Large trans-ethnic meta-analysis identifies AKR1C4 as a novel gene associated with age at menarche

STUDY QUESTION

Does the expansion of genome-wide association studies (GWAS) to a broader range of ancestries improve the ability to identify and generalise variants associated with age at menarche (AAM) in European populations to a wider range of world populations?

SUMMARY ANSWER

By including women with diverse and predominantly non-European ancestry in a large-scale meta-analysis of AAM with half of the women being of African ancestry, we identified a new locus associated with AAM in African-ancestry participants, and generalised loci from GWAS of European ancestry individuals.

WHAT IS KNOWN ALREADY

AAM is a highly polygenic puberty trait associated with various diseases later in life. Both AAM and diseases associated with puberty timing vary by race or ethnicity. The majority of GWAS of AAM have been performed in European ancestry women.

STUDY DESIGN, SIZE, DURATION

We analysed a total of 38 546 women who did not have predominantly European ancestry backgrounds: 25 149 women from seven studies from the ReproGen Consortium and 13 397 women from the UK Biobank. In addition, we used an independent sample of 5148 African-ancestry women from the Southern Community Cohort Study (SCCS) for replication.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Each AAM GWAS was performed by study and ancestry or ethnic group using linear regression models adjusted for birth year and study-specific covariates. ReproGen and UK Biobank results were meta-analysed using an inverse variance-weighted average method. A trans-ethnic meta-analysis was also carried out to assess heterogeneity due to different ancestry.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed consistent direction and effect sizes between our meta-analysis and the largest GWAS conducted in European or Asian ancestry women. We validated four AAM loci (1p31, 6q16, 6q22 and 9q31) with common genetic variants at P < 5 × 10-7. We detected one new association (10p15) at P < 5 × 10-8 with a low-frequency genetic variant lying in AKR1C4, which was replicated in an independent sample. This gene belongs to a family of enzymes that regulate the metabolism of steroid hormones and have been implicated in the pathophysiology of uterine diseases. The genetic variant in the new locus is more frequent in African-ancestry participants, and has a very low frequency in Asian or European-ancestry individuals.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Extreme AAM (<9 years or >18 years) were excluded from analysis. Women may not fully recall their AAM as most of the studies were conducted many years later. Further studies in women with diverse and predominantly non-European ancestry are needed to confirm and extend these findings, but the availability of such replication samples is limited.

WIDER IMPLICATIONS OF THE FINDINGS

Expanding association studies to a broader range of ancestries or ethnicities may improve the identification of new genetic variants associated with complex diseases or traits and the generalisation of variants from European-ancestry studies to a wider range of world populations.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was provided by CHARGE Consortium grant R01HL105756-07: Gene Discovery For CVD and Aging Phenotypes and by the NIH grant U24AG051129 awarded by the National Institute on Aging (NIA). The authors have no conflict of interest to declare.

0952 Parent-Child Perceptions About Healthy Sleep Promotion in a Mobile Health Sleep Extension Intervention

Introduction

Over half of school-aged children sleep insufficiently and sleep promoting interventions are urgently needed. To effectively promote pediatric sleep health, it is critical to obtain feedback from youth and their families about acceptable intervention strategies. This qualitative study examined perceptions about healthy sleep promotion in parent-child dyads participating in a mobile health sleep extension intervention.

Methods

A total of 26 parent-child dyads (child mean age 11 years, SD = 0.67; 46% non-Latinx White; 19% Black) participated in a mobile intervention to extend child sleep duration over 11 weeks (2-week baseline; 7-week intervention; 2-week follow-up). Participants wore a FitBit during the study, were provided with a sleep duration goal, and received general sleep health-promoting electronic messages using the University of Pennsylvania’s Way to Health platform. Following the intervention, parents and their children separately completed a semi-structured telephone interview to capture perceptions of the intervention strategies. Three coders developed a codebook using an inductive approach to identify emergent themes and conducted coding in NVivo.

Results

Emergent themes fell into domains of intervention acceptability/feasibility and barriers. Mobile messaging about the child’s sleep duration goal was well-received, although child participants in particular desired more personalized messaging, with sleep promotion targeted to their specific sleep habits. Parents and children both discussed ancillary benefits to intervention participation, including an enhanced focus on sleep. Barriers to sleep extension during the intervention and maintenance of any gains post-intervention were related to: competing child academic, social, and extracurricular demands; family factors (work schedules; family rules and norms); and the challenges of limiting ubiquitous electronic devices.

Conclusion

Despite high parent-child acceptability of a mobile child sleep extension intervention, individual and contextual barriers may limit long-term adherence. Tailoring healthy sleep messages to target these factors could improve sustained benefits to child sleep.

Support

Sleep Research Society Foundation and K23HD094905 (AAW); NIH/NCATS UL1TR001878 (JAM and DFD) and K01HL123612 (JAM).

Effect of high-dose cholecalciferol (vitamin D3) on bone and body composition in children and young adults with HIV infection: a randomized, double-blind, placebo-controlled trial

It is unknown whether vitamin D supplementation positively impacts body composition and bone outcomes in children and young adults with HIV. This RCT found that despite increasing 25(OH)D concentrations, high dose vitamin D₃ supplementation did not impact bone or body composition in children and young adults with HIV infection.

INTRODUCTION

The objective of this paper was to determine the impact of high-dose daily cholecalciferol (vitamin D₃) supplementation on body composition and bone density, structure, and strength in children and young adults with perinatally acquired (PHIV) or behaviorally acquired (BHIV) HIV infection.

METHODS

Participants were randomized to receive vitamin D₃ supplementation (7000 IU/day) or placebo for 12 months. Serum 25-hydroxyvitamin D [25(OH)D] concentrations, dual energy X-ray absorptiometry (DXA) of the whole body and lumbar spine, and peripheral quantitative computed tomography (pQCT) of tibia sites were acquired at 0, 6, and 12 months. DXA and pQCT outcomes were expressed as sex- and population-ancestry specific Z-scores relative to age and adjusted for height or tibia length, as appropriate.

RESULTS

Fifty-eight participants (5.0 to 24.9 years) received vitamin D₃ supplements (n = 30) or placebo (n = 28). At enrollment, groups were similar in age, sex, population ancestry, growth status, serum 25(OH)D concentrations, body composition, and size-adjusted bone measures. Median 25(OH)D concentrations were similar (17.3 ng/mL in the vitamin D₃ supplementation group vs 15.6 ng/mL in the placebo group), and both groups had mild bone deficits. At 12 months, 25(OH)D rose significantly in the vitamin D supplementation group but not in the placebo group (26.4 vs 14.8 ng/mL, respectively, p < 0.008). After adjusting for population ancestry, sex, antiretroviral therapy use, and season, there were no significant treatment group differences in bone or body composition outcomes.

CONCLUSIONS

Despite increasing 25(OH)D concentrations, 12 months of high-dose vitamin D₃ supplementation did not impact bone or body composition in children and young adults with HIV infection.

The National Osteoporosis Foundation's position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations

Lifestyle choices influence 20-40 % of adult peak bone mass. Therefore, optimization of lifestyle factors known to influence peak bone mass and strength is an important strategy aimed at reducing risk of osteoporosis or low bone mass later in life. The National Osteoporosis Foundation has issued this scientific statement to provide evidence-based guidance and a national implementation strategy for the purpose of helping individuals achieve maximal peak bone mass early in life. In this scientific statement, we (1) report the results of an evidence-based review of the literature since 2000 on factors that influence achieving the full genetic potential for skeletal mass; (2) recommend lifestyle choices that promote maximal bone health throughout the lifespan; (3) outline a research agenda to address current gaps; and (4) identify implementation strategies. We conducted a systematic review of the role of individual nutrients, food patterns, special issues, contraceptives, and physical activity on bone mass and strength development in youth. An evidence grading system was applied to describe the strength of available evidence on these individual modifiable lifestyle factors that may (or may not) influence the development of peak bone mass (Table 1). A summary of the grades for each of these factors is given below. We describe the underpinning biology of these relationships as well as other factors for which a systematic review approach was not possible. Articles published since 2000, all of which followed the report by Heaney et al. [1] published in that year, were considered for this scientific statement. This current review is a systematic update of the previous review conducted by the National Osteoporosis Foundation [1]. [Table: see text] Considering the evidence-based literature review, we recommend lifestyle choices that promote maximal bone health from childhood through young to late adolescence and outline a research agenda to address current gaps in knowledge. The best evidence (grade A) is available for positive effects of calcium intake and physical activity, especially during the late childhood and peripubertal years-a critical period for bone accretion. Good evidence is also available for a role of vitamin D and dairy consumption and a detriment of DMPA injections. However, more rigorous trial data on many other lifestyle choices are needed and this need is outlined in our research agenda. Implementation strategies for lifestyle modifications to promote development of peak bone mass and strength within one's genetic potential require a multisectored (i.e., family, schools, healthcare systems) approach.

