopeptides and serum C-telopeptides from type I collagen using a lateral flow-based immunoassay

Measuring bone turnover markers could detect early stages of osteoporosis and early responses to anti-osteoporotic treatments. Currently, commonly used bone turnover markers, N-telopeptides (NTx) and C-telopeptides (CTx), are measured using ELISA tests, which demands time and increases cost. Bone turnover markers need to be measured more easily for general use. Lateral flow-based immunoassay would be an appropriate method for this context. This study was performed to investigate the precision of a newly developed lateral flow-based immunoassay for measuring the urinary NTx and serum CTx, and their correlations with ELISA measurements. Urine NTx and serum CTx concentrations were determined by photoscan of newly developed strips, using a lateral flow-based immunoassay for 36 subjects (mean age 66.2 years, SD 7.5 years; four males and 32 females). Repeated measurement of urinary NTx and serum CTx were performed three times, using this technology for a precision test. The correlation of the lateral flow-based immunoassay with the ELISA measurements was analyzed. Precision of the newly developed lateral flow based immunoassay was 0.974 (ICC, 95% confidence interval, 0.955 to 0.986) and 0.995 (ICC, 95% confidence interval, 0.991 to 0.997) for urinary NTx and serum CTx, respectively. The correlation of lateral flow based immunoassay with ELISA was 0.913 for urinary NTx and 0.872 for serum CTx. These results suggest that measuring the urinary NTx and serum CTx, using a lateral flow-based immunoassay, is a relevant method for point-of-care testing and screening of bone resorption markers.

Growth hormone is positively associated with surrogate markers of bone turnover during puberty

BACKGROUND

Puberty is characterized by increases in growth hormone (GH) and insulin-like growth factor-1 (IGF-1) and the pubertal growth spurt. Bone formation and resorption also increase, consistent with increased bone metabolism.

OBJECTIVE

To determine the relationship between pubertal bone metabolism, GH and IGF-1. We hypothesized that bone turnover peaks at the time of greatest pubertal GH secretion.

DESIGN AND SUBJECTS

Subjects included 86 girls and boys, 9-17 years-old (BMI 10th-90th percentiles). Because higher endogenous GH secretion is associated with a higher nadir following oral glucose, we used the GH nadir following a 2-h OGTT as indicative of GH status. Fasting serum IGF-1, aminoterminal propeptide of type 1 procollagen (P1NP) and carboxy-terminal collagen crosslinks (CTX) were obtained. Subjects were grouped per expected timing of peak growth. Group 1: Tanner 1 girls and Tanner 1-2 boys (period preceding peak growth), Group 2: Tanner 2-3 girls and Tanner 3-4 boys (period of peak growth) and Group 3: Tanner 4-5 girls and Tanner 5 boys (period following peak growth).

RESULTS

GH peaked at mid-puberty (Group 2) and IGF-1 in late puberty (Group 3). P1NP and CTX were highest in mid-puberty compared with early and late puberty (P = 0·0009 and 0·006 in girls and P = 0·005 and 0·04 in boys). GH, but not IGF-1, correlated with P1NP (r = 0·46 in both genders, P ≤ 0·008) and CTX (r = 0·37 and 0·38, P = 0·04 and 0·02 in girls and boys, respectively). Similarly, on regression modelling, GH (but not IGF-1) predicted both bone turnover markers in both genders.

CONCLUSION

GH is strongly associated with pubertal bone metabolism, independent of systemic IGF-1 in girls and boys.

Concerted actions of insulin-like growth factor 1, testosterone, and estradiol on peripubertal bone growth: a 7-year longitudinal study

A better understanding of how bone growth is regulated during peripuberty is important for optimizing the attainment of peak bone mass and for the prevention of osteoporosis in later life. In this report we used hierarchical models to evaluate the associations of insulin-like growth factor 1 (IGF-1), estradiol (E(2) ), and testosterone (T) with peripubertal bone growth in a 7-year longitudinal study. Two-hundred and fifty-eight healthy girls were assessed at baseline (mean age 11.2 years) and at 1, 2, 3.5, and 7 years. Serum concentrations of IGF-1, E(2) , and T were determined. Musculoskeletal properties in the left lower leg were measured using peripheral quantitative computed tomography (pQCT). Serum levels of IGF-1, E(2) , and T increased dramatically before menarche, whereas they decreased, plateaued, or increased at a lower rate, respectively, after menarche. IGF-1 level was positively associated with periosteal circumference (PC) and total bone mineral content (tBMC) throughout peripuberty but not after adjustment for muscle cross-sectional area (mCSA). On the other hand, IGF-1 was associated with tibial length (TL) independently of mCSA before menarche. T was positively associated with TL, PC, tBMC, and cortical volumetric bone mineral density, independent of mCSA, before menarche but not after. E(2) was associated with TL positively before menarche but negatively after menarche. These findings suggest that during puberty, circulating IGF-1 promotes bone periosteal apposition and mass accrual indirectly, probably through stimulating muscle growth, whereas the effects of sex steroids on bone growth differ before and after menarche, presenting a biphasic pattern. Hence the concerted actions of these hormones are essential for optimal bone development in peripuberty.

