Babette S. Zemel

New intrauterine growth curves based on United States data.

OBJECTIVE: The objective of this study was to create and validate new intrauterine weight, length, and head circumference growth curves using a contemporary, large, racially diverse US sample and compare with the Lubchenco curves. METHODS: Data on 391 681 infants (Pediatrix Medical Group) aged 22 to 42 weeks at birth from 248 hospitals within 33 US states (1998–2006) for birth weight, length, head circumference, estimated gestational age, gender, and race were used. Separate subsamples were used to create and validate curves. Smoothed percentile curves (3rd to 97th) were created by the Lambda Mu Sigma (LMS) method. The validation sample was used to confirm representativeness of the curves. The new curves were compared with the Lubchenco curves. RESULTS: Final sample included 257 855 singleton infants (57.2% male) who survived to discharge. Gender-specific weight-, length-, and head circumference-for-age curves were created (n = 130 111) and successfully validated (n = 127 744). Small-for-gestational age and large-for-gestational age classifications using the Lubchenco curves differed significantly from the new curves for each gestational age (all P < .0001). The Lubchenco curves underestimated the percentage of infants who were small-for-gestational-age except for younger girls (≤36 weeks), for whom it was more likely to be overestimated; underestimated percentage of infants (≤36 weeks) who were large-for-gestational-age; and overestimated percentage of infants (>36 weeks) who were large-for-gestational-age. CONCLUSIONS: The Lubchenco curves may not represent the current US population. The new intrauterine growth curves created and validated in this study, based on a contemporary, large, racially diverse US sample, provide clinicians with an updated tool for growth assessment in US NICUs. Research into the ability of the new definitions of small-for-gestational-age and large-for-gestational-age to identify high-risk infants in terms of short-term and long-term health outcomes is needed.

International Society for Clinical Densitometry 2007 Adult and Pediatric Official Positions

The International Society for Clinical Densitometry (ISCD) periodically convenes Position Development Conferences (PDCs) in order to establish standards and guidelines for the assessment of skeletal health. The most recent Adult PDC was held July 20-22, 2007, in Lansdowne, Virginia, USA; the first Pediatric PDC was June 20-21, 2007 in Montreal, Quebec, Canada. PDC topics were selected according to clinical relevancy, perceived need for standardization, and likelihood of achieving agreement. Each topic area was assigned to a task force for a comprehensive review of the scientific literature. The findings of the review and recommendations were presented to adult and pediatric international panels of experts. The panels voted on the appropriateness, necessity, quality of the evidence, strength, and applicability (worldwide or variable according to local requirements) of each recommendation. Those recommendations that were approved by the ISCD Board of Directors become Official Positions. This is a review of the methodology of the PDCs and selected ISCD Official Positions.

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. (ClinicalTrials.gov registration number: NCT00143936) SETTING 3 academic medical centers. PATIENTS 307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m(2) (SD, 3.5 kg/m(2)). INTERVENTION A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low-glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d; <or=30% calories from fat). Both diets were combined with comprehensive behavioral treatment. MEASUREMENTS Weight at 2 years was the primary outcome. Secondary measures included weight at 3, 6, and 12 months and serum lipid concentrations, blood pressure, urinary ketones, symptoms, bone mineral density, and body composition throughout the study. RESULTS Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years. LIMITATION Intensive behavioral treatment was provided, patients with dyslipidemia and diabetes were excluded, and attrition at 2 years was high. CONCLUSION Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years. PRIMARY FUNDING SOURCE National Institutes of Health.

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.

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. DESIGN The Bone Mineral Density in Childhood Study was a multicenter longitudinal study with annual assessments for up to 7 yr. SETTING The study was conducted at five clinical centers in the United States. PARTICIPANTS Two thousand fourteen healthy children (992 males, 22% African-Americans) aged 5-23 yr participated in the study. INTERVENTION There were no interventions. MAIN OUTCOME MEASURES Reference percentiles for BMC and aBMD of the total body, lumbar spine, hip, and forearm were obtained using dual-energy x-ray absorptiometry for Black and non-Black children. Adjustment factors for height status were also calculated. RESULTS Extended reference curves for BMC and aBMD of the total body, total body less head, lumbar spine, total hip, femoral neck, and forearm for ages 5-20 yr were constructed relative to sex and age for Black and non-Black children. Curves are similar to those previously published for 7-17 year olds. BMC and aBMD values were greater for Black vs. non-Black children at all measurement sites. CONCLUSIONS We provide here dual-energy x-ray absorptiometry reference data on a well-characterized cohort of 2012 children and adolescents. These reference curves provide the most robust reference values for the assessment and monitoring of bone health in children and adolescents in the literature to date.

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.

Effect of testosterone replacement on trabecular architecture in hypogonadal men.

We evaluated the effect of testosterone treatment on trabecular architecture by μMRI in 10 untreated severely hypogonadal men. After 2 years, μMRI parameters of trabecular connectivity improved significantly, suggesting the possibility that testosterone improves trabecular architecture.

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 Crohns 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 Crohns 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.

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.

Longitudinal Assessment of Bone Density and Structure in an Incident Cohort of Children With Crohn's Disease

BACKGROUND & AIMS The impact of childhood Crohns disease (CD) on volumetric bone mineral density (vBMD), bone structure, and muscle mass have not been established. The objective of this longitudinal study was to assess musculoskeletal outcomes in an incident cohort of children with CD using peripheral quantitative computed tomography (pQCT). METHODS Tibia pQCT was performed in 78 CD subjects (ages, 5-18 years) at diagnosis and in 67 over the subsequent year. pQCT outcomes were converted to sex- and race-specific z scores based on reference data in over 650 controls. Multivariable linear regression models identified factors associated with changes in bone outcomes. RESULTS At diagnosis, CD subjects had significant deficits in trabecular vBMD (z score, -1.32+/-1.32; P< .001), cortical section modulus (a measure of bone geometry and strength) (z score, -0.44+/-1.11; P< .01), and muscle (z score, -0.96+/-1.02; P< .001) compared with controls. Over the first 6 months, trabecular vBMD and muscle z scores improved significantly (both, P< .001); however, section modulus worsened (P= .0001), and all 3 parameters remained low after 1 year. Increases in muscle z scores were associated with less severe declines in cortical section modulus z scores. Improvements in trabecular vBMD z scores were greater in prepubertal subjects. Glucocorticoids were associated with increases in cortical vBMD. CONCLUSIONS Substantial deficits in trabecular vBMD, cortical bone geometry, and muscle were observed at CD diagnosis. Trabecular vBMD improved incompletely; however, cortical deficits progressed despite improvements in muscle. Glucocorticoids were not associated with bone loss. Therapies to improve bone accrual in childhood CD are needed.