Association of 25-hydroxyvitamin D with areal and volumetric measures of bone mineral density and parathyroid hormone: impact of vitamin D-binding protein and its assays

A comparison of the association of different forms of 25-hydroxyvitamin D [25(OH)D] with parathyroid hormone (PTH) and with areal and volumetric bone mineral density (BMD) demonstrated that bioavailable and free 25(OH)D do not provide a better index of vitamin D status in terms of bone health compared to total 25(OH)D.

INTRODUCTION

This study aims to compare measures of vitamin D-binding protein (DBP) using a monoclonal versus polyclonal ELISA and assess correlations of total versus estimated free and bioavailable 25(OH)D with BMD and PTH concentrations.

METHODS

DXA and peripheral quantitative CT (pQCT) scans were obtained in 304 adults (158 black, 146 white), ages 21-80 years. Free and bioavailable 25(OH)D were calculated from total 25(OH)D, DBP, and albumin concentrations. Multivariable linear regression with standardized beta coefficients was used to evaluate associations of bone measures and PTH with total, free, and bioavailable 25(OH)D.

RESULTS

Measures of DBP obtained using a monoclonal versus polyclonal ELISA were not correlated (r s = 0.02, p = 0.76). Free and bioavailable 25(OH)D based on the polyclonal assay were lower in black versus white participants (p < 0.0001); this race difference was not evident using the monoclonal assay. Adjusted for age, sex, calcium intake, and race, all forms of 25(OH)D were negatively associated with PTH, but the absolute coefficient was greatest for total 25(OH)D (-0.34, p < 0.001) versus free/bioavailable 25(OH)D (-0.18/-0.24 depending on DBP assay, p ≤ 0.003). In analyses stratified on race, none of the measures of 25(OH)D were associated with BMD across DXA and pQCT sites.

CONCLUSIONS

The monoclonal versus polyclonal ELISA yielded highly discrepant measures of DBP, particularly among black individuals, likely related to established race differences in DBP polymorphisms. Contrary to prior studies, our findings indicate that using DBP to estimate bioavailable and free 25(OH)D does not provide a better index of vitamin D status in terms of bone health.

Use of proton pump inhibitors is associated with fractures in young adults: a population-based study

Proton pump inhibitors (PPIs) are associated with risk for fracture in osteoporotic adults. In this population-based study, we found a significant association between PPIs and fracture in young adults, with evidence of a dose-response effect. Young adults who use PPIs should be cautioned regarding risk for fracture.

INTRODUCTION

Proton pump inhibitors (PPIs) are associated with fracture in adults with osteoporosis. Because PPI therapy may interfere with bone accrual and attainment of peak bone mineral density, we studied the association between use of PPIs and fracture in children and young adults.

METHODS

We conducted a population-based, case-control study nested within records from general medical practices from 1994 to 2013. Participants were 4-29 years old with ≥ 1 year of follow-up who lacked chronic conditions associated with use of long-term acid suppression. Cases of fracture were defined as the first incident fracture at any site. Using incidence density sampling, cases were matched with up to five controls by age, sex, medical practice, and start of follow-up. PPI exposure was defined as 180 or more cumulative doses of PPIs. Conditional logistic regression was used to estimate the odds ratio and confidence interval for use of PPIs and fracture.

RESULTS

We identified 124,799 cases and 605,643 controls. The adjusted odds ratio for the risk of fracture associated with PPI exposure was 1.13 (95% CI 0.92 to 1.39) among children aged < 18 years old and 1.39 (95% CI 1.26 to 1.53) among young adults aged 18-29 years old. In young adults but not children, we observed a dose-response effect with increased total exposure to PPIs (p for trend <0.001).

CONCLUSIONS

PPI use was associated with fracture in young adults, but overall evidence did not support a PPI-fracture relationship in children. Young adults who use PPIs should be cautioned regarding potentially increased risk for fracture, even if they lack traditional fracture risk factors.

Anthropometric models of bone mineral content and areal bone mineral density based on the bone mineral density in childhood study

New models describing anthropometrically adjusted normal values of bone mineral density and content in children have been created for the various measurement sites. The inclusion of multiple explanatory variables in the models provides the opportunity to calculate Z-scores that are adjusted with respect to the relevant anthropometric parameters.

INTRODUCTION

Previous descriptions of children's bone mineral measurements by age have focused on segmenting diverse populations by race and sex without adjusting for anthropometric variables or have included the effects of a single anthropometric variable.

METHODS

We applied multivariate semi-metric smoothing to the various pediatric bone-measurement sites using data from the Bone Mineral Density in Childhood Study to evaluate which of sex, race, age, height, weight, percent body fat, and sexual maturity explain variations in the population's bone mineral values. By balancing high adjusted R(2) values with clinical needs, two models are examined.

RESULTS

At the spine, whole body, whole body sub head, total hip, hip neck, and forearm sites, models were created using sex, race, age, height, and weight as well as an additional set of models containing these anthropometric variables and percent body fat. For bone mineral density, weight is more important than percent body fat, which is more important than height. For bone mineral content, the order varied by site with body fat being the weakest component. Including more anthropometrics in the model reduces the overlap of the critical groups, identified as those individuals with a Z-score below -2, from the standard sex, race, and age model.

CONCLUSIONS

If body fat is not available, the simpler model including height and weight should be used. The inclusion of multiple explanatory variables in the models provides the opportunity to calculate Z-scores that are adjusted with respect to the relevant anthropometric parameters.

Changes in trabecular bone density in incident pediatric Crohn's disease: a comparison of imaging methods

This study of changes in dual energy x-ray absorptiometry (DXA) spine BMD following diagnosis and treatment for childhood Crohn's disease demonstrated that changes in conventional posteroanterior BMD results were confounded by impaired growth, and suggested that lateral spine measurements and strategies to estimate volumetric BMD were more sensitive to disease and treatment effects.

INTRODUCTION

We previously reported significant increases in peripheral quantitative CT (pQCT) measures of trabecular volumetric bone mineral density (vBMD) following diagnosis and treatment of pediatric Crohn's disease (CD). The objective of this study was to compare pQCT trabecular vBMD and three DXA measures of spine BMD in this cohort: (1) conventional posteroanterior BMD (PA-BMD), (2) PA-BMD adjusted for height Z (PA-BMDHtZ), and (3) width-adjusted volumetric BMD (WA-BMD) estimated from PA and lateral scans.

METHODS

Spine DXA [lumbar (L1-4) for posteroanterior and L3 for lateral] and tibia pQCT scans were obtained in 65 CD subjects (ages 7-18 years) at diagnosis and 12 months later. BMD results were converted to sex, race, and age-specific Z-scores based on reference data in >650 children (ages 5-21 years). Multivariable linear regression models identified factors associated with BMD Z-scores.

