Mid-arm circumference is a reliable method to estimate adiposity in preterm and term infants.

BACKGROUND: Premature birth is associated with increased adipose deposition after birth. Standard anthropometry (body weight, length, and head circumference) may not adequately assess fat deposition. Validated methods to assess adiposity are needed to optimize growth quality in preterm infants. The purpose of this study was to identify covariates of infant body fat. METHODS: Air displacement plethysmography (ADP), standard anthropometry, and body circumferences were measured at hospital discharge in preterm (n = 28; 31-35 wk postmenstrual age (PMA)) and term (n = 28; 38-41 wks PMA) infants. RESULTS: Body weight, length, and head circumference were lower for preterm infants (P < 0.05) at hospital discharge compared with that of term infants. Despite smaller body size and younger PMA, preterm infant percent body fat (%BF) by ADP was 12.33 ± 4.15% vs. 9.64 ± 4.01% in term infants (P = 0.01). Mid-arm circumference (MAC) is a covariate of %BF in both preterm and term infants (adjusted R(2) = 0.49; P < 0.001). In preterm infants alone, MAC accounted for 60.4% of the variability of percent body fat (%BF) by ADP (P < 0.01). CONCLUSIONS: Preterm infants have increased body fat deposition as they approach term-corrected age, and MAC is a reliable, low-cost measure for monitoring infant body fat deposition in preterm and term infants.

Estimation of length or height in infants and young children using ulnar and lower leg length with dual-energy X-ray absorptiometry validation.

AIM: We compared the accuracy and reproducibility of using ulnar and lower leg length measurements to predict length and height in infants and children aged 0 to 6 years. METHOD: Length/height and ulnar and lower leg length were measured in 352 healthy preterm and term-born children (167 males, 185 females) (Mean age= 2.6±1.6 years). Ulna length was measured as the distance between the proximal olecranon process and the distal styloid process of the ulna. Tibia length was measured as the distance from the proximal aspect of the medial condyle and the most distal aspect of the medial malleolus of the tibia using a segmometer. Length measurements were taken using an infant length board in children less than 24 months of age, whereas a portable stadiometer was used to measure height in older children. Equations were developed using ulnar and lower leg length and age. Intra- and inter-examiner variability (n=167) was calculated, and dual-energy X-ray absorptiometry scans (n=126) were used to determine accuracy of limb lengths. RESULTS: Ulnar and lower leg length explained over 95% of the variability in length/height in term infants and children, but less in preterm infants (R(2) =0.80-0.87). In preterm infants, the limits of agreement (LOA) for males were -2.44 to 2.44cm and -2.88 to 2.88cm for the ulna and lower leg respectively, whereas the LOA for females were -1.90 to 1.90cm and -1.87 to 1.87cm respectively. In older children, the LOA for males were -5.53 to 4.48cm and -5.59 to 4.62cm for the ulna and lower leg respectively, whereas the LOA for females were -5.57 to 5.01cm and -6.02 to 5.02cm respectively. Intra- and inter-examiner variability was low for all measurements in both sexes and age groups. INTERPRETATION: Length and height measurements using infant length board or stadiometer are reproducible. Because of the wide limits of agreement, estimation of length and height in children using ulnar and lower leg length is not an acceptable alternative to traditional methods.

Massage improves growth quality by decreasing body fat deposition in male preterm infants.

OBJECTIVES: To assess the effect of massage on weight gain and body fat deposition in preterm infants. STUDY DESIGN: Preterm infants (29-32 weeks) were randomized to the massage group (n = 22, 12 girls, 10 boys) or the control group (n = 22, 12 girls, 10 boys). Treatment was masked with massage or control care administered twice-daily by licensed massage therapists (6 d/wk for 4 weeks). Body weight, length, Ponderal Index (PI), body circumferences, and skinfold thickness (triceps, mid-thigh, and subscapular [SSF]) were measured. Circulating insulin-like growth factor I, leptin, and adiponectin levels were determined by enzyme-linked immunosorbent assay. Daily dietary intake was collected. RESULTS: Energy and protein intake as well as increase in weight, length, and body circumferences were similar. Male infants in the massage group had smaller PI, triceps skinfold thickness, mid-thigh skinfold thickness, and SSF and increases over time compared with control male infants (P < .05). Female infants in the massage group had larger SSF increases than control female infants (P < .05). Circulating adiponectin increased over time in control group male infants (group × time × sex interaction, P < .01) and was correlated to PI (r = 0.39, P < .01). CONCLUSIONS: Twice-daily massage did not promote greater weight gain in preterm infants. Massage did, however, limit body fat deposition in male preterm infants. Massage decreased circulating adiponectin over time in male infants with higher adiponectin concentrations associated with increased body fat. These findings suggest that massage may improve body fat deposition and, in turn, growth quality of preterm infants in a sex-specific manner.

