UK reference data for the Hologic QDR Discovery dual-energy x ray absorptiometry scanner in healthy children and young adults aged 6-17 years

Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled trial

BACKGROUND

Findings from the Maternal Vitamin D Osteoporosis Study (MAVIDOS) trial demonstrated a positive effect of gestational cholecalciferol supplementation on offspring bone mineral density (BMD) at age 4 y. Demonstrating the persistence of this effect is important to understanding whether maternal vitamin D supplementation could be a useful public health strategy to improving bone health.

OBJECTIVES

We investigated whether gestational vitamin D supplementation increases offspring BMD at ages 6-7 y in an exploratory post-hoc analysis of an existing trial.

METHODS

In the MAVIDOS randomized controlled trial, pregnant females <14 wk' gestation with a singleton pregnancy and serum 25-hydroxyvitamin D 25-100nmol/l at 3 United Kingdom hospitals (Southampton, Sheffield, and Oxford) were randomly assigned to either 1000 IU/d cholecalciferol or placebo from 14 to 17-wk gestation until delivery. Offspring born at term to participants recruited in Southampton were invited to the childhood follow-up at ages 4 and 6-7 y. The children had a dual-energy X-ray absorptiometry (DXA, Hologic discovery) scan of whole-body-less-head (WBLH) and lumbar spine, from which bone area, bone mineral content (BMC), BMD, and bone mineral apparent density (BMAD) were derived. Linear regression was used to compare the 2 groups adjusting for age, sex, height, weight, duration of consumption of human milk, and vitamin D use at 6-7 y.

RESULTS

A total of 454 children were followed up at ages 6-7 y, of whom 447 had a usable DXA scan. Gestational cholecalciferol supplementation resulted in higher WBLH BMC [0.15 SD, 95% confidence interval (CI): 0.04, 0.26], BMD (0.18 SD, 95% CI: 0.06, 0.31), BMAD (0.18 SD, 95% CI: 0.04, 0.32), and lean mass (0.09 SD, 95% CI: 0.00, 0.17) compared with placebo. The effect of pregnancy cholecalciferol on bone outcomes was similar at ages 4 and 6-7 y.

CONCLUSIONS

Supplementation with cholecalciferol 1000 IU/d during pregnancy resulted in greater offspring BMD and lean mass in mid-childhood compared with placebo in this exploratory post-hoc analysis. These findings suggest that pregnancy vitamin D supplementation may be an important population health strategy to improve bone health.

TRIAL REGISTRATION NUMBER

This trial was registered at the ISRCTN (https://doi.org/10.1186/ISRCTN82927713) as 82927713 and EUDRACT (https://www.clinicaltrialsregister.eu/ctr-search/trial/2007-001716-23/results) as 2007-001716-23.

Body Composition and Metabolism in Adults With Molecularly Confirmed Silver-Russell Syndrome

CONTEXT

Low birth weight, as seen in Silver-Russell syndrome (SRS), is associated with later cardiometabolic disease. Data on long-term outcomes and adult body composition in SRS are limited.

OBJECTIVE

To evaluate body composition and metabolic health in adults with SRS.

METHODS

This was an observational study of 25 individuals with molecularly confirmed SRS, aged ≥ 18 years, from research facilities across the UK. Body composition and metabolic health were assessed at a single appointment. Individuals with SRS were compared with unaffected men and women (from the Southampton Women's Survey [SWS]). Fat mass, lean mass, bone mineral density (BMD), blood pressure, lipids, and blood glucose were measured.

RESULTS

Twenty-five adults with SRS were included (52% female). The median age was 32.9 years (range, 22.0 to 69.7). Fat percentage was greater in the SRS group than the SWS cohort (44.1% vs 30.3%, P < .001). Fat mass index was similar (9.6 vs 7.8, P = .3). Lean mass percentage (51.8% vs 66.2%, P < .001) and lean mass index (13.5 kg/m2 vs 17.3 kg/m2, P < .001) were lower in the SRS group than the SWS cohort. BMD was lower in the SRS group than the SWS cohort (1.08 vs 1.24, P < .001; all median values). Total cholesterol was ≥ 5 mmol/L in 52.0%. Triglyceride levels were ≥ 1.7 mmol/L in 20.8%. Fasting blood glucose levels were ≥ 6.1 mmol/L in 25.0%. Hypertension was present in 33.3%.

CONCLUSION

Adults with SRS have an unfavorable body composition and predisposition to cardiometabolic disease. These results support the need for a health surveillance strategy to mitigate adverse outcomes.

Reference values for bone mass in young athletes: a cross-sectional study in São Paulo, Brazil

Reference values for bone mass in young athletes need to be used for screening purposes, and country/regional reference values should be used to improve precision of comparisons. The aim of the present study was to develop reference values for bone health variables in Brazilian young athletes. The bone mass content (BMC), bone mass density (BMD), and total body less head (TBLH) BMD using dual-energy X-ray absorptiometry were measured in 702 young athletes (327 men and 375 women) aged 8.5-18.5 years, divided into 5 groups, according to their age: group 1 (8.5-10.5 years), group 2 (10.6-12.5 years), group 3 (12.6-14.5 years), group 4 (14.6-16.5 years), and group 5 (16.6-18.5 years). Comparisons between the sexes and ages were performed and age-sex-smoothed reference values were constructed. Male athletes presented high BMC and BMD than female athletes in age groups 3, 4, and 5 (p < 0.005) and high TBLH BMD than female athletes in age groups 4 and 5 (p < 0.005). Reference values, including the percentiles are presented for the bone health variables of each sex and age group. The age-, sex-, and ethnic-specific reference data for bone variables presented in this study enabled more precise reference data for young Brazilian athletes. These data may assist in monitoring changes during an athletes' growth and different phases of athletic training.

Reference values of bone mineral density of proximal femur for Southeast Asian children and adolescents

Bone mineral density (BMD) of the proximal femur helps evaluate bone density in children with reduced mechanical loading of the lower extremities. This study provides the first reference values of bone mineral density of proximal femur according to age and sex for Southeast Asian children and adolescents.   OBJECTIVES: The study aimed to (1) establish normative data of BMD of the proximal femur (femoral neck and total hip), measured by dual-energy X-ray absorptiometry (DXA), for healthy Thai children aged 5 to 18 years and (2) ascertain the relationships between BMD, growth, and puberty.

METHODS

Proximal femur scans of 170 boys and 191 girls obtained from DXA (Lunar Prodigy Pro, GE, and software enCORE version 7.53) were un-analyzed and then re-analyzed with the upgraded software enCORE version 17 SP2 for BMD assessment. The bone mineral apparent density of the femoral neck (FNBMAD) was calculated.

RESULTS

Sex and Tanner stage-specific BMD normative data were generated. BMD values of the femoral neck and total hip increased with age and pubertal progression. FNBMAD values were not markedly influenced by age and puberty. Using multiple linear regression analysis, age and weight affected FNBMD and total hip BMD in boys and girls, but height and Tanner stage only influenced girls. Age did not significantly influence FNBMAD in either sex. Tanner stage weakly influenced FNBMAD only in boys.

CONCLUSIONS

We established normative reference data for BMD of the proximal femur measured by DXA in Thai children aged 5 to 18 years. Our reference data will help clinicians and researchers assess and interpret the BMD of the proximal femur for Southeast Asian children.

Official Position of the Brazilian Association of Bone Assessment and Metabolism (ABRASSO) on the evaluation of body composition by densitometry-part II (clinical aspects): interpretation, reporting, and special situations

OBJECTIVE

To present an updated and evidence-based guideline for the use of dual-energy x-ray absorptiometry (DXA) to assess body composition in clinical practice.

MATERIALS AND METHODS

This Official Position was developed by the Scientific Committee of the Brazilian Association of Bone Assessment and Metabolism (Associação Brasileira de Avaliação Óssea e Osteometabolismo, ABRASSO) and experts in the field who were invited to contribute to the preparation of this document. The authors searched current databases for relevant publications in the area of body composition assessment. In this second part of the Official Position, the authors discuss the interpretation and reporting of body composition parameters assessed by DXA and the use of DXA for body composition evaluation in special situations, including evaluation of children, persons with HIV, and animals.