RESULTS

At CD diagnosis, all BMD Z-scores were lower compared with the reference children (all p values <0.01). The pQCT vBMD Z-scores (-1.46 ± 1.30) were lower compared with DXA PA-BMD (-0.75 ± 0.98), PA-BMDHtZ (-0.53 ± 0.87), and WA-BMD (-0.61 ± 1.10) among CD participants. Only PA-BMD Z-scores were correlated with height Z-scores at baseline (R = 0.47, p < 0.0001). pQCT and WA-BMD Z-scores increased significantly over 12 months to -1.04 ± 1.26 and -0.20 ± 1.14, respectively. Changes in all four BMD Z-scores were positively associated with changes in height Z-scores (p < 0.05). Glucocorticoid doses were inversely associated with changes in WA-BMD (p < 0.01) only.

CONCLUSIONS

Conventional and height Z-score-adjusted PA DXA methods did not demonstrate the significant increases in trabecular vBMD noted on pQCT and WA-BMD scans. WA-BMD captured glucocorticoid effects, potentially due to isolation of the vertebral body on the lateral projection. Future studies are needed to identify the BMD measure that provides greatest fracture discrimination in CD.

Fitting of bone mineral density with consideration of anthropometric parameters

A new model describing normal values of bone mineral density in children has been evaluated, which includes not only the traditional parameters of age, gender, and race, but also weight, height, percent body fat, and sexual maturity. This model may constitute a better comparative norm for a specific child with given anthropometric values.

INTRODUCTION

Previous descriptions of children's bone mineral density (BMD) by age have focused on segmenting diverse populations by race and gender without adjusting for anthropometric variables or have included the effects of anthropometric variables over a relatively homogeneous population.

METHODS

Multivariate semi-metric smoothing (MS(2)) provides a way to describe a diverse population using a model that includes multiple effects and their interactions while producing a result that can be smoothed with respect to age in order to provide connected percentiles. We applied MS(2) to spine BMD data from the Bone Mineral Density in Childhood Study to evaluate which of gender, race, age, height, weight, percent body fat, and sexual maturity explain variations in the population's BMD values. By balancing high adjusted R (2) values and low mean square errors with clinical needs, a model using age, gender, race, weight, and percent body fat is proposed and examined.

RESULTS

This model provides narrower distributions and slight shifts of BMD values compared to the traditional model, which includes only age, gender, and race. Thus, the proposed model might constitute a better comparative standard for a specific child with given anthropometric values and should be less dependent on the anthropometric characteristics of the cohort used to devise the model.

CONCLUSIONS

The inclusion of multiple explanatory variables in the model, while creating smooth output curves, makes the MS(2) method attractive in modeling practically sized data sets. The clinical use of this model by the bone research community has yet to be fully established.

Special report on the 2007 adult and pediatric Position Development Conferences of the International Society for Clinical Densitometry

The International Society for Clinical Densitometry (ISCD) conducts Position Development Conferences (PDCs) for the purpose of establishing standards and guidelines in the field of bone densitometry. Topics for consideration are selected according to clinical relevance, a perceived need for standardization, and the likelihood of achieving agreement. Questions regarding nomenclature, indications, acquisition, analysis, quality control, interpretation, and reporting of bone density tests for each topic area are assigned to task forces for a comprehensive review of the scientific literature. The findings of the review and recommendations are then presented to an international panel of experts at the PDC. The expert panel votes on potential Official Positions for appropriateness, necessity, quality of the evidence, strength of the recommendation, and applicability (worldwide or variable according to local requirements). Recommendations that are approved by the ISCD Board of Directors become Official Positions. The first Pediatric PDC was 20-21 June 2007 in Montreal, QC, Canada. The most recent Adult PDC was held 20-22 July 2007, in Lansdowne, VA, USA. This Special Report summarizes the methodology of the ISCD PDCs and presents selected Official Positions of general interest.

Body composition and metabolic factors in obese children and adolescents

OBJECTIVE

Body composition is associated with metablic factors in adults; however, data are limited regarding obese children. This study was undertaken to assess body composition, regional fat distribution, and metabolic factors in obese 6-18-y-old children and adolescents.

DESIGN

Cross-sectional assessment.

SUBJECTS

Thirty-six obese children and adolescents, (mean+/-s.e.m.) age 11.8+/-0.5 y, BMI 34.1+/-1.2 kg/m(2).

MEASUREMENTS

Body composition was assessed by dual energy X-ray absorptiometry and computerized tomography. Fasting insulin, glucose and leptin levels, and the homeostasis model assessment of insulin sensitivity (HOMA-IR) were assessed.

RESULTS

The girls had significantly lower glucose levels than the boys. The ethnic group differences (African American children vs white children) in fat mass, total CT fat, subcutaneous CT fat, insulin level, leptin level, and higher HOMA-IR were not significant after adjusting for age or pubertal stage. These differences in abdominal fat and subcutaneous abdominal fat were also not independent of total body fat or BMI. No ethnic group differences in visceral abdominal fat were noted. Insulin level and HOMA IR were associated with leptin level (independent of fat mass) and fat mass. Leptin level was associated with fat mass, total CT fat, and subcutaneous CT fat; however the associations between the CT fat measures and leptin were not independent of total body fat mass.

CONCLUSIONS

Neither visceral abdominal fat, subcutaneous abdominal fat, insulin levels, or insulin resistance differed by ethnic group when adjusted for age or pubertal status. This contrasts with findings in adults and non-obese children which suggest lower levels of visceral fat and higher insulin levels and insulin resistance in African American children and adolescents.

Prevalence and risk factors for overweight and obesity in children from Seychelles, a country in rapid transition: the importance of early growth

OBJECTIVES

To establish the prevalence of overweight and obesity and related risk factors in children from Seychelles (Indian Ocean), a country in rapid economic and epidemiological transition.

DESIGN

Cross-sectional study with retrospective access to early life data.

SUBJECTS

All children from all schools of Seychelles, in four selected school grades (kindergarten, fourth, seventh and tenth year of obligatory school) in 1999. A total of 5514 children aged 4.5-17.4 y were measured, corresponding to 83.5% of the eligible population.

MEASUREMENTS

Overweight and obesity, using age- and sex-specific body mass index (BMI) cut-off points as defined by the International Obesity Task Force.

RESULTS

Some 12.6% (95% confidence interval: 11.8-13.5%) of the children were overweight and 3.8% (3.3-4.4%) were obese. Weight gain (kg) during the first year of life was strongly associated with subsequent overweight (odds ratio 1.46, 95% confidence interval 1.27-1.67) and obesity (1.59, 1.29-1.97) in childhood, independently of birth weight. Increased maternal BMI (kg/m(2)) was also associated with overweight (1.07, 1.03-1.10) and obesity (1.09, 1.04-1.14) in the offspring.

CONCLUSION

Prevalence of overweight and obesity among school children in Seychelles was as high as or higher than in some industrialized countries. If confirmed in other environments, the strong association between weight gain during the first year of life and subsequent obesity in childhood could affect the way optimal infant weight gain is defined in countries where public health priorities are changing.

Effect of hydroxyurea therapy on resting energy expenditure in children with sickle cell disease

Effects of hydroxyurea therapy on resting energy expenditure (REE) in children with sickle cell disease have not been evaluated. Eight children with sickle cell disease were examined before hydroxyurea therapy and again 6.9 +/- 3.5 months after hydroxyurea initiation. Resting energy expenditure, dietary intake, and growth were assessed. In six children, baseline REE was elevated, and REE decreased an average of 17% with hydroxyurea. This was associated with a significant increase in fetal hemoglobin. These pilot data suggest that hydroxyurea may curtail the hypermetabolic state observed in children with sickle cell disease and may offer a clinically important secondary benefit.

Energy expenditure and intake in children with sickle cell disease during acute illness

BACKGROUND

Children with sickle cell disease have frequent bouts of pain and infection which may increase energy expenditure, decrease energy intake and lead to a subsequent energy deficit.

METHODS

Two groups of African-American children with sickle cell disease-SS genotype were enrolled in this study upon hospital admission for a sickle cell disease related illness: a younger (<6 years, n=14, 7 M) and older group (> or =6 years, n=17, 8 M). Body composition and dietary intake were assessed, and sleeping (younger) or resting energy expenditure (older) were measured by indirect calorimetry at admission and one month later at steady state.

