Influence of weight, age and puberty on bone size and bone mineral content in healthy children and adolescents

Bone Mineral Density and Serum 25OHD in Children and Adolescents With Juvenile Idiopathic Arthritis

Low bone mass is one of the complications of juvenile idiopathic arthritis (JIA). However, a study focusing on the low bone mass in children and adolescents with JIA in Southeast Asian countries is limited. This study aimed to evaluate the bone mineral density (BMD) of Thai patients with JIA and identify factors correlated with BMD. A cross-sectional study was conducted at a tertiary-care center. The BMD of the lumbar spines (BMDLS) and the total body (BMDTB) were measured by dual-energy X-ray absorptiometry. Thirty-eight patients were enrolled between July 2015 and January 2016. No patient had low BMDLS, and only 2 (5.3%) had low BMDTB. Serum 25-hydroxyvitamin D (25OHD) levels were significantly positively correlated with the BMDTB Z-score (coefficient: 0.047; 95% confidence interval = 0.011-0.082; P = .012). Our study demonstrated a very low prevalence of low bone mass. Optimization of the serum 25OHD level should be encouraged.

Early Life Exposure to a Diet With a Supramolecular Lipid Structure Close to That of Mammalian Milk Improves Early Life Growth, Skeletal Development, and Later Life Neurocognitive Function in Individually and Socially Housed Male C57BL/6J Mice

Breastfeeding (duration) can be positively associated with infant growth outcomes as well as improved cognitive functions during childhood and later life stages. (Prolonged) exposure to optimal lipid quantity and quality, i.e., the supramolecular structure of lipids, in mammalian milk, may contribute to these beneficial effects through nutritional early-life programming. In this pre-clinical study, we exposed male C57BL/6J mice from post-natal Days 16 to 42 (i.e., directly following normal lactation), to a diet with large lipid droplets coated with bovine milk fat globule membrane-derived phospholipids, which mimic more closely the supramolecular structure of lipid droplets in mammalian milk. We investigated whether exposure to this diet could affect growth and brain development-related parameters. As these outcomes are also known to be affected by the post-weaning social environment in mice, we included both individually housed and pair-wise housed animals and studied whether effects of diet were modulated by the social environment. After Day 42, all the animals were fed standard semi-synthetic rodent diet. Growth and body composition were assessed, and the mice were subjected to various behavioral tests. Individual housing attenuated adolescent growth, reduced femur length, and increased body fat mass. Adult social interest was increased due to individual housing, while cognitive and behavioral alterations as a result of different housing conditions were modest. The diet increased adolescent growth and femur length, increased lean body mass, reduced adolescent anxiety, and improved adult cognitive performance. These effects of diet exposure were comparable between individually and socially housed mice. Hence, early life exposure to a diet with lipid droplets that mimic the supramolecular structure of those in mammalian milk may improve adolescent growth and alters brain function in both socially and individually housed mice. These findings suggest that lipid structure in infant milk formula may be a relevant target for nutritional solutions, targeting both healthy infants and infants facing growth challenges.

Influence of weight status on bone mineral content measured by DXA in children

INTRODUCTION

Childhood obesity is a public health problem with repercussions in later life. As tissue formation peaks in childhood we determined how weight status influences bone mineral content.

MATERIAL AND METHODS

We studied 553 children aged 4-18 years over 10 years (46.8% girls). We measured age, weight, height and through bone densitometry (DXA), bone mineral content (BMC), bone mineral density (BMD), and waist, arm and hip circumferences. The patients were divided into groups using the body mass index z-score: underweight, normal weight, overweight, obese and very obese.

RESULTS

BMC and BMD values were highest in the normal-weight and overweight groups. Logistic regression showed bone mineralization was inversely associated with waist circumference, the association being positive for weight and age. No differences were found according to sex.

