Bone mineral acquisition during adolescence and early adulthood: a study in 574 healthy females 10-24 years of age

Fractures in Childhood and Young Adulthood According to Maternal Smoking in Late Pregnancy. A Danish Cohort Study

Fractures account for the most frequent cause of hospitalization during childhood and numbers have increased over time. Of all fractures in childhood and young adulthood, 66% are recurrent fractures, suggesting that some people are predestined for fractures. The aim of this study was to investigate the association between maternal smoking during late pregnancy and the risk of fractures in the children.The study included 11,082 mothers and their children from the cohort "Healthy Habits for Two" born between 1984 and 1987. Information about maternal smoking during pregnancy came from questionnaires filled out in pregnancy, while information about fractures was derived from the Danish National Patient Registry. Over a follow-up of 24 years (1994-2018), Cox regression with multiple failures was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for fractures in childhood and young adulthood according to maternal smoking in late pregnancy. Information about body mass index (BMI) and smoking status in young adulthood was included as time variant covariates.During an age span of 8-32 years, 6,420 fractures were observed. Of the mothers, 39.1% smoked during late pregnancy. Compared to children of mothers who did not smoke, children of mothers who smoked 1-9 cigarettes per day and 10+ cigarettes per day had an increased risk of fractures (HR 1.14 [CI: 1.06; 1.21] and HR 1.14 [CI: 1.07; 1.22], respectively). After adjusting for BMI and smoking status in young adulthood, the findings were slightly strengthened, showing an increased risk of fractures of 23 and 25% in children of mothers smoking 1-9 cigarettes per day and 10+ cigarettes per day, respectively.Maternal smoking during late pregnancy was associated with a higher risk of fractures in the child. This result indicates that exposure to cigarette smoke in utero may play a role in lifelong bone health.

Evaluation of Trabecular Bone Microarchitecture and Bone Mineral Density in Young Women, Including Selected Hormonal Parameters

The absence of non-invasive methods for assessing bone material and structural changes is a significant diagnostic challenge. Dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) testing is the gold standard for osteoporosis diagnosis. BMD and the trabecular bone score (TBS) have facilitated targeted osteoporosis prevention and treatment in clinical settings. The findings from this study indicate that BMD modulation in young women is influenced by various hormones, potentially compromising the diagnostic precision of BMD for subclinical bone demineralization. A total of 205 women aged 19 to 37 underwent anthropometric measurements and hormonal tests. BMD was determined using DXA, and TBS values were computed from the lumbar spine L1-L4 segment. The multivariate analysis findings suggest that BMD might not be determined by hormones. The relationship between TBS and TSH was statistically significant in the univariate analysis, which indicates the efficacy of further studies to determine the link between TBS and specific hormones. Analyzing the strength of the correlation between TBS and hormones in the univariate analysis shows which factors are worth considering in further analyses. This makes it possible to create better techniques that will help identify young women who are at a higher risk of developing osteoporosis.

Hormonal and natural contraceptives: a review on efficacy and risks of different methods for an informed choice

The debate about contraception has become increasingly important as more and more people seek safe and effective contraception. More than 1 billion women of reproductive age worldwide need a method of family planning, and wellbeing, socio-economic status, culture, religion and more influence the reasons why a woman may ask for contraception. Different contraceptive methods exist, ranging from 'natural methods' (fertility awareness-based methods - FABMs) to barrier methods and hormonal contraceptives (HCs). Each method works on a different principle, with different effectiveness.FABMs and HCs are usually pitted against each other, although it's difficult to really compare them. FABMs are a valid alternative for women who cannot or do not want to use hormone therapy, although they may have a high failure rate if not used appropriately and require specific training. HCs are commonly used to address various clinical situations, although concerns about their possible side effects are still widespread. However, many data show that the appropriate use of HC has a low rate of adverse events, mainly related to personal predisposition.The aim of this review is to summarize the information on the efficacy and safety of FABMs and HCs to help clinicians and women choose the best contraceptive method for their needs.

Detailed MRI evaluation of the spine: a 2-year follow-up study of young individuals reporting different training doses

OBJECTIVE

To characterize the discs and vertebrae in detail over time in a group of adolescent individuals with varying training doses using magnetic resonance imaging (MRI).

METHOD

Thirty-five students were recruited from regular high schools (n=13) as well as schools with athlete competitive skiing programmes (n = 22). The thoraco-lumbar spine of all individuals was examined at baseline and at 2-year follow-up using the same 1.5T scanner and imaging protocol. The individuals were grouped based on their reported training dose: low-to-normal training dose (≤5 h/week, n = 11, mean age 16.5 ± 0.5 years) and high training dose (>5 h/week, n = 24, mean age 17.2 ± 0.6 years.) RESULTS: At baseline, the signal intensity in the discs and vertebrae were significantly lower in individuals reporting high compared to low-to-normal training dose. The vertebral signal changed significantly over the 2-year period in both groups. However, only individuals reporting low-to-normal training dose displayed an overall disc signal change. Interestingly, the regional analysis displayed at baseline high annular signals in the more training-active individuals followed by a reduction over the two-year period.

CONCLUSION

This study suggests that disc degeneration is manifested earlier in individuals reporting a higher training dose. Over a 2-year period, however, the degeneration process did not accelerate further. Also, a significant difference in the vertebral signal, at baseline and follow-up as well as over time, could be seen between groups of individuals reporting high versus low-to-normal training dose.

Intestinal Vitamin D Receptor Is Dispensable for Maintaining Adult Bone Mass in Mice With Adequate Calcium Intake

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3)-mediated intestinal calcium (Ca) absorption supplies Ca for proper bone mineralization during growth. We tested whether vitamin D receptor (VDR)-mediated 1,25(OH)2D3 signaling is critical for adult Ca absorption and bone by using mice with inducible Vdr gene knockout in the whole intestine (villin-CreERT2+/- × Vdrf/f, WIK) or in the large intestine (Cdx2-CreERT2+/- ×Vdrf/f, LIK). At 4-month-old, Vdr alleles were recombined (0.05 mg tamoxifen/g BW, intraperitoneally [i.p.], 5 days) and mice were fed diets with either 0.5% (adequate) or 0.2% (low) Ca. Ca absorption was examined after 2 weeks while serum 1,25(OH)2D3, bone mass, and bone microarchitecture were examined after 16 weeks. Intestinal and renal gene expression was measured at both time points (n = 12/genotype/diet/time point). On the 0.5% Ca diet, all phenotypes in WIK and LIK mice were similar to the controls. Control mice adapted to the 0.2% low-Ca diet by increasing renal Cyp27b1 mRNA (3-fold), serum 1,25(OH)2D3 level (1.9-fold), and Ca absorption in the duodenum (Dd, + 131%) and proximal colon (PCo, + 28.9%), which prevented bone loss. In WIK mice, low-Ca diet increased serum 1,25(OH)2D3 (4.4-fold) but Ca absorption remained unaltered in the Dd and PCo. Consequently, significant bone loss occurred in WIK mice (e.g., cortical thickness, Ct.Th, -33.7%). LIK mice adapted to the low-Ca diet in the Dd but not the PCo, and the effect on bone phenotypes was milder (e.g., Ct.Th, -13.1%). Our data suggest intestinal VDR in adult mice prevents bone loss under low Ca intake but is dispensable under adequate calcium intake.