RESULTS

Energy expenditure was not different between the two timepoints for younger children, but was slightly elevated at steady state (+50 kcal/d, P=0.049) in the older group. After controlling for gender, changes in fat-free mass and dietary intake, the significance disappeared. Energy intake in both groups was significantly depressed at admission compared to follow-up (P<0.01).

CONCLUSIONS

These children and adolescents did not expend excess energy during their acute illness, however, an energy deficit was observed secondary to poor energy intake. Since 20% of patients with sickle cell disease have multiple hospitalizations per year, these results provide justification for the development and evaluation of nutrition care protocols to maintain adequate caloric intake during hospitalization and recovery.

Red blood cell folate and serum vitamin B12 status in children with sickle cell disease

PURPOSE

To determine red blood cell (RBC) folate and serum vitamin B12 levels in children with sickle cell disease, SS-type, and to evaluate the associations of these nutrient levels with growth and hematologic parameters.

PATIENTS AND METHODS

Subjects enrolled in this prospective, cross-sectional study were recruited from one tertiary care setting. Complete blood counts, measurement of red blood cell (RBC) folate and serum vitamin B12, anthropometric measures (height, weight, skinfold measurements), pubertal status, and 24-hour dietary recalls were obtained from 70 patients ages 1 to 19 years.

RESULTS

Low RBC folate levels were found in 15% of the children. Fifty-seven percent of the sample had inadequate dietary folate intake. Three percent of the children had low serum vitamin B12 levels. All children and adolescents sampled had adequate dietary intake of vitamin B12. Both RBC folate (P = 0.01) and serum vitamin B12 levels (P < 0.01) decreased with increasing age.

CONCLUSIONS

More than half of the subjects had inadequate intake of folate from food, and despite daily folate supplementation, 15% had low RBC folate levels. Low serum vitamin B12 levels were rare, and dietary vitamin B12 intake was adequate. Additional research is needed to explore the effects of improved folate status, the need for folate supplementation, and the relationship of folate, vitamin B12, and homocysteine levels and the risk for vascular damage and stroke in children with sickle cell disease.

Iron status of children with sickle cell disease

BACKGROUND

Dietary iron requirements are unclear in children with SS-type sickle cell disease.

METHODS

Iron status was assessed in 104 nontransfused African American children (aged 0.5 to 17.6 years) with sickle cell disease who receive no iron supplement. Dietary iron intake was not measured at the time of this study.

RESULTS

Serum ferritin was normal or high in all children. Other hematologic and biochemical indicators of iron deficiency were in the normal range in most children.

CONCLUSIONS

Unlike previous studies, this sample of children and adolescents did not show signs of iron deficiency.

Longitudinal relationship among growth, nutritional status, and pulmonary function in children with cystic fibrosis: analysis of the Cystic Fibrosis Foundation National CF Patient Registry

OBJECTIVE

To determine prospectively the relationship among growth, nutritional status, and pulmonary function over a 4-year period in a large cohort of children with cystic fibrosis (CF).

STUDY DESIGN

CF Foundation National CF Patient Registry data collected from 1991 to 1995 for 968 children (507 male) aged 5 to 8 years with pancreatic insufficiency and forced expiratory volume in 1 second within 60% to 140% of predicted values (FEV(1)%) were analyzed longitudinally. Variables hypothesized to affect FEV(1)% included age, sex, z scores for height, weight, percent of height-appropriate body weight, and annual number of days hospitalized.

RESULTS

The significant decline in FEV(1)% was curvilinear and dependent on baseline FEV(1)%; children with initial FEV(1)% > or = 90 declined 2.6 U/y more than those with initial FEV(1)% <90. Boys gained but girls declined in z scores for height. Girls decreased in z scores for weight at a greater rate than boys. The z scores for weight and percent of height-appropriate body weight were significantly associated with longitudinal changes in FEV(1)%, after adjustment was done for hospitalizations.

CONCLUSIONS

Growth, nutritional status, and pulmonary function are not stable in prepubertal children with CF and pancreatic insufficiency. Important sex-related differences in growth occur before puberty. Growth and nutritional status are associated with changes in FEV(1)%, suggesting that nutritional intervention may slow the decline in pulmonary function in children with CF.

Prospective evaluation of growth, nutritional status, and body composition in children with cystic fibrosis

BACKGROUND

Several cross-sectional studies have shown improvement in the growth of children with cystic fibrosis (CF) because of increased awareness of and more comprehensive care of their special nutritional needs. However, longitudinal data on the nutritional status of these children are rare.

OBJECTIVE

The objective was to compare changes in growth, body composition, and nutritional status between children with and without CF.

DESIGN

This was a prospective 3-y cohort study of 25 children aged 5-10 y with CF, mild pulmonary disease, and pancreatic insufficiency and of 26 healthy control children. Three methods were used to assess body composition: measurements of skinfold thickness, total body water by deuterium oxide, and total-body electrical conductivity. Growth and body-composition changes over time were analyzed by a longitudinal mixed-effects model.

RESULTS

Over the 3 y of the study, the statural growth of the boys with CF was slower than that of the control subjects (P = 0.004). The same divergence over time between the boys with and without CF was observed for fat-free mass assessed by skinfold-thickness measurements and total body water (P = 0.008 and 0.02, respectively) and for fat mass assessed by skinfold-thickness measurements and total-body electrical conductivity (P = 0.009 and 0.001, respectively). The differences in the pattern of changes in growth and body composition were less striking for girls.

CONCLUSIONS

Despite comprehensive care, the growth of boys with CF was impaired on the basis of height, fat-free mass, and fat mass, when observed longitudinally. Caution should be used when interpreting cross-sectional measurements because they often do not detect suboptimal growth.

Early risk factors for increased adiposity: a cohort study of African American subjects followed from birth to young adulthood

BACKGROUND

Obesity is an increasing concern in the United States. Effective prevention of obesity requires the risk factors to be well defined. African Americans have a high risk of obesity.

OBJECTIVE

The objective of this study was to identify risk factors, present at birth, for increased adiposity in adulthood in an African American population.

DESIGN

In this retrospective analysis of a prospective cohort study, anthropometric and socioeconomic variables were collected at birth. A representative sample of 447 African American subjects was followed up until young adulthood, when skinfold thickness was measured. Associations between the independent variables and increased adiposity (skinfold thickness above the 85th percentile) were explored by using unadjusted and adjusted analyses.

RESULTS

Three variables measured at birth were independently associated with adiposity in young adulthood, explaining 12% of the variance. The odds ratios (with 95% CIs) of these variables for increased adiposity were 2.7 (1.2, 6.2) for female sex, 4.0 (1.4, 11. 2) for first-born status, and 1.15 (1.06, 1.25) for each unit increment in maternal prepregnancy body mass index (BMI; in kg/m(2)). After adjustment for these variables, birth weight for gestational age and socioeconomic variables were not associated with adiposity.

CONCLUSIONS

This cohort study of African American subjects was the first to identify first-born status as an independent risk factor for increased adiposity in adulthood in a US population. The results of the study strengthen previous reports of the effect of female sex and maternal BMI on adulthood obesity. Identification of risk factors early in life may help target prevention toward high-risk children and allow healthy lifestyles to be established before the onset of obesity.

Growth, body composition, and nutritional status in children and adolescents with Crohn's disease

OBJECTIVE

To examine growth, body composition, and nutritional status in a large sample of children, adolescents, and young adults with Crohn's disease (CD).

METHODS

One hundred thirty-two subjects (48 females) with CD, aged 5 to 25 years, and 66 healthy control subjects (37 females) of similar age. Growth, nutritional status, and body composition were measured by anthropometry and dual-energy x-ray absorptiometry. Genetic potential of linear growth was predicted using the adjusted heights of Himes et al. Pubertal status and skeletal age were assessed. Average Pediatric Crohn's Disease Activity Index (PCDAI) and lifetime steroid exposure (in milligrams per day) were obtained from medical charts. The variables were examined in relation to gender and measures of disease activity.