The impact of inflammation on bone mass in children

Bone is a dynamic tissue. Skeletal bone integrity is maintained through bone modeling and remodeling. The mechanisms underlying this bone mass regulation are complex and interrelated. An imbalance in the regulation of bone remodeling through bone resorption and bone formation results in bone loss. Chronic inflammation influences bone mass regulation. Inflammation-related bone disorders share many common mechanisms of bone loss. These mechanisms are ultimately mediated through the uncoupling of bone remodeling. Cachexia, physical inactivity, pro-inflammatory cytokines, as well as iatrogenic factors related to effects of immunosuppression are some of the common mechanisms. Recently, cytokine signaling through the central nervous system has been investigated for its potential role in bone mass dysregulation in inflammatory conditions. Growing research on the molecular mechanisms involved in inflammation-induced bone loss may lead to more selective therapeutic targeting of these pathological signaling pathways.

Interpretation and application of bone turnover markers in children and adolescents

PURPOSE OF REVIEW

To assess recent research findings on various biochemical bone turnover markers and to assess their use in monitoring bone growth in children and adolescents.

RECENT FINDINGS

There are very few recent studies that investigate various serum and urine analytes that reflect bone formation and resorption to monitor bone health during longitudinal growth. In infants and young children, the measurement of bone markers in serum is suggested because of the practical difficulties associated with urine collection and by the circadian and intraindividual variation in urinary markers. During the prepubertal growth, bone turnover values are similar in age-matched boys and girls. The increase in different bone turnover markers coincides with the pubertal growth spurt. This starts later in boys and the increase in bone turnover markers also occurs later, is greater and lasts longer when compared with girls. Recent studies demonstrated that bone size increases and bone turnover decreases until mid-twenties.

SUMMARY

More than one bone formation and resorption marker should be measured to monitor longitudinal growth and bone mineral accrual, because sensitivities and predictive values of single markers are still poor. It is important to find new and more sensitive markers that could better characterize linear growth.

Bone mineral density acquisition in peripubertal female rhythmic gymnasts is directly associated with plasma IGF1/IGF-binding protein 3 ratio

OBJECTIVES

Intense physical activity in peripubertal girls may delay menarche and cause menstrual disorders and estrogen deficiency, particularly in sport disciplines that require strict weight control. It may also have a deleterious effect on bone mass acquisition. The aim of this study was to determine the time-course of bone mass accretion in peripubertal elite female rhythmic gymnasts (FRGs) over a 1-year period, as well as the anthropometric and hormone parameters that could be helpful for predicting bone mineral density (BMD) gain.

METHODS AND DESIGN

We conducted a 1-year follow-up study in 29 FRGs (10.7-16.1 years old). Whole body composition and BMD of the whole body, proximal femur, lumbar spine, mid-radius, and skull were measured by dual energy X-ray absorptiometry (DXA). Moreover, baseline growth- and bone metabolism-related hormones such as IGF1, IGF-binding protein 3 (IGFBP3), leptin, and bone markers were measured.

RESULTS

BMD increased significantly at all bone sites throughout puberty, particularly between Tanner stages II and IV-V (P=0.025 to P<0.001). The IGF1 level, IGF1/IGFBP3 ratio, and leptin level were higher in late pubertal stages (i.e. IV-V) compared with early stage (i.e. I). In simple and multivariate analyses, only the IGF1/IGFBP3 ratio was strongly correlated with the BMD change at all bone sites (r=0.49, P=0.02 to r=0.77, P<0.0001).

CONCLUSION

This 1-year follow-up study of peripubertal FRGs showed that BMD gain was maximal around Tanner stage III. The plasma IGF1/IGFBP3 ratio was associated with bone mass acquisition in this period, and it may thus serve as a surrogate marker of bone mass gain in this population.

Hormonal determinants of bone turnover before and after attainment of peak bone mass

INTRODUCTION

Bone turnover decreases from adolescence into adulthood, but does not reach a nadir until the fourth decade. Biochemical markers of bone turnover reflect different processes before and after peak bone mass, so hormonal influences on bone turnover may differ before and after peak bone mass.

OBJECTIVES

To describe the changes in bone turnover and hormones relevant to bone metabolism from adolescence into adulthood, and to identify which hormones correlate with bone turnover before and after peak bone mass.