DISCUSSION

Studies of the relationship between weight and bone mineralization report contradictory results, often because of different study designs. Moreover, studies in children are either few or with small samples. Our findings in a large sample show the importance of weight status in bone mineralization given the risk of bone fractures or osteoporosis.

CONCLUSIONS

Weight status influenced bone mineralization. BMC and BMD decreased in children with a higher degree of obesity. Waist circumference correlated negatively with bone mineralization.

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.

Bone Density in the Obese Child: Clinical Considerations and Diagnostic Challenges

The prevalence of obesity in children has reached epidemic proportions. Concern about bone health in obese children, in part, derives from the potentially increased fracture risk associated with obesity. Additional risk factors that affect bone mineral accretion, may also contribute to obesity, such as low physical activity and nutritional factors. Consequences of obesity, such as inflammation, insulin resistance, and non-alcoholic fatty liver disease, may also affect bone mineral acquisition, especially during the adolescent years when rapid increases in bone contribute to attaining peak bone mass. Further, numerous pediatric health conditions are associated with excess adiposity, altered body composition, or endocrine disturbances that can affect bone accretion. Thus, there is a multitude of reasons for considering clinical assessment of bone health in an obese child. Multiple diagnostic challenges affect the measurement of bone density and its interpretation. These include greater precision error, difficulty in positioning, and the effects of increased lean and fat tissue on bone health outcomes. Future research is required to address these issues to improve bone health assessment in obese children.

Maternal predictors of neonatal bone size and geometry: the Southampton Women's Survey

Early growth is associated with later risk of osteoporosis and fractures. In this study, we aimed to evaluate the relationships between maternal lifestyle and body composition and neonatal bone size, geometry and density in the offspring. Participants were recruited from the Southampton Women's Survey, a unique prospective cohort of 12,500 initially non-pregnant women aged 20-34 years, resident in Southampton, UK. These women were studied in detail before and during pregnancy, and the offspring underwent anthropometric and bone mineral assessment (using dual energy-X-ray absorptiometry) at birth. A total of 841 mother-baby pairs were studied (443 boys and 398 girls). The independent predictors of greater neonatal whole body bone area (BA) and bone mineral content included greater maternal birthweight, height, parity, triceps skinfold thickness and lower walking speed in late pregnancy. Maternal smoking was independently associated with lower neonatal bone mass. Neonatal BA adjusted for birth length (a measure of bone width) was predicted positively by maternal parity and late pregnancy triceps skinfold thickness and negatively by late pregnancy walking speed. These findings were similar in both genders. We have confirmed, in a large cohort, previous findings that maternal lifestyle and body build predict neonatal bone mineral; additionally, maternal parity and fat stores and walking speed in late pregnancy were associated with neonatal bone geometry. These findings may suggest novel public health strategies to reduce the burden of osteoporotic fracture in future generations.

Determinants of bone mineral content and bone area in Indian preschool children

The objective of this study was to examine the lifestyle factors that influence total body bone mineral content (TB BMC) and total body bone area (TB BA) in Indian preschool children. TB BMC and TB BA were measured by dual-energy X-ray absorptiometry (Lunar DPX PRO) in 71 apparently healthy children aged 2-3 years. A fasting blood sample was analyzed for serum concentrations of ionized calcium (iCa), intact parathyroid hormone (iPTH), phosphorus (iP) and 25-hydroxyvitamin D(3) (25 OHD). Dietary intake of energy, protein, calcium and phosphorus was estimated from a 3-day diet recall. The daily physical activity and sunlight exposure were recorded by a questionnaire. The study children were shorter than their age-gender matched WHO counterparts with a mean height for age Z score of -1.3 ± 1.5. The mean dietary intake of calcium was 46% of the Indian recommended dietary intakes (RDI). Seventy-three percent of children had low iCa concentrations, and 57% were deficient in vitamin D. Generalized linear model analysis revealed that height, lean body mass, weight, activity, sunlight exposure in minutes and dietary intakes of calcium, zinc and iron were the significantly influencing factors (p < 0.05) of TB BMC and TB BA. In conclusion, attaining optimal height for age, achieving the goals of overall nutrition with adequate calcium, iron and zinc intakes as well as adequate physical activity and sunlight exposure play an important role in achieving better TB BMC and TB BA in preschool children.