CONCLUSION

This document offers recommendations for the use of DXA in body composition evaluation, including indications, interpretation, and applications, to serve as a guiding tool in clinical practice and research for health care professionals in Brazil.

A growth area: A review of the value of clinical studies of child growth for palaeopathology

Studies of living children demonstrate that early life stress impacts linear growth outcomes. Stresses affecting linear growth may also impact later life health outcomes, including increased cardiometabolic disease risk. Palaeopathologists also assess the growth of children recovered from bioarchaeological contexts. Early life stresses are inferred to affect linear growth outcomes, and measurements of skeletal linear dimensions alongside other bioarchaeological information may indicate the types of challenges faced by past groups. In clinical settings, the impacts of stress on growing children are typically measured by examining height. Palaeopathologists are limited to examining bone dimensions directly and must grapple with incomplete pictures of childhood experiences that may affect growth. Palaeopathologists may use clinical growth studies to inform observations among past children; however, there may be issues with this approach. Here, we review the relationship between contemporary and palaeopathological studies of child and adolescent growth. We identify approaches to help bridge the gap between palaeopathological and biomedical growth studies. We advocate for: the creation of bone-specific growth reference information using medical imaging and greater examination of limb proportions; the inclusion of children from different global regions and life circumstances in contemporary bone growth studies; and greater collaboration and dialogue between palaeopathologists and clinicians as new studies are designed to assess linear growth past and present. We advocate for building stronger bridges between these fields to improve interpretations of growth patterns across human history and to potentially improve interventions for children living and growing today.

Effects of vitamin D and high dairy protein intake on bone mineralization and linear growth in 6- to 8-year-old children: the D-pro randomized trial

BACKGROUND

Vitamin D and dairy protein may stimulate bone mineralization and linear growth in children, but previous studies show inconsistent results and have not examined their combined effects.

OBJECTIVES

To investigate combined and separate effects of vitamin D supplementation and high-protein (HP) compared with normal-protein (NP) yogurt intake on children's bone mineralization and linear growth.

METHODS

In a 2 × 2-factorial trial, 200 healthy, 6- to 8-year-old, Danish, children with light skin (55°N) were randomized to 20 µg/d vitamin D3 or placebo and to substitute 260 g/d dairy with HP (10 g protein/100 g) or NP (3.5 g protein/100 g) yogurt for 24 weeks during an extended winter. Outcomes were total body less head (TBLH) and lumbar spine bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) by dual-energy X-ray absorptiometry, height, and biomarkers of bone turnover and growth. The primary outcome was TBLH BMD.

RESULTS

In total, 184 children (92%) completed the study. The baseline serum 25-hydroxyvitamin D was 80.8 ± 17.2 nmol/L, which increased by 7.2 ± 14.1 nmol/L and decreased by 32.3 ± 17.5 nmol/L with vitamin D and placebo, respectively. The baseline protein intake was 15.4 ± 2.4 energy percentage (E%), which increased to 18.3 ± 3.4 E% with HP. There were no vitamin D-yogurt interactions and no main effects of either intervention on TBLH BMD. However, vitamin D supplementation increased lumbar spine BMD and TBLH BMC compared to placebo, whereas HP groups showed lower increments in lumbar spine BMD, TBLH BMC and BA, and plasma osteocalcin compared to NP groups. Height, growth factors, and parathyroid hormone levels were unaffected.

CONCLUSIONS

Although there were no effects on whole-body BMD, vitamin D increased bone mass and spinal BMD, whereas high compared with normal dairy protein intake had smaller incremental effects on these outcomes. This supports a recommended vitamin D intake of around 20 µg/d during winter but not use of HP dairy products for improved bone mineralization among healthy, well-nourished children. This trial was registered at clinicaltrials.gov as NCT03956732.

Bone mineral density in high-level endurance runners: part A-site-specific characteristics

PURPOSE

Physical activity, particularly mechanical loading that results in high-peak force and is multi-directional in nature, increases bone mineral density (BMD). In athletes such as endurance runners, this association is more complex due to other factors such as low energy availability and menstrual dysfunction. Moreover, many studies of athletes have used small sample sizes and/or athletes of varying abilities, making it difficult to compare BMD phenotypes between studies.

METHOD

The primary aim of this study was to compare dual-energy X-ray absorptiometry (DXA) derived bone phenotypes of high-level endurance runners (58 women and 45 men) to non-athletes (60 women and 52 men). Our secondary aim was to examine the influence of menstrual irregularities and sporting activity completed during childhood on these bone phenotypes.

RESULTS

Female runners had higher leg (4%) but not total body or lumbar spine BMD than female non-athletes. Male runners had lower lumbar spine (9%) but similar total and leg BMD compared to male non-athletes, suggesting that high levels of site-specific mechanical loading was advantageous for BMD in females only and a potential presence of reduced energy availability in males. Menstrual status in females and the number of sports completed in childhood in males and females had no influence on bone phenotypes within the runners.

CONCLUSION

Given the large variability in BMD in runners and non-athletes, other factors such as variation in genetic make-up alongside mechanical loading probably influence BMD across the adult lifespan.

Reference values for bone mineral density in healthy Mexican children and adolescents

INTRODUCTION

Clinical assessment of bone health by Dual-Energy X-ray Absorptiometry (DXA) in the paediatric population requires robust reference values. The International Society for Clinical Densitometry (ISCD) recommends that country/regional reference values ideally should be used to improve precision in bone health assessment.

OBJECTIVE

The aim of this study was to provide reference values for relevant bone health variables for healthy Mexican children and adolescents aged 5 to 18 years.

METHODS

This was a cross-sectional, stratified and population-based study, that measured a representative sample of healthy Mexican children and adolescents with DXA. We constructed age- and sex-smoothed reference values for areal bone mineral density (aBMD) of total body less head (TBLH), total body (TB), lumbar spine (LS), and bone mineral apparent density (BMAD) for LS, by means of Generalized Additive Models for Location, Scale and Shape (GAMLSS).

RESULTS

Reference data including the 3th, 5th, 10th, 25th, 50th, 75th, 90th, 95th and 97th centiles, along with lambda (L), mu (M) and sigma (S) values, are given for each variable of interest for each sex at 0.25 years intervals. Reference values relative to height and Tanner-stage for both sexes are also provided. Finally, formulas to enable Z score estimation for clinical use are also presented CONCLUSIONS: The sex, age, height, Tanner-stage and ethnic-specific reference data provided in this study should enable more precise assessment of bone health in the Mexican paediatric population. The data presented may also allow for future evaluation of potential similarities and differences across different ethnic groups.

Bone Development in Transgender Adolescents Treated With GnRH Analogues and Subsequent Gender-Affirming Hormones

CONTEXT

Hormonal interventions in adolescents with gender dysphoria may have adverse effects, such as reduced bone mineral accrual.

OBJECTIVE

To describe bone mass development in adolescents with gender dysphoria treated with gonadotropin-releasing hormone analogues (GnRHa), subsequently combined with gender-affirming hormones.

DESIGN

Observational prospective study.

SUBJECTS

51 transgirls and 70 transboys receiving GnRHa and 36 transgirls and 42 transboys receiving GnRHa and gender-affirming hormones, subdivided into early- and late-pubertal groups.

MAIN OUTCOME MEASURES

Bone mineral apparent density (BMAD), age- and sex-specific BMAD z-scores, and serum bone markers.

RESULTS

At the start of GnRHa treatment, mean areal bone mineral density (aBMD) and BMAD values were within the normal range in all groups. In transgirls, the mean z-scores were well below the population mean. During 2 years of GnRHa treatment, BMAD stabilized or showed a small decrease, whereas z-scores decreased in all groups. During 3 years of combined administration of GnRHa and gender-affirming hormones, a significant increase of BMAD was found. Z-scores normalized in transboys but remained below zero in transgirls. In transgirls and early pubertal transboys, all bone markers decreased during GnRHa treatment.