Intrauterine growth restriction decreases endochondral ossification and bone strength in female rats.

Intrauterine growth restriction (IUGR) modifications to postnatal skeletal growth may increase adult fracture, especially in females who have greater risk of osteoporosis. Little is known about the effect of IUGR on the patterns of postnatal endochondral ossification and bone development. Here for the first time we reveal bone formation, mineralization, and strength in IUGR female rats during early postnatal life and adulthood. Endochondral ossification rate of the hypertrophic zone (HZ) and hypertrophic cell length (HCL) at distal femur and proximal tibia, and primary ossification center (POC) of the whole femur and tibia were quantified at birth to day 21. Bone area (BA), bone mineral content (BMC), and bone density by dual-energy X-ray absorptiometry and bone strength determined from three-point bending were measured at days 21 and 120. IUGR femur and tibia HZ, HCL, and POC were significantly diminished at birth to day 21. IUGR decreased BA and BMC as well as femur/tibia diameter, length, stiffness, and peak load values at days 21 and 120. Our findings demonstrate a negative long-term effect of IUGR on bone size, mineral content, and strength in weanling and adult female rats. We speculate that IUGR decreases endochondral ossification responsiveness, and in turn, postnatal linear skeletal growth, mineralization, and strength in female rats.

Multiple increased osteoclast functions in individuals with neurofibromatosis type 1.

Skeletal abnormalities including scoliosis, tibial dysplasia, sphenoid wing dysplasia, and decreased bone mineral density (BMD) are associated with neurofibromatosis type 1 (NF1). We report the cellular phenotype of NF1 human-derived osteoclasts and compare the in vitro findings with the clinical phenotype. Functional characteristics (e.g., osteoclast formation, migration, adhesion, resorptive capacity) and cellular mechanistic alterations (e.g., F-actin polymerization, MAPK phosphorylation, RhoGTPase activity) from osteoclasts cultured from peripheral blood of individuals with NF1 (N = 75) were assessed. Osteoclast formation was compared to phenotypic, radiologic, and biochemical data. NF1 osteoprogenitor cells demonstrated increased osteoclast forming capacity. Human NF1-derived osteoclasts demonstrated increased migration, adhesion, and in vitro bone resorption. These activities coincided with increased actin belt formation and hyperactivity in MAPK and RhoGTPase pathways. Although osteoclast formation was increased, no direct correlation of osteoclast formation with BMD, markers of bone resorption, or the clinical skeletal phenotype was observed suggesting that osteoclast formation in vitro cannot directly predict NF1 skeletal phenotypes. While NF1 haploinsufficiency produces a generalized osteoclast gain-in-function and may contribute to increased bone resorption, reduced BMD, and focal skeletal defects associated with NF1, additional and perhaps local modifiers are likely required for the development of skeletal abnormalities in NF1.

Validity and reliability of perinatal biomarkers of adiposity after storage as dried blood spots on paper.

OBJECTIVE: To validate use of chip-based immunoaffinity capillary electrophoresis on dried blood spot samples (DBSS) to measure obesity-related hormones. METHODS: Chip-based immunoaffinity capillary electrophoresis was used to measure adiponectin, leptin and insulin in capillary serum and DBSS in pregnant women and infant heelstick at birth and six weeks. Concordance of measurements was determined with Pearson's correlation and Bland-Altman plots. RESULTS: We report high concordance between results obtained from serum and DBSS. CONCLUSIONS: Ease of sample collection and storage makes DBSS an optimal method for use in studies involving neonates and young children, as well as studies conducted in areas where freezer storage is not available.

Pediatric 25-hydroxyvitamin D concentrations in neurofibromatosis type 1.