Height adjustment in assessing dual energy x-ray absorptiometry measurements of bone mass and density in children

CONTEXT

In children, bone mineral content (BMC) and bone mineral density (BMD) measurements by dual-energy x-ray absorptiometry (DXA) are affected by height status. No consensus exists on how to adjust BMC or BMD (BMC/BMD) measurements for short or tall stature.

OBJECTIVE

The aim of this study was to compare various methods to adjust BMC/BMD for height in healthy children.

DESIGN

Data from the Bone Mineral Density in Childhood Study (BMDCS) were used to develop adjustment methods that were validated using an independent cross-sectional sample of healthy children from the Reference Data Project (RDP).

SETTING

We conducted the study in five clinical centers in the United States.

PARTICIPANTS

We included 1546 BMDCS and 650 RDP participants (7 to 17 yr of age, 50% female).

INTERVENTION

No interventions were used.

MAIN OUTCOME MEASURES

We measured spine and whole body (WB) BMC and BMD Z-scores for age (BMC/BMD(age)), height age (BMC/BMD(height age)), height (BMC(height)), bone mineral apparent density (BMAD(age)), and height-for-age Z-score (HAZ) (BMC/BMD(haz)).

RESULTS

Spine and WB BMC/BMD(age)Z and BMAD(age)Z were positively (P < 0.005; r = 0.11 to 0.64) associated with HAZ. Spine BMD(haz) and BMC(haz)Z were not associated with HAZ; WB BMC(haz)Z was modestly associated with HAZ (r = 0.14; P = 0.0003). All other adjustment methods were negatively associated with HAZ (P < 0.005; r = -0.20 to -0.34). The deviation between adjusted and BMC/BMD(age) Z-scores was associated with age for most measures (P < 0.005) except for BMC/BMD(haz).

CONCLUSIONS

Most methods to adjust BMC/BMD Z-scores for height were biased by age and/or HAZ. Adjustments using HAZ were least biased relative to HAZ and age and can be used to evaluate the effect of short or tall stature on BMC/BMD Z-scores.

International longitudinal pediatric reference standards for bone mineral content

To render a diagnosis pediatricians rely upon reference standards for bone mineral density or bone mineral content, which are based on cross-sectional data from a relatively small sample of children. These standards are unable to adequately represent growth in a diverse pediatric population. Thus, the goal of this study was to develop sex and site-specific standards for BMC using longitudinal data collected from four international sites in Canada and the United States. Data from four studies were combined; Saskatchewan Paediatric Bone Mineral Accrual Study (n=251), UBC Healthy Bones Study (n=382); Penn State Young Women's Health Study (n=112) and Stanford's Bone Mineral Accretion study (n=423). Males and females (8 to 25 years) were measured for whole body (WB), total proximal femur (PF), femoral neck (FN) and lumbar spine (LS) BMC (g). Data were analyzed using random effects models. Bland-Altman was used to investigate agreement between predicted and actual data. Age, height, weight and ethnicity independently predicted BMC accrual across sites (P<0.05). Compared to White males, Asian males had 31.8 (6.8) g less WB BMC accrual; Hispanic 75.4 (28.2) g less BMC accrual; Blacks 82.8 (26.3) g more BMC accrual with confounders of age, height and weight controlled. We report similar findings for the PF and FN. Models for females for all sites were similar with age, height and weight as independent significant predictors of BMC accrual (P<0.05). We provide a tool to calculate a child's BMC Z-score, accounting for age, size, sex and ethnicity. In conclusion, when interpreting BMC in pediatrics we recommend standards that are sex, age, size and ethnic specific.