CONCLUSIONS

BMAD z-scores decreased during GnRHa treatment and increased during gender-affirming hormone treatment. Transboys had normal z-scores at baseline and at the end of the study. However, transgirls had relatively low z-scores, both at baseline and after 3 years of estrogen treatment. It is currently unclear whether this results in adverse outcomes, such as increased fracture risk, in transgirls as they grow older.

Revisiting the radiographic assessment of osteoporosis-Osteopenia in children 0-2 years of age. A systematic review

BACKGROUND

Imaging for osteoporosis has two major aims, first, to identify the presence of low bone mass (osteopenia), and second, to quantify bone mass using semiquantitative (conventional radiography) or quantitative (densitometry) methods. In young children, densitometry is hampered by the lack of reference values, and high-quality radiographs still play a role although the evaluation of osteopenia as a marker for osteoporosis is subjective and based on personal experience. Medical experts questioned in court over child abuse, often refer to the literature and state that 20-40% loss of bone mass is warranted before osteopenia becomes evident on radiographs. In our systematic review, we aimed at identifying evidence underpinning this statement. A secondary outcome was identifying normal references for cortical thickness of the skeleton in infants born term, < 2 years of age.

METHODS

We undertook systematic searches in Medline, Embase and Svemed+, covering 1946-2020. Unpublished material was searched in Clinical trials and International Clinical Trials Registry Platform (ICTRP). Both relevant subject headings and free text words were used for the following concepts: osteoporosis or osteopenia, radiography, children up to 6 years.

RESULTS

A total 5592 publications were identified, of which none met the inclusion criteria for the primary outcome; the degree of bone loss warranted before osteopenia becomes visible radiographically. As for the secondary outcome, 21 studies were identified. None of the studies was true population based and none covered the pre-defined age range from 0-2 years. However, four studies of which three having a crossectional and one a longitudinal design, included newborns while one study included children 0-2 years.

CONCLUSIONS

Despite an extensive literature search, we did not find any studies supporting the assumption that a 20-40% bone loss is required before osteopenia becomes visible on radiographs. Reference values for cortical thickness were sparse. Further studies addressing this important topic are warranted.

Bone Mineral Reference Values for Athletes 11 to 20 Years of Age

Objectives. Training for sport is associated with the development of bone minerals, and the need for reference data based on athletes is often indicated. The purpose of this study was to develop a reference for bone mineral density (BMD) and content (BMC) specific for youth athletes of both sexes participating in several sports. Methods DEXA (dual energy X-ray absorptiometry) was used for total body measurements of bone minerals in 1385 athletes 11 to 20 years, 1019 males and 366 females. The athletes were training in several sports at Hungarian academies. Reference values for total bone mineral density and bone mineral content, and also BMD excluding the head (total body less head, TBLH) were developed using the LMS chartmaker pro version 2.3. Results. The centile distributions for BMD and BMC of the athletes differed significantly from those of the age- and sex-specific references for the general population. The youth athletes had higher BMD and BMC than those of the reference for the general population. Conclusion. The potential utility of the DEXA reference for male and female youth athletes may assist in monitoring changes in the BMC and BMD associated with normal growth and maturation, and perhaps more importantly, may be useful in monitoring changes specific to different phases of sport-specific training protocols.

CATS II Long-term Anthropometric and Metabolic Effects of Maternal Sub-optimal Thyroid Function in Offspring and Mothers

CONTEXT AND OBJECTIVES

The Controlled Antenatal Thyroid Screening Study I (CATS-I) was a randomized controlled trial investigating the effects of levothyroxine therapy for suboptimal gestational thyroid function (SGTF), comparing outcomes in children of treated (SGTF-T) with untreated (SGTF-U) women during pregnancy. This follow-up study, CATS-II, reports the long-term effects on anthropometric, bone, and cardiometabolic outcomes in mothers and offspring and includes a group with normal gestational thyroid function (NGTF).

DESIGN & PARTICIPANTS

332 mothers (197 NGTF, 56 SGTF-U, 79 SGTF-T) aged 41.2±5.3 years (mean±SD) and 326 paired children assessed 9.3±1.0 years after birth for (i) body mass index (BMI); (ii) lean, fat, and bone mass by dual-energy X-ray absorptiometry; (iii) blood pressure, augmentation index, and aortic pulse-wave-velocity; and (iv) thyroid function, lipids, insulin, and adiponectin. The difference between group means was compared using linear regression.

RESULTS

Offspring's measurements were similar between groups. Although maternal BMI was similar between groups at CATS-I, after 9 years (at CATS-II) SGTF-U mothers showed higher BMI (median [interquartile ratio] 28.3 [24.6-32.6] kg/m2) compared with NGTF (25.8 [22.9-30.0] kg/m2; P = 0.029), driven by fat mass increase. At CATS-II SGTF-U mothers also had higher thyroid-stimulating hormone (TSH) values (2.45 [1.43-3.50] mU/L) than NGTF (1.54 [1.12-2.07] mU/L; P = 0.015), since 64% had never received levothyroxine. At CATS-II, SGTF-T mothers had BMI (25.8 [23.1-29.8] kg/m2, P = 0.672) and TSH (1.68 [0.89-2.96] mU/L; P = 0.474) values similar to NGTF mothers.

CONCLUSIONS

Levothyroxine supplementation of women with SGTF did not affect long-term offspring anthropometric, bone, and cardiometabolic measurements. However, absence of treatment was associated with sustained long-term increase in BMI and fat mass in women with SGTF.

Bones and Birth Control in Adolescent Girls

Peak bone mass acquisition during adolescence is an important determinant of adult bone health. Knowledge about the effects of different contraceptives on peak bone mass acquisition could influence choice of method recommended. This review summarizes normal bone acquisition during adolescence, discusses methods of assessing bone health in this age group, and reviews the effects of different contraceptive options on bone health, both in adults and in adolescents. Based on the evidence, long-acting reversible contraceptives do not appear to affect peak bone mass acquisition or future fracture risk and remain the first-line contraceptive choice for adolescents. Oral contraceptives with doses of ethinyl estradiol greater than 30 μg should be used in preference to lower-dose preparations, and the adverse effects of depo medroxyprogesterone acetate (DMPA) on bone health are reversible on discontinuation of the medication. Concerns about bone health should not prevent use of DMPA in an adolescent who prefers this method.

Assessing bone mineralisation in children with chronic kidney disease: what clinical and research tools are available?

Mineral and bone disorder in chronic kidney disease (CKD-MBD) is a triad of biochemical imbalances of calcium, phosphate, parathyroid hormone and vitamin D, bone abnormalities and soft tissue calcification. Maintaining optimal bone health in children with CKD is important to prevent long-term complications, such as fractures, to optimise growth and possibly also to prevent extra-osseous calcification, especially vascular calcification. In this review, we discuss normal bone mineralisation, the pathophysiology of dysregulated homeostasis leading to mineralisation defects in CKD and its clinical consequences. Bone mineralisation is best assessed on bone histology and histomorphometry, but given the rarity with which this is performed, we present an overview of the tools available to clinicians to assess bone mineral density, including serum biomarkers and imaging such as dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. We discuss key studies that have used these techniques, their advantages and disadvantages in childhood CKD and their relationship to biomarkers and bone histomorphometry. Finally, we present recommendations from relevant guidelines-Kidney Disease Improving Global Outcomes and the International Society of Clinical Densitometry-on the use of imaging, biomarkers and bone biopsy in assessing bone mineral density. Given low-level evidence from most paediatric studies, bone imaging and histology remain largely research tools, and current clinical management is guided by serum calcium, phosphate, PTH, vitamin D and alkaline phosphatase levels only.

Bone density in children: what are we measuring?

The measurement of bone density is a frequent request in the assessment of children with concerns about bone health due to chronic disease or recurrent fractures. Dual energy X-ray absorptiometry (DXA) remains the recommended modality and is widely available. However, the interpretation and reporting of results in growing individuals needs to be undertaken by individuals who are familiar with scanning children and the potential pitfalls.