A 2-Year Longitudinal Study of Bone Mineral Density in Collegiate Distance Runners

ABSTRACT

Brimacomb, OE, Martinez, MP, McCormack, WP, and Almstedt, HC. A 2-year longitudinal study of bone mineral density in collegiate distance runners. J Strength Cond Res XX(X): 000-000, 2022-The purpose of this investigation was to examine changes in bone mineral density (BMD) of male and female collegiate distance runners over 2 years. Bone mineral density of 29 collegiate distance runners (16 men and 13 women) were measured 5 times over 24 months using dual-energy x-ray absorptiometry (DXA) at the anterior-posterior (AP) and lateral (LAT) spine, femoral neck (FN), total hip (TH), whole body (WB), and ultradistal (UD) forearm. Repeated-measures multivariate analysis of covariance, with bone-free lean mass (BFLM) as covariate, was used to compare mean BMD values. Adjusted for BFLM, there were no significant differences (p > 0.05) in BMD at any site between sexes. There were no significant differences at the AP or LAT spine, FN, or WB between visit 1 and 5 for either sex. There was a significant increase in BMD (p = 0.044) at the UD forearm over 2 years in males. However, 56% of the men (n = 9) had a Z-score < -1.0 at the UD forearm. Seven of 11 women had Z-scores < -1.0 at the LAT spine and 4 of 13 had Z-scores < -1.0 at the AP spine. There were no significant changes in BMD at any site over the 2-year time frame, except a significant increase in BMD at the nondominant forearm in men. The spine appears to be an area of concern for women in this study when examining Z-score results. Coaches and medical staff need to continually educate collegiate endurance athletes about the importance of achieving and maintaining BMD through their college years.

Comparison of quantitative ultrasonography and dual X-ray absorptiometry for bone status assessment in South African children living with HIV

Children living with HIV (CLHIV) have decreased bone mineral content (BMC) and density (BMD), increasing risk for fracture and future osteoporosis. While DXA is the gold-standard for bone assessments, it lacks availability in resource-constrained settings (RCS). Quantitative ultrasound (QUS) offers an alternative owing to its portability, low cost, ease of handling, and lack of ionizing radiation. While QUS has detected reduced bone quality in CLHIV, the relationship between QUS and DXA in this population remains unexplored. At baseline and 12 months, BMC and BMD of the whole body, lumbar spine, and radius were measured by DXA in a longitudinal cohort of CLHIV in Johannesburg, South Africa. Calcaneal speed of sound (SOS) and broadband ultrasound attenuation (BUA) and radius SOS were obtained by QUS, and calcaneal stiffness index (SI) was calculated. Spearman correlations, with and without HIV stratification, were performed between QUS and DXA measurements at each visit and for absolute difference in measurements between visits. At baseline and 12-months, calcaneal BUA and SI displayed strong positive correlations with DXA, with only modest correlations between radial QUS and DXA at baseline. Longitudinal measures of QUS did not correlate with DXA. At both baseline and 12-months, individuals with DXA whole-body BMD z-score < -1 displayed significantly lower calcaneal BUA and SI. Cross-sectionally, calcaneal QUS correlates strongly with whole body DXA and may represent a viable diagnostic alternative in RCS. Longitudinally, the two methods do not correlate well, possibly reflecting that each method assesses distinct aspects of bone architecture.

Bone mineral density, nutrient intake, and physical activity among young women from Uganda

Few studies have characterized bone mineral density (BMD) among health young African women. In our study of 496 Ugandan women age ≤25 years, we found that women had healthy BMD that were lower on average than the standard reference ranges. Reference ranges available for BMD measurements need greater precision.

PURPOSE

Data describing bone mineral density (BMD), nutrient intake, and body composition among healthy, young women in sub-Saharan Africa are limited. Using baseline data from a cohort of young, healthy Ugandan women, we summarize bone health and associated risk factors for reduced bone mass.

METHODS

Using baseline data from Ugandan women ages 16-25 years who enrolled in an ongoing cohort study of bone health with concurrent use of injectable contraception and oral HIV pre-exposure prophylaxis, we describe the distribution of BMD, nutrient intake, physical activity, and body composition. The association of low BMD (1 or more standard deviations below the age, sex, and race-matched reference range from the USA) and calcium intake, vitamin D intake, physical activity, and body composition was estimated using multivariable logistic regression.

RESULTS

In 496 healthy, Ugandan women with median age of 20 years (interquartile range [IQR] 19-21) and median fat:lean mass ratio of 0.55 (IQR 0.46-0.64), median lumbar spine and total hip BMD was 0.9g/cm2 (IQR 0.9-1.0) each. For lumbar spine, Z-score distributions were lower overall than the reference population and 9.3% and 36.3% of women had Z-score >2 and >1 standard deviations below the reference range, respectively. For total hip, Z-scores were similar to the reference population and 1.0% and 12.3% of women had Z-score >2 and >1 standard deviations below the reference range, respectively. In the week prior to enrollment, 41.1% of women consumed >7 servings of calcium, 56.5% had >7 servings of vitamin D, and 98.6% reported ≥2.5 h of physical activity. Having greater body fat was associated with greater frequency of low lumbar spine BMD (p<0.01 for fat:lean mass ratio, total body fat percentage, waist circumference, and BMI).

CONCLUSION

Young Ugandan women exhibited healthy levels of BMD that were lower than the reference range population.

The Influence of Low Energy Availability on Bone Mineral Density and Trabecular Bone Microarchitecture of Pubescent Female Athletes: A Preliminary Study

The influence of low energy availability (LEA) on bone mineral density (BMD) and trabecular bone microarchitecture in pubescent female athletes is unclear. This study aimed to investigate the influence of LEA on BMD and trabecular bone microarchitecture in 21 pubescent female athletes (age, 12−15 years; 11 track and field athletes, 10 gymnasts). We used two indices to assess LEA: energy availability and the percent of ideal body weight. Dual-energy X-ray absorptiometry was used to obtain total body less head, lumbar spine BMD Z-scores, and lumbar trabecular bone scores (TBS). Pearson’s or Spearman’s correlation coefficients were used to assess the relationship among EA, percent of ideal body weight, and bone parameters. The threshold for statistical significance was set at p < 0.05. The percent of ideal body weight was significantly correlated with the BMD Z-scores of the total body less head (r = 0.61; p < 0.01), lumbar spine (r = 0.55; p < 0.01), and lumbar TBS (r = 0.47; p = 0.03). However, energy availability was not correlated with bone parameters. These findings suggest that screening for low ideal body weight may be a useful predictor of low BMD and insufficient trabecular bone microarchitecture in pubescent female athletes.

Body composition in sexual precocity

PURPOSE OF REVIEW

In this review, we have summarized the current data on the effect of sexual precocity and treatment with gonadotropin-releasing hormone analogues (GnRHa) on body composition.

RECENT FINDINGS

Higher body weight and weight gain in infancy and childhood may increase the risk of early puberty in girls. The relation between BMI and pubertal onset in boys is controversial. Current studies draw attention to the fact that a similar relationship may exist in boys too. Obesity prevalence is high among girls with central precocious puberty (CPP) and treatment with GnRHa has a different effect on BMI according to baseline body composition. Although BMI values of normal weight girls tend to increase under treatment, they return to normal following treatment. The few studies that have followed up body composition longitudinally in girls show a gradual increase in adiposity, decrease in muscle mass and bone mineral density during GnRHa treatment, whereas bone mass was preserved after treatment. Adequate data are not available in boys to determine the effect of GnRHa therapy on body composition.

SUMMARY

Body composition and fat distribution should be monitored longitudinally in patients with CPP treated with GnRHa to ascertain the long-term effects of therapy.

Persistently lower bone mass and bone turnover among South African children living with well controlled HIV

OBJECTIVE

We evaluated longitudinal trends and associations between bone mass, bone turnover and inflammatory markers among South African children living with HIV (CLHIV) and controls.

DESIGN

We previously reported decreased bone mass among CLHIV independent of marked inflammation and increased bone turnover. The goal of this study was to evaluate longitudinal changes in bone mass, bone turnover and inflammation over 2 years.

METHODS

Longitudinal analyses were conducted among 220 CLHIV and 220 controls. Anthropometric measurements, physical activity, antiretroviral regimen, virologic and immunologic status, whole body (WB) and lumbar spine (LS) bone mineral content (BMC) and bone mineral density (BMD) were collected (enrollment, 12 and 24 months). Bone turnover markers including C-telopeptide of type I collagen (CTx) and procollagen type I N-terminal propeptide (P1NP) and inflammatory markers including interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble CD14 and high-sensitivity C-reactive protein (hsCRP) were collected at enrollment and 24 months.