OBJECTIVE: Low 25-hydroxyvitamin D (25OHD) concentrations have been associated with tumors and osteopenia or fractures in adults with neurofibromatosis type 1 (NF1). We report 25OHD concentrations in 109 children with NF1 and 218 controls matched for age, sex, geographic location, and time of year. METHODS: Children with NF1 were recruited (n=109; 2-17 years), and clinical data and dual-energy X-ray absorptiometry measurements were obtained. 25OHD concentrations were measured in subjects and controls. RESULTS: More NF1 individuals (50%) were in the 25OHD insufficient or deficient range (<30 ng/mL) (1 ng/mL = 2.496 nmol/L) compared to controls (36%) (p = 0.0129). 25OHD concentrations were higher in individuals with neurofibromas after controlling for age (p = 0.0393), and were negatively associated with whole-body subtotal bone mineral density (BMD) z-scores (p = 0.0385). CONCLUSIONS: More children with NF1 had 25OHD concentrations <30 ng/mL, potentially because of increased pigmentation and/or decreased sunlight exposure. In contrast to adults, decreased 25OHD concentrations were not associated with neurofibromas, and there was no positive association between 25OHD and BMD.

Newborn adiposity measured by plethysmography is not predicted by late gestation two-dimensional ultrasound measures of fetal growth.

Noninvasive measures of fetal and neonatal body composition may provide early identification of children at risk for obesity. Air displacement plethysmography provides a safe, precise measure of adiposity and has recently been validated in infants. Therefore, we explored relationships between term newborn percent body fat (%BF) measured by air displacement plethysmography to 2-dimensional ultrasound (2-D US) biometric measures of fetal growth and maternal and umbilical cord endocrine activity. A total of 47 mother/infant pairs were studied. Fetal biometrics by 2-D US and maternal blood samples were collected during late gestation (35 wk postmenstrual age); infants were measured within 72 h of birth. Fetal biometrics included biparietal diameter, femur length, head circumference, abdominal circumference (AC), and estimated fetal weight (EFW). Serum insulin, insulin-like growth factor (IGF) 1, IGF binding protein-3, and leptin concentrations were measured in umbilical cord and maternal serum. The mean %BF determined by plethysmography was 10.9 +/- 4.8%. EFW and fetal AC had the largest correlations with newborn %BF (R(2) = 0.14 and 0.10, respectively; P < 0.05); however, stepwise linear regression modeling did not identify any fetal biometric parameters as a significant predictor of newborn %BF. Newborn mid-thigh circumference (MTC; cm) and ponderal index (PI; weight, kg/length, cm(3)) explained 21.8 and 14.4% of the variability in %BF, respectively, and gave the best stepwise linear regression model (%BF = 0.446 MTC + 0.347 PI -29.692; P < 0.001). We conclude that fetal growth biometrics determined by 2-D US do not provide a reliable assessment of %BF in term infants.

Fitness of children with standard-risk acute lymphoblastic leukemia during maintenance therapy: response to a home-based exercise and nutrition program.

BACKGROUND: Altered nutrient intake and decreased exercise in response to cancer therapies and their side effects, particularly corticosteroids, may be key factors in the increased body weight and differences in physical fitness reported in survivors of childhood acute lymphoblastic leukemia (ALL). PURPOSE: To assess (1) the effect of a home-based nutrition and exercise intervention program on cardiovascular fitness, strength, and flexibility in children with ALL during maintenance therapy and (2) the feasibility of conducting and evaluating a home-based exercise and nutrition program in this patient population. DESIGN: Children ages 4 to 10 years with standard-risk ALL were randomized when starting maintenance therapy to a 12-month home-based exercise and nutrition program (n=6, 3 males/3 females) or control (n=7, 4 males/3 females) group. Assessment of anthropometrics, dietary intake, physical activity, and fitness was performed at baseline and 6 and 12 months of study. RESULTS: Although age, body size, and nutrient intakes were similar between both subject groups at 0, 6, and 12 months, exercise and nutrition program children had greater improvement in physical activity and cardiovascular fitness between 6 and 12 months than control children. CONCLUSIONS: These results suggest that a home-based exercise intervention during maintenance therapy encouraged greater physical activity and improved cardiovascular fitness in children with standard-risk ALL. Further investigation involving larger populations of children with ALL is warranted.

Nasal ventilation alters mesenchymal cell turnover and improves alveolarization in preterm lambs.