DESIGN/PARTICIPANTS

Two measurements of bone turnover markers and hormones were obtained 5-9 years apart in 116 healthy males and females recruited from secondary schools and general practices. Correlations were examined cross-sectionally and longitudinally.

RESULTS

Dehydroepiandrosterone sulphate (DHEAS) correlated negatively with bone turnover cross-sectionally and longitudinally (r-0.59 to -0.69) in males and females under the age of 25 years. IGF-1 correlated positively with aminoterminal propeptide of type I procollagen (PINP) cross-sectionally and longitudinally (r 0.35) in women over the age of 25 years. After correction for change in BMI, there were significant longitudinal correlations between DHEAS and bone turnover in women under 25 years (r-0.62, -0.66) and IGF-1 and PINP in women over 25 years (r 0.56).

CONCLUSIONS

We have described changes in bone turnover and hormones from adolescence into adulthood. Dehydroepiandrosterone sulphate correlates with bone turnover before peak bone mass which may represent a direct effect on bone metabolism or the role of dehydroepiandrosterone sulphate as a substrate for conversion to other sex steroids. IGF-1 is correlated with aminoterminal propeptide of type I procollagen in women after peak bone mass, which may reflect an influence on cortical modelling.

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Isotopic and dental evidence for infant and young child feeding practices in an imperial Roman skeletal sample

This study integrates isotopic, palaeopathological, and historical evidence to investigate infant and young child feeding practices in a Roman period (1st to 3rd centuries AD) skeletal sample from the Isola Sacra necropolis (Rome, Italy). Stable isotope analysis of bone collagen from 37 rib samples indicates that transitional feeding began by the end of the first year and weaning occurred by 2-2.5 years of age. Both delta(15)N and delta(13)C data clearly show the trophic level effect associated with breastfeeding. Childhood diet is investigated using dental pathology data in the deciduous dentitions of 78 individuals aged between 1 and 12 years. The presence of calculus, caries, and tooth wear in young children suggests that individuals were provided complementary foods and other items that impacted their dental health at an early age. The isotopic and dental data are generally consistent with the historical evidence from the Roman period with respect to the general timetable of weaning and the character of complementary foods. This is the first study to integrate isotopic and deciduous dental pathology data to explore infant and young child feeding practices in the Roman world.

Analysis of biochemical markers of bone metabolism in Asian elephants (Elephas maximus)

Two human enzyme immunoassays (EIA) and one radioimmunoassay (RIA) were validated and used to measure osteocalcin (OC), bone alkaline phosphatase (BAP), and the cross-linked telopeptide domain of type I collagen (ICTP), in serum from Asian elephants (Elephas maximus). Sera from four adult females sampled on 7 consecutive days were also analyzed to assess the existence and magnitude of intraindividual day-to-day variability of the serum concentration of these markers. Sample dilution curves were parallel with assay standard curves, which demonstrated that excellent cross reactivity existed between assay antibodies and elephants marker antigens. Statistically significant inverse correlations were found between age and concentrations of all three markers: BAP, r = -0.862 (P < 0.01); OC, r = -0.788 (P < 0.002); and ICTP, r = -0.848 (P < 0.01). Strong positive correlations were found between BAP and OC (r = 0.797, P < 0.01), OC and ICTP (r = 0.860, P < 0.01), and between BAP and ICTP (r = 0.958, P < 0.01). No statistically significant intraindividual variability was found over 7 days in the four adult females for any of the markers assessed (OC: P = 0.089; ICTP: P = 0.642; BAP: P = 0.146; n=4 in each case). The overall coefficient of variability observed in this group of animals was 10.3%, 7.4%, and 5.5% for OC, BAP, and ICTP, respectively. These results suggest a potential role for biochemical markers of bone turnover in monitoring skeletal health and bone disease in Asian elephants.

Improvement in biomarkers of bone formation during infliximab therapy in pediatric Crohn's disease: results of the REACH study

BACKGROUND & AIMS

Crohn's disease (CD) is associated with altered bone metabolism. This study examined changes in bone formation and resorption after infliximab induction and associations between bone biomarkers, linear growth, and disease activity (Pediatric Crohn's Disease Activity Index [PCDAI]) after 54 weeks of infliximab therapy.

METHODS

One hundred twelve subjects ages 6-17 years with moderate to severe CD received infliximab induction (5 mg/kg/dose) at weeks 0, 2, and 6; week-10 responders were randomized to infliximab every 8 or every 12 weeks maintenance therapy. Serum bone-specific alkaline phosphatase (BSAP), N-terminal propeptide of type 1 collagen (P1NP), urine C-telopeptide of collagen cross-links (CTX-1), and deoxypyrodinoline (DPD) were collected at baseline and 10 weeks. PCDAI and height z-scores were assessed at baseline and at 10 and 54 weeks.

