Normative data and percentile curves for Dual Energy X-ray Absorptiometry in healthy Indian girls and boys aged 5-17 years

Genotype-phenotype analysis of a rare type of osteogenesis imperfecta in four Chinese families with WNT1 mutations

BACKGROUNDS

Osteogenesis imperfecta (OI) is a rare inherited disease characterized by increased bone fragility and vulnerability to fractures. Recently, WNT1 is identified as a new candidate gene for OI, here we detect pathogenic mutations in WNT1 and analyze the genotype-phenotype association in four Chinese families with OI.

METHODS

We designed a targeted next generation sequencing panel with known fourteen OI-related genes. We applied the approach to detect pathogenic mutations in OI patients and confirmed the mutations with Sanger sequencing and cosegregation analysis. Clinical fractures, bone mineral density (BMD) and the other clinical manifestations were evaluated. We also observed the effects of bisphosphonates in OI patients with WNT1 mutations.

RESULTS

Four compound heterozygous mutations (c.110T>C; c.505 G>T; c. 385G>A; c.506 G>A) in WNT1 were detected in three unrelated families. These four mutations had not been reported yet. A recurrent homozygous mutation (c.506dupG) was identified in the other two families. These patients had moderate to severe OI, white to blue sclera, absence of dentinogenesis imperfecta and no brain malformation. We did not observe clear genotype-phenotype correlation in WNT1 mutated OI patients. Though bisphosphonates increased BMD in WNT1 related OI patients, height did not increase and fracture continued.

CONCLUSIONS

We reported four novel heterozygous variants and confirmed a previous reported WNT1 mutation in four Chinese families with a clinical diagnosis of OI. Our study expanded OI spectrum and confirmed moderate to severe bone fragility induced by WNT1 defects.

Body composition in males with adolescent idiopathic scoliosis: a case-control study with dual-energy X-ray absorptiometry

Background

In contrast to the well-characterized body growth and development of females with adolescent idiopathic scoliosis (AIS), the pubertal growth pattern of male patients has not been well-documented. Recently, significantly lower body weight (BW) and body mass index (BMI) were reported in males with AIS, and were thought to be related to curve progression. A case–control study was carried out to characterize the body composition and bone status of males with AIS, with the aim of gaining a better understanding of lower BW among these patients.

Methods

Forty-seven males with AIS and forty age- and gender-matched healthy controls were recruited. Standing height (SH) and BW were measured. The SH of the males who had AIS was corrected using Bjure’s equation, and then the BMI was calculated. Body composition, including subcranial fat mass (FM), lean mass (LM), and bone mineral content (BMC), and bone mineral density (BMD) were analyzed using dual-energy X-ray absorptiometry. The LM index (LMi) and the FM index (FMi) were calculated by dividing the FM and LM by the square of the SH. Logistic regression analysis was employed for comparison between AIS and controls.

Results

The AIS patients had comparable age and Tanner staging for pubic hair as the controls. After adjustment for age, the AIS patients showed comparable SH but significantly lower BW and BMI than that of the controls. The LM, LMi, BMC and BMD were also significantly lower in the AIS patients than in the controls. However, the difference in BMC between two groups was not significant by adjusting for age, FM and LM.

Conclusion

The male AIS patients showed abnormal body composition, presenting as significantly lower LM than the controls. The lower BMC observed in the patients might due to the abnormal body composition.

Correlation of Bone Mineral Parameters with Anthropometric Measurements and the Effect of Glucocorticoids on Bone Mineral Parameters in Congenital Adrenal Hyperplasia

OBJECTIVE

To correlate the bone mineral parameters [bone mineral content (BMC) and bone mineral density (BMD)] using Dual energy X ray Absorptiometry (DXA) scan with anthropometric measurements and to study the effect of glucocorticoid therapy on BMC/BMD in children with Congenital adrenal hyperplasia (CAH).

METHODS

A cross-sectional study was carried out in the Pediatric Endocrinology unit from January 2012 through March 2013 at Kanchi Kamakoti CHILDS Trust hospital, Chennai. Thirteen CAH children aged 0-132 mo with classic salt wasting due to 21 hydroxylase deficiency were included in the study. All children were treated with T.hydrocortisone @10-15 mg/m(2)/d twice daily and T. fludrocortisone 50 μg once daily orally at the time of enrollment into the study. The duration of glucocorticoid (hydrocortisone) treatment from the date of diagnosis till the time of enrollment into the study was noted and categorized as children receiving < 5 and > 5 y of glucocorticoid therapy. None received Vitamin D/calcium supplementation at the time of enrollment. BMC and areal BMD for the lumbar spine and total body less head (TBLH) were measured with Lunar DXA machine.