RATIONALE: Bronchopulmonary dysplasia (BPD) is a frequent cause of morbidity in preterm infants that is characterized by prolonged need for ventilatory support in an intensive care environment. BPD is characterized histopathologically by persistently thick, cellular distal airspace walls. In normally developing lungs, by comparison, remodeling of the immature parenchymal architecture is characterized by thinning of the future alveolar walls, a process predicated on cell loss through apoptosis. OBJECTIVES: We hypothesized that minimizing lung injury, using high-frequency nasal ventilation to provide positive distending pressure with minimal assisted tidal volume displacement, would increase apoptosis and decrease proliferation among mesenchymal cells in the distal airspace walls compared with a conventional mode of support (intermittent mandatory ventilation). METHODS: Accordingly, we compared two groups of preterm lambs: one group managed by high-frequency nasal ventilation and a second group managed by intermittent mandatory ventilation. Each group was maintained for 3 days. MEASUREMENTS AND MAIN RESULTS: Oxygenation and ventilation targets were sustained with lower airway pressures and less supplemental oxygen in the high-frequency nasal ventilation group, in which alveolarization progressed. Thinning of the distal airspace walls was accompanied by more apoptosis, and less proliferation, among mesenchymal cells of the high-frequency nasal ventilation group, based on morphometric, protein abundance, and mRNA expression indices of apoptosis and proliferation. CONCLUSIONS: Our study shows that high-frequency nasal ventilation preserves the balance between mesenchymal cell apoptosis and proliferation in the distal airspace walls, such that alveolarization progresses.

Analysis of radiographic characteristics of anterolateral bowing of the leg before fracture in neurofibromatosis type 1.

BACKGROUND: Anterolateral leg bowing is associated with neurofibromatosis type 1 (NF1) frequently leading to fracture and nonunion of the tibia. The objective of the study was to characterize the radiographic findings of tibial dysplasia in NF1. METHODS: This study is a retrospective review of radiographs of tibial dysplasia obtained within 52 years, between 1950 and 2002, from the Shriners Hospitals for Children, Salt Lake City, and of peripheral quantitative computed tomographic images of 3 individuals with anterolateral bowing of the leg without fracture compared with age- and sex-matched controls. RESULTS: Individuals with NF1 with bowing of the leg have the appearance of thicker cortices with medullary narrowing on plain film radiographs. The peripheral quantitative computed tomographic images of individuals with NF1 with anterolateral bowing show an unusual configuration of the tibia. CONCLUSIONS: Anterolateral bowing of the leg in NF1 is associated with the appearance of thicker cortices with medullary narrowing rather than thinning of the long bone cortex on plain film radiographs as currently used as a qualifier in the sixth diagnostic criterion for the clinical diagnosis of NF1. Individuals with NF1 who have anterolateral bowing of the leg have differences in tibial geometry compared with age- and sex-matched controls. CLINICAL RELEVANCE: The characterization of the radiographic findings of long bone bowing in NF1 helps clarify the NF1 clinical diagnostic criteria.

Do parents accurately perceive their child's weight status?

INTRODUCTION: Few studies have evaluated the accuracy of parental perceptions of their child's weight status. METHODS: A cross-sectional sample of children aged 5 to 12 years and their parents (n = 576 parent-child pairs) was enrolled from four schools. Child height and weight were measured. The parents classified their child on Likert scales ranging from "extremely overweight" to "extremely underweight." Parental perceptions were compared with their child's weight status according to body mass index (BMI) age-gender percentiles. Fisher-Halton-Freeman tests, chi(2), and logistic regression were used to compare demographic factors between parents who inaccurately estimated and those who accurately estimated child weight status. RESULTS: Misclassification occurred 25% of the time (95% confidence interval: 21.4-28.5). All parents of children with a BMI greater than or equal to the 95th percentile classified their child in a category other than "extremely overweight," and 75% of children with a BMI from the 85th to less than the 95th percentile were misclassified as "about right" or "underweight." Boys were more likely to be misclassified than were girls (29% vs 21%, P = .03). CONCLUSIONS: The majority of parents of obese and overweight children underestimate their child's weight status. Parents of boys are more likely to perceive their child's weight incorrectly.

Evaluation of the Gold Medal Schools program.