The Utility of DXA Assessment at the Forearm, Proximal Femur, and Lateral Distal Femur, and Vertebral Fracture Assessment in the Pediatric Population: 2019 ISCD Official Position

Dual-energy X-ray absorptiometry (DXA) is widely used in the evaluation of bone fragility in children. Previous recommendations emphasized total body less head and lumbar spine DXA scans for clinical bone health assessment. However, these scan sites may not be possible or optimal for all groups of children with conditions that threaten bone health. The utility of DXA scans of the proximal femur, forearm, and radius were evaluated for adequacy of reference data, precision, ability of predict fracture, and applicability to all, or select groups of children. In addition, the strengths and limitations of vertebral fracture assessment by DXA were evaluated. The new Pediatric Positions provide guidelines on the use of these additional measures in the assessment of skeletal health in children.

Dual-energy X-ray absorptiometry pitfalls in Thalassemia Major

BACKGROUND

Low mineral mass and reduced bone strength with increased fracture risk are the main causes of morbidity in Thalassemia Major (TM). The pathogenesis is multifactorial and includes ineffective erythropoiesis with medullary expansion, multiple endocrine dysfunctions, direct iron bone deposition, deferoxamine-induced bone dysplasia, and reduced physical activity associated with disease complications. Dual-energy X-ray absorptiometry (DXA) is the "gold standard" for bone mineral density (BMD) assessment and for bone strength and quality evaluation. This method identifies patients at greater risk of fragility fractures, guiding treatment and monitoring response to therapy. In TM, DXA shows limitations concerning BMD calculation accuracy and fracture risk prediction. One of the main challenges in the assessment of bone health in patients with TM is the accurate interpretation of densitometric results.

PURPOSE

This review investigates the major pitfalls in DXA implementation and interpretation in TM.

METHODS

Available literature has been assessed.

CONCLUSIONS

DXA shows limitations in assessing bone mineral "status" in TM, especially in the paediatric population, due to the peculiar characteristics of bone architecture and deformities associated with the disease. A radiological technique adjustment in this population is mandatory.

Physical changes, laboratory parameters, and bone mineral density during testosterone treatment in adolescents with gender dysphoria

INTRODUCTION

Current treatment guidelines for adolescents with gender dysphoria recommend therapy with gonadotropin-releasing hormone agonists (GnRHa) and testosterone in transgender males. However, most evidence on the safety and efficacy of testosterone is based on studies in adults.

AIM

This study aimed to investigate the efficacy and safety of testosterone treatment in transgender adolescents.

METHODS

The study included 62 adolescents diagnosed with gender dysphoria who had started GnRHa treatment and had subsequently received testosterone treatment for more than 6 months.

MAIN OUTCOME MEASURE

Virilization, anthropometry, laboratory parameters, and bone mineral density (BMD) were analyzed.

RESULTS

Adolescents were treated with testosterone for a median duration of 12 months. Voice deepening began within 3 months in 85% of adolescents. Increased hair growth was first reported on the extremities, followed by an increase of facial hair. Acne was most prevalent between 6 and 12 months of testosterone therapy. Most adolescents had already completed linear growth; body mass index and systolic blood pressure increased but diastolic blood pressure did not change. High-density lipoprotein (HDL) cholesterol and sex hormone binding globulin significantly decreased, but hematocrit, hemoglobin, prolactin, androstenedione, and dehydroepiandrosterone sulfate significantly increased, although not all changes were clinically significant. Other lipids and HbA1c did not change. Vitamin D deficiency was seen in 32-54% throughout treatment. BMD z-scores after 12 to 24 months of testosterone treatment remained below z-scores before the start of GnRHa treatment.

CLINICAL IMPLICATIONS

Adolescents need to be counseled about side effects with potential longer term implications such as increased hematocrit and decreased HDL cholesterol and decreased BMD z-scores. They should be advised on diet, including adequate calcium and vitamin D intake; physical exercise; and the use of tobacco and alcohol to avoid additional risk factors for cardiovascular disease and osteoporosis.

STRENGTHS & LIMITATIONS

Strengths are the standardized treatment regimen and extensive set of safety parameters investigated. Limitations are the limited duration of follow-up and lack of a control group so some of the observed changes may be due to normal maturation rather than to treatment.

CONCLUSION

Testosterone effectively induced virilization beginning within 3 months in the majority of adolescents. Acne was a common side effect, but no short-term safety issues were observed. The increased hematocrit, decreased HDL cholesterol, and decreased BMD z-scores are in line with previous studies. Further follow-up studies will need to establish if the observed changes result in adverse outcomes in the long term. Stoffers IE, de Vries MC, Hannema SE. Physical Changes, Laboratory Parameters, and Bone Mineral Density During Testosterone Treatment in Adolescents with Gender Dysphoria. J Sex Med 2019;16:1459-1468.

Lumbar Spine Bone Mineral Apparent Density in Children: Results From the Bone Mineral Density in Childhood Study

CONTEXT

Dual-energy X-ray absorptiometry (DXA) is a cornerstone of pediatric bone health assessment, yet differences in height-for-age confound the interpretation of areal bone mineral density (aBMD) measures. To reduce the confounding of short stature on spine bone density, use of bone mineral apparent density (BMAD) and height-for-age Z-score (HAZ)‒adjusted aBMD (aBMDHAZ) are recommended. However, spine BMAD reference data are sparse, and the degree to which BMAD and aBMDHAZ account for height-related artifacts in bone density remains unclear.

OBJECTIVE

We developed age-, sex-, and population ancestry‒specific spine BMAD reference ranges; compared height-adjustment methods in accounting for shorter stature; and assessed the stability of these measures over time.

DESIGN

Secondary analysis of data from a previous longitudinal study.

PARTICIPANTS

Children and adolescents aged 5 to 19 years at baseline (n = 2014; 922 males; 22% black) from the Bone Mineral Density in Childhood Study.

MAIN OUTCOME MEASURES

Lumbar spine BMAD and aBMDHAZ from DXA.

RESULTS

Spine BMAD increased nonlinearly with age and was greater in blacks and females (all P < 0.001). Age-specific spine BMAD z-score reference curves were constructed for black and non‒black males and females. Overall, both BMAD and aBMDHAZz scores reduced the confounding influence of shorter stature, but neither was consistently unbiased across all age ranges. Both BMAD and aBMDHAZz scores tracked strongly over 6 years (r = 0.70 to 0.80; all P < 0.001).

CONCLUSION

This study provided robust spine BMAD reference ranges and demonstrated that BMAD and aBMDHAZ partially reduced the confounding influence of shorter stature on bone density.

Analysis of bone mass and its relationship with body composition in school-aged children and adolescents based on stage of puberty and site specificity: A retrospective case-control study

The aim of this study was to better understand the relationship of bone mass with body composition based on different stages of puberty and to illuminate the contribution of site-specific fat mass and lean mass (FM and LM) compared with bone mass in school-aged children and adolescents in Chongqing, China.A total of 1179 healthy subjects of both sexes were recruited. Bone mineral content (BMC), bone mineral density (BMD), bone area, and both FM and LM were measured by dual-energy X-ray absorptiometry (DXA). The fat mass and lean mass indexes (FMI and LMI, respectively) were calculated as the FM (kg) and LM (kg) divided by the height in meters squared, respectively.Most of the bone mass indicators were significantly higher for postpubertal boys than for girls at the same stage (P < .001). The proportion of subjects with normal bone mass increased, while the proportion of subjects with osteopenia and osteoporosis decreased with increased body weight regardless of gender and puberty stage (P < .01). FM and LM were significantly positively related to bone mass regardless of gender and puberty stage (P < .0001). FMI and LMI were significantly positively related to bone mass in most conditions (P < .05 and P < .0001, respectively). Four components of the FM and LM were linearly and significantly associated with BMD and BMC for TB and TBHL. Among them, the head fat mass and head lean mass showed the greatest statistical contribution.In the process of assessing bone status, we recommend measuring fat and lean masses, including the fat and lean masses of the head.