RESULTS

The mean height, weight and BMI of children were 87.3 ± 33 cm, 13.49 ± 11.2 kg and 14 ± 4.07 kg/m(2) respectively. TBLH BMC was 369.14 ± 312.18 g and TBLH BMD was 0.63 ± 0.11 g/cm(2). There was a significant correlation between height and total body less head BMC/BMD in the index series [P < 0.05, significant]. The TBLH and spine BMD were also assessed with regards to the duration of glucocorticoid therapy and it has been observed that TBLH and spine BMD decreased with increased duration of steroid therapy (p < 0.05, significant).

CONCLUSIONS

In the absence of normative data or z scores, BMC/BMD correlates well with height for age. Children who received more than 5 y of glucocorticoid treatment had lower TBLH and spine BMD scores and hence, calcium and Vitamin D supplementation should be considered.

Bone status of Indian children and adolescents with type 1 diabetes mellitus

OBJECTIVE

Low bone mineral density has been reported in children and adolescents with type 1 diabetes (T1DM). The aims of this cross-sectional study were to study growth, serum IGF1 concentrations and bone health parameters assessed by Dual Energy X-ray Absorptiometry (DXA).

METHODS

Height was measured and converted to Z scores (HAZ). Serum IGF1 concentrations were measured (ELISA) in a subset. Bone mineral content for total body (less head) (TBBMC) and lumbar spine was measured (n=170, 77 boys, 6-16years old) and converted to Z scores using local normative data.

RESULT

Mean age was 11.1±3.8years, disease duration was 2.2±2.5years and HbA1C was 10.1±1.8%. Diabetic children were shorter than reference population (HAZ -0.6±1.1); Z scores for height and total body bone area (TBBA) for height were <-2SD in 12% & 6% respectively. Serum IGF1 Z scores were lower amongst group with longer disease duration (-1.58±1.3 vs -2.63±0.7; P=0.037). Disease duration (β=-0.180, P=0.000) and metabolic control (HbA1C; β=-0.096, P=0.042) were negative predictors of HAZ and TBBA for height Z in younger children. Using the Molgaard approach, children with longer disease duration had lower HAZ (-0.31±0.92 vs -1.28±1.11; P=0.000; "short bones") and TBBA for height Z scores (0.12±1.62 vs -0.53±0.94; P=0.044; "slender bones"). Older children (tanner stages 4 and 5) had lower BMC and BA as compared to reference population possibly due to delayed growth spurt.

CONCLUSION

Longer duration of diabetes was associated with shorter and slender but appropriately mineralized bones. Small and slender bones in diabetic children may increase risk of fragility fractures in the future. This article is part of a Special Issue entitled "Bone and diabetes".

Relationship of insulin-like growth factor 1 and bone parameters in 7-15 years old apparently, healthy Indian children

OBJECTIVE

Growth hormone through insulin-like growth factor 1 (IGF-1) plays an important role in both bone growth and mineralization. This cross-sectional study was carried out to evaluate the relationship between serum IGF-1 concentrations and dual energy X-ray (DXA) measured whole body less head bone area (BA), lean body mass (LBM), and bone mineral content (BMC).

METHODS

One hundred and nineteen children (boys = 70, age = 7.3-15.6 years) were studied for their anthropometric parameters by standard methods and bone and body composition by DXA. Their fasting serum IGF-1 concentrations were assessed by enzyme-linked immunosorbent assay and Z-scores were calculated using available reference data. Bone and body composition parameter Z-scores were calculated using ethnic reference data.

RESULTS

Mean age of the boys and girls was similar (11.5 ± 1.8 years). The mean serum IGF-1concentrations and IGF-1 Z-scores were similar (P > 0.1) between boys and girls and were of the order of (302.3 ± 140.0 and - 1.4 ± 1.1, respectively). The LBM for age and BA for age Z-score was greater in children with IGF-1 Z-score > median than children with IGF-1 Z-score < median. The mean BMC for age Z-scores were 0.4 ± 0.9 and - 0.2 ± 0.8 in children with above and below the median of IGF-1 Z-score (P > 0.1).