RESULTS

Males and females with CD did not differ by age, disease duration, or PCDAI. Males with CD had significantly lower values for growth and nutritional status than control subjects (z-scores for weight: -0.66 +/- 1.18 vs. 0.26 +/- 0.95, P = 0.00002; height -0.81 +/- 1.14 vs. 0.28 +/- 0.93, P = 0.00001; adjusted height -1.05 +/- 1.03 vs. 0.40 +/- 1.03, P = 0.00001) and delayed skeletal age of 0.9 +/- 1.6 years. Impaired linear growth in the males was present regardless of pubertal stage. Associations between disease severity indicators and growth parameters were more consistent for females.

CONCLUSIONS

Crohn's disease is associated with impaired growth. Despite similarities in disease duration, activity, and lifetime steroid exposure, growth in males was more impaired. Gender may confer risk for impaired growth in CD.

A prospective study of body composition changes in children with cystic fibrosis

Recent cross-sectional studies of children with cystic fibrosis (CF) have shown an improvement in their growth with improved nutritional status, but there are only a few longitudinal studies in this population. A four-year prospective study was conducted in 25 children with CF and 26 controls, ages 5 to 10 years at baseline, to describe changes in body composition using three independent methods of assessment: skinfold thickness, total body water by deuterium dilution, and total body electrical conductivity (TOBEC). The statural growth of the boys with CF was slower than that of the control boys. Using different methods, the fat-free mass and fat-mass increases were shown to be slower in boys with CF than in controls. These differences were less significant in girls. Despite comprehensive care, the growth of boys with CF may still not be optimal, as observed longitudinally.

Impact of acute illness on nutritional status of infants and young children with sickle cell disease

OBJECTIVE

To evaluate changes in growth, nutritional status, body composition, and energy and nutrient intakes during illness and usual state of health in infants and young children with sickle cell disease.

DESIGN

Sixteen children, aged 0.4 to 5.6 years, with SS type sickle cell disease (SCD-SS) were assessed at the time of hospital admission for an acute illness episode and during an 18-hour overnight follow-up visit 2 to 6 weeks after the acute illness episode when in a state of usual health. Main outcome measures included growth in height and weight compared with reference standards, body composition determined by the skinfold thickness technique and total body electrical conductivity, and dietary intake determined by 24-hour recall during hospital admission and at follow-up.

RESULTS

Height, weight, and weight-for-height z scores did not differ from national reference data; triceps skinfold thickness and arm fat area z scores were less. Mean +/- standard error body fat was 15.6 +/- 2.1% at the time of hospital admission, as measured by total body electrical conductivity, and was not significantly different from the follow-up value (16.2 +/- 2.2%). Mean energy intake was 44 +/- 9% of Recommended Dietary Allowances at the time of admission and differed significantly from the follow-up value of 90 +/- 9% (P < .05).

APPLICATIONS

Infants and children with sickle cell disease appear to be at nutritional risk during an acute illness episode, as indicated by body fat measures and inadequate intakes of energy and macronutrients. Energy intake may be suboptimal for several days surrounding an admission for an acute illness in children with sickle cell disease. Physicians and other health practitioners should be alert to inadequate nutrient intakes of their patients during this time period and may consider supplemental energy to avoid a potential net negative energy balance.

Total and resting energy expenditure in children with sickle cell disease

OBJECTIVE

To investigate energy balance in children with sickle cell disease (SCD) as the possible cause of impaired growth and undernutrition.

STUDY DESIGN

Growth, resting (REE), total (TEE), and activity-related (AEE) energy expenditure and dietary intake were examined in 36 African American children with SCD (20 girls and 16 boys) and 30 control subjects (15 girls and 15 boys) of similar age (mean, 11.2 years) and ethnicity. TEE was measured by means of the doubly labeled water technique and REE by indirect calorimetry. AEE was calculated as TEE minus REE. Fat free mass (FFM) was calculated from skinfold prediction equations.

RESULTS

REE was significantly increased (131 kcal/d) in children with SCD (P =.001), after adjusting for sex and FFM. Children with SCD tended to have lower TEE (214 kcal/d) than control subjects, but there was no difference after adjusting for FFM and sex (P =.57). Children with SCD had significantly (P =.025) lower AEE (268 kcal/d) but only marginally (P =.08) lower AEE after adjusting for FFM and sex.

CONCLUSIONS

The elevated REE and lower AEE, in combination with poor growth status, indicate chronic energy deficiency in children with SCD. Further studies are needed to determine the best approaches to the treatment and prevention of undernutrition in children with SCD.

Risk factors for low bone mineral density in children and young adults with Crohn's disease

OBJECTIVE

Low bone mineral density (BMD) is a recognized complication of Crohn's disease (CD). The aim of this study was to identify the risk factors for low BMD in pediatric patients with CD.

STUDY DESIGN

One hundred nineteen subjects with CD ranging in age from 5 to 25 years were enrolled. BMD of the lumbar spine was measured by dual-energy x-ray absorptiometry. Growth parameters were assessed by examination. Disease-specific variables and use of selected medications were determined by chart review.

RESULTS

Powerful risk factors for low BMD z-score included hypoalbuminemia, exposure to nasogastric tube feeds, total parenteral nutrition, 6-mercaptopurine, and corticosteroids. Corticosteroid dosing at a level >7.5 mg/d, 5000 mg lifetime cumulative dose, or >12 months of lifetime exposure were significant risk factors for low BMD z-score. Weaker but significant associations with low BMD z-scores included measures of disease severity such as pediatric Crohn's disease activity index, hospital admissions, and length of hospital stay. Site and duration of disease were not predictive.

CONCLUSIONS

The presence of several clinically available factors was predictive of poor bone mineral status in this sample of subjects with CD. Hypoalbuminemia, corticosteroid exposure, nasogastric tube feeds, total parenteral nutrition, and 6-mercaptopurine were the most powerful risk factors for low bone mineral status.

Discrepancies in pediatric bone mineral density reference data: potential for misdiagnosis of osteopenia

OBJECTIVE

To evaluate published pediatric dual-energy x-ray absorptiometry bone mineral density (BMD) reference data by comparing the diagnostic classification of measured BMD in children at risk for osteopenia as healthy or osteopenic according to reference source.

STUDY DESIGN

Spine BMD was measured in 95 children, ages 9 to 15 years, at risk for osteopenia because of childhood disease. The BMD results were converted to age-specific z scores for each of the 5 reference data sets, and the z -score distributions were compared.

RESULTS

Between 11% and 30% of children were classified as osteopenic (z score < -2.0) depending on the reference data set. The 2 sex-specific reference data sets yielded similar diagnostic classification of boys and girls: 10% of boys and 11% to 16% of girls were osteopenic (P =.4). The 3 sex-nonspecific reference data sets classified 9% to 13% of girls and 24% to 44% of boys as osteopenic; the diagnosis of osteopenia was significantly greater in boys (P <.01).

CONCLUSIONS

The use of different published reference data for the assessment of children at risk for osteopenia results in inconsistent diagnostic classification of BMD results. These inconsistencies can be partially attributed to sex-nonspecific reference data that result in misclassification of boys as osteopenic.

Bone mineral density in children and young adults with Crohn's disease

Reduced bone mineral density (BMD) has been reported in adults with Crohn's disease (CD). Less is known about abnormal BMD in children and young adults with CD. The aims of this study are to determine the prevalence of low BMD and to evaluate the effect of growth and pubertal development on BMD in children and young adults with CD. One hundred-nineteen patients with CD underwent dual-energy X-ray absorptiometry (DXA) to determine BMD. Anthropometry and pubertal development were measured. Bone age was measured only in patients older than 8 years of age and who had not grown in height during the last year. One hundred-nineteen patients (72 male, 47 female) were evaluated. Seventy percent of patients had BMD z-scores < or = -1.0 and 32% had z-scores < or = -2.0. Weight and height z-scores were significantly associated with BMD z-scores. BMD z-scores based on bone age and on chronological age were highly correlated, except when the chronological age BMD z-score was < or = -2.0. BMD z-score was significantly different between males and females for the group (-1.75 +/- 1.06 vs. -1.08 +/- 1.00), respectively. Children and young adults with CD have a high prevalence of low BMD and routine evaluation by DXA is indicated. In patients with a chronological age-based BMD z-score < or = -2.0, a bone age-based BMD should be considered.