Diagnosis of osteoporotic vertebral fractures in children

Osteoporosis is a generalised disorder of the skeleton with reduced bone density and abnormal bone architecture. It increases bone fragility and renders the individual susceptible to fractures. Fractures of the vertebrae are common osteoporotic fractures. Vertebral fractures may result in scoliosis or kyphosis and, because they may be clinically silent, it is imperative that vertebral fractures are diagnosed in children accurately and at an early stage, so the necessary medical care can be implemented. Traditionally, diagnosis of osteoporotic vertebral fractures has been from lateral spine radiographs; however, a small number of studies have shown that dual energy x-ray absorptiometry is comparable to radiographs for identifying vertebral fractures in children, while allowing reduced radiation exposure. The diagnosis of vertebral fractures from dual energy x-ray absorptiometry is termed vertebral fracture assessment. Existing scoring systems for vertebral fracture assessment in adults have been assessed for use in children, but there is no standardisation and observer reliability is variable. This literature review suggests the need for a semiautomated tool that (compared to the subjective and semiquantitative methods available) will allow more reliable and precise detection of vertebral fractures in children.

Revised reference curves of bone mineral density according to age and sex for Iranian children and adolescents

Bone health evaluation in children requires an appropriate reference database. We have shown higher curves for spine aBMD in Iranian subjects than Americans, but lower curves for femoral neck and total body. These results can be used as reference values to assist Iranian clinicians in interpreting and monitoring bone densitometry results.

PURPOSE

Bone health evaluation requires an appropriate reference database that can identify the bone deficit according to age, sex, puberty, and race. The aim of this study was to determine bone mineral density Z-scores in Iranian children and adolescents and their comparability with other reference data.

METHODS

A sample of 476 healthy children and adolescents, aged 9-18 years, from Kawar (an urban community, 50 km east of Shiraz, Iran) was selected and bone mineral measurements of the lumbar spine, femoral neck, and total body (less head) were done. Sex-specific height-for-age, weight-for-age, and BMI-for-age Z-scores, as well as bone mineral density Z-scores, were calculated.

RESULTS

Extended reference curves for bone mineral content (BMC) and areal bone mineral density (aBMD) of the total body less head, lumbar spine, and femoral neck, for ages 9-18 years were constructed relative to sex and age. We found that median, - 2SD, and + 2SD curves for the lumbar spine aBMD were higher in Iranian subjects than in the American participants, but the curves of the femoral neck and total body were lower. Also, we showed that subjects with a lower height-for-age Z-score had a lower BMC and aBMD Z-score in the lumbar spine, femoral neck, and total body (p < 0.001).

CONCLUSIONS

Relevant differences in bone mineral density and its curves exist between Iranian children and adolescents and other databases, revealing a significant potential for misdiagnosis. However, our results can be used to provide reference databases to assist clinicians in interpreting, assessing, and monitoring bone densitometry.

Serum 25-hydroxyvitamin D and bone mineral density among children and adolescents in a Northwest Chinese city

Although vitamin D is essential for bone health, little is known about prevalence of vitamin D deficiency and low bone mineral density (BMD) among children, especially those in developing countries. It also remains unclear whether serum 25-hydroxyvitamin D [25(OH)D] is associated with BMD among children. We investigated these questions among children and adolescents in Yinchuan (latitude: 38° N), Ningxia, an economically underdeveloped province in Northwest China. A total of 1582 children (756 boys and 826 girls), aged 6-18 years, were recruited from schools using the stratified random sampling method in fall 2015. Serum 25(OH)D concentrations were measured by enzyme-linked immunosorbent assay, and BMD was quantified by dual-energy X-ray absorptiometry. Vitamin D deficiency (defined as serum 25(OH)D ≤ 37.5 nmol/L) was present in 35.5% of study subjects. There were no clear patterns of differences in serum 25(OH)D concentrations across the four age groups compared (6-9 years, 10-13 years, 14-16 years, and 17-18 years). The prevalence of low total body less head (TBLH) BMD (defined as a Z-score of ≤ -2.0 standard deviations away from the mean BMD values of the Chinese pediatric reference population) among children examined was 1.8% and was not significantly different among the four age groups considered. Linear regression analysis revealed that age, weight, and height were significantly and positively associated with TBLH BMD and that the strongest determinant of TBLH BMD was age in boys and weight in girls. There were no significant correlations between serum 25(OH)D concentrations and BMD obtained for total body and at various skeletal sites (r ranged from -0.005 to 0.014) regardless of whether children evaluated were sufficient, insufficient, or deficient in vitamin D. In conclusion, more than one-third of children and adolescents in a Northwest Chinese city were deficient in vitamin D but only <2% of them developed low BMD.

Progressive bone impairment with age and pubertal development in neurofibromatosis type I

Bone density impairment represents an established complication in adults with neurofibromatosis type 1, while few data exist in the pediatric population. Age- and gender-adjusted bone mass decreases with age and pubertal development, identifying childhood as the best time frame to introduce prevention strategies aiming at peak bone mass achievement.

PURPOSE

The present study aims at evaluating bone mineral density (BMD) in a population of children with neurofibromatosis type I (NF-1), with particular focus on changes occurring during growth and pubertal development.

METHODS

Bone metabolic markers and bone status [by dual-energy X-ray absorptiometry scans (DXA) of the total body and lumbar spine with morphometric analysis] were assessed in 50 children (33 males; mean age ± SD, 11.6 ± 4 years). Bone mineral apparent density (BMAD), trabecular bone score (TBS), and bone strain (BS) of the lumbar spine (LS) DXA were also obtained.

RESULTS

In our cohort areal BMD (aBMD) Z-score was below the mean in 88% of the patients at LS (70% after correction for bone size) and in 86% considering total body (TB) DXA. However, aBMD Z-score was < - 2 in 12% after correction for bone size at LS and TB, respectively. Lumbar spine aBMD Z-score (r = - 0.54, P < 0.0001), LS BMAD Z-score (r = - 0.53, P < 0.0001), and TB Z-score (r = - 0.39, P = 0.005) showed a negative correlation with growth and pubertal development (P = 0.007, P = 0.02, P = 0.01, respectively), suggesting that patients failed to gain as much as expected for age.

CONCLUSION

Bone density impairment becomes more evident with growth and pubertal development in NF-1 patients, thus identifying childhood as the best time frame to introduce prevention strategies aiming at peak bone mass achievement. TBS and BS, providing bone DXA qualitative information, could be useful during longitudinal follow-up for better characterizing bone impairment in these patients.

Use of dual energy X-ray absorptiometry in pediatric patients

Dual Energy X-ray Absorptiometry (DXA) is a vital tool for assessing bone health in patients at risk for fragility fractures. In pediatric patients, this technology is used in conjunction with clinical fracture history to diagnosis osteoporosis and monitor treatment response. Childhood and adolescence is characterized by linear growth and bone mass accrual; thus there are important differences in the interpretation of bone measurements obtained by DXA in these young patients. This review aims to explore the current indications for DXA use and interpretation of DXA in the pediatric age group using currently available reference databases. Limitations of DXA in pediatric patients, specifically in children with short stature, will be explored. We will review several pathophysiologic mechanisms that may lead to low bone density in children, discussing representative diseases and the recommendations for monitoring bone health with DXA in these conditions. Finally, we will highlight new methods by which DXA imaging can gather additional information on bone health in children and may improve our ability to predict fractures and osteoporosis.