CONCLUSION

Serum IGF-1 levels were more strongly associated with BA and LBM, suggesting that its effect on bone is greater with respect to periosteal bone acquisition and through its effect on muscle mass.

Influence of Vitamin D Receptor Gene Fok1 Polymorphism on Bone Mass Accrual Post Calcium and Vitamin D Supplementation

OBJECTIVE

To examine the association of vitamin D receptor (VDR) gene polymorphisms of the Fok1 locus on bone mass accrual in Indian girls used to a low calcium intake.

METHODS

An intervention trial was undertaken in 102 girls aged 8-16 y, attending a state run school in Pune city, India. All girls received 500 mg calcium daily and 30,000 IU of vitamin D3 quarterly for one year. Dietary calcium intake was evaluated. Bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured at total body using Dual Energy X-ray Absorptiometry (Lunar DPX-PRO). Polymorphisms of the Fok1 locus of the vitamin D Receptor (VDR) gene were detected using SYBR Green quantitative polymerase chain reaction.

RESULTS

The prevalence of Fok1 polymorphism was 43.1% (Ff), 9.8% (ff) and 47.1% (FF). At baseline, FF genotype had significantly lower BMD as compared to ff and Ff genotype (p < 0.05). At baseline, majority of girls (82.4%) were hypocalcemic with low calcium intake. Post-supplementation, FF genotype had significantly lower bone mass as compared to ff and Ff genotype. Significant increase in BMC [Ff (17.9%); ff (18.1%); FF (17.4%)], and BMD [Ff (5.4 %); ff (6.3%); FF (4.8%)] was observed post supplementation (p value < 0.05), though percentage increase in BMC and BMD was similar for three Fok1 polymorphisms (p > 0.1).

CONCLUSIONS

VDR gene polymorphism, as defined by Fok1 genotype had no positive influence on bone mass accrual in response to calcium supplementation.

Bone mineral content has stronger association with lean mass than fat mass among Indian urban adolescents

INTRODUCTION

There are conflicting reports on the relationship of lean mass (LM) and fat mass (FM) with bone mineral content (BMC). Given the high prevalence of Vitamin D deficiency in India, we planned the study to evaluate the relationship between LM and FM with BMC in Indian children and adolescents. The objective of the study was to evaluate the relationship of BMC with LM and FM.

MATERIALS AND METHODS

Total and regional BMC, LM, and FM using dual energy X-ray absorptiometry and pubertal staging were assessed in 1403 children and adolescents (boys [B]: 826; girls [G]: 577). BMC index, BMC/LM and BMC/FM ratio, were calculated.

RESULTS

The age ranged from 5 to 18 years, with a mean age of 13.2 ± 2.7 years. BMC adjusted for height (BMC index and BMC/height ratio) was comparable in both genders. There was no difference in total BMC between genders in the prepubertal group but were higher in more advanced stages of pubertal maturation. The correlation of total as well as regional BMC was stronger for LM (B: Total BMC - 0.880, trunk - 0.715, leg - 0.894, arm - 0.891; G: Total BMC - 0.827, leg - 0.846, arm - 0.815 (all value indicate r (2), P < 0.0001 for all) when compared with FM (B: Total BMC - 0.776, trunk - 0.676, leg - 0.772, arm - 0.728; G: Total BMC - 0.781, leg - 0.741, arm - 0.689; all P < 0.0001) except at trunk BMC (LM - 0.682 vs. FM - 0.721; all P < 0.0001), even after controlling for age, height, pubertal stage, and biochemical parameters.

CONCLUSIONS

BMC had a stronger positive correlation with LM than FM.