A six-month study of growth and energy expenditure in children with cystic fibrosis taking a pulmonary inhalation medication (rhDNase)

OBJECTIVE

To characterize the effects of recombinant human deoxyribonuclease (rhDNase) on growth velocity, body composition, resting energy expenditure (REE) and food intake in children with cystic fibrosis (CF).

METHODS

A prospective, six-month pilot study was conducted in twenty-one subjects with CF (twelve male, nine female, ages 11.5+/-3.1 years) measured at baseline, two and six months post-baseline. Repeated measures ANOVA was used to examine the change in variables across time.

RESULTS

The majority (75%) of subjects had minimal lung disease at baseline (FEV1: 80%-119% predicted). As expected for growing children, weight and height gains (1.6 kg and 2.5 cm) were observed between baseline and six months (p=0.0001). No change was observed in weight z-scores from six months prior to initiation of rhDNase therapy to six months post, though a significant decline (p=0.049) in Ht z-score was observed over this twelve-month period. Triceps skinfolds and mid-arm muscle circumference increased from baseline to six months (p<0.01); respective z-scores remained stable. Energy intake remained constant during the period it was studied from baseline to two months of therapy: 120%+/-27% RDA. REE, though slightly elevated compared to healthy children (baseline 106%+/-8% predicted), remained stable throughout the study and at a level which may be expected for children with minimal lung disease. A trend (p=0.057) towards a decrease in the number of subjects requiring hospitalization for pulmonary exacerbations during the trial period was observed.

CONCLUSIONS

In summary, these pilot data from younger children with milder CF-related lung disease do not confirm anecdotal reports of improved rate of weight gain, caloric intake or decreases in the elevated REE. Future research might focus on documentation of the possible nutritional effects of rhDNase in clinical trials of children with more severe lung disease.

Growth, nutritional status, body composition, and energy expenditure in prepubertal children with Alagille syndrome

OBJECTIVES

To describe the patterns of growth, nutritional status, body composition, and resting energy expenditure (REE) in prepubertal children with Alagille syndrome (AGS) before the onset of end-stage liver disease.

STUDY DESIGN

Thirteen prepubertal subjects with AGS (8 male; mean age, 6.8 2.8 years) were evaluated for growth parameters, body composition by skinfolds and by dual-energy x-ray absorptiometry, and REE by indirect calorimetry. The children with AGS were compared with a healthy, age-matched reference group of 37 prepubertal children.

RESULTS

Compared with healthy children, children with AGS had significantly reduced (P <. 05) growth (weight, weight z score, height, height z score), nutritional status (midarm circumference, triceps skinfold, and midarm muscle area), and body composition (fat mass and fat-free mass). Subscapular thickness, percent body fat, and REE were not different. The AGS subgroup (n = 4) with REE greater than 110% predicted value had a reduced percent body fat (P <.02).

CONCLUSIONS

Growth and body composition abnormalities are common in prepubertal children with AGS.

Evaluation of low density spine software for the assessment of bone mineral density in children

Pediatric dual-energy X-ray absorptiometry spine scans often cannot be analyzed with standard software due to a failure to identify the bone edges of low density vertebrae. Low density spine (LDS) software improves bone detection compared with standard software. The objective of this study was to compare bone mineral density (BMD) measurements obtained with the standard and LDS software in 27 healthy nonobese, 32 obese, and 41 chronically ill children, ages 2-18 years. Lumbar spine (L1-L4) BMD, measured by standard analysis, ranged from 0.531-1.244 gm/cm2. Reanalysis with the LDS software resulted in a systematic increase (mean +/- SD) in estimated bone area of 17.0+/-5.0%, an increase in bone mineral content of 6.1+/-6.3%, and a mean decrease in BMD of 8.7+/-1.7% (all p < 0.001). This resulted in a mean decrease in BMD Z score of 0.7+/-0.2. Linear regression models, predicting standard BMD from LDS BMD, were fit for the three subject groups (R2 = 0.993-0.995). Small differences in slopes were detected across groups (p = 0.07); LDS BMD predicted higher standard BMD in obese subjects. In conclusion, LDS analysis resulted in a clinically significant decrease in measured BMD. The association between analysis methods was exceptionally high (R2 > 0.99), indicating that LDS BMD accurately predicts standard BMD. Although LDS BMD in obese subjects predicts higher standard BMD results than in nonobese subjects, the small difference is of questionable clinical significance. LDS software is a useful tool for the assessment of BMD in children.

Long-term follow-up of participants in the Collaborative Perinatal Project: tracking the next generation

This report describes the methods used in conducting a long-term follow-up study and the factors associated with the successful location of subjects. In 1987-91, we selected, from among the women who were born in 1959-66 as members of the Philadelphia and Providence cohorts of the Collaborative Perinatal Project (CPP), 391 who were preterm at birth, 413 who were small-for-gestational age (SGA) and 978 who were term and appropriately grown; 1314 were from Philadelphia and 468 from Providence. Tracing was accomplished using original CPP records, telephone directories, voter registration and driver's licence records, birth certificate files and credit bureaux. A total of 61% of the women were located, 55% at Philadelphia and 77% at Providence. After adjustment, the odds ratio for ease of location, compared with women who were term and appropriately grown, was 0.85 [95% CI 0.66-1.11] for women who were preterm and 1.02 [0.78-1.34] for women who were SGA. In Philadelphia, African-American women were more likely than white women to be located, but in Providence, African-American women were less likely than white women to be located. Women whose own mothers were older at the time of their birth were more likely to be located, as were those who had more siblings followed in the CPP. Compared with women who did not complete their original CPP examinations at ages 4 and 7 years, those whose original CPP follow-up was more complete were more likely to be located. These findings demonstrate that long-term follow up in a US urban setting can be accomplished, and that successful location was not associated with birth status.

Growth of hypercholesterolemic children completing physician-initiated low-fat dietary intervention

OBJECTIVE

To evaluate the growth of hypercholesterolemic children completing an innovative, physician-initiated, home-based nutrition education program or standard nutrition counseling that aims to lower dietary fat intake.

STUDY DESIGN

From suburban pediatric practices, 261 3.9- to 9.9-year-old children with elevated cholesterol levels and 81 children with nonelevated cholesterol levels were identified. The children with hypercholesterolemia were randomly assigned to the home-based education program, standard nutrition counseling, or an at-risk control group. Height, weight, skinfold measures, and dietary intake were evaluated at baseline, 3, 6, and 12 months; changes in anthropometric measures among treatment groups were compared over time.

RESULTS

The intervention groups demonstrated significant decreases in fat and saturated fat intake after the interventions; however, weight z-score, height z-weight-for-height-median, and sum of skinfolds did not vary among the treatment groups over the year. At baseline, height z-score, weight z-score, and weight-for-height-median were positively associated with caloric intake, whereas weight z-score, weight-for-height-median, and sum of skinfolds were positively associated with fat intake. When the groups were combined and the children were grouped by average fat intake quintiles, no association between fat intake and changes in weight z-score, height z-score, or weight-for-height-media was observed. Differences over time in sum of skinfolds among fat intake quintile groups (suggesting a negative association between fat intake and body fat) that approached statistical significance (p = 0.06) were observed.

CONCLUSIONS

These results support the safety, with respect to growth, of physician-initiated dietary intervention and lower fat diets for children with hypercholesterolemia. In addition, low dietary fat intake was associated with lower body fat.

Age-related changes in cardiovascular disease risk factors of hypercholesterolemic children

OBJECTIVE

To describe the age-related changes in cardiovascular disease risk factors in young, hypercholesterolemic (HC) children.