RESULTS

Compared with controls, CLHIV had significantly lower mean WB-BMC, WB-BMD, WB-BMC z scores, LS-BMC and LS-BMD as well as lower bone formation (P1NP) and resorption (CTx), and higher hsCRP and soluble CD14 over 24 months. CLHIV on efavirenz (EFV) had consistently lower TNF-alpha and IL-6 compared with those on ritonavir-boosted lopinavir (LPV/r) at all time points.

CONCLUSION

Over 2 years of follow-up, South African CLHIV had persistently lower bone mass, bone turnover, and macrophage activation. Lower bone mass and higher pro-inflammatory cytokine profiles were consistently observed among those on LPV/r-based compared with EFV-based regimens.

Dual-energy X-ray absorptiometry bone densitometry in pediatrics: a practical review and update

The assessment of pediatric bone mineral content and density is an evolving field. In this manuscript we provide a practical review and update on the interpretation of dual-energy X-ray absorptiometry (DXA) in pediatrics including historical perspectives as well as a discussion of the recently published 2019 Official Position Statements of the International Society of Clinical Densitometry (ISCD) that apply to children.

Hormonal replacement therapy in adolescents and young women with chemo- or radio-induced premature ovarian insufficiency: Practical recommendations

In women with premature ovarian insufficiency (POI), hormonal therapy (HT) is indicated to decrease the risk of morbidity and to treat symptoms related to prolonged hypoestrogenism. While general recommendations for the management of HT in adults with POI have been published, no systematic suggestions focused on girls, adolescents and young women with POI following gonadotoxic treatments (chemotherapy, radiotherapy, stem cell transplantation) administered for pediatric cancer are available. In order to highlight the challenging issues specifically involving this cohort of patients and to provide clinicians with the proposal of practical therapeutic protocol, we revised the available literature in the light of the shared experience of a multidisciplinary team of pediatric oncologists, gynecologists and endocrinologists. We hereby present the proposals of a practical scheme to induce puberty in prepubertal girls and a decisional algorithm that should guide the clinician in approaching HT in post-pubertal adolescents and young women with iatrogenic POI.

Oral contraceptive use, bone mineral density, and bone turnover markers over 12 months in college-aged females

INTRODUCTION

The purpose of this study was to compare bone mineral density (BMD) and bone turnover markers between combined oral contraceptive (COC) and non-COC users over 12 months.

MATERIALS AND METHODS

COC users (n = 34, age = 19.2 ± 0.5) and non-COC users (n = 28, age = 19.3 ± 0.6) provided serum at baseline, 6 months, and 12 months. C-terminal telopepetides (CTX) and pro-collagen type 1 N-terminal propeptides (P1NP) were determined using ELISA. BMD was measured at the three time points using dual-energy x-ray absorptiometry (DXA).

RESULTS

COC users had greater CTX than non-COC users at baseline (18.6 ± 8.2 vs. 13.8 ± 5.3 ng/mL, P = 0.021) and 6 months (20.4 ± 10.3 vs. 14.2 ± 8.5 ng/mL, P = 0.018). Controlling for lean mass, groups were similar in BMD. Over 12 months, non-COC users maintained BMD at the spine, while the COC users declined 2.2% in lateral spine BMD (0.773 ± 0.014 to 0.756 ± 0.014 g/cm², P = 0.03) and 0.7% in anterior-posterior spine BMD (1.005 ± 0.015 to 0.998 ± 0.015 g/cm², P = 0.069). Non-COC users increased in BMD of the whole body over 12 months (P < 0.001) while COC users had no change. Women who began COCs within 4 years after menarche had lower BMD at the hip and whole body. Women taking very low dose COCs (20 mcg ethinyl estradiol, EE) significantly declined in CTX, P1NP, and lateral spine BMD in comparison to participants using low dose COCs (30/35 mcg EE).

CONCLUSION

College-aged women who did not use COCs increased BMD of the whole body, while COC users had elevated bone turnover, declines in spinal BMD, and lack of bone acquisition of the whole body over 12 months. Young females who initiate COC use early after menarche may experience skeletal detriments.

Concurrent Bilateral Anterior Tibial Stress Fractures and Vitamin D Deficiency in an Adolescent Female Athlete: Treatment With Early Surgical Intervention

Case: A 16-year-old African American multi-sport female athlete presents with bilateral worsening activity-related leg pain for 5 months. Multiple bilateral anterior tibial diaphyseal stress fractures and significant vitamin D deficiency were identified. She was treated with a combination of vitamin D supplements and static intramedullary nailing of the bilateral tibias resulting in clinical and radiographic healing and return to sports. Discussion: Vitamin D deficiency and high level of activity in a young athlete may be the etiology to atypical multiple stress fractures. In athletes who may want to return to sport rapidly, early operative intervention and correction of vitamin D deficiency may be treatment options. Level of Evidence: Level V- case report.

Effect of Childbirth Age on Bone Mineral Density in Postmenopausal Women

BACKGROUND

In postmenopausal women, there is rapid bone loss due to estrogen depletion. In women, reproductive factors such as age at menarche, breastfeeding, and parity are considered risk factors of osteoporosis. Many reports suggest that obesity is associated with a reduced risk of osteoporosis. This nationwide, population-based study aims to identify the association between maternal age and osteoporosis risk in postmenopausal women of different obesity classifications.

METHODS

We assessed data from the Korean National Health and Nutrition Examination Survey 2010-2012. The study included 1,328 postmenopausal women, after excluding women with missing data for reproductive history among 4,546 postmenopausal women in the survey. Multivariate regression was used to identify the association between childbirth age and postmenopausal bone mineral density after adjustments for confounding factors.

RESULTS

The prevalence of postmenopausal osteoporosis was 35.24% (n = 468). After dividing the subjects into obese and non-obese groups based on body mass index (BMI) and waist circumference, there were significant differences between non-osteoporosis and osteoporosis groups with regard to age at first childbirth, age at last childbirth, and parity in the BMI-based general obesity group. The prevalence of osteoporosis was highest in women older than 35 years old at last childbirth. The prevalence of osteoporosis was also greater in women with parity ≥ 4 compared to those with lower parity levels.

CONCLUSION

Postmenopausal women of older age at last childbirth and higher parity were at increased risk of osteoporosis in the BMI-based non-general obesity group.

Contraceptive care for Canadian youth

Sexual and reproductive health is an important component of comprehensive health care for youth. This statement provides guidance for selecting and prescribing contraceptives for youth, including commonly prescribed hormonal contraceptives-the pill, patch, ring and injectable progestin-and long-acting reversible contraceptives (LARCs). LARCs, including subdermal implants (which are not available in Canada) and intrauterine contraceptives (IUCs), are substantially more effective during typical use than hormonal contraceptives. This statement endorses LARCs as the first-line option for contraception for Canadian youth, while emphasizing that providers must collaborate with youth to select a contraceptive method that is acceptable, safe, effective and practical for them. Strategies that eliminate obstacles to initiating and continuing contraception are provided.

Sexual Dimorphism and the Origins of Human Spinal Health

Recent observations indicate that the cross-sectional area (CSA) of vertebral bodies is on average 10% smaller in healthy newborn girls than in newborn boys, a striking difference that increases during infancy and puberty and is greatest by the time of sexual and skeletal maturity. The smaller CSA of female vertebrae is associated with greater spinal flexibility and could represent the human adaptation to fetal load in bipedal posture. Unfortunately, it also imparts a mechanical disadvantage that increases stress within the vertebrae for all physical activities. This review summarizes the potential endocrine, genetic, and environmental determinants of vertebral cross-sectional growth and current knowledge of the association between the small female vertebrae and greater risk for a broad array of spinal conditions across the lifespan.

Muscle functions and bone strength are impaired in adolescents with type 1 diabetes

BACKGROUND

Sarcopenia and osteoporosis are among the late complications of type 1 diabetes (T1D) in adults. Whether and to what extent musculoskeletal impairment is present in childhood and adolescence has yet to be determined. The aim of this study was to assess volumetric bone mineral density (BMD) and dynamic muscle function in adolescents with T1D and to assess the clinical and biochemical predictors of their musculoskeletal system.