The effect of the ketogenic diet on the developing skeleton

The ketogenic diet (KD) is a medically supervised, high fat, low carbohydrate and restricted protein diet which has been used successfully in patients with refractory epilepsy. Only one published report has explored its effect on the skeleton. We postulated that the KD impairs skeletal health parameters in patients on the KD. Patients commenced on the KD were enrolled in a prospective, longitudinal study, with monitoring of Dual-energy X-ray absorptiometry (DXA) derived bone parameters including bone mineral content and density (BMD). Areal BMD was converted to bone mineral apparent density (BMAD) where possible. Biochemical parameters, including Vitamin D, and bone turnover markers, including osteocalcin, were assessed. Patients were stratified for level of mobility using the gross motor functional classification system (GMFCS). 29 patients were on the KD for a minimum of 6 months (range 0.5-6.5 years, mean 2.1 years). There was a trend towards a reduction in lumbar spine (LS) BMD Z score of 0.1562 (p=0.071) per year and 20 patients (68%) had a lower BMD Z score at the end of treatment. While less mobile patients had lower baseline Z scores, the rate of bone loss on the diet was greater in the more mobile patients (0.28 SD loss per year, p=0.026). Height adjustment of DXA data was possible for 13 patients, with a mean reduction in BMAD Z score of 0.19 SD. Only two patients sustained fractures. Mean urinary calcium-creatinine ratios were elevated (0.77), but only 1 patient developed renal calculi. Children on the KD exhibited differences in skeletal development that may be related to the diet. The changes were independent of height but appear to be exaggerated in patients who are ambulant. Clinicians should be aware of potential skeletal side effects and monitor bone health during KD treatment. Longer term follow up is required to determine adult/peak bone mass and fracture risk throughout life.

Bone mineral density reference standards for Chinese children aged 3-18: cross-sectional results of the 2013-2015 China Child and Adolescent Cardiovascular Health (CCACH) Study

OBJECTIVES

No nationwide paediatric reference standards for bone mineral density (BMD) are available in China. We aimed to provide sex-specific BMD reference values for Chinese children and adolescents (3-18 years).

METHODS

Data (10 818 participants aged 3-18 years) were obtained from cross-sectional surveys of the China Child and Adolescent Cardiovascular Health in 2015, which included four municipality cities and three provinces. BMD was measured using Hologic Discovery Dual Energy X-ray Absorptiometry (DXA) scanner. The DXA measures were modelled against age, with height as an independent variable. The LMS statistical method using a curve fitting procedure was used to construct reference smooth cross-sectional centile curves for dependent versus independent variables.

RESULTS

Children residing in Northeast China had the highest total body less head (TBLH) BMD while children residing in Shandong Province had the lowest values. Among children, TBLH BMD was higher for boys as compared with girls; but, it increased with age and height in both sexes. Furthermore, TBLH BMD was higher among US children as compared with Chinese children. There was a large difference in BMD for height among children from these two countries. US children had a much higher BMD at each percentile (P) than Chinese children; the largest observed difference was at P50 and P3 and the smallest difference was at P97.

CONCLUSIONS

This is the first study to present a sex-specific reference dataset for Chinese children aged 3-18 years. The data can help clinicians improve interpretation, assessment and monitoring of densitometry results.

Novel Leptin Receptor Mutations Identified in Two Girls with Severe Obesity Are Associated with Increased Bone Mineral Density

BACKGROUND

Recessive mutations in the leptin receptor (LEPR) are a rare cause of hyperphagia and severe early-onset obesity. To date, the phenotype has only been described in 25 obese children, some of whom also had altered immune function, hypogonadotropic hypogonadism, reduced growth hormone secretion, hypothalamic hypothyroidism or reduced adult height. We provide a detailed description of the phenotype of 2 affected girls to add to this knowledge.

METHODS

Whole-exome sequencing and targeted sequencing were used to detect the LEPR mutations. RNA analysis was performed to assess the effect of splice-site mutations.

RESULTS

In 2 unrelated girls with severe obesity, three novel LEPR mutations were detected. Longitudinal growth data show normal childhood growth, and in the older girl, a normal adult height despite hypogonadotropic hypogonadism and the lack of an obvious pubertal growth spurt. Bone age is remarkably advanced in the younger (prepubertal) girl, and bone mineral density (BMD) is high in both girls, which might be directly or indirectly related to leptin resistance.

CONCLUSION

The spectrum of clinical features of LEPR deficiency may be expanded with increased BMD. Future observations in LEPR-deficient subjects should help further unravel the role of leptin in human bone biology.

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.

Correlation Between Central and Peripheral Bone Mineral Density Around the Elbow Measured by Dual-Energy X-Ray Absorptiometry in Healthy Children and Adolescents

This pilot study was performed to evaluate the correlation between central bone mineral density (BMD) and peripheral BMD around the elbow in children and adolescents and to compare BMD values across skeletal sites. Twenty-seven healthy volunteers between 5 and 18 yr of age were recruited for the study. Anthropometric measurements including height and weight were performed. Central BMD at the lumbar spine and left femur and peripheral BMD at the supracondylar area, medial condyle, lateral condyle, and olecranon were measured using dual-energy X-ray absorptiometry (DXA). Higher BMD levels were found in the central skeleton (lumbar spine and femur) than in peripheral sites around the elbow (p < 0.001). BMD values around the elbow ranged from 44.4% to 63.2% compared to the BMD values of the central skeleton. Among the peripheral sites around the elbow, the highest BMD was observed at the supracondylar area and olecranon, and the lowest BMD was found at the lateral condyle. Peripheral DXA measurements around the elbow were significantly correlated with central DXA measurements at the lumbar spine and femur. In conclusion, this study demonstrated that the measurements of BMD around the elbow were correlated with BMD at central sites. Given the small sample size in this pilot study, further study with a large cohort is required to use the BMD measurements around the elbow as a valid clinical tool for fracture risk assessment and population-based epidemiological studies.

Amalgamated Reference Data for Size-Adjusted Bone Densitometry Measurements in 3598 Children and Young Adults-the ALPHABET Study

The increasing use of dual-energy X-ray absorptiometry (DXA) in children has led to the need for robust reference data for interpretation of scans in daily clinical practice. Such data need to be representative of the population being studied and be "future-proofed" to software and hardware upgrades. The aim was to combine all available pediatric DXA reference data from seven UK centers to create reference curves adjusted for age, sex, ethnicity, and body size to enable clinical application, using in vivo cross-calibration and making data back and forward compatible. Seven UK sites collected data on GE Lunar or Hologic Scanners between 1996 and 2012. Males and females aged 4 to 20 years were recruited (n = 3598). The split by ethnic group was white 2887; South Asian 385; black Afro-Caribbean 286; and mixed heritage 40. Scans of the total body and lumbar spine (L₁ to L₄ ) were obtained. The European Spine Phantom was used to cross-calibrate the 7 centers and 11 scanners. Reference curves were produced for L₁ to L₄ bone mineral apparent density (BMAD) and total body less head (TBLH) and L₁ to L₄ areal bone mineral density (aBMD) for GE Lunar Prodigy and iDXA (sex- and ethnic-specific) and for Hologic (sex-specific). Regression equations for TBLH BMC were produced using stepwise linear regression. Scans of 100 children were randomly selected to test backward and forward compatibility of software versions, up to version 15.0 for GE Lunar and Apex 4.1 for Hologic. For the first time, sex- and ethnic-specific reference curves for lumbar spine BMAD, aBMD, and TBLH aBMD are provided for both GE Lunar and Hologic scanners. These curves will facilitate interpretation of DXA data in children using methods recommended in ISCD guidelines. The databases have been created to allow future updates and analysis when more definitive evidence for the best method of fracture prediction in children is agreed. © 2016 American Society for Bone and Mineral Research.

Sex- and Site-Specific Normative Data Curves for HR-pQCT

The purpose of this study was to develop age-, site-, and sex-specific centile curves for common high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite-element (FE) parameters for males and females older than 16 years. Participants (n = 866) from the Calgary cohort of the Canadian Multicentre Osteoporosis Study (CaMos) between the ages of 16 and 98 years were included in this study. Participants' nondominant radius and left tibia were scanned using HR-pQCT. Standard and automated segmentation methods were performed and FE analysis estimated apparent bone strength. Centile curves were generated for males and females at the tibia and radius using the generalized additive models for location, scale, and shape (GAMLSS) package in R. After GAMLSS analysis, age-, sex-, and site-specific centiles (10th, 25th, 50th, 75th, 90th) for total bone mineral density and trabecular number as well as failure load have been calculated. Clinicians and researchers can use these reference curves as a tool to assess bone health and changes in bone quality. © 2016 American Society for Bone and Mineral Research.