RESULTS

Models were adjusted for bone age, gender, height, and steroid use. Baseline BSAP and P1NP levels were negatively associated with PCDAI (both P = .01). BSAP and P1NP increased during induction (both P < .001) and were associated with 54-week increases in height z-score (P < .05 and P < .001, respectively). Improvements in P1NP were associated with 54-week decreases in PCDAI (P = .01). CTX-1 and DPD also increased during induction (P < .001 and P = .01, respectively) but were not associated with changes in PCDAI. Changes in CTX-1 were associated with improvements in height z-score (P < .002).

CONCLUSIONS

Infliximab therapy is associated with dramatic increases in BSAP and P1NP, consistent with inhibition of tumor necrosis factor-alpha effects on osteoblasts. The increases in CTX-1 and DPD likely reflect coupling of bone formation and resorption and increases in linear growth.

Interpretation of biomarkers of bone metabolism in children: impact of growth velocity and body size in healthy children and chronic disease

OBJECTIVES

To determine the effects of growth, maturation, and whole body bone mineral content (WB-BMC) accrual on biomarkers of bone formation (bone-specific alkaline phosphatase [BSAP]) and resorption (urine deoxypyridinoline/creatinine [DPD]) in healthy children and children with Crohn's disease.

STUDY DESIGN

BSAP and DPD were measured at baseline, with growth and dual energy x-ray absorptiometry (DXA) WB-BMC measured at baseline and 6 months in 202 control subjects and 110 subjects with Crohn's disease, ages 5 to 21 years. Multivariable linear regression identified determinants of biomarkers in control subjects and subjects with Crohn's disease.

RESULTS

In control subjects, BSAP and DPD were significantly and independently associated with sex, Tanner stage, WB-BMC, height velocity, and WB-BMC accrual rates; these covariates explained 77% to 80% of the variability in the bone biomarkers, respectively. Subjects with Crohn's disease had lower height-for-age (P < .001) and WB-BMC-for-height (P <.05) than control subjects. Crohn's disease was associated with lower BSAP (P < .001) and greater DPD (P < .001), independent of growth, maturation, baseline WB-BMC, and WB-BMC accrual, compared with control subjects.

CONCLUSIONS

These data illustrate the potential confounding effects of growth and WB-BMC on bone metabolism biomarkers in children. After adjustment for these effects, Crohn's disease was associated with lower biomarkers of bone formation and greater bone resorption.

Bone turnover marker profile in relation to the menstrual cycle of premenopausal healthy women

OBJECTIVE

To explore the bone turnover marker profile during the menstrual cycle of premenopausal women.

DESIGN

This was a noninterventional study. Levels of bone turnover markers, including serum C-terminal telopeptide of type I collagen (sCTX), bone-specific alkaline phosphatase, osteocalcin, procollagen type 1 N propeptide, and urinary N-terminal telopeptide of type I collagen, were measured in blood and urine samples during one menstrual cycle. Levels were expressed as raw test results and percent change from serum luteinizing hormone peak. Differences in mean levels of bone turnover markers between menstrual phases and subphases were examined.

RESULTS

Fifty-five women comprised the per-protocol population. Mean sCTX values were 0.48 ng/mL during the follicular phase (FP), 0.47 ng/mL at serum luteinizing hormone peak, and 0.43 ng/mL during the luteal phase (LP). Additionally, the mean percent change from luteinizing hormone peak varied from +4.35% during the FP to -5.11% during the LP (P = 0.0014). Mean sCTX levels during the early and through mid FP were significantly higher than levels during the mid and late LP. The pattern for urinary N-terminal telopeptide of type I collagen was similar to that of sCTX but not statistically significant. There was a statistically significant tendency for procollagen type I N propeptide levels to be lower during the FP relative to the LP. Levels of osteocalcin and bone-specific alkaline phosphatase did not vary significantly during the menstrual cycle.

CONCLUSIONS

Levels of some bone turnover markers varied during the menstrual cycle. A statistically significant change in sCTX (9.46%) occurred between the FP and LP of the menstrual cycle.

Vitamin D: a growing perspective

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

Chromosomal regions 22q13 and 3p25 may harbor quantitative trait loci influencing both age at menarche and bone mineral density

Late age at menarche (AAM), an important type of endocrinopathy in females, is associated with lower bone mineral density (BMD), a major risk factor for osteoporosis. The correlation is mainly mediated through common genetic factors, which are largely unknown. A bivariate genome-wide linkage scan was conducted on 2,522 females from 414 Caucasian pedigrees to identify quantitative trait loci influencing both AAM and BMD. The strongest linkage signal was detected on chromosome 22q13. Other regions such as the 3q13, 3p25, 7p15, and 15q13 were also suggested. The inferred promising candidate genes in the linkage regions may contribute to our understanding of pathogenesis of endocrinopathy and osteoporosis in females.