Reference data and percentile curves of body composition measured with dual energy X-ray absorptiometry in healthy Chinese children and adolescents

Measurements of body composition by dual-energy X-ray absorptiometry (DXA) have evident value in evaluating skeletal and muscular status in growing children and adolescents. This study aimed to generate age-related trends for body composition in Chinese children and adolescents, and to establish gender-specific reference percentile curves for the assessment of muscle-bone status. A total of 1541 Chinese children and adolescents aged from 5 to 19 years were recruited from southern China. Bone mineral content (BMC), lean mass (LM) and fat mass (FM) were measured for total body and total body less head (TBLH). After 14 years, total body LM was significantly higher in boys than girls (p < 0.001). However, total body FM was significantly higher in girls than boys in age groups 13-19 years (p < 0.01). Both LM and FM were consistent independent predictors of total body and subcranial bone mass in both sexes, even after adjustment for the well-known predictors of BMC. The results of multiple linear regression identified LM as the stronger predictor of total body and subcranial skeleton BMC while the fat mass contributed less. For all the subjects, significant positive correlations were observed between total body LM, height, total body BMC and subcranial BMC (p < 0.01). Subcranial BMC had a better correlation with LM than total body BMC. We have also presented gender-specific percentile curves for LM-for-height and BMC-for-LM which could be used to evaluate and follow various pediatric disorders with skeletal manifestations in this population.

Calcium and vitamin D metabolism in children in developing countries

Low dietary calcium intakes and poor vitamin D status are common findings in children living in developing countries. Despite many of the countries lying within the tropics and subtropics, overcrowding, atmospheric pollution, a lack of vitamin D-fortified foods, and social customs that limit skin exposure to sunlight are major factors in the development of vitamin D deficiency. Low dietary calcium intakes are typically observed as a consequence of a diet limited in dairy products and high in phytates and oxalates which reduce calcium bioavailability. Calcium intakes of many children are a third to a half of the recommended intakes for children living in developed countries, yet the consequences of these low intakes are poorly understood as there is limited research in this area. It appears that the body adapts very adequately to these low intakes through reducing renal calcium excretion and increasing fractional intestinal absorption. However, severe deficiencies of either calcium or vitamin D can result in nutritional rickets, and low dietary calcium intakes in association with vitamin D insufficiency act synergistically to exacerbate the development of rickets. Calcium supplementation in children from developing countries slightly increases bone mass, but the benefit is usually lost on withdrawal of the supplement. It is suggested that the major effect of calcium supplementation is on reducing the bone remodelling space rather than structurally increasing bone size or volumetric bone density. Limited evidence from one study raises concerns about the use of calcium supplements in children on habitually low calcium intakes as the previously supplemented group went through puberty earlier and had a final height several centimetres shorter than the controls.

A normal reference of bone mineral density (BMD) measured by dual energy X-ray absorptiometry in healthy thai children and adolescents aged 5-18 years: a new reference for Southeast Asian Populations

Ethnic-specific normative data of bone mineral density (BMD) is essential for the accurate interpretation of BMD measurement. There have been previous reports of normative BMD data for Caucasian and Asian children including Japanese, Chinese, Korean and Indian. However, the normative BMD data for Southeast Asian including Thai children and adolescents are not currently available. The goals of our study were 1) to establish normative data of BMD, bone mineral content (BMC), bone area (BA) and lean body mass (LBM) for healthy Thai children and adolescents; aged 5–18 years measured by dual energy X-ray absorptiometry (DXA, Lunar Prodigy) and 2) to evaluate the relationships between BMD vs. age, sex, puberty, weight, height, calcium intake and the age of menarche in our population. Gender and age-specific BMD (L2-4; LS and total body; TB), BMADLS (apparent BMD of the lumbar spine), BMC (L2-4 and total body), BA (L2-4 and total body) and LBM were evaluated in 367 children (174 boys and 193 girls). All parameters increased progressively with age. A rapid increase in BMD, BMC and BMADLS was observed at earlier ages in girls. Gender and Tanner stage-specific BMD normative data were also generated. The dynamic changes of BMD values from childhood to early and late puberty of Thai children appeared to be consistent with those of Caucasian and Asian populations. Using a multiple-regression, weight and Tanner stage significantly affected BMDLS, BMDTB and BMADLS in both genders. Only in girls, height was found to have significant influence on BMDTB and BMADLS. The positive correlation between BMD and several demographic parameters, except the calcium intake, was observed. In summary, we established a normal BMD reference for Thai children and adolescents and this will be of useful for clinicians and researchers to appropriately assess BMD in Thais and other Southeast Asian children.