METHODS

Ninety-five children and adolescents (59 boys and 36 girls, mean age 16.2±1.2years) with T1D were included in this cross-sectional study. Study participants were divided into two groups according to the duration of the disease (<6years and >9years, respectively). Volumetric BMD of the non-dominant tibia was assessed using peripheral quantitative computed tomography (pQCT). Dynamic muscle function was evaluated using jumping mechanography. Gender- and height-specific Z-scores were calculated using published reference data. HbA1c was evaluated retrospectively as an average over the past 5years.

RESULTS

Relative muscle power (P_max/mass) and force (F_max/body weight) were significantly decreased in T1D subjects (mean Z-scores -0.4±1.0; p<0.001, and -0.3±1.1; p<0.01, respectively). The duration of T1D negatively affected P_max/mass (p<0.01) but not F_max/body weight (p=0.54). Patients with T1D had also decreased trabecular BMD, the Strength-Strain Index and cortical thickness (mean Z-scores -0.8±1.3; -0.5±0.8 and -1.1±0.8, respectively, p<0.001 for all) whereas cortical BMD was increased when compared to controls (Z-score 1.2±0.90, p<0.001). No association was observed between the HbA1c and 25-hydroxyvitamin D levels and bone or muscle parameters.

CONCLUSION

T1D influences the musculoskeletal system in adolescence. Decreased muscle function could contribute to the osteoporosis reported in adult diabetic patients.

Musculoskeletal system in children and adolescents with inflammatory bowel disease: normal muscle force, decreased trabecular bone mineral density and low prevalence of vertebral fractures

Low bone mineral density (BMD) and an increased fracture incidence are two extraintestinal complications associated with inflammatory bowel disease (IBD). We aimed to evaluate musculoskeletal traits and assess vertebral fracture (VF) rate in children and adolescents with IBD. Seventy patients with IBD with a median age of 13.8 years were included. The BMD and geometric parameters of the non-dominant tibia were assessed using pQCT. Dynamic muscle functions were evaluated using jumping mechanography. VFs were assessed according to the semiquantitative standardized method by Genant. The muscle functions adjusted for the patients' weight did not differ from the reference population. A low trabecular BMD (Z-score - 1.6; p < 0.001) and cortical thickness (Z-score - 0.7; p < 0.001) were found in children and adolescents with IBD. Conversely, an increased cortical BMD (Z-score 1.1; p < 0.001) was noted. No significant association was found between the 25-OHD serum levels and the bone or muscle measurements. One patient with asymptomatic VF was identified.

CONCLUSION

IBD in childhood or adolescents affects bones but not muscles. Bone changes are independent of the 25-OHD serum level. A thoracolumbar spine X-ray should not be routinely recommended in children with IBD. What is Known: • Low bone mineral density and an increased fracture rate are the complications associated with IBD. • Bone strength and structural development is strongly dependent on skeletal muscle stimulation. What is New: • Children with IBD have altered bone density and geometry but normal dynamic muscle functions. • Thoracolumbar spine X-ray should be indicated on an individual basis in children with IBD.

Predicting bone mineral acquisition during puberty: data from a 3-year follow-up study in Hamamatsu, Japan

Although most adult bone mass is acquired before adolescence, only a few studies have assessed bone turnover markers in children. Thus, the utility of bone markers to evaluate and predict bone mineral accrual in children is unclear. The present study assessed the association between serum bone markers at 11 years of age and subsequent changes in bone gain. Information on bone minerals and bone markers at baseline and at the 3-year follow-up were obtained from 121 children who registered as fifth-grade students in 2010, in Hamamatsu, Japan. Whole-body bone mineral content (WBBMC) and whole-body bone mineral density (WBBMD) were measured using dual-energy X-ray absorptiometry. Boys showed significant (P < 0.05) positive relationships between intact osteocalcin at baseline and WBBMC at follow-up (β = 0.24), between tartrate-resistant acid phosphatase isoenzyme 5b (TRAP5b) and WBBMC (β = 0.34), and between TRAP5b and WBBMD (β = 0.34), after adjusting for potential confounding factors. In girls, adjusted means of 3-year gain in both WBBMC and WBBMD significantly increased from the lowest to highest quartiles of type 1 collagen cross-linked C-terminal telopeptide. In boys, adjusted means of 3-year gain in both WBBMC and WBBMD significantly increased from the lowest to highest quartiles of TRAP5b. Children with a high concentration of bone turnover markers tended to exhibit substantial accrual of bone minerals. These results suggest that serum levels of circulating biomarkers at age 11 predict subsequent bone mineral accrual.

Effect of Extended 30 μg Ethinyl Estradiol with Continuous Low-Dose Ethinyl Estradiol and Cyclic 20 μg Ethinyl Estradiol Oral Contraception on Adolescent Bone Density: A Randomized Trial

STUDY OBJECTIVE

To compare changes in lumbar spine bone mineral density after 12 months of a 91-day extended regimen or 28-day combined oral contraceptive with those in a healthy reference group not using hormonal contraceptives.

DESIGN

Phase 2, multicenter, open-label, randomized, controlled study.

SETTING

Forty-five academic centers, clinical research centers, and community practices in the United States.

PARTICIPANTS

Eight hundred twenty-nine postmenarcheal adolescent girls aged 12-18 years.

INTERVENTIONS

Adolescents were randomly assigned to 91-day levonorgestrel (LNG)/ethinyl estradiol (EE) extended regimen (84 days of LNG 150 μg/EE 30 μg with 7 days of EE 10 μg [LNG/EE extended regimen]) or 28 days of LNG/EE (21 days of LNG 100 μg/EE 20 μg with 7 days of placebo [LNG/EE 21/7]) for 12 months. A reference group not seeking hormonal contraception was also evaluated.

MAIN OUTCOME MEASURES

The primary end point was mean percent change in lumbar spine bone mineral density measured using dual-energy x-ray absorptiometry.

RESULTS

Of 1361 adolescents randomized/enrolled, 829 were included in the primary analysis. Mean changes in lumbar spine bone mineral density were +2.26% with LNG/EE extended regimen, +1.45% with LNG/EE 21/7, and +2.50% in the reference group. Noninferiority of the LNG/EE extended regimen compared with the reference group was shown. A statistically significant treatment difference was found between LNG/EE 21/7 and the reference group (1.05%; 95% confidence interval, 0.61%-1.49%) but not between LNG/EE extended regimen and the reference group (0.23%; 95% confidence interval, -0.20% to 0.67%). No new safety signals were noted.

CONCLUSION

Compared with the reference group, bone accrual was statistically significantly lower among LNG/EE 21/7 users but not among LNG/EE 30-μg extended regimen users. Additional research is needed to clarify the clinical relevance of these findings.

Efavirenz is associated with higher bone mass in South African children with HIV

BACKGROUND

We investigate if switching from a ritonavir-boosted lopinavir (LPV/r)-based to an efavirenz-based antiretroviral therapy (ART) regimen is associated with beneficial bone development.

METHODS

The CHANGES Bone Study follows HIV-infected children who participated in a noninferiority randomized trial in Johannesburg, South Africa evaluating the safety and efficacy of preemptive switching to efavirenz (n = 106) compared with remaining on LPV/r (n = 113). HIV-uninfected children were also recruited. Whole-body and lumbar spine bone mineral content (BMC) were assessed by dual-energy X-ray absorptiometry at a cross-sectional visit. BMC Z-scores adjusted for sex, age, and height were generated. Physical activity and dietary intake were assessed. CD4 percentage and viral load were measured. We compared bone indices of HIV-infected with HIV-uninfected children and LPV/r with efavirenz by intent-to-treat.

RESULTS

The 219 HIV-infected (52% boys) and 219 HIV-uninfected (55% boys) children were 6.4 and 7.0 years of age, respectively. Mean ART duration for HIV-infected children was 5.7 years. Whole-body BMC Z-score was 0.17 lower for HIV-infected children compared with HIV-uninfected children after adjustment for physical activity, dietary vitamin D and calcium (P = 0.03). Whole-body BMC Z-score was 0.55 higher for HIV-infected children switched to efavirenz compared with those remaining on LPV/r after adjustment for physical activity, dietary vitamin D and calcium, CD4 percentage, and viral load (P < 0.0001).