Serum calcium and phosphorus concentration and alkaline phosphatase activity in healthy children during growth and development

Introduction. Many changes happen during growth and development in an organism as a result of important hormone changes, especially biohumoral ones. These changes make a problem when interpreting biochemical results in pediatric population. The most important changes are intensive calcium and phosphorus metabolic turnover in bone tissue with changes in alkaline phosphatase activity as a result of osteoblast activity. The aim of this study was to follow the serum calcium and phosphorus concentration and alkaline phosphatase activity in children 1-15 years old in different growth and development period and of different sexes and to fortify the influence of growth and development dynamics on biohumoral status in healthy male and female children. Material and methods. We evaluated 117 healthy children of both sexes from 1-15 years of age and divided them into three age groups: 1-5, 6-10 and 11-15 years. We followed the serum calcium and phosphorus concentration and alkaline phosphatase activity in different groups and in different sexes. Results and conclusion. Our investigation found significantly higher values of serum calcium in boys than in girls with no important changes between the age groups and significantly higher values of serum phosphorus in the youngest age group in all children and in different sexes with no important sex differences. Alkaline phosphatase activity followed the growth spurt and was the biggest in 6-10 years group in girls and in 11-15 years group in boys.

The relationship between the GH/IGF-I axis and serum markers of bone turnover metabolism in healthy children

CONTEXT

There is evidence to suggest that IGF-I plays a role in regulating bone turnover.

OBJECTIVE

To evaluate the relationships between serum concentrations of IGF-I and IGF-binding protein-3 (IGFBP-3), and bone metabolism markers in healthy children.

DESIGN AND SETTING

Prospective cross-sectional study.

SUBJECTS AND METHODS

A cohort of 579 boys and 540 girls, all healthy Caucasian, were included in this study. Serum IGF-I and IGFBP-3 concentrations, bone alkaline phosphatase (BAP) and CrossLaps (markers of bone formation and bone resorption respectively) levels were evaluated as a function of age, gender, pubertal stage and body mass index.

RESULTS

Serum IGF-I SDS levels were positively correlated with BAP and CrossLaps SDS levels before and after puberty, and also with CrossLaps during puberty (weak correlation). Serum IGFBP-3 SDS levels were positively correlated with BAP and CrossLaps levels before, during (weak correlation) and after puberty (for BAP levels only).

CONCLUSIONS

This study demonstrated the independent association between serum IGF-I and IGFBP-3 concentrations with both serum bone formation and resorption markers in healthy children. Physiological differences before, during and after puberty in the association of serum IGF-I and IGFBP-3 levels with the serum bone metabolism markers were found. These differences may be related to differences in interactions between sex steroid hormones and the GH/IGF-I system, bone metabolism and growth during the pubertal transition. Improvements in our understanding of life course determinants of the IGF-I system and bone metabolism are required to shed further light on the role of the GH/IGF-I axis in bone remodelling.

Letrozole treatment of precocious puberty in girls with the McCune-Albright syndrome: a pilot study

CONTEXT

Girls with McCune-Albright syndrome (MAS) and related disorders have gonadotropin-independent precocious puberty due to estrogen secretion from ovarian cysts. Their puberty does not respond to GnRH agonist therapy, and short-acting aromatase inhibitors have had limited effectiveness.

OBJECTIVE

Our objective was to assess the effectiveness of the potent, third-generation aromatase inhibitor letrozole in decreasing pubertal progression in girls with MAS and to assess the response of indices of bone turnover associated with the patients' polyostotic fibrous dysplasia.

DESIGN

Subjects were evaluated at baseline and every 6 months for 12-36 months while on treatment with letrozole 1.5-2.0 mg/m(2).d.

SETTING

This was an open-label therapeutic trial at a single clinical center.

PATIENTS

Patients included nine girls aged 3-8 yr with MAS and/or gonadotropin-independent puberty.

MAIN OUTCOME MEASURES

Measures included rates of linear growth, bone age advance, mean ovarian volume, estradiol, episodes of vaginal bleeding, and levels of the indices of bone metabolism: serum osteocalcin, alkaline phosphatase, urinary hydroxyproline, pyridinoline, deoxypyridinoline, and N-telopeptides.