Utah's Gold Medal Schools program supports the adoption of school policies that provide opportunities for nutritious food choices and regular physical activity. The effectiveness of Gold Medal Schools was evaluated via anthropometric measurements and dietary and physical activity surveys. The study population included first-, third-, and fifth-grade elementary school students and parents from four schools in Tooele County, UT. Two schools implemented Gold Medal Schools (intervention) and two did not (comparison). Data were collected at baseline (June 2005) and 1 year (May 2006). Body mass index (calculated as kg/m(2)) z scores increased significantly in the comparison group (0.53+/-0.38; P<0.05), but not in the intervention group (0.21+/-0.47; P=0.484), from baseline to 1 year. Children in the Gold Medal Schools cohort reported drinking fewer soft drinks per day (excluding diet drinks) at 1 year (P=0.008) and walking or biking to school more often at baseline and 1 year (P<0.001) than non-Gold Medal Schools children. While children in both groups increased the days per week they walked or biked to school, a substantial improvement was observed for the non-Gold Medal Schools students only (P<0.001). Overall, this pilot study suggests that Gold Medal Schools positively impacted body mass index z scores and health behaviors among elementary-aged students.

Peripheral quantitative computed tomography of the tibia: pediatric reference values.

Peripheral quantitative computed tomography (pQCT) has been used in a number of pediatric studies. Reference data for children are primarily limited to the radius. The purpose of this study was to establish normal reference ranges for pQCT measurements of the tibia for children. A cross-sectional sample of healthy, white, non-Hispanic children aged 5-18 years (n=416; 197 boys) was measured at the distal tibia metaphysis and diaphysis by pQCT to assess trabecular and cortical bone, respectively. Differences were determined between and within genders by height for bone geometry, density, and strength. Height-specific normal ranges were calculated, and gender-specific centile curves were generated. A positive, linear relationship was found between tibia cortical bone geometry and strength parameters and height (r2 >or=0.58, p<0.001), with mean values greater for boys than girls (p

Peripheral quantitative computed tomography in children and adolescents: the 2007 ISCD Pediatric Official Positions.

Peripheral quantitative computed tomography (pQCT) has mainly been used as a research tool in children. To evaluate the clinical utility of pQCT and formulate recommendations for its use in children, the International Society of Clinical Densitometry (ISCD) convened a task force to review the literature and propose areas of consensus and future research. The types of pQCT technology available, the clinical application of pQCT for bone health assessment in children, the important elements to be included in a pQCT report, and quality control monitoring techniques were evaluated. The review revealed a lack of standardization of pQCT techniques, and a paucity of data regarding differences between pQCT manufacturers, models and software versions and their impact in pediatric assessment. Measurement sites varied across studies. Adequate reference data, a critical element for interpretation of pQCT results, were entirely lacking, although some comparative data on healthy children were available. The elements of the pQCT clinical report and quality control procedures are similar to those recommended for dual-energy X-ray absorptiometry. Future research is needed to establish evidence-based criteria for the selection of the measurement site, scan acquisition and analysis parameters, and outcome measures. Reference data that sufficiently characterize the normal range of variability in the population also need to be established.

Bone mineral density in children and adolescents with neurofibromatosis type 1.

OBJECTIVE: To assess whether children and adolescents with neurofibromatosis type 1 (NF1) have decreased bone mineral density (BMD). STUDY DESIGN: Bone densitometry of the whole body, hip, and lumbar spine was used in a case-to-control design (84 individuals with NF1: 293 healthy individuals without NF1). Subjects were 5 to 18 years old. Subjects with NF1 were compared with control subjects by using an analysis-of-covariance with a fixed set of covariates (age, weight, height, Tanner stage, and sex). RESULTS: Subjects with NF1 had decreased areal BMD (aBMD) of the hip (P <.0001), femoral neck (P <.0001), lumbar spine (P = .0025), and whole body subtotal (P <.0001). When subjects with NF1 were separated in groups with and without a skeletal abnormality, those who did not have a skeletal abnormality still had statistically significant decreases in aBMD compared with control subjects (P <.0001 for whole body subtotal aBMD), although they were less pronounced than in those with osseous abnormalities. CONCLUSIONS: These data suggest that individuals with NF1 have a unique generalized skeletal dysplasia, predisposing them to localized osseous defects. Dual energy x-ray absorptiometry may prove useful in identifying individuals with NF1 who are at risk for clinical osseous complications and monitoring therapeutic trials.

Anthropometric and laboratory assessment of very low birth weight infants: the most helpful measurements and why.