CONCLUSION

South African HIV-infected children receiving ART have lower bone mass compared with HIV-uninfected controls. Accrued bone mass is positively associated with switching to efavirenz-based ART compared with remaining on LPV/r, providing additional rationale for limiting LPV/r exposure once viral suppression has been achieved.

Posterior Surgery for Adolescent Idiopathic Scoliosis With Pedicle Screws and Ultrahigh-Molecular Weight Polyethylene Tape: Achieving the Ideal Thoracic Kyphosis

STUDY DESIGN

Prospective clinical case series.

OBJECTIVES

To describe our surgical procedure and results for posterior correction and fusion with a hybrid approach using pedicle screws, hooks, and ultrahigh-molecular weight polyethylene tape with direct vertebral rotation (DVR) (the PSTH-DVR procedure) for treatment of adolescent idiopathic scoliosis (AIS) with satisfactory correction in the coronal and sagittal planes.

SUMMARY OF BACKGROUND DATA

Introduction of segmental pedicle screws in posterior surgery for AIS has facilitated good correction and fusion. However, procedures using only pedicle screws have risks during screw insertion, higher costs, and decreased postoperative thoracic kyphosis. We have obtained good outcomes compared with segmental pedicle screw fixation in surgery for AIS using a relatively simple operative procedure (PSTH-DVR) that uses fewer pedicle screws.

METHODS

The subjects were 30 consecutive patients with AIS who underwent the PSTH-DVR procedure and were followed for a minimum of 2 years. Preoperative flexibility, preoperative and postoperative Cobb angles, correction rates, loss of correction, thoracic kyphotic angles (T5-T12), coronal balance, sagittal balance, and shoulder balance were measured on plain radiographs. Rib hump, operation time, estimated blood loss, spinal cord monitoring findings, complications, and scoliosis research society (SRS)-22 scores were also examined.

RESULTS

The mean preoperative curve of 58.0 degrees (range, 40-96 degrees) was corrected to a mean of 9.9 degrees postoperatively, and the correction rate was 83.6%. Fusion was obtained in all patients without loss of correction. In 10 cases with preoperative kyphosis angles (T5-T12) <10 degrees, the preoperative mean of 5.8 degrees improved to 20.2 degrees at the final follow-up. Rib hump and coronal, sagittal and shoulder balances were also improved, and good SRS-22 scores were achieved at final follow-up.

CONCLUSIONS

The correction of deformity with PSTH-DVR is equivalent to that of all-pedicle screw constructs. The procedure gives favorable correction, is advantageous for kyphosis compared with segmental screw fixation, and uses the minimum number of pedicle screws. Therefore, the PSTH-DVR procedure may be useful for treatment of idiopathic scoliosis.

The Female Athlete Triad

The number of girls participating in sports has increased significantly since the introduction of Title XI in 1972. As a result, more girls have been able to experience the social, educational, and health-related benefits of sports participation. However, there are risks associated with sports participation, including the female athlete triad. The triad was originally recognized as the interrelationship of amenorrhea, osteoporosis, and disordered eating, but our understanding has evolved to recognize that each of the components of the triad exists on a spectrum from optimal health to disease. The triad occurs when energy intake does not adequately compensate for exercise-related energy expenditure, leading to adverse effects on reproductive, bone, and cardiovascular health. Athletes can present with a single component or any combination of the components. The triad can have a more significant effect on the health of adolescent athletes than on adults because adolescence is a critical time for bone mass accumulation. This report outlines the current state of knowledge on the epidemiology, diagnosis, and treatment of the triad conditions.

Body composition and bone density reference data for Korean children, adolescents, and young adults according to age and sex: results of the 2009-2010 Korean National Health and Nutrition Examination Survey (KNHANES)

We established the timing of peak bone mass acquisition and body composition maturation and provide an age- and sex-specific body composition and bone density reference database using dual-energy X-ray absorptiometry in Korean subjects 10-25 years of age. Reference percentiles and curves were developed for bone mineral content (BMC), bone mineral density (BMD) of the whole body, the lumbar spine, and the femoral neck, and for fat mass (FM) and lean mass (LM) of 1969 healthy participants (982 males) who participated in the 2009-2010 Korean National Health and Nutrition Examination Survey. Additionally, bone mineral apparent density (BMAD), FM index, and LM index were calculated to adjust for body size. BMC and BMD at all skeletal sites as well as LM increased with age, reaching plateaus at 17-20 years of age in females and 20-23 years of age in males. The femoral neck was the first to reach a bone mass plateau, followed by the lumbar spine and then the whole body. Spine BMAD increased with age in both sexes, but femoral and whole-body BMAD remained the same over time. Females displayed a dramatic increase in FM during puberty, but the FM of males decreased until mid-puberty. These findings indicate that bone health and body composition should be monitored using a normal reference database until the late second to early third decade of life, when statural growth and somatic maturation are completed.

Growth hormone deficiency during young adulthood and the benefits of growth hormone replacement

Until quite recently, the management of children with growth hormone deficiency (GHD) had focussed on the use of recombinant human GH (rhGH) therapy to normalise final adult height. However, research over the past two decades that has demonstrated deficits in bone health and cardiac function, as well as impaired quality of life in adults with childhood-onset GHD (CO-GHD), has questioned this practice. Some of these studies suggested that there may be short-term benefits of rhGH in certain group of adolescents with GHD during transition, although the impact of GHD and replacement during the transition period has not been adequately investigated and its long-term benefits remain unclear. GH therapy remains expensive and well-designed long-term studies are needed to determine the cost effectiveness and clinical benefit of ongoing rhGH during transition and further into adulthood. In the absence of compelling data to justify widespread continuation of rhGH into adult life, there are several questions related to its use that remain unanswered. This paper reviews the effects of growth hormone deficiency on bone health, cardiovascular function, metabolic profile and quality of life during transition and young adulthood.

Relationships between self-reported lifetime physical activity, estimates of current physical fitness, and aBMD in adult premenopausal women

Osteoporosis is common, and physical activity is important in its prevention and treatment. Of the categories of historical physical activity (PA) examined, we found that weight-bearing and very hard physical activity had the strongest relationships with areal bone mineral density (aBMD) throughout growth and into adulthood, while for measures of strength, only grip strength proved to be an independent predictor of aBMD.

PURPOSE/INTRODUCTION

To examine relationships between aBMD (total body, lumbar spine, proximal femur, tibial shaft, distal radius) and estimates of historical PA, current strength, and cardiovascular fitness in adult premenopausal women.

METHODS

One hundred fifty-two adult premenopausal women (40 ± 9.6 years) undertook aBMD (dual-energy X-ray absorptiometry (DXA)) and completed surveys to estimate historical physical activity representative of three decades (Kriska et al. [1]), while subsets underwent functional tests of isokinetic strength (hamstrings and quadriceps), grip strength (hand dynamometer), and maximum oxygen uptake (MaxV02; cycle ergometer). Historical PA was characterized by demand (metabolic equivalents, PA > 3 METS; PA > 7 METS) and type (weight-bearing; high impact).

RESULTS

Significant positive independent predictors varied by decade and site, with weight-bearing exercise and PA > 3 METS significant for the tibial shaft (10-19 decade) and only PA > 7 METS significant for the final two decades (20-29 and 30-39 years; total body and total hip). A significant negative correlation between high impact activity and tibial shaft aBMD appeared for the final decade. For strength measures, only grip strength was an independent predictor (total body, total hip), while MaxV02 provided a significant independent prediction for the tibial shaft.

CONCLUSIONS

Past PA > 7 METS was positively associated with aBMD, and such activity should probably constitute a relatively high proportion of all weekly PA to positively affect aBMD. The findings warrant more detailed investigations in a prospective study, specifically also investigating the potentially negative effects of high impact PA on tibial aBMD.