METHODS

Hypercholesterolemic (n = 227) and nonhypercholesterolemic (NHC) (n = 80) children between the ages of 4 and 10 years were identified. Height, weight, skin-fold and blood pressure measurements, and total cholesterol levels were measured. The HC group also had insulin levels evaluated. The groups were compared by analysis of variance. Simple Spearman correlations evaluated the associations between factors within each group.

RESULTS

The HC and NHC groups had similar mean ages, heights, and weights, both contained 51% girls, and all were white subjects. Percent weight-for-height median, and biceps, triceps, suprailiac and subscapular skin-fold measurements were all larger for the HC group. A significant age interaction demonstrated that the HC group's larger suprailiac and sum of skin-fold measures were expressed in the 8.0- to 9.9-year-old children, but not the 4.0- to 5.9-year-olds. For both groups, systolic blood pressure was associated with the measures of adiposity. For the HC group, insulin levels were also associated with adiposity.

CONCLUSIONS

These results suggest that: (1) children with HC have greater body fat, (2) the expression of the hypercholesterolemia precedes the expression of increased body fat, (3) body fat increases with age, and (4) altered insulin and blood pressure levels are expressed in association with the increased body fat in children with HC. Confirmation with longitudinal data is necessary.

Plasma zinc status, growth, and maturation in children with sickle cell disease

OBJECTIVE

The objective of this study was to determine the relation of plasma zinc (Zn) status to growth and maturation in children with SS genotype sickle cell disease.

STUDY DESIGN

A cross-sectional study of 104 subjects who were 50% female and ranged in age from 0.4 to 18 years was performed. Measures included plasma Zn concentration (Znp), height, weight, skinfold thicknesses, elbow breadth, upper arm muscle area, and fat-free mass and fat mass by total body electrical conductivity. Skeletal maturation was assessed by hand-wrist x-ray evaluation and sexual maturation by Tanner stage.

RESULTS

A total of 44% of the patients had low Znp (<10.7 micromol/L [70 microg/dl]); those with low Znp had significantly lower SD scores for height (p = 0.003), weight (p = 0.003), upper arm muscle area (p = 0.045), fat-free mass (p = 0.025), and elbow breadth (p = 0.017) and greater skeletal maturation delay (p = 0.04). In older children (>9 years) low Znp was associated with decreased Tanner scores for pubic hair (p = 0.001) and breast and genital maturation (p = 0.009). No significant differences were seen in age, sex, or fat stores according to Zn status.

CONCLUSIONS

Decreased plasma Zn is common in children with SS genotype sickle cell disease and is associated with decreased linear growth, skeletal growth, muscle mass, and sexual and skeletal maturation.

Body composition, energy expenditure, and energy intake in patients with Williams syndrome

OBJECTIVE

To evaluate the body composition, resting energy expenditure (REE), and energy intake of adolescents and adults with Williams syndrome (WS) compared with matched healthy control subjects.

METHODS

Body composition was determined by total body electrical conductivity and anthropometric measurements in six subjects with WS from the WS Clinic at Children's Hospital of Philadelphia and six healthy control subjects matched for age, height, and pubertal stage. REE was measured by open-circuit indirect calorimetry. Dietary intake was assessed by 3-day dietary records.

RESULTS

Subjects with WS had similar anthropometric measurements to the control group except for a significantly lower percent body fat (17.1%+/-5.2% vs. 25.0%+/-6.7%). Dietary intake (measured in kilocalories per day) was similar between the two groups. REE was statistically higher by 155 kcal/day in the WS group after controlling for age, gender, and body composition. In addition, the WS group had a significantly higher percent predicted REE according to the World Health Organization equation, which adjusts for age, gender, and body weight.

CONCLUSION

Adolescents and adults with WS have a similar dietary intake but a lower body fat than healthy control subjects. A higher REE may contribute to the thin body habitus and reduced total body fat stores of people with WS.

Evaluation of methodology for nutritional assessment in children: anthropometry, body composition, and energy expenditure

Nutritional status in children is an indicator of health and well-being at both the individual and the population level. Screening for malnutrition should be an integral part of pediatric care universally. Nutritional intervention requires repeated measurement of nutritional status to assess severity and to track progress over time. Methodological issues in the assessment of nutritional status are reviewed with emphasis on anthropometric measurement, body composition, and energy expenditure of children at risk for malnutrition. Use of reference data, measurement error, maturational effects, and hereditary factors are among the issues reviewed and serve as guidelines in the interpretation of measurement of nutritional status.

Differences in resting energy expenditure in prepubertal black children and white children

OBJECTIVE

To evaluate differences in resting energy expenditure (REE) of black and white prepubertal children.

SUBJECTS

The study subjects were 34 prepubertal children 5 to 12 years of age and weighing 90% to 206% ideal body weight. Girls represented 59% of the study subjects; 44% were white children and 56% were black children.

METHODS

Fat-free mass (FFM), fat mass, and the percentage of body fat were determined by total body electrical conductivity. Fasting REE was measured by open-circuit indirect calorimetry.

RESULTS

Although weight, height, FFM, fat mass, percentage of body fat, and age were similar between the ethnic groups (black vs. white children), the black subjects had a significantly lower REE (1312 +/- 38 kcal/day) compared with the white subjects (1524 +/- 43 kcal/day) after adjusting for age, gender, weight, FFM, and fat mass. Fat-free mass and ethnic group were the only significant predictors of REE (R2 = 0.70).

CONCLUSION

Resting energy expenditure is significantly higher in this sample of white children compared with the black children after adjusting for body size and composition. Both FFM and ethnic background were significant determinants of REE in prepubertal children.

Prospective evaluation of resting energy expenditure, nutritional status, pulmonary function, and genotype in children with cystic fibrosis

Growth failure and malnutrition are common clinical features in cystic fibrosis (CF), but the relationships among resting energy expenditure (REE), pulmonary function, and nutritional status, are poorly understood. To better understand these relationships, REE, growth, nutritional status, and pulmonary function were measured prospectively in 25 prepubertal children with CF and 26 prepubertal control subjects of similar age and gender over a 3-y period. All subjects with CF had pancreatic insufficiency and mild pulmonary disease. REE was elevated for the CF children compared with control subjects throughout the study. This increased REE was not associated with declining pulmonary function. Longitudinal analyses revealed different patterns of change over time in boys and girls, such that REE significantly increased in the girls with CF and pulmonary function decreased in the boys. Boys with CF experienced a decline in weight Z score and percent ideal body weight, whereas the girls with CF experienced a decline in height Z score. Pulmonary function was not associated with REE, but nutritional status (percent ideal body weight) and genotype (delta F508 homozygotes versus others) were predictive of changes in pulmonary function over time. Fat free mass and height were found to be the best predictors of REE, and after accounting for these important body size and composition variables, differences in REE between boys and girls and CF and control groups increased over time. These findings identify the importance of investigating gender differences in the course of disease and considering REE as an early indicator of disease severity independent of pulmonary function.

Energy expenditure of children and adolescents with severe disabilities: a cerebral palsy model

Spastic quadriplegic cerebral palsy (SQCP) is a severe disability that is associated with abnormal physical activity, body composition, and food intake and with frequent malnutrition. This study examined the pattern of dietary intake, anthropometry, and energy expenditure in a group of subjects with SQCP aged 2-18 y and a normal control group. The energy expenditure pattern was determined from resting energy expenditure (REE, n = 61 SQCP; n = 37 control group) by using indirect calorimetry and from total energy expenditure (TEE, n = 32 SQCP; n = 32 control group) by using the doubly labeled water method. Physical activity, including the chronic spasticity of SQCP, was estimated from the ratio of TEE to REE. Abnormal growth and body composition were common and dietary intake was markedly overreported in the children with SQCP. Children with SQCP were divided according to body fat stores determined by triceps-skinfold-thickness measurements. The children with low fat stores had a lower REE adjusted for fat-free mass compared with the SQCP and control groups with adequate fat stores. TEE was significantly lower for the SQCP group than for the control group. The ratio of TEE to REE, indicating energy for nonbasal needs, was significantly lower in the SQCP children than in the control group, with the adequately nourished SQCP children having lower ratios than the more poorly nourished SQCP group. The nonbasal energy expenditure, such as for physical activity and spasticity, of children with SQCP was low. The nutrition-related growth failure and abnormal pattern of REE are likely related to inadequate energy intake.