Prophylactic oral bisphosphonate therapy in duchenne muscular dystrophy

INTRODUCTION

We assessed prophylactic use of bisphosphonate (BP) in Duchenne muscular dystrophy (DMD) patients on glucocorticoid (GC) therapy.

METHODS

Fifty-two DMD patients on daily GC were offered BP (oral risedronate). Patients were reviewed for tolerability, side effects, bone pain, and fracture frequency. Bone mineral density (BMD) was determined by annual dual energy X-ray absorptiometry. BP-treated patients were compared with 15 BP-naïve patients (untreated cohort).

RESULTS

Side effects occurred in 9 patients. Thirty-six patients continued BP therapy for over 12 months (mean, 3.6 years). Five treated patients reported bone pain. Three treated patients suffered a vertebral fracture, significantly less than in the untreated cohort (5/15). Lumbar spine adjusted BMD Z-scores remained unchanged in treated patients and were significantly greater than in the untreated cohort.

CONCLUSIONS

Prophylactic oral risedronate therapy was tolerated by most DMD patients. It appears to maintain BMD and may reduce fracture rate in DMD patients on GC. Muscle Nerve 54: 79-85, 2016.

Result of Proficiency Test and Comparison of Accuracy Using a European Spine Phantom among the Three Bone Densitometries

Background

Although dual energy X-ray absorptiometry (DXA) is known to standard equipment for bone mineral density (BMD) measurements. Different results of BMD measurement using a number of different types of devices are difficult to use clinical practice. The purpose of this study was to evaluate discrepancy and standardizations of DXA devices from three manufactures using a European Spine Phantom (ESP).

Methods

We calculated the accuracy and precision of 36 DXA devices from three manufacturers (10 Hologic, 16 Lunar, and 10 Osteosys) using a ESP (semi-anthropomorphic). The ESP was measured 5 times on each equipment without repositioning. Accuracy was assessed by comparing BMD (g/cm²) values measured on each device with the actual value of the phantom. Precision was assessed by the coefficient of variation (CVsd).

Results

Lunar devices were, on average, 22%, 8.3%, and 5% overestimation for low (L1) BMD values, medium (L2), and high (L3) BMD values. Hologic devices were, on average, 6% overestimation for L1 BMD, and 5% and 6.2% underestimation for L2 and L3 BMD values. Osteosys devices was, on average, 12.7% (0.063 g/cm²), 6.3% (0.062 g/cm²), and 5% (0.075 g/cm²) underestimation for L1, L2, and L3, respectively. The mean CVsd for L1-L3 BMD were 0.01%, 0.78%, and 2.46% for Lunar, Hologic, and Osteosys devices respectively.

Conclusions

The BMD comparison in this study demonstrates that BMD result of three different devices are significant different between three devices. Differences of BMD between three devices are necessary to BMD standardization.

Bone density assessment in a tertiary paediatric centre over 13 years: Referral patterns and limitations

AIM

This study aims to examine the referral practices for the Royal Children's Hospital (RCH) bone density service over the past 13 years and to demonstrate referral patterns and possible limitations to accessing paediatric bone densitometry.

METHODS

All patients attending the RCH Healthy Bones Unit for bone densitometry from 1 July 1999 to 30 June 2012, aged under 18 years of age, were included. Densitometry results were downloaded directly from the Hologic scanner into an Excel document. However, the referring unit and indication for referral were collected manually from either the referral card or the hospital's scanned medical records system.

RESULTS

A total of 5767 bone densitometry scans were performed over the study period on 3004 patients. The majority of referrals were made by the Endocrinology department, followed by Adolescent Medicine, Gastroenterology and Neurology. Relatively few referrals were made by general paediatrics. The most common indication for bone density test overall was eating disorders, followed by steroid use, osteogenesis imperfecta and other collagen disorders and inflammatory bowel disease. The lowest lumbar spine z-scores by indication were for cerebral palsy and other causes of immobility.

CONCLUSIONS

Multiple childhood diseases predispose to low bone density; however, paediatric bone densitometry is still underutilised and not appropriately supported by subsidies.

Optimizing bone health in children and adolescents

The pediatrician plays a major role in helping optimize bone health in children and adolescents. This clinical report reviews normal bone acquisition in infants, children, and adolescents and discusses factors affecting bone health in this age group. Previous recommended daily allowances for calcium and vitamin D are updated, and clinical guidance is provided regarding weight-bearing activities and recommendations for calcium and vitamin D intake and supplementation. Routine calcium supplementation is not recommended for healthy children and adolescents, but increased dietary intake to meet daily requirements is encouraged. The American Academy of Pediatrics endorses the higher recommended dietary allowances for vitamin D advised by the Institute of Medicine and supports testing for vitamin D deficiency in children and adolescents with conditions associated with increased bone fragility. Universal screening for vitamin D deficiency is not routinely recommended in healthy children or in children with dark skin or obesity because there is insufficient evidence of the cost-benefit of such a practice in reducing fracture risk. The preferred test to assess bone health is dual-energy x-ray absorptiometry, but caution is advised when interpreting results in children and adolescents who may not yet have achieved peak bone mass. For analyses, z scores should be used instead of T scores, and corrections should be made for size. Office-based strategies for the pediatrician to optimize bone health are provided. This clinical report has been endorsed by American Bone Health.

Human proximal femur bone adaptation to variations in hip geometry

The study of bone mass distribution at proximal femur may contribute to understand the role of hip geometry on hip fracture risk. We examined how bone mineral density (BMD) of proximal femur adapts to inter individual variations in the femoral neck length (FNL), femoral neck width (FNW) and neck shaft angle (NSA). A parameterized and dimensionally scalable 3-D finite element model of a reference proximal femur geometry was incrementally adjusted to adopt physiological ranges at FNL (3.90-6.90cm), FNW (2.90-3.46cm), and NSA (109-141º), yielding a set of femora with different geometries. The bone mass distribution for each femur was obtained with a suitable bone remodelling model. The BMDs at the integral femoral neck (FN) and at the intertrochanteric (ITR) region, as well as the BMD ratio of inferomedial to superolateral (IM:SL) regions of FN and BMD ratio of FN:ITR were used to represent bone mass distribution. Results revealed that longer FNLs present greater BMD (g/cm(3)) at the FN, mainly at the SL region, and at the ITR region. Wider FNs were associated with reduced BMD at the FN, particularly at the SL region, and at the ITR region. Larger NSAs up to 129° were associated with BMD diminutions at the FN and ITR regions and with increases of the IM:SL BMD ratio while NSAs larger than 129° resulted in decrease of the IM:SL BMD ratio. These findings suggest hip geometry as moderator of the mechanical loading influence on bone mass distribution at proximal femur with higher FNL favoring the BMD of FN and ITR regions and greater FNW and NSA having the opposite effect. Augmented values of FNL and FNW seem also to favor more the BMD at the superolateral than at the inferomedial FN region.

A comparative study of dual-X-ray absorptiometry and quantitative ultrasonography for the evaluating bone status in subjects with Rett syndrome

Rett syndrome, an X-linked neurodevelopmental disorder primarily affecting girls, is frequently characterized by a reduced bone mineral density (BMD) with an increased risk of fragility fractures. The aim of the study was to assess bone status by DXA technique and by quantitative ultrasound (QUS) in subjects with Rett syndrome and to evaluate which DXA or QUS parameters better correlate with clinical features. In 156 Rett subjects (mean age 13.6 ± 8.2 years) and in 62 controls, we measured BMD at femoral neck (BMD-FN) and at total femur (BMD-TF). Apparent volumetric bone mineral density (vBMAD) was also calculated. In all subjects, QUS parameters at phalanges by Bone Profiler-IGEA (amplitude-dependent speed of sound: AD-SoS and bone transmission time: BTT) were evaluated. We found that both DXA parameters and QUS parameters were significantly lower in Rett subjects than in controls. All clinical characteristics were positively correlated to BMD-FN, BMD-TF, AD-SoS, and BTT (p < 0.001) but not with vBMAD-FN. All ultrasonographic parameters were significantly correlated to BMD-FN and BMD-TF, whereas vBMAD-FN showed only positive significant correlation with densitometric parameters (p < 001). In Rett subjects BMD-FN was predicted primarily by weight and movement capacity, whereas vBMAD-FN was predicted by weight, height, and calcium intake. Moreover, AD-SoS was predicted by weight, height, and age, while BTT was predicted only by height. In conclusion, in our study the performance of QUS at phalanges was similar to those of BMD at femur, therefore, both areal BMD at femur and QUS at phalanges (AD-SoS and BTT) may be equally useful in the evaluation of skeletal status in Rett patients.