RESULTS

Girls had decreased rates of growth (P < or = 0.01) and bone age advance (P < or = 0.004) and cessation or slowing in their rates of bleeding over 12-36 months of therapy. Mean ovarian volume, estradiol, and indices of bone metabolism fell after 6 months (P < or = 0.05) but tended to rise by 24-36 months. Uterine volumes did not change. One girl had a ruptured ovarian cyst after 2 yr of treatment.

CONCLUSIONS

This preliminary study suggests that letrozole may be effective therapy in some girls with MAS and/or gonadotropin-independent precocious puberty. Possible adverse effects include ovarian enlargement and cyst formation.

Parathyroid hormone is elevated but bone markers and density are normal in young female subjects who consume inadequate dietary calcium

Dietary Ca and osteocalcin (OC), parathyroid hormone (PTH), 25-hydroxyvitamin D (25-OH-D), insulin-like growth factor (IGF)-I and sex hormone binding globulin (SHBG) were assessed simultaneously to bone mineral density (BMD) in 200 adolescent girls (aged 11–15 years) and 100 young women (aged 20–23 years), selected from the lowest and highest end of the Ca intake distribution of a larger population sample. Ca intake was evaluated by food frequency questionnaires, BMD was measured by dual energy x-ray absorptiometry at ultradistal and proximal radius of non-dominant arm, bone age was estimated from x-rays of left hand and wrist according to. Surprisingly, mean Ca intakes were below the dietary reference intakes in the subgroups of girls and women with the highest measured Ca consumption. Postmenarcheal, but not premenarcheal girls showed radial densities as high as the women and in no group was BMD associated with Ca intake. In all adolescents serum PTH was negatively related to dietary Ca. In girls before menarche IGF-I was positively associated with bone age, while in the same subjects the negative relationship between SHBG and BMD pointed to the crucial role of bioavailable sex steroids on bone mass apposition in early puberty. OC levels decreased progressively with age, while serum 25-OH-D significantly increased after menarche. In conclusion, although in adolescents low Ca intake has not been shown to induce any immediate deleterious effect on radial density, the compensatory hypersecretion of PTH supports the need for an adequate Ca intake to achieve peak bone mass.

Bone mineral density in postmenarchal adolescent girls in the United States: associated biopsychosocial variables and bone turnover markers

PURPOSE

During adolescence, bone formation prevails over resorption, resulting in accumulation of 40% of peak bone mass throughout this time period. Although multiple studies have explored bone mass accrual during the early stages of puberty, less is known about factors that may influence bone accrual during later years of adolescence. In the present cross-sectional study we examined relationships among bone mineral density (BMD) and demographic factors, behavioral variables, and bone metabolism markers in postmenarchal adolescent girls.

METHODS

The population was comprised of 389 healthy postmenarchal adolescent girls aged 11-18 years, who were recruited into a prospective study of the effect of depot medroxyprogesterone acetate (DMPA) on bone health in adolescents. At the baseline visit, investigators collected demographic, reproductive health, and lifestyle data, and performed a complete physical examination. Body mass index (BMI) was calculated. Before study initiation, BMD at the lumbar spine, total hip, and femoral neck was measured by dual-energy X-ray absorptiometry (DXA), and markers of bone metabolism (serum bone-specific alkaline phosphatase [BAP], serum osteocalcin, and urinary N-telopeptide [uNTX]) were measured. The baseline data from this study were analyzed to evaluate possible correlates of BMD in postmenarchal adolescent girls. Potential associations between BMD values and other parameters were assessed by analysis of variance and Pearson's correlation coefficient.

RESULTS

Participants enrolled in the study had a mean (+/- SD) chronological age of 14.9 +/-1.7 years (range 11-18), mean gynecologic age of 39.9 +/-23.0 months (range 1-120) postmenarche, and mean BMI of 23.5 +/-4.6 kg/m(2) (range 16.0-42.2). Racial/ethnic distribution was 46% African American, 35% Caucasian, and 19% other races; 9% had previously been pregnant. Positive correlations were observed between lumbar spine BMD and chronological age (r = .301, p < .0001), gynecologic age (r = .349, p < .0001), and BMI (r = .371, p < .0001). Total hip and femoral neck BMD values were significantly higher (p < .05 and p < .05, respectively) in African American participants compared with non-African American participants. Previous history of pregnancy was significantly associated with a lower BMD at the lumbar spine (p < .0001) and the total hip (p < .01) when compared with the BMD of adolescents who had never been pregnant. Cigarette smoking and alcohol use were not associated with significant differences in BMD. Negative correlations were observed between gynecologic age and the levels of BAP (r = -.564, p < .0001), osteocalcin (r = -.349, p < .0001), and uNTX (r = -.281, p < .0001), and between lumbar spine BMD and BAP (r = -.363, p < .0001), osteocalcin (r = -.129, p < .05), and uNTX (r = -.202, p < .001) levels.