Dual-energy X-ray absorptiometry interpretation and reporting in children and adolescents: the revised 2013 ISCD Pediatric Official Positions

The International Society for Clinical Densitometry Official Revised Positions on reporting of densitometry results in children represent current expert recommendations to assist health care providers determine which skeletal sites should be measured, which, if any, adjustments should be made, reference databases to be used, and the elements to include in a dual-energy X-ray absorptiometry report. The recommended scanning sites remain the total body less head and the posterior-anterior spine. Other sites such as the proximal femur, lateral distal femur, lateral vertebral assessment, and forearm are discussed but are only recommended for specific pediatric populations. Different methods of interpreting bone density scans in children with short stature or growth delay are presented. The use of bone mineral apparent density and height-adjusted Z-scores are recommended as suitable size adjustment techniques. The validity of appropriate reference databases and technical considerations to consider when upgrading software and hardware remain unchanged. Updated reference data sets for all contemporary bone densitometers are listed. The inclusion of relevant demographic and health information, technical details of the scan, Z-scores, and the wording "low bone mass or bone density" for Z-scores less than or equal to -2.0 standard deviation are still recommended for clinical practice. The rationale and evidence for the development of the Official Positions are provided. Changes in the grading of quality of evidence, strength of recommendation, and worldwide applicability represent a change in current evidence and/or differences in opinion of the expert panelists used to validate the position statements for the 2013 Position Development Conference.

Arterial stiffness in obese children: Role of adiposity and physical activity

OBJECTIVE

To explore association of adiposity and physical activity with arterial stiffness and to propose optimal waist circumference cutoffs, corresponding to 90(th) percentile of NHANES (National Health and Nutrition Examination Survey) for Indian children and adolescents.

MATERIALS AND METHODS

Data on weight, height, waist circumference, physical activity and right Carotid artery Intima-Media-Thickness (CIMT), pulse wave velocity (PWV), elasticity modulus (Ep), stiffness index(β), arterial compliance (AC) were assessed in 250 children (72 normal-weight and 178 overweight/obese) aged 6-17 years from Pune city, India. Body composition was measured using Dual energy X-ray absorptiometry.

RESULTS

Total, 37.1% normal-weight and 98.2% overweight/obese children had high adiposity (>95(th) body fat percentile). Positive association of PWV and Ep (r = 0.5) also β(r = 0.25) with BMI (Body Mass Index), waist circumference and body fat (P < 0.05) was observed. Physical activity was inversely associated with PWV (r =-0.2), β(r =-0.13), Ep (r =-0.12) and positively with AC (r = 0.12) (P < 0.05). PWV significantly increased with increasing body fat for each tertile of physical activity (P < 0.05). Regression analysis revealed waist circumference, BMI, body fat and physical activity as independent associates for PWV after adjusting for age (P < 0.05). The cutoff of waist circumference yielding sensitivity and specificity for predicting the risk of high PWV was (-0.43, -0.44) for boys and girls with sensitivity in boys (girls) of 78% (87%) and specificity in boys (girls) 51% (70%). The observed cutoffs are less than the NHANES-III cutoff values of waist circumference for 90(th) percentiles according to age and sex.

CONCLUSION

High adiposity and low physical activity are adversely related to arterial stiffness in Indian children.

Effect of one-year growth hormone therapy on body composition and cardio-metabolic risk in Indian children with growth hormone deficiency

Growth hormone (GH) deficiency in children manifests as short stature but is also associated with metabolic disturbances. Paucity of GH is also likely to be associated with increased intima media thickness. Data on body composition (BC) and carotid intima media thickness (cIMT) in children with growth hormone deficiency (GHD) from developing countries are very scarce. Therefore, objectives of present study were to assess effect of 1 year of rhGH therapy on (i) BC and lipid profile (LP) in a cohort of Indian GHD children and (ii) effect on atherosclerotic markers - cIMT in subsample. Anthropometry, BC [% body fat (BF), % lean body mass (LBM), bone mineral content (BMC)] (DXA) and LP were measured in 49 pre-pubertal GHD-children (9.3 ± 3.1 years) at baseline and after 1 year of rhGH therapy. On subset of 20 children, cIMT of right common carotid artery was also measured. Baseline BC parameters were compared with age-gender matched healthy controls (n = 49). At baseline % BF was 23 ± 9 %, LBM was 9 ± 3 kg and BMC was 0.306 ± 0.15 kg in GHD- children; BF was comparable, while lean and bone were less than controls (p < 0.05). Post therapy, significant reduction in fat (15%), and cIMT (7%) and increase in LBM and BMC by 40% and 44%, respectively (p < 0.05) was seen. Our cohort of untreated GHD children had abnormal BC and cIMT as compared to controls. rhGH therapy for 1 year had beneficial effect on BC and cardiovascular risk factors.

