Bone density and cortical structure after pediatric renal transplantation.

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area.

Vitamin D deficiency is common in children and adolescents with chronic kidney disease.

Here we determined if vitamin D deficiency is more common in children with chronic kidney disease compared to healthy children. In addition, we sought to identify disease-specific risk factors for this deficiency, as well as its metabolic consequences. We found that nearly half of 182 patients (ages 5 to 21) with kidney disease (stages 2 to 5) and a third of age-matched 276 healthy children were 25-hydroxyvitamin D deficient (<20 ng/ml).

Bone density and structure in long-term survivors of pediatric allogeneic hematopoietic stem cell transplantation.

Children requiring allogeneic hematopoietic stem cell transplantation (alloHSCT) have multiple risk factors for impaired bone accrual. The impact of alloHSCT on volumetric bone mineral density (vBMD) and cortical structure has not been addressed. Tibia peripheral quantitative computed tomography (pQCT) scans were obtained in 55 alloHSCT recipients, ages 5 to 26 years, a median of 7 (range, 3-16) years after alloHSCT.

Quantitative computed tomography and computed tomography in children.

Quantitative computed tomography (QCT) methodologies have been instrumental in deepening our understanding of bone acquisition and strength during childhood. Important publications in the last year have drawn attention to the functional muscle-bone unit, showing that factors such as population ancestry, bone size, and muscle composition are additional dimensions of bone strength that affect muscle-bone relationships. The role of adiposity in pediatric bone health is complex and may vary by sex, puberty stage, and degree of obesity.

Revised reference curves for bone mineral content and areal bone mineral density according to age and sex for black and non-black children: results of the bone mineral density in childhood study.

Context: Deficits in bone acquisition during growth may increase fracture risk. Assessment of bone health during childhood requires appropriate reference values relative to age, sex, and population ancestry to identify bone deficits.

Objective: The objective of this study was to provide revised and extended reference curves for bone mineral content (BMC) and areal bone mineral density (aBMD) in children.

Body composition abnormalities in long-term survivors of pediatric hematopoietic stem cell transplantation.

Objective: To quantify lean mass (LM) and fat mass (FM) in survivors of childhood allogeneic hematopoietic stem-cell transplantation (alloHSCT) compared with healthy reference participants and identify risk factors for body composition abnormalities.

Study Design: Whole body LM and FM were measured with dual energy x-ray absorptiometry in 54 survivors (ages 5-25 years) and 894 healthy reference participants in a cross-sectional study. Multivariate regression models were used to compare sex- and race-specific Z-scores for LM for height (LM-Ht) and FM for height (FM-Ht) in survivors and reference participants and to identify correlates of LM-Ht and FM-Ht Z-scores in alloHSCT.

Optimal monitoring time interval between DXA measures in children.

The monitoring time interval (MTI) is the expected time in years necessary to identify a change between two measures that exceeds the measurement error. Our purpose was to determine MTI values for dual-energy X-ray absorptiometry (DXA) scans in normal healthy children, according to age, sex, and skeletal site. 2014 children were enrolled in the Bone Mineral Density in Childhood Study and had DXA scans of the lumbar spine, total hip, nondominant forearm, and whole body.

Skeletal health of children and adolescents with inflammatory bowel disease.

Current evidence points to suboptimal bone health in children and adolescents with inflammatory bowel disease (IBD) when compared with their healthy peers. This compromise is evident from diagnosis. The clinical consequences and long-term outcome of this finding are still unknown.

Vitamin D status in children and young adults with perinatally acquired HIV infection.

Background & Aims: To assess vitamin D (Vit-D) [serum 25-hydroxyvitamin D (25-OHD) concentrations] in children and young adults with perinatally acquired HIV compared to geographically similar healthy children.

Methods: 25-OHD in children and young adults with HIV was compared to a healthy group. Vit-D deficiency and insufficiency were defined as 25-OHD <11 ng/mL and 25-OHD <30 ng/mL, respectively.

Volumetric bone mineral density and bone structure in childhood chronic kidney disease.

Chronic kidney disease (CKD) is associated with increased fracture risk and skeletal deformities. The impact of CKD on volumetric bone mineral density (vBMD) and cortical dimensions during growth is unknown. Tibia quantitative computed tomographic scans were obtained in 156 children with CKD [69 stages 2 to 3, 51 stages 4 to 5, and 36 stage 5D (dialysis)] and 831 healthy participants aged 5 to 21 years.

Characterization of low bone mass in young patients with thalassemia by DXA, pQCT and markers of bone turnover.

Previous reports using dual x-ray absorptiometry (DXA) suggest that up to 70% of adults with thalassemia major (Thal) have low bone mass. However, few studies have controlled for body size and pubertal delay, variables known to affect bone mass in this population. In this study, bone mineral content and areal density (BMC, aBMD) of the spine and whole body were assessed by DXA, and volumetric BMD and cortical geometries of the distal tibia by peripheral quantitative computed tomography (pQCT) in subjects with Thal (n = 25, 11 male, 10 to 30 years) and local controls (n=34, 15 male, 7 to 30 years).