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.

The correlation between calcaneus stiffness index calculated by QUS and total body BMD assessed by DXA in Chinese children and adolescents

Few studies have shown comparison data between calcaneus stiffness index (SI) calculated by quantitative ultrasound (QUS) and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) in the Chinese population. This study was aimed to examine the correlations between calcaneus SI calculated by QUS and total body BMD and bone mineral content (BMC) measured by DXA in Chinese children and adolescents. We measured the total body BMD and BMC using Lunar Prodigy (GE Healthcare), and speed of sound (SOS), broadband ultrasound attenuation (BUA), and a calculated SI of the left os calcis using Lunar Achilles Express (GE Healthcare) in 392 healthy Chinese schoolchildren and adolescents aged 5-19 years. The short-term precision for DXA was 0.5 % for total body BMD. The precision for QUS was 1.8 % for SI, 2.9 % for BUA, and 0.4 % for SOS. Pearson's correlation coefficients (r) were calculated to assess the possible correlations between the total body BMC by DXA and SI calculated by QUS. There were significantly positive correlations between SI of the left os calcis and total body BMD (r = 0.693, p < 0.001, n = 392) and BMC (r = 0.690, p < 0.001, n = 392). For all the subjects, significant positive correlations were observed between the calcaneal SI and the age, weight, height, BMI, total body BMD, total body BMC, total body lean mass, and total body fat mass, with r ranging from 0.310 (total body fat mass) to 0.693 (total body BMD) (p < 0.001, n = 392). In conclusion, QUS bone densitometry is a useful measuring method showing the physiological bone development in childhood and adolescence.

Children with nephrotic syndrome have greater bone area but similar volumetric bone mineral density to healthy controls

BACKGROUND

Glucocorticoid use has been associated with an increased fracture risk and reduced bone mineral density (BMD), particularly in the trabecular compartment. However the contribution of the underlying inflammatory disease process to these outcomes is poorly understood. Childhood nephrotic syndrome (NS) typically follows a relapsing-remitting course often requiring recurrent courses of glucocorticoids, but with low systemic inflammation during remission. NS therefore represents a useful clinical model to investigate the effects of glucocorticoids on BMD and bone geometry in childhood.

METHODS

Children with NS were compared to age and sex matched healthy controls. Body composition and areal BMD (whole body, lumbar spine and hip) were assessed by DXA. Peripheral quantitative computed tomography (pQCT) scans were obtained at metaphyseal (4%) and diaphyseal (66%) sites of the tibia to determine volumetric BMD and bone cross-sectional geometry. Lifetime cumulative glucocorticoid exposure was calculated from medical records.

RESULTS

29 children with NS (55% male, age 10.7±3.1years) were compared to 29 healthy controls (55% male, age 11.0±3.0years). The children with NS were of similar height SDS to controls (p=0.28), but were heavier (0.65±1.28SDS vs -0.04±0.89SDS, p=0.022) and had greater body fat percentage SDS (0.31±1.01 vs -0.52±1.10, p=0.008). Tibial trabecular and cortical vBMD were similar between the two groups but bone cross-sectional area (CSA) was significantly greater in children with NS at both the metaphysis (954±234mm(2) vs 817±197mm(2), p=0.002) and diaphysis (534.9±162.7mm(2) vs 463.2±155.5mm(2), p=0.014). Endosteal and periosteal circumferences were greater in children with NS than controls (both p<0.01), resulting in reduced cortical thickness (2.4±0.7mm vs 2.8±0.7mm, p=0.018), but similar cortical CSA (p=0.22). The differences in cortical geometry were not statistically significant when weight was included as a confounding factor. There were no associations between cumulative steroid exposure, duration of NS or number of relapses and any bone parameter.

CONCLUSIONS

Tibial bone CSA is increased in children with NS. We speculate that this is a compensatory response to increased body weight. Defects in trabecular BMD were not identified in this cohort of children with NS.

High bone mineral apparent density in children with X-linked hypophosphatemia

Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck.

INTRODUCTION

BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients.

METHODS

A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated.

RESULTS

Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3-2.7); p < 0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (-0.0 to 2.1); p = 0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p = 0.02). BMAD of the spine was evaluated according to the Molgaard's approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of -0.4 (-1.0 to 0.1); p = 0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8-2.1); p < 0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach.

CONCLUSIONS

Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.

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.

Advances in bone imaging for osteoporosis

The diagnosis and management of osteoporosis have been improved by the development of new quantitative methods of skeletal assessment and by the availability of an increasing number of therapeutic options, respectively. A number of imaging methods exist and all have advantages and disadvantages. Dual-energy X-ray absorptiometry (DXA) is the most widely available and commonly utilized method for clinical diagnosis of osteoporosis and will remain so for the foreseeable future. The WHO 10-year fracture risk assessment tool (FRAX(®)) will improve clinical use of DXA and the cost-effectiveness of therapeutic intervention. Improved reporting of radiographic features that suggest osteoporosis and the presence of vertebral fracture, which are powerful predictors of future fractures, could increase the frequency of appropriate DXA referrals. Quantitative CT remains predominantly a research tool, but has advantages over DXA--allowing measurement of volumetric density, separate measures of cortical and trabecular bone density, and evaluation of bone shape and size. High resolution imaging, using both CT and MRI, has been introduced to measure trabecular and cortical bone microstructure. Although these methods provide detailed insights into the effects of disease and therapies on bone, they are technically challenging and not widely available, so they are unlikely to be used in clinical practice.

Selective reduction in trabecular volumetric bone mineral density during treatment for childhood acute lymphoblastic leukemia

During treatment of childhood acute lymphoblastic leukemia (ALL) fracture incidence is increased. Studies using DXA, which measures a composite of both trabecular and cortical BMD, have shown reduced BMD during treatment. We investigated changes in compartmental (cortical and trabecular) volumetric BMD (vBMD) and bone geometry using peripheral quantitative computed tomography. These outcomes were also analysed in relation to adiposity and treatment factors. Thirty nine patients with ALL (64% male, median age 7.2 years (4.1-16.9)) were compared to 34 healthy controls (50% male, median age 9.1 years (4.4-18.7)). DXA-derived age-specific standard deviation scores (SDS) of the lumbar spine (LS) and femoral neck (FN) were reduced in subjects with ALL compared to controls (p ≤ 0.01). This persisted following adjustment for body size using height-specific SDS (LS -0.72 ± 1.02 vs -0.18 ± 0.72, p=0.01; FN -1.53 ± 0.96 vs -0.74 ± 0.74, p=0.001) and bone mineral apparent density (BMAD) SDS (LS -0.76 ± 1.14 vs 0.04 ± 1.08, p=0.01; FN -1.63 ± 1.38 vs -0.16 ± 1.20, p<0.001). Radial and tibial trabecular vBMD was also reduced (196.5 ± 54.9 mg/cm(3) vs 215.2 ± 39.9 mg/cm(3), p=0.03 and 232.8 ± 60.3mg/cm(3) vs 267.5 ± 60.2mg/cm(3), p=0.002, respectively), but cortical vBMD at the radius and tibia was similar in patients and controls. A lowered tibial bone strength index (BSI) was identified in patients with ALL (53.9 ± 23.1mg/mm(4) vs 82.5 ± 27.8 mg/mm(4), p<0.001) suggesting lower fracture threshold from compressive forces. No relationships with measures of adiposity, duration of treatment or cumulative corticosteroid dose were identified. Our findings therefore suggest that reduction in trabecular vBMD during childhood ALL treatment may contribute to the observed increased fracture incidence and bony morbidity in this group.