Pubertal induction in hypogonadism: Current approaches including use of gonadotrophins

Primary disorders of the gonad or those secondary to abnormalities of the hypothalamic pituitary axis result in hypogonadism. The range of health problems of childhood and adolescence that affect this axis has increased, as most children now survive chronic illness, but many have persisting deficits in gonadal function as a result of their underlying condition or its treatment. An integrated approach to hormone replacement is needed to optimize adult hormonal and bone health, and to offer opportunities for fertility induction and preservation that were not considered possible in the past. Timing of presentation ranges from birth, with disorders of sexual development, through adolescent pubertal failure, to adult fertility problems. This review addresses diagnosis and management of hypogonadism and focuses on new management strategies to address current concerns with fertility preservation. These include Turner syndrome, and fertility presevation prior to childhood cancer treatment. New strategies for male hormone replacement therapy that may impinge upon future fertility are emphasized.

Age at First Delivery and Osteoporosis Risk in Korean Postmenopausal Women: The 2008-2011 Korea National Health and Nutrition Examination Survey (KNHANES)

It has been reported in several studies that there may be a significant correlation between reproductive history and the risk of osteoporosis due to the effect of estrogen. Under this hypothesis, however, it is unclear whether the age at first delivery has any major influences on the risk of osteoporosis. Therefore, this study aimed to investigate the relationship between the age at first delivery and the risk of osteoporosis in Korean menopausal women. This study was performed using data from the 2008–2011 Korea National Health and Nutrition Examination Survey and included 2,530 Korean postmenopausal women. The diagnosis of osteoporosis was made using the World Health Organization T-score criteria (T-score ≤ -2.5, at the femoral neck or lumbar spine). Participants were categorized into 3 groups according to age at first delivery: ≤23, 24–29, and ≥30 years. Older age, lower body mass index, lower calcium intake, later menarche, and earlier menopause increased the risk of osteoporosis, whereas hormone therapy and oral contraceptive use were associated with a decreased risk of osteoporosis. Postmenopausal women whose first delivery occurred at age 24–29 years were shown to have a significantly increased risk of osteoporosis (odds ratio, 2.124; 95% confidence interval, 1.096–4.113; P = 0.026) compared to those who first gave birth after the age of 30 years. These findings suggest that postmenopausal women whose first delivery occurred in their mid to late 20s, a period during which bone mass slowly accumulates to the peak, are at an increased risk of osteoporosis.

Bone mineral density: reference values and correlates for Bangladeshi women aged 16-65 years

BACKGROUND

Studies examining the reference values of bone mineral density (BMD) and their patterns at different ages are largely based on data generated from developed countries. The objective of this study was to estimate reference values of BMD, along with their correlates, for women living in urban and suburban areas of Bangladesh.

METHODS

Dual-energy X-ray absorptiometry scans were performed on 500 women 16-65 years of age. Reference values at the lumbar spine (LS) and femoral neck (FN) were estimated after adjusting for height and weight. In addition, multiple linear regression analysis was used to examine correlates of BMD at the LS and FN.

RESULTS

Mean BMD was highest at the LS and FN in women 16-19 (1.001-1.007 g/cm(2)) and 16-22 years of age (0.880-0.888 g/cm(2)), respectively, and gradually declined with increasing age thereafter. BMD decreased at an annual rate of 0.0027 g/cm(2) at the LS and 0.0046 g/cm(2) at the FN among women aged 16-45 years. For women 46-65 years of age, the respective figures were 0.0073 and 0.0083 g/cm(2). In both age groups, body weight was positively associated with BMD at both sites, and with height only at the LS. In addition, years of pill use was positively associated with BMD at the LS among women aged 16-45 years. BMD levels at both sites began to decline during the early twenties among Bangladeshi women.

CONCLUSIONS

Age-specific BMD data generated in this study could be useful for interpreting bone densitometry data among women in Bangladesh and other South Asian countries.

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.

Lumbar trabecular bone mineral density distribution in patients with and without vertebral fractures: a case-control study

PURPOSE

The proportion of load transmitted through the lumbar neural arch increases with aging, spinal degeneration, and lordosis, effectively shielding the lumbar vertebral bodies from load. This stress shielding may contribute to bone loss in the vertebral body, leading to increased fracture risk. To test his hypothesis, we performed a study to determine if vertebral body fractures were associated with a higher neural arch/vertebral body volumetric bone mineral density (vBMD) ratio.

METHODS

Trabecular vBMD was calculated by quantitative CT in the L3 vertebral body and neural arch (pars interarticularis) of 36 women with vertebral compression fractures and 39 controls. Neural arch/vertebral body vBMD ratio was calculated, and its relationship to fracture status was determined using linear regression models adjusted for age and body mass index.

RESULTS

Vertebral body trabecular vBMD was lower in fracture cases as compared to controls (mean ± SD, 49.0 ± 36.0 vs. 87.5 ± 36.8 mg/cm(3), respectively; P < 0.001), whereas trabecular vBMD of the neural arch was similar (96.1 ± 57.6 in cases vs. 118.2 ± 57.4 mg/cm(3) in controls; P = 0.182). The neural arch/vertebral body vBMD ratio was significantly greater in the fracture group than in controls (2.31 ± 1.07 vs. 1.44 ± 0.57, respectively; P < 0.001).

CONCLUSION

These results support the hypothesis that stress shielding is a contributor to vertebral body bone loss and may increase fracture risk. Although further studies are needed, there may be a role for interventions that can shift vertebral loading in the spine to help prevent fracture.

The association between breastfeeding, maternal smoking in utero, and birth weight with bone mass and fractures in adolescents: a 16-year longitudinal study

The aim of this birth cohort study was to determine whether early life factors (birth weight, breastfeeding, and maternal smoking) were associated with bone mass and fractures in 16-year-old adolescents. The results suggest that breastfeeding is associated with higher bone mass and lower fracture risk at age 16 but not in utero smoking or birth weight.

INTRODUCTION

There are limited data on early life influences on bone mass in adolescence but we have previously reported in utero smoking, breastfeeding, and birth weight were associated with bone mass at age 8.

METHODS

Birth weight, breastfeeding intention and habit, and maternal smoking during pregnancy were assessed at phase one in 1988-1999 and by recall during phase two in 1996-1997. Bone mineral density (BMD) was measured by dual-energy X-ray densitometry. Fractures were assessed by questionnaire. Subjects included 415 male and female adolescents from Southern Tasmania representing 29 % of those who originally took part in a birth cohort study in 1988 and 1989.

RESULTS

Breastfeeding (assessed in a number of ways) was associated with a 2-3 % increase in BMD at all sites apart from the radius and around a one third reduction in fracture risk which persisted after adjustment for confounders. In univariate analysis, birth weight was associated with BMD at the hip, radius, and total body but this did not persist in multivariate analysis and there was no association with fracture. Smoking in utero had no association with BMD at any site or fracture.

CONCLUSIONS

Breastfeeding is associated with a beneficial increase in bone mass at age 16 and a reduction in fracture risk during adolescence. The association previously observed at 8 years of age is no longer present for birth weight or smoking in utero.

Impact of oral contraceptive on bone metabolism

Oral contraceptives are used by numerous women very often throughout a prolonged period of time and more and more and more frequently early in life, within the first reproductive years. According to the close relationship between estrogen and bone metabolism, the question of the impact of combined oral contraceptive (COC) on bone needs to be addressed. During adulthood, most studies have reported that COC, even those containing a low dose of ethinyl-estradiol had neutral or possibly beneficial effect on bone health. Use of COC within the perimenopausal years prevents the activation of bone metabolism and the decrease in bone mass. In adolescent girls, the skeletal effect of COC is of greater concern. Recent data suggest that the oral contraception may impede the development of peak bone mass, particularly when started within the teen years. Initiation of COC within the first 3 years after menarche would be a strong determinant of bone mass acquisition impairment. Whether this bone impact is also dependent on the dose of ethinyl-estradiol has not been fully elucidated. To date epidemiological studies did not report association between use of combined oral contraceptive and the risk of fracture.