IGF-1 and IGF-binding proteins and bone mass, geometry, and strength: relation to metabolic control in adolescent girls with type 1 diabetes

Children and adolescents with poorly controlled type 1 diabetes mellitus (T1DM) are at risk for decreased bone mass. Growth hormone (GH) and its mediator, IGF-1, promote skeletal growth. Recent observations have suggested that children and adolescents with T1DM are at risk for decreased bone mineral acquisition. We examined the relationships between metabolic control, IGF-1 and its binding proteins (IGFBP-1, -3, -5), and bone mass in T1DM in adolescent girls 12-15 yr of age with T1DM (n = 11) and matched controls (n = 10). Subjects were admitted overnight and given a standardized diet. Periodic blood samples were obtained, and bone measurements were performed. Serum GH, IGFBP-1 and -5, glycosylated hemoglobin (HbA(1c)), glucose, and urine magnesium levels were higher and IGF-1 values were lower in T1DM compared with controls (p < 0.05). Whole body BMC/bone area (BA), femoral neck areal BMD (aBMD) and bone mineral apparent density (BMAD), and tibia cortical BMC were lower in T1DM (p < 0.05). Poor diabetes control predicted lower IGF-1 (r(2) = 0.21) and greater IGFBP-1 (r(2) = 0.39), IGFBP-5 (r(2) = 0.38), and bone-specific alkaline phosphatase (BALP; r(2) = 0.41, p < 0.05). Higher urine magnesium excretion predicted an overall shorter, lighter skeleton, and lower tibia cortical bone size, mineral, and density (r(2) = 0.44-0.75, p < 0.05). In the T1DM cohort, earlier age at diagnosis was predictive of lower IGF-1, higher urine magnesium excretion, and lighter, thinner cortical bone (r(2) >or=0.45, p < 0.01). We conclude that poor metabolic control alters the GH/IGF-1 axis, whereas greater urine magnesium excretion may reflect subtle changes in renal function and/or glucosuria leading to altered bone size and density in adolescent girls with T1DM.

Bone mineral density and bone histomorphometry in children on long-term dialysis

Bone mineral density (BMD) at the lumbar vertebrae (L(1)-L(4)) was assessed by dual-energy X-ray absorptiometry (DXA) in 20 children with chronic kidney disease (CKD) on dialysis, and its results were compared with bone biopsy and biochemical parameters. Biopsy specimens provided evidence of hyperparathyroid bone disease in eight cases (40%), and low bone turnover in 12 (60%). For BMD, expressed as Z-scores relative to normal, median Z-scores were -1.05 (range -2.36 to 1.06) for hyperparathyroid patients and -1.05 (range -4.40 to -0.03) for low bone turnover patients, with no statistical differences between groups (P = 0.512). In relation to BMD, of the whole sample, five (25%) had a Z-score under -2.0. When it was corrected for height, BMD was in the normal range. Additionally, there were no significant differences in single samples of serum calcium, alkaline phosphatase, phosphorus and intact parathyroid hormone (PTH) between groups with high or low bone turnover. Assessment of nutritional status, through height/age, showed that ten patients had Z-scores below -2.0 (median -2.12, range -7.13 to 0.73). In conclusion, renal osteodystrophy (ROD) seems to have a high prevalence among CKD pediatric patients, although only approximately a quarter of them developed changes in BMD. In children with CKD, measurements of bone mineral density may not be used for classification of various forms of ROD.

Pediatric DXA: technique and interpretation

This article reviews dual X-ray absorptiometry (DXA) technique and interpretation with emphasis on the considerations unique to pediatrics. Specifically, the use of DXA in children requires the radiologist to be a "clinical pathologist" monitoring the technical aspects of the DXA acquisition, a "statistician" knowledgeable in the concepts of Z-scores and least significant changes, and a "bone specialist" providing the referring clinician a meaningful context for the numeric result generated by DXA. The patient factors that most significantly influence bone mineral density are discussed and are reviewed with respect to available normative databases. The effects the growing skeleton has on the DXA result are also presented. Most important, the need for the radiologist to be actively involved in the technical and interpretive aspects of DXA is stressed. Finally, the diagnosis of osteoporosis should not be made on DXA results alone but should take into account other patient factors.