CONCLUSIONS

Our data demonstrate that chronological age, gynecologic age, race/ethnicity, BMI, and previous history of pregnancy are markedly associated with BMD in postmenarchal adolescent girls. Bone accretion in the postmenarchal years continues in the face of a slowdown in bone turnover during this time period.

Correlates of the peak height velocity in girls with idiopathic scoliosis

STUDY DESIGN

Prospective longitudinal.

OBJECTIVE

Determine correlates of the peak height velocity (PHV) in girls with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Only identifiable retrospectively, the PHV is the most useful known maturity marker in idiopathic scoliosis. Clinically useful correlates are needed to make PHV timing helpful.

METHODS

A total of 24 immature girls with idiopathic scoliosis were followed with serial heights, sexual staging, skeletal ages, spinal radiographs, insulin-like growth factor (IGF)-1, IGF binding protein-3, dehydroepiandrosterone sulfate, estradiol, bone-specific alkaline phosphatase, and osteocalcin levels. These markers were correlated to PHV timing.

RESULTS

There were 14 girls who had identifiable growth peaks that averaged 10.5 +/- 1.8 cm/y at age 11.7 +/- 1 years. At the PHV, all girls were Risser 0 with open triradiate cartilages. On a skeletal age radiograph, digital uncapped phalangeal epiphyses were indicative of pre-PHV and fused epiphyses of post-PHV. Capped but unfused epiphyses were indeterminate. Tanner stage 1 for breast strongly indicates pre-PHV. Stage 3 for breast and pubic hair occurred at or after the PHV, and stage 4 always occurred after PHV. Higher IGF-1 and estradiol levels after PHV are potentially discriminatory.

CONCLUSIONS

The PHV occurs during Risser 0 with open triradiate cartilages. If triradiate cartilages are open, then Tanner stages, IGF-1, estradiol levels, and the appearance of the epiphyses on a skeletal age radiograph are useful in determining status before or after PHV.

COL1A1 Sp1 polymorphism associates with bone density in early puberty

Optimal acquisition of bone mass in puberty is a key determinant of the lifetime risk of osteoporosis and has a strong genetic basis. We investigated the relationship between the COL1A1 Sp1 polymorphism and BMD in early puberty, and how the genotypes relate to bone size and geometry as well as bone turnover and material properties in 247 10- to 13-year-old girls. Bone properties were measured using DXA, pQCT, and ultrasound. Also, serum P1NP, OC, B-ALP, and TRACP 5b were assessed. Our results showed that girls with the TT genotype had significantly lower BMC and BMD of the total body, lumbar spine, and proximal femur, as well as BUA at the calcaneus, than those with the GT and GG genotype. They also had significantly lower B-ALP, as well as P1NP/TRACP 5b and (OC + B-ALP)/TRACP 5b, compared to the others. These findings indicate that the COL1A1 polymorphism is associated with low bone properties in early puberty and suggest a possible physiological effect on collagen metabolism and bone turnover. This information may contribute to the identification of children at risk for suboptimal acquisition of peak bone mass and may ultimately be of value in the planning of early preventive strategies for osteoporosis.

Generalized osteopenia in adolescent idiopathic scoliosis--association with abnormal pubertal growth, bone turnover, and calcium intake?

STUDY DESIGN

A cross-sectional study in girls with adolescent idiopathic scoliosis (AIS) and healthy counterparts of similar age.

OBJECTIVES

To study the association of bone mass with anthropometric parameters, bone turnover, and calcium intake in 621 girls with AIS, aged 11-6-years, and compare the results with 300 healthy girls of similar age.

SUMMARY OF BACKGROUND DATA

Generalized low bone mass has been documented in AIS, yet the cause of low bone mineral density in AIS is unknown.

METHODS

Corrected height and arm span, bone mineral density and bone mineral content of proximal femur, lumbar spine, and distal tibia, and bone turnover markers (bone alkaline phosphatase [bALP] and deoxypyridinoline) were evaluated.

RESULTS

From age 13 years and older, the AIS group had longer anthropometric parameters (P < 0.05), generalized lower bone mass (P < 0.035), and 38.6% higher in bALP (P < 0.004) when compared with controls. A stronger inverse correlation between bALP and bone mass was noted in the AIS group. The bALP was positively correlated with bone area of tibia (P = 0.013) in the AIS group only. Deoxypyridonine of the AIS group was not different from the controls until age 15 years. The mean calcium intake of the AIS group was very low (only 361 mg/day), and calcium intake was significantly associated with bone mass in the AIS group. Low bone mass in AIS could be explained by faster anthropometric bone growth, higher bone turnover, and lower calcium intake in multiple regression analysis.