Sex hormone replacement in Turner syndrome

The cardinal features of Turner syndrome (TS) are short stature, congenital abnormalities, infertility due to gonadal dysgenesis, with sex hormone insufficiency ensuing from premature ovarian failure, which is involved in lack of proper development of secondary sex characteristics and the frequent osteoporosis seen in Turner syndrome. But sex hormone insufficiency is also involved in the increased cardiovascular risk, state of physical fitness, insulin resistance, body composition, and may play a role in the increased incidence of autoimmunity. Severe morbidity and mortality affects females with Turner syndrome. Recent research emphasizes the need for proper sex hormone replacement therapy (HRT) during the entire lifespan of females with TS and new hypotheses concerning estrogen receptors, genetics and the timing of HRT offers valuable new information. In this review, we will discuss the effects of estrogen and androgen insufficiency as well as the effects of sex HRT on morbidity and mortality with special emphasis on evidence based research and areas needing further studies.

Effects of hypogonadism on bone metabolism in female adolescents and young adults

Gonadal steroids, including androgens and oestrogens, play a critical part in bone metabolism, and conditions associated with a deficiency of gonadal steroids can reduce BMD in adults and impair bone accrual in adolescents. In addition, other associated hormone alterations, for example, insulin-like growth factor 1 deficiency or high cortisol levels, can further exacerbate the effect of hypogonadism on bone metabolism, as can factors such as calcium and vitamin D deficiency, low body weight and exercise status. This Review discusses the effects of different hypogonadal states on bone metabolism in female adolescents and young adults, with particular emphasis on conditions associated with low energy availability, such as anorexia nervosa and athletic amenorrhoea, in which many factors other than hypogonadism affect bone. In contrast to most hypogonadal conditions, in which replacement of gonadal steroids is sufficient to normalize bone accrual rates and BMD, gonadal steroid replacement may not be sufficient to normalize bone metabolism in these states of energy deficit.

The timing of BMD and geometric adaptation at the proximal femur from childhood to early adulthood in males and females: a longitudinal study

During adolescence, the peak velocity in bone mass accretion preceded the peak velocity of estimated geometry at the hip. Whether this pattern continues into adulthood when maximum values are achieved remains unknown. The purpose of this study was (1) to identify the ages at which peak values of areal BMD (aBMD), cross-sectional area (CSA), and section modulus (Z) occur, (2) to determine the percent of adult peak attained during adolescence, and (3) to determine the relationship between body composition and the timing of the adult peak values. One-hundred and sixty-five (92 females) individuals' aBMD, CSA, and Z values were assessed serially at the narrow neck (NN), intertrochanter (IT), and shaft (S) using hip structural analysis (HSA). Peak bone values and the ages of attainment were assessed using factorial MANOVA. In males, aBMDp (NN 19.4 ± 2.7 years, IT 20 ± 3.4 years, and S 21.8 ± 2.8 years) occurred significantly earlier than CSAp at all sites (NN 21.6 ± 3.2 years, IT 21.1 ± 3.4 years, and S 22.3 ± 3.1 years) and earlier than Zp at the NN (22 ± 3.2 years) and IT (21.3 ± 2.9 years). In females, aBMDp (NN 17.9 ± 2.7 years, IT 18.7 ± 3.5 years, and S 19.7 ± 3.3 years) occurred significantly earlier than CSAp at all sites (NN 20.6 ± 3.6 years, IT 19.4 ± 3.9 years, and S 21.0 ± 3.3 years) and earlier than Zp at the NN (20.7 ± 3.4 years) and S (20.6 ± 3.5 years). The changes in bone mass precede changes in geometric CSA, and this timing may be integral for the development and maintenance of bone strength.

Bone microarchitecture is impaired in adolescent amenorrheic athletes compared with eumenorrheic athletes and nonathletic controls

CONTEXT

Bone mineral density (BMD) is lower in young amenorrheic athletes (AA) compared to eumenorrheic athletes (EA) and nonathletic controls and may contribute to fracture risk during a critical time of bone accrual. Abnormal bone microarchitecture is an independent determinant of fracture risk and has not been assessed in young athletes and nonathletes.

OBJECTIVE

We hypothesized that bone microarchitecture is impaired in AA compared to EA and nonathletes despite weight-bearing exercise.

DESIGN AND SETTING

We conducted this cross-sectional study at the Clinical Research Center of Massachusetts General Hospital.

SUBJECTS AND OUTCOME MEASURES

We assessed BMD and bone microarchitecture in 50 subjects [16 AA, 18 EA, and 16 nonathletes (15-21 yr old)] using dual-energy x-ray absorptiometry and high-resolution peripheral quantitative computed tomography.

RESULTS

Groups did not differ for chronological age, bone age, body mass index, or vitamin D levels. Lumbar BMD Z-scores were lower in AA vs. EA and nonathletes; hip and femoral neck BMD Z-scores were highest in EA. At the weight-bearing tibia, athletes had greater total area, trabecular area, and cortical perimeter than nonathletes, whereas cortical area and thickness trended lower in AA. Trabecular number was lower and trabecular separation higher in AA vs. EA and nonathletes. At the non-weight-bearing radius, trabecular density was lower in AA vs. EA and nonathletes. Later menarchal age was an important determinant of impaired microarchitecture. After controlling for covariates, subject grouping accounted for 18-24% of the variability in tibial trabecular number and separation.

CONCLUSION

In addition to low BMD, AA have impaired bone microarchitecture compared with EA and nonathletes. These are the first data to show abnormal bone microarchitecture in AA.

Efficacy and harms of nasal calcitonin in improving bone density in young patients with inflammatory bowel disease: a randomized, placebo-controlled, double-blind trial

OBJECTIVES

There are very few published studies of agents having the potential to improve bone health in children with inflammatory bowel disease (IBD). The objective of this study was to establish the efficacy and safety of intranasal calcitonin in improving bone mineral density (BMD) in young patients with IBD and to define additional factors that impact bone mineral accrual.

METHODS

We conducted a randomized, placebo-controlled, double-blind clinical trial in 63 participants, ages 8-21 years, with a spinal BMD Z-score ≤ -1.0 s.d. measured by dual energy X-ray absorptiometry. Subjects were randomized to 200 IU intranasal calcitonin (n=31) or placebo (n=32) daily. All received age-appropriate calcium and vitamin D supplementation. Subsequent BMD measurements were obtained at 9 and 18 months.

RESULTS

Intranasal calcitonin was well tolerated. Adverse event frequency was similar in both treatment groups, and such events were primarily minor, reversible, and limited to the upper respiratory tract. The BMD Z-score change documented at screening and 9 months and screening and 18 months did not differ between the two therapeutic arms. In participants with Crohn's disease, the spinal BMD Z-score improved between screening and 9 months (change in spine BMD Z-score (ΔZSBMD)(9-0)) in the calcitonin group (ΔZSBMD(9-0)(calcitonin)=0.21 (0.37), ΔZSBMD(9-0)(placebo)=-0.15 (0.5), P=0.02); however, this was only a secondary subgroup analysis. Bone mineral accrual rate during the trial did not lead to normalization of BMD Z-score in this cohort. Factors favoring higher bone mineral accrual rate were lower baseline BMD and higher baseline body mass index Z-score, improvement in height Z-score, higher serum albumin, hematocrit and iron concentration, and more hours of weekly weight-bearing activity. Factors associated with lower bone mineral accrual rate were more severe disease-as indicated by elevated inflammatory markers, need for surgery, hospitalization, and the use of immunomodulators-and higher daily caffeine intake.

CONCLUSIONS

Intranasal calcitonin is well tolerated but does not offer a long-term advantage in youth with IBD and decreased BMD. Bone mineral accrual rate remains compromised in youth with IBD and low BMD raising concerns for long-term bone health outcomes. Improvement in nutritional status, catch-up linear growth, control of inflammation, increase in weight-bearing activity, and lower daily caffeine intake may be helpful in restoring bone density in children with IBD and low BMD.