Resting energy expenditure in clinical pediatrics: measured versus prediction equations

OBJECTIVE

To evaluate the use of resting energy expenditure (REE) prediction equations compared with measured REE in children referred for REE to aid clinical care.

SUBJECTS

One hundred two patients, aged 0.2 to 20.5 years, 55% female, with a nutritional diagnosis of failure to thrive (76%), obesity (19%), or other (5%).

METHODS

We measured REE by indirect calorimetry and compared with prediction equations: Food and Agriculture/World Health Organization/United Nations University (FAO/WHO/UNU) equation, Harris-Benedict (H-B) equation, and two equations from Schofield, one using weight (SCHO-WT) and one using weight and height (SCHO-HTWT).

RESULTS

The SCHO-HTWT equation more closely predicted measured REE (100% +/- 19%), compared with the WHO equation (99% +/- 22%), the SCHO-WT equation, (99% +/- 21%), and the H-B equation (92% +/- 25%). The SCHO-HTWT equation was the best at predicting REE for obese subjects (95% +/- 17%), for those with failure to thrive (101% +/- 20%), and for children from birth to 3 years of age (101% +/- 23%). Nevertheless, the prediction equations closely predicted REE in only about 40% of subjects.

CONCLUSION

These findings suggest that the SCHO-HTWT equation predicts REE in children with clinical nutritional problems better than equations that use weight alone. In view of the wide variability in REE measurements, however, we believe that REE should be measured in patients for whom knowledge of caloric expenditure is required for clinical care.

Body composition in children with spastic quadriplegic cerebral palsy

OBJECTIVE

To determine the pattern of body composition and nutritional status in a group of prepubertal children with spastic quadriplegic cerebral palsy (SQCP) compared with healthy control children.

STUDY DESIGN

Subjects were enrolled for this cross-sectional study from two tertiary care settings. One hundred thirty-six subjects with SQCP, 2 to 12 years of age, were evaluated by anthropometric measures, or by anthropometric and total body water (TBW) measures (n = 28), with 39 control subjects.

RESULTS

Body composition and nutritional status indicators were significantly reduced in children with SQCP. Accretion of fat-free mass with age was smaller for children with SQCP. Calculation of body fat from two skin folds correlated best with measures of fat mass from TBW.

CONCLUSION

Malnutrition is common in children with SQCP. Clinically available, serial anthropometric measures enable the clinician to identify malnourished children with SQCP.

Bone mineral content and dietary calcium intake in children prescribed a low-lactose diet

Bone density is related to body size and other factors including dietary calcium intake. The purpose of this study was to determine the effect of a low-lactose, low-calcium diet on the bone mineral content (BMC) of prepubertal children with documented lactose intolerance. Radial BMC was determined by single-photon absorptiometry. Dietary intake was assessed by 24-h recall and two 3-day food records, and weight and height were measured. The group of lactose-intolerant children was compared with a group of healthy children of similar age, gender, race, and size and to the prediction equations based on body size from Chan's Utah children. Nineteen children, ages 9.6 +/- 1.9 years, participated in the study. They were relatively short compared with standards (height Z score, -0.30 +/- 0.83). BMC was 0.428 +/- 0.081 g/cm in the study group versus 0.440 +/- 0.116 g/cm in the comparison group (n = 19; p > 0.05). Both the study group and the size-selected comparison group had lower BMC than the Utah children. The diet of the study group was low in calcium: 84% of the Recommended Dietary Allowance in children < 11 years old and 32% in children > 11. Calcium intake was associated (p = 0.03) with BMC in the study group after adjusting for body size. The low-lactose diet resulted in a low calcium intake, and BMC was associated with calcium intake in prepubertal children with lactose intolerance. Evaluation of dietary calcium intake should be considered in this group of patients, with follow-up dietary counseling, calcium supplementation (diet or medication), and bone density assessment when clinically indicated.

The contribution of adrenal and gonadal androgens to the growth in height of adolescent males

Gonadal androgens are known to regulate the rate of growth in height during adolescence, particularly in males, but little is known of the role of adrenal androgens in this process. In a prospective multiple regression model we show that both adrenal and gonadal androgens contribute to the increasing rate of growth in height prior to peak height velocity and the decreasing rate of height growth in later adolescence. Since adrenal androgen secretion begins in mid-childhood, long before gonadal maturation and the secretion of testicular androgens, these findings may prove helpful in explaining population variation in adolescent growth.

Blood pressure, body fat, and dehydroepiandrosterone sulfate variation in adolescence

Several significant interrelations among variation in blood pressure, body fat, and adrenal androgen levels, as assessed by serum dehydroepiandrosterone sulfate concentrations, were found in black male and female adolescents, aged 12 to 16 years. In girls, high levels of dehydroepiandrosterone sulfate were associated with significantly higher levels of blood pressure (alpha = 0.05), even after adjusting for the significant association between increased levels of dehydroepiandrosterone sulfate and body fat. The increased body fat (i.e., body mass index) found with higher levels of dehydroepiandrosterone sulfate in girls was related to significantly greater (alpha = 0.05) accumulations of fat in the upper trunk, as opposed to the limb. In boys, high levels of serum dehydroepiandrosterone sulfate, low body mass index, and significantly higher blood pressure were interrelated (alpha = 0.05). In addition to the interaction of increased body mass index or body fat and increased levels of dehydroepiandrosterone sulfate in association with higher blood pressure, high levels of the adrenal androgen, even in boys with low body mass index, were associated independently with relatively higher blood pressure. Body proportion analyses for these boys indicated that they were tall and thin, in contrast to the other boys with low body mass index, who were generally short and thin.

Pulse rate, blood pressure and body composition in black adolescents: the Philadelphia Blood Pressure Project

Patterns of pulse rate, blood pressure (BP), and body size and composition are investigated in a black urban sample of over 600 adolescents (aged 12-17) in Philadelphia as part of the Philadelphia Blood Pressure Project. Supine and seated pulse rates decline after the age of 13 in both males and females, and females have significantly higher pulse rates than males, ranging from 1.6 to 4.7 beats/30 sec higher depending upon chronological age and position. Seated pulse rates are consistently higher than supine in both sexes ranging from 1.3 to 2.9 beats/30 sec depending upon chronological age. Pulse rate and both systolic blood pressure (SBP) and diastolic phase IV blood pressure (DBP) show a positive association throughout adolescence for females (r = 0.16 SBP, r = 0.24 DBP) but not for males (r = -0.06 SBP, r = 0.06 DBP). Females in the highest diastolic IV blood pressure stratum (greater than 85%) maintain higher pulse rates throughout adolescence, while males with the highest DBP have higher pulse rates in early adolescence (ages 12-14) but lower pulse rates in later adolescence (ages 16 and 17). Females with the highest DBP also show consistently higher measures of relative fatness (triceps skinfolds) throughout adolescence. Males with the highest DBP have greater triceps skinfolds in early adolescence and lower triceps in later adolescence, a pattern similar to that shown for pulse rate. For DBP, triceps is significantly and positively associated with pulse rate in the upper DBP percentile group (p less than 0.05). Thus, females with the highest blood pressure during adolescence are characterized by higher pulse rate and greater fatness. Males show this same pattern in early adolescence; whereas, in contrast, the older adolescent males in our sample with the highest DBP are characterized by lower pulse rates, relatively decreased fatness, and increased muscularity. Our findings suggest that, at least in some older black male adolescents, a higher DBP may reflect a decrease in cardiac output as indicated by a lower pulse rate, or an increase in peripheral vascular resistance, possibly associated with relatively decreased fatness and increased muscle mass for size.