Bone-related complications of transfusion-dependent beta thalassemia among children and adolescents

Thalassemia and the blood transfusion complications associated with it predispose children to poor bone health. This study was conducted to determine the prevalence of bone-related abnormalities and identify the bone health predictors within this population. One hundred and forty transfusion-dependent beta thalassemic subjects 8-18 years old in Mashhad, Iran, participated in this cross-sectional study. Anthropometric measures, dietary intake, bone-related biomarkers and bone densitometry, were assessed. The incidence of underweight and short stature was 33.6 and 41.4 %, respectively, which were indicators of malnutrition among thalassemic subjects in this study. Low bone density was detected in the lumbar spine and femoral region in 82 and 52 % of subjects, respectively. Hypocalcemia and hypophosphatemia were seen in 22 and 18.2 %, whilst vitamin D deficiency was present in more than 85 % of thalassemic children and adolescents. The relationships between weight, height and other anthropometric indices, serum calcium and bone markers, intake of macronutrients, zinc and vitamin E with bone mineral density (BMD) and bone mineral content (BMC) in the lumbar spine and femoral area were positively related, indicating that better nutritional status were associated with higher BMD and BMC values. Puberty, gender and serum osteocalcin were negative predictors for BMD and BMC values, whereas age, weight and height were the positive predictors. High incidence of low bone density and deficit in other aspects of bone health among thalassemia patients makes routine bone health assessment necessary for this vulnerable group. Considering influencing factors, dietary counseling and preventive supplementation therapy for this high risk group of children and adolescents may be necessary, although this should be assessed by intervention studies.

Enhanced effect of zinc and calcium supplementation on bone status in growth hormone-deficient children treated with growth hormone: a pilot randomized controlled trial

Reduced bone mineral content in growth hormone-deficient children (GHD) has been reported. Calcium, zinc, and vitamin D play an important role in bone formation. Hence, the aim of this pilot randomized controlled study was to evaluate the effect of calcium, vitamin D, and zinc supplementation in prepubertal GHD children treated with GH on bone health parameters. After 1 year of treatment with GH (20 mg/m(2)/week), 31 GHD (mean age 8.7 ± 2.8 years, 18 boys) prepubertal children were randomised to receive calcium (500 mg/day) and vitamin D (60,000 IU/3 months) [Group A] or a similar supplement of calcium, vitamin D, and zinc (as per Indian Recommended Allowance) [Group B] along with GH therapy for the next 12 months. The two groups were similar in anthropometric and body composition parameters at baseline (p > 0.1). After 1 year of GH therapy, height-adjusted % gain was similar in both groups, 48 % in bone mineral content (BMC) and 45 % in bone area (BA). Height-adjusted % increase in BMC was significantly (p < 0.05) higher in the second year than in the first in both the groups. This % increase in BMC and BA was greater in Group B (51 and 36 % respectively) than in Group A (49 and 34 %), although marginally (p < 0.05). Supplementation of calcium and vitamin D along with GH therapy in GHD Indian children has the potential for enhancing bone mass accrual; this effect was further enhanced through the addition of zinc supplement.

Age trends of bone mineral density and percentile curves in healthy Chinese children and adolescents

The clinical utility of dual-energy X-ray absorptiometry (DXA) measurement requires appropriate normative values, designed to be diverse with respect to age, gender and ethnic background. The purpose of this study was to generate age-related trends for bone density in Chinese children and adolescents, and to establish a gender-specific reference database. A total of 1,541 Chinese children and adolescents aged from 5 to 19-years were recruited from southern China. Bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) were measured for the total body (TB) and total body less head (TBLH). The height-for-age, height-for-BA, and BMC-for-BA percentile curves were developed using the least mean square method. TB BMD and TBLH BMD were highly correlated. After 18 years, TB BMD was significantly higher in boys than girls. For TB BMC and TBLH BMC, gender differences were found in age groups 12 years and 16-19 years; however, the TBLH BMD was significantly different between genders >16 years. The head region accounted for 13-52 and 16-49 % of the TB BMC in boys and girls, respectively. Furthermore, the percentages were negatively correlated with age and height. This study describes a gender-specific reference database for Chinese children and adolescents aged 5-19 years. These normative values could be used for clinical assessment in this population.