Bone mineral density in adult survivors of childhood acute leukemia: impact of hematopoietic stem cell transplantation and other treatment modalities

Femoral and lumbar bone mineral densities (BMDs) were measured in 159 adults enrolled in the Leucémies de l'Enfant et de l'Adolescent program, a French prospective multicentric cohort of childhood leukemia survivors. BMDs were expressed as Z-scores, and multivariate linear regression analyses were used to construct association models with potential risk factors. Mean age at evaluation and follow-up was 23 and 14.7 years, respectively. In the whole cohort, mean femoral Z-score was -0.19 ± 0.08. Two factors were associated with lower femoral BMD transplantation (-0.49 ± 0.15 vs -0.04 ± 0.10 in the chemotherapy group; P = .006) and female sex (-0.34 ± 0.10 vs -0.03 ± 0.13; P = .03). Among patients who received a transplant, the only significant risk factor was hypogonadism (-0.88 ± 0.16 vs -0.10 ± 0.23; P = .04). A slight reduction in lumbar BMD (mean Z-score, -0.37 ± 0.08) was detected in the whole cohort without difference between the transplantation and chemotherapy groups. Among patients who received a transplant, younger age at transplantation was correlated with a low lumbar BMD (P = .03). We conclude that adults who had received only chemotherapy for childhood leukemia have a slight reduction in their lumbar BMD and a normal femoral BMD. Patients who received a transplant with gonadal deficiency have a reduced femoral BMD which might increase the fracture risk later in life.

Effect of maturational timing on bone mineral content accrual from childhood to adulthood: evidence from 15 years of longitudinal data

A higher bone mass may reduce the risk of osteoporosis and fractures. The role of maturational timing for optimizing bone mass is controversial due to the lack of prospective evidence from childhood to adulthood. The purpose of this study was to examine the long term relationship between the onset of maturation and bone mineral content (BMC) development. Two hundred thirty individuals (109 males and 121 females) from the Saskatchewan Pediatric Bone Mineral Accrual Study (PBMAS) were classified into maturity groups based on age of peak height velocity. BMC was serially assessed using dual energy X-ray absorptiometry (DXA). Multilevel models were constructed to examine the independent development of BMC by maturity group. When age, body size, and body composition were controlled early maturing females had on average 3-4%, 62.2 ± 16.8g (p<0.05), more total body BMC than their average maturing peers by 20 years of age. In contrast, late maturing females had 50.7 ± 15.6g less total body BMC. No maturational effects were found at either the lumbar spine or femoral neck (p>0.05) in females. There were no significant differences in BMC development at any site among male maturational groups (p>0.05). In this group of healthy participants, there appears to be a sex-dependent effect on the relationship between maturational timing and total body BMC development. Early, average and late maturing males displayed similar BMC development. Late maturing females had compromised BMC accrual compared to their early and average maturing peers.

Age at onset of puberty predicts bone mass in young adulthood

OBJECTIVE

To determine whether the commencement and length of puberty influences dual x-ray absorptiometry (DXA) values of bone mineral content (BMC) and bone mineral density (BMD) in the axial and appendicular skeleton at skeletal maturity.

STUDY DESIGN

From the Bone Mineral Density in Childhood Study, we identified children who began puberty and completed sexual and skeletal development and examined whether the timing and length of puberty influence DXA values of BMC and BMD at skeletal maturity.

RESULTS

A total of 78 girls and 85 boys began puberty and completed skeletal maturity; 4.4 ± 0.8 and 4.5 ± 0.8 years later, respectively. Multiple linear regression analyses indicated that the age of onset of puberty was a strong negative predictor of DXA bone measurements at skeletal maturity, independent of bone values at the beginning of puberty, and the length of puberty. This negative relation was observed for all BMC and BMD measurements at all skeletal sites, in both boys and girls (all P < .0001). In contrast, length of puberty had no relation to any measures of bone.

CONCLUSIONS

In healthy adolescent males and females, bone mass and bone density at skeletal maturity are inversely related to the timing of puberty.

Adverse interaction of low-calcium diet and low 25(OH)D levels on lumbar spine mineralization in late-pubertal girls

No consensus has been reached on the serum 25-hydroxyvitamin D [25(OH)D] levels required to ensure optimal bone health around menarche. We searched for a possible interaction of 25(OH)D levels and calcium intake on lumbar spine mineralization and on biologic features of bone metabolism in healthy late-pubertal girls. Lumbar spine parameters (ie, area, mineral content, and density) and calcium intake were evaluated in 211 healthy white adolescent girls at pubertal stages IV-V (11 to 16.9 years), together with biologic markers of calcium and bone metabolism and with International External Quality Assessment Scheme for Vitamin D Metabolite (DEQAS)-validated serum 25(OH)D levels. A high prevalence of 25(OH)D levels ≤ 30 nmol/L (41%), ≤ 40 nmol/L (61%), and ≤ 50 nmol/L (70%) was found during winter-spring. Parathyroid hormone (PTH) levels were inversely associated with 25(OH)D levels (p = .0021). In contrast, lumbar spine mineral content and density were not associated with 25(OH)D, excepted when calcium intake was below 600 mg/day (p = .0081). Girls with such low calcium intake and 25(OH)D levels of 40 nmol/L or less (9% of the cohort) had a 0.4 to 0.7 SD lower mean areal bone mineral density Z-score than girls with higher calcium intake and/or higher 25(OH)D status. The adverse association between lumbar spine mineralization and combined calcium deficiency-low 25(OH)D levels remained significant in the 91 girls who could be followed over 4 years after their initial evaluation. We conclude that low 25(OH)D levels (≤40 nmol/L) are observed frequently during winter-spring in late-pubertal European girls, which may exacerbate the negative impact of calcium deficiency on lumbar spine mineralization.

Peak bone mass from longitudinal data: implications for the prevalence, pathophysiology, and diagnosis of osteoporosis

We estimated peak bone mass (PBM) in 615 women and 527 men aged 16 to 40 years using longitudinal data from the Canadian Multicentre Osteoporosis Study (CaMos). Individual rates of change were averaged to find the mean rate of change for each baseline age. The age range for PBM was defined as the period during which bone mineral density (BMD) was stable. PBM was estimated via hierarchical models, weighted according to 2006 Canadian Census data. Lumbar spine PBM (1.046 ± 0.123 g/cm(2)) occurred at ages 33 to 40 years in women and at 19 to 33 years in men (1.066 ± 0.129 g/cm(2)). Total hip PBM (0.981 ± 0.122 g/cm(2)) occurred at ages 16 to 19 years in women and 19 to 21 years in men (1.093 ± 0.169 g/cm(2)). Analysis of Canadian geographic variation revealed that the levels of PBM and of mean BMD in those over age 65 sometimes were discordant, suggesting that PBM and subsequent rates of bone loss may be subject to different genetic and/or environmental influences. Based on our longitudinally estimated PBM values, the estimated Canadian prevalences of osteoporosis (T-score < -2.5) were 12.0% (L(1)-L(4)) and 9.1% (total hip) in women aged 50 years and older and 2.9% (L(1)-L(4)) and 0.9% (total hip) in men aged 50 years and older. These were higher than prevalences using cross-sectional PBM data. In summary, we found that the age at which PBM is achieved varies by sex and skeletal site, and different reference values for PBM lead to different estimates of the prevalence of osteoporosis. Furthermore, lack of concordance of PBM and BMD over age 65 suggests different determinants of PBM and subsequent bone loss.

Growth, calcium status and vitamin D receptor (VDR) promoter genotype in European children with normal or low calcium intake

Calcium homeostasis and bone metabolism require the vitamin D receptor (VDR) to function properly, as evidenced in patients and transgenic mice with VDR mutations. We have shown that (A/G) polymorphism at the -1012 locus of the VDR promoter (rs4516035) is frequent in European populations, may influence VDR expression, is associated with height in French adolescent girls, and is associated with their lumbar spine mineral density in case of insufficient milk intake. Here, an association study was performed in a cohort of Moldovan children and adolescents, living at latitude similar to the first cohort but receiving a cereal-based diet with very low milk/dairy product intakes. Children and adolescents in this cohort had similar 25-(OH) D levels, but a short stature and low serum calcium levels, compared to the first cohort. Their height remained associated with the A-1012G VDRp genotype. In addition, their serum calcium levels were associated with VDRp polymorphism, excepted when their 25-(OH) D levels were low (below 33 nmol/L). In conclusion, the -1012 VDRp genotype appears to be associated with height in European children whatever their calcium/dairy product intakes, and may modulate their calcium homeostasis in conditions of low calcium/milk intakes when vitamin D status is sufficient.