Very low birth weight (VLBW; < or =1500 g), preterm infants have numerous physiological and developmental concerns, including growth and the provision of adequate nutrients to sustain growth. Growth is an important health care outcome measure for VLBW infants. Provision of energy and nutrients at levels to support growth and development is the goal of nutrition support for VLBW infants. Anthropometry and laboratory data are useful components of growth and nutrition assessment. The objectives of this paper are to describe: 1) the clinical application and interpretation of anthropometric measures of growth, and 2) the utilization and interpretation of laboratory tests of nutritional status in VLBW infants.

Determination of body composition in children with cerebral palsy: bioelectrical impedance analysis and anthropometry vs dual-energy x-ray absorptiometry.

The object of this study was to determine whether bioelectrical impedance analysis (BIA) and anthropometry can be used to determine body composition for clinical and research purposes in children with cerebral palsy. Eight individuals with cerebral palsy (two female, mean age=10 years, mean gross motor function classification=4.6 [severe motor impairment]) recruited from an outpatient tertiary care setting underwent measurement of fat mass, fat-free mass, and percentage body fat using BIA, anthropometry (two and four skinfold equations), and dual-energy x-ray absorptiometry. Correlation coefficients were calculated for fat mass, fat-free mass, and percent body fat for these measures as determined by BIA and anthropometry when compared with dual-energy x-ray absorptiometry. Correlation coefficients were excellent for determination of fat-free mass for all methods (ie, all were above 0.9). Correlations were moderate for determination of fat mass and percent body fat (range=0.4 to 0.8).

Dietary supplement use is prevalent among children with a chronic illness.

OBJECTIVE: To determine the nature and prevalence of dietary supplement use among chronically ill children. DESIGN: This descriptive study used a self-report questionnaire. SUBJECTS: A convenience sample of parents of 505 chronically ill children and adolescents seen in subspecialty medical clinics in Salt Lake City, UT. The medical conditions studied included asthma, cystic fibrosis, diabetes, cancer, liver and renal transplantations, seizures, and rheumatological and neurobehavioral disorders. Statistics Sample characteristics were described using frequencies, percentages, means, and standard deviations. chi 2 tests were used to compare sex, ethnicity, parental education level, and dietary supplement use variations among the various diagnostic categories. Analysis of variance with Bonferroni correction for multiple comparisons was used to determine differences among diagnosis groups for continuous variables, and the Kruskal-Wallis test was used to test categorical variables. RESULTS: The population sampled was predominately white (88.5%), with a mean age of 9.9+/-5.3 years. Sixty-two percent of the population used dietary supplements, and 30% used nonprescribed supplements. Significant differences were noted among diagnosis groups, with the highest nonprescribed use reported in children with cancer (solid tumors=46%; leukemia=44%), cystic fibrosis (35%), neurobehavioral disorders (35%), and rheumatological disorders (34%). Only 20% of those using nonprescribed dietary supplements had discussed this use with the health care provider. CONCLUSIONS: Dietary supplement use is prevalent among chronically ill children, especially among those with a poor prognosis or for whom there are limited medical treatments. Few pediatric health care providers are aware of their patients' use of nonprescribed supplements. This is a concern because of the unknown effects of many supplements on growth and development and the potential for adverse drug interactions.

Plasma and erythrocyte selenium and glutathione peroxidase activity in preterm infants at risk for bronchopulmonary dysplasia.

The purpose of this study was to examine the relationships between selenium status, as measured by plasma and erythrocyte selenium and glutathione peroxidase (GPx) activity, and other postnatal factors, including selenium intake, gestational age, and oxygen dependence in preterm infants at risk for bronchopulmonary dysplasia. Eighteen preterm infants of 30 wk gestational age or less were included. At postnatal wk 1 and 4, selenium concentrations and GPx activity were measured and oxygen dependence and daily selenium intakes were determined from the medical chart. Plasma and erythrocyte selenium concentrations decreased from wk 1 to wk 4, whereas erythrocyte GPx activity increased. Increased selenium intakes during wk 1 were associated with increased erythrocyte GPx activity at both time-points, as well as a decreased need for supplemental oxygen on d 28. Preterm infants display increasing erythrocyte GPx activity despite declines in plasma and erythrocyte selenium. GPx activity might be enhanced by very early selenium supplementation.