Normative data and percentile curves of bone mineral density in healthy Iranian children aged 9-18 years

We provide the first reference values for bone mineral content and bone mineral density according to age and sex in Iranian children and adolescents. The prevalence of hypovitaminosis D was high, and levels of physical activity were low in our sample. Multiple regression analyses showed age, BMI, and Tanner stage to be the main indicators of bone mineral apparent density.

PURPOSE

Normal bone structure is formed in childhood and adolescence. The potential determinants which interact with genetic factors to influence bone density include gender, nutritional, lifestyle, and hormonal factors. This study aimed to evaluate bone mineral content (BMC) and the bone mineral density (BMD) and factors that may interfere with it in Iranian children.

METHODS

In this cross-sectional study, 476 healthy Iranian children and adolescents (235 girls and 241 boys) aged 9-18 years old participated. BMC and BMD of the lumbar spine, femoral neck, and total body were measured by dual-energy X-ray absorptiometry using a Hologic Discovery device, and bone mineral apparent density (BMAD) of the lumbar spine and the femoral neck were calculated.

RESULTS

We present percentile curves by age derived separately for BMC, BMD, and BMAD of the lumbar spine, left femoral neck, and total body excluding the head for boys and girls. Maximum accretion of BMC and BMD was observed at ages of 11-13 years (girls) and 12-15 years (boys).The prevalence of hypovitaminosis D was high and physical activity was low in our participants. However, in multiple regression analyses, age, BMI, and Tanner stage were the main indicators of BMD and BMAD CONCLUSION: These normative data aid in the evaluation of bone density in Iranian children and adolescents. Further research to evaluate the evolution of BMD in Iranian children and adolescents is needed to identify the reasons for significant differences in bone density values between Iranian populations and their Western counterparts.

Vitamin D receptor gene polymorphisms and bone mass indices in post-menarchal Indian adolescent girls

To study the association between vitamin D receptor (VDR) gene polymorphisms and bone mass indices in adolescent girls, a cross-sectional study was conducted in 120 post-menarchal girls aged 15-18 years in Pune city, India. Serum levels of ionised calcium, inorganic phosphorous, parathyroid hormone and 25-hydroxy vitamin-D were measured. Bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured at total body (TB), lumbar spine (LS) and left femoral neck (FN) using dual energy X-ray absorptiometry. Polymorphisms of the VDR gene at the Fok1 and Bsm1 loci were detected using SYBR Green quantitative polymerase chain reaction. The overall distribution of genotypes at the Bsm1 locus in this study was 33.3 % Bb, 29.2 % bb and 37.5 % BB while that for the Fok1 locus was 44.2 % Ff, 7.5 % ff and 48.3 % FF. There were no significant differences in the blood parameters when classified according to Bsm1 or Fok1 genotypes. Subjects with BB genotype have significantly higher mean TBBMC, TBBA, TBBMD and LSBMD than Bb and bb (p < 0.05) and showed a tendency for association with LSBMC and LSBA (p < 0.1). Subjects with Ff genotype showed a tendency for association with left FNBMC and FNBA (p < 0.1). Bsm1 genotype did not show an association with FN bone indices whereas Fok1 genotype did not show association with TB or LS bone indices. In conclusion, the present study demonstrates VDR gene polymorphism, defined by Bsm1 genotype, has an influence on total body and lumbar spine bone mass indices in post-menarchal Indian girls.

Dose optimisation for intraoperative cone-beam flat-detector CT in paediatric spinal surgery

BACKGROUND

During surgery for spinal deformities, accurate placement of pedicle screws may be guided by intraoperative cone-beam flat-detector CT.

OBJECTIVE

The purpose of this study was to identify appropriate paediatric imaging protocols aiming to reduce the radiation dose in line with the ALARA principle.

MATERIALS AND METHODS

Using O-arm® (Medtronic, Inc.), three paediatric phantoms were employed to measure CTDI(w) doses with default and lowered exposure settings. Images from 126 scans were evaluated by two spinal surgeons and scores were compared (Kappa statistics). Effective doses were calculated. The recommended new low-dose 3-D spine protocols were then used in 15 children.