CONCLUSIONS

Results from the current study showed that an abnormally faster growth rate and higher bone turnover in the patient with AIS might lead to increased bone dimensions. Calcium intake in patients with AIS was very low and likely to be insufficient for normal bone mineralization. Therefore, low bone mass in AIS may result from abnormal bone mineralization qualitatively and quantitatively and, thus, fails to catch up with increased bone growth during the peripubertal period.

Pediatric reference intervals for bone markers

Bone markers are specific bone-derived molecules that reflect bone remodeling activity and can be classified into two categories: bone formation and bone resorption markers. Children have significantly elevated bone marker levels due to high skeletal growth velocity and rapid bone turnover during childhood growth. Many physiological and pathological processes may influence bone metabolism and bone marker concentrations during childhood growth. Measurements of bone markers may be useful in investigating skeletal diseases in children and monitoring the response to treatment. This review documents recent advances in analytical methods, preanalytical considerations related to each marker and particularly highlights the most valuable bone formation markers, bone alkaline phosphatase and osteocalcin, and bone resorption markers, pyridinium cross-links and cross-linked telopeptides. Age- and sex-specific pediatric reference intervals and their limitations in clinical application are also discussed.

Differential effects of sex hormones on peri- and endocortical bone surfaces in pubertal girls

CONTEXT

The role of sex steroids in bone growth in pubertal girls is not yet clear. Bone biomarkers are indicators of bone metabolic activity, but their value in predicting bone quality has not been studied in growing girls.

OBJECTIVE

This study examines the association of sex hormones and bone markers with bone geometry and density in pubertal girls.

DESIGN

The study was designed as a 2-yr longitudinal study in pubertal girls. Measurements were performed at baseline and at 1- and 2-yr follow-ups.

SETTING

The study was conducted in a university laboratory.

PARTICIPANTS

A total of 258 10- to 13-yr-old healthy girls at the baseline participated.

METHODS

Peripheral quantitative computed tomography was used to scan the left tibial shaft. Serum 17beta-estradiol (E2), testosterone (T), SHBG, osteocalcin (OC), bone-specific alkaline phosphatase, and tartrate-resistant acid phosphatase isoform 5b were assessed. Data were analyzed using hierarchical linear models with random effect.

RESULTS

E2 was a positive predictor for total bone mineral density (BMD), cortical thickness, and a negative predictor for endocortical circumference but had no predictive value for total bone cross-sectional area or periosteal circumference. T was a positive predictor for total cross-sectional area and periosteal circumference as well as endocortical circumference, and a negative predictor for total BMD. OC was negatively correlated with cortical BMD (R2 = 0.325; P < 0.001).

CONCLUSIONS

In pubertal girls, E2 and T have different influences on bone properties at the long bone shaft. The results suggest that, at the endocortical surface, E2 inhibits bone resorption during rapid growth, and later, after menarche, acts at higher concentrations to promote bone formation. At the periosteal surface, T promotes bone formation, whereas E2 does not affect it. In addition, OC might be used as a predictor of cortical BMD.

Changes in bone mineral density, body composition and biochemical markers of bone turnover during weight gain in adolescents with severe anorexia nervosa: a 1-year prospective study

Osteoporosis is a serious complication of anorexia nervosa and in affected adolescents may result in a permanent deficit in bone mass. The pathophysiology of this bone disease has not been clearly defined. In this prospective study of 26 young women with anorexia nervosa aged 13-20 years (mean 16.5) we have measured changes in bone mineral density, total body composition and biochemical indices of bone turnover over 1 year. Over this period there was a mean weight gain of 10 kg and significant height gain with baseline and final values for body mass index of 14.2+/-1.7 and 17.6+/-2.3 kg/m2 (P<0.001). However, no significant changes were seen in bone mineral density in the spine or proximal femur during the study; total body bone mineral content was significantly higher than baseline at 3 months and 12 months (P=0.001 and P<0.0001), but total body bone mineral density at 3 months was significantly lower than baseline (P=0.003). Serum osteocalcin and bone-specific alkaline phosphatase values increased significantly and remained higher than baseline at all time points whereas urinary NTX/creatinine excretion showed a non-significant increase over the first 6 months of the study, but at 12 months, the mean value was significantly lower than baseline. Mean serum 25-hydroxyvitamin D levels showed a significant decrease at 6 months (P<0.05), but returned towards baseline thereafter. There was a significant increase in serum parathyroid hormone levels at all time points compared to baseline, these occurring within the normal range. These results indicate that although weight gain in young anorexics is associated with linear growth, bone mineral density does not increase. Whether this deficit can be corrected subsequently requires longer-term prospective studies.