Sex differences in bone size and bone mineral density exist before puberty. The Copenhagen School Child Intervention Study (CoSCIS)

BACKGROUND

The aim of this study was to provide normative data of bone mineral density (BMD; g/cm(2)) of the forearm and the calcaneus, evaluated by peripheral dual X ray absorbtiometry (DXA), in children aged 6 to 7 years of age and to evaluate the association with anthropometrics and sex.

MATERIAL AND METHODS

368 boys and 326 girls with a mean age of 6.7 +/- 0.4 years participated. BMD was measured by DXA in the forearms and the os calcanei, with average values presented in this report. Measurements of weight, height, skinfolds, the width of distal radius and ulna, and the femur condyles were collected and body composition estimated from skinfolds measurements.

RESULTS

There was no difference in calcaneus BMD when comparing boys and girls, whereas the boys had 4.5% (0.013 g/cm(2)) higher forearm BMD than the girls (P < 0.001). Calcaneal BMD (mean 0.318 g/cm(2)) was 11% higher than forearm BMD (mean 0.283 g/cm(2)). Linear relationship was found between calcaneus BMD and weight (partial r = 0.50), Fat free mass (FFM) (partial r = 0.50), Fat mass (FM) (partial r = 0.45), % body fat (partial r = 0.29) and knee width (partial r = 0.46), all P < 0.000 respectively. Adjusted for weight the relationship between calcaneus BMD and FFM, FM, %body fat and knee width disappeared. There were significant relationships between the forearm BMD and weight (partial r = 0.37), FFM (partial r = 0.39), FM (partial r = 0.28), %body fat (partial r = 0.14) and wrist width (partial r = 0.24), all P < 0.000 respectively. Adjusted for body weight, the relationship remained between forearm BMD and FFM (r = 0.10), FM (R = -0.10) and % body fat (r = -0.12), all P < 0.000 respectively. Children measured in the spring had 3.5% (P < 0.01) higher calcaneus BMD than children measured in the winter.

CONCLUSION

Seven year old boys have higher BMD in the forearm but not in the calcaneus in comparison with girls of a similar age. Body weight is the best predictor of calcaneus BMD, accounting for 25% of the variance whereas body weight and FFM are the best predictors of forearm BMD, each accounting for 17% of the variance, respectively.

Whole body bone mineral accretion in healthy children and adolescents

Data on accretion in bone size and bone mineral content (BMC) are needed to evaluate bone mineralisation during childhood. Whole body bone mineral content (BMC) and bone area (BA) were determined by dual energy x ray absorptiometry (Hologic 1000/W) with a one year interval in healthy girls (n = 192) and boys (n = 140) aged 6-19 years. Annual accretion in BMC (DeltaBMC (g/year)) and BA (DeltaBA (cm2/year)) according to sex and pubertal stages were calculated. DeltaBA and DeltaBMC were highly significantly associated with pubertal stages in girls and boys. Centile curves for DeltaBA and DeltaBMC according to sex and age were constructed using the LMS method. Peak DeltaBA and DeltaBMC values were reached earlier in girls (12.3 and 12.5 years, respectively) than in boys (13.4 and 14. 2 years, respectively). The DeltaBA peak was dissociated in time from the DeltaBMC peak, indicating that increase in bone size occurs before increase in bone mineral content. Assuming that 32.2% of BMC consist of calcium, the median (90th centile) annual bone calcium accretion in pubertal stage III was 220 mg/day (302) and 317 mg/day (386) for girls and boys, respectively. To obtain an average bone calcium accretion, a high calcium absorption is needed during puberty. This may have implications for dietary calcium requirements at this time.