A cross-sectional study of vitamin D and insulin resistance in children.

Objective: Vitamin D deficiency is common and has been associated with several non-bone/calcium related outcomes. The objective was to determine the association between serum 25-hydroxyvitamin D (25-OH-D) and fasting glucose, insulin and insulin sensitivity in obese and non-obese children. PATIENTS/SETTING/DESIGN: Cross-sectional study of 85 children aged 4-18 years recruited from the local Philadelphia community and Sleep Center.

Mechanical loads and cortical bone geometry in healthy children and young adults.

Muscle and bone form a functional unit. While muscle size is a useful surrogate of mechanical load on bone, the independent contributions to bone strength of muscle force, muscle size, gravitational load (body weight), and physical activity have not been assessed. Three hundred twenty-one healthy participants (32% black, 47% male), aged 5-35 years were assessed.

Attenuated maximal muscle strength and peak power in children with sickle cell disease.

Dominant hand maximal handgrip strength evaluated with a handgrip dynamometer and peak power evaluated with a force plate, adjusted for body size and composition, were compared in African-American children aged 5 to 13 years, with and without type SS sickle cell disease (SCD-SS). Children with SCD-SS (n = 35; age, 9.0 ± 2.

BMD-associated variation at the Osterix locus is correlated with childhood obesity in females.

Recent genome wide association studies (GWAS) have revealed a number of genetic variants robustly associated with bone mineral density (BMD) and/or osteoporosis. Evidence from epidemiological and clinical studies has shown an association between BMD and BMI, presumably as a consequence of bone loading. We investigated the 23 previously published BMD GWAS-derived loci in the context of childhood obesity by leveraging our existing genome-wide genotyped European American cohort of 1106 obese children (BMI ≥ 95th percentile) and 5997 controls (BMI < 95th percentile).

Association of chronic kidney disease with muscle deficits in children.

The effect of chronic kidney disease (CKD) on muscle mass in children, independent of poor growth and delayed maturation, is not well understood. We sought to characterize whole body and regional lean mass (LM) and fat mass (FM) in children and adolescents with CKD and to identify correlates of LM deficits in CKD. We estimated LM and FM from dual energy x-ray absorptiometry scans in 143 children with CKD and 958 controls at two pediatric centers.

Vitamin D deficiency and parathyroid hormone levels following renal transplantation in children.

The objectives were to determine the prevalence of vitamin D deficiency [25(OH)D < 10 ng/ml] in pediatric renal transplant (RTx) recipients, compared with controls and identify correlates of changes in 25(OH)D and intact parathyroid hormone (iPTH) levels following transplantation. Serum 25(OH)D, 1,25(OH)(2)D, and iPTH were measured once in 275 healthy controls and at transplantation, and 3 and 12 months posttransplantation in 58 RTx recipients. Multivariate logistic regression models determined the odds ratio (OR) of vitamin D deficiency in RTx recipients vs.

Clinical and genetic correlates of exercise performance in young children with cystic fibrosis.

Exercise performance in individuals with cystic fibrosis has been shown to be related to the extent of pulmonary dysfunction and undernutrition and genetic profile. The aim of this study was to examine these relationships in young children with cystic fibrosis. The participants were 64 children ages 8 to 11 years (M = 9.

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.

Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial.

Background: Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss.

Objective: To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program.

Design: Randomized parallel-group trial.

Determinants of changes in linear growth and body composition in incident pediatric Crohn's disease.

Background & Aims: Pediatric Crohn's disease (CD) is associated with growth, lean mass (LM), and fat mass (FM) deficits. This study assessed and identified determinants of changes in height and body composition in children with CD following.

Methods: Whole-body LM and FM were assessed using dual-energy x-ray absorptiometry in 78 CD subjects at diagnosis, 6, 12, and a median of 43 months (range, 24-63) later.

Tracking of bone mass and density during childhood and adolescence.

Context: Whether a child with low bone mineral density (BMD) at one point in time will continue to have low BMD, despite continued growth and maturation, is important clinically. The stability of a characteristic during growth is referred to as "tracking."

Objective: We examined the degree of tracking in bone mineral content (BMC) and BMD during childhood and adolescence and investigated whether tracking varied according to age, sexual maturation, and changes in growth status.

Effects of sex, race, and puberty on cortical bone and the functional muscle bone unit in children, adolescents, and young adults.

Context: Sex and race differences in bone development are associated with differences in growth, maturation, and body composition.

Objective: The aim of the study was to determine the independent effects of sex, race, and puberty on cortical bone development and muscle-bone relations in children and young adults.

Design And Participants: We conducted a cross-sectional study of 665 healthy participants (310 male, 306 black) ages 5-35 yr.

Energy expenditure in obesity associated with craniopharyngioma.

Background And Purpose: Obesity is a common yet incompletely understood complication of childhood craniopharyngioma. We hypothesized that craniopharyngioma is associated with specific defects in energy balance compared to obese control children.

Methods: Eleven craniopharyngioma patients were recruited for a study on body composition and energy balance.

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.