RESULTS

The lowest acceptable exposure as judged by image quality for intraoperative use was 70 kVp/40 mAs, 70 kVp/80 mAs and 80 kVp/40 mAs for the 1-, 5- and 12-year-old-equivalent phantoms respectively (kappa = 0,70). Optimised dose settings reduced CTDI(w) doses 89-93%. The effective dose was 0.5 mSv (91-94,5% reduction). The optimised protocols were used clinically without problems.

CONCLUSIONS

Radiation doses for intraoperative 3-D CT using a cone-beam flat-detector scanner could be reduced at least 89% compared to manufacturer settings and still be used to safely navigate pedicle screws.

School-based calcium-vitamin D with micronutrient supplementation enhances bone mass in underprivileged Indian premenarchal girls

Low adult bone mass is linked to osteoporosis and fractures and is dependent on the extent of childhood and adolescent bone mineralization. The aim of the study was to investigate the effect of 1-year supplementation of calcium, multivitamin with zinc along with vitamin-D on bone mass accrual of school-going premenarchal girls from low income groups in Pune, India. Double-blind, matched-pair, cluster, randomization study was carried out in 214 premenarchal girls (8-12 years) from 2 schools in Pune, India. The two schools together formed 3 classes with 3 clusters each of age-matched girls of which one cluster was allocated to either one of the intervention groups (Ca-group:500 mg/d calcium, Ca+MZ-group:500 mg/d calcium+multivitamin tablet containing 15 mg/d zinc) or control group (C-group: multivitamin tablet without any minerals); all subjects received vitamin-D supplementation. Anthropometry, biochemical parameters, total body bone mineral content (TBBMC) and bone mineral density (TBBMD) (Dual energy X-ray absorptiometry) were assessed at baseline and endline. Post supplementation, mean percent increase in TBBMC was significantly higher in Ca-group (22.3%) and Ca+MZ-group (20.8%) compared to C-group (17.6%) (p<0.05) with no significant differences observed between Ca+MZ and Ca groups (p>0.1). Improvement in TBBMC-for-age Z-scores was higher in the two calcium supplemented groups (13.6%-22%) compared to the C-group (no improvement). Calcium supplementation, with or without multivitamins and zinc, showed a promising improvement in bone health especially with regards to improvement in bone related Z-scores in our population of underprivileged premenarchal girls.

Poor bone health in underprivileged Indian girls: an effect of low bone mass accrual during puberty

A socio-economic gradient exists for most reasons of morbidity and mortality including delayed puberty in lower (LSES) as compared to higher (HSES) socio-economic stratum and puberty is an important factor affecting bone status in children and adolescents. Thus, a cross-sectional study was conducted on 195 age-matched pairs of girls (8-17years) from LSES and HSES in Pune City, India to assess the hypothesis that socio-economic factors working through late puberty would have a negative association with bone status of adolescents. Height, weight and Tanner stage were assessed. Total body bone mineral content (TBBMC), total body bone area (TBBA), total body bone mineral density (TBBMD), lean body mass (LBM) and total body fat mass (TBFM) were measured using GE Lunar DPX Pro Pencil Beam DXA (Wisconsin, USA) scanner. Mean TBBMC (1172±434g), TBBA (1351±356cm(2)), TBBMD (0.846±0.104g/cm(2)), LBM (21,622±5306g) and TBFM (7746±5194g) in LSES girls were significantly lower than that of HSES girls [TBBMC (1483±525g), TBBA (1533±380cm(2)), TBBMD (0.942±0.119g/cm(2)), LBM (24,308±5829g) and TBFM (12,196±7404g)] (p<0.01). There was a significant effect of age and puberty on all bone parameters. The differences in TBBMC, TBBA, LBM and TBFM between the 2 socio-economic strata at Tanner stage I were not significant (p>0.1) whereas there were significant differences in these parameters from Tanner stages II to V (p<0.05). The percentage difference between LSES and HSES girls in TBBMC, TBBA, TBBMD, LBM and TBFM was 3.4%, 0%, 3.7%, 0.2% and 17.3% respectively at Tanner stage I which increased to 19.1%, 9.7%, 10.4%, 8.8% and 31.2% respectively at Tanner stage V. In conclusion, our results suggest that pubertal years may provide a window of opportunity to promote bone health in adolescent girls from the lower socio-economic stratum.