Accuracy of skinfold and bioelectrical impedance assessments of body fat percentage in ambulatory individuals with cerebral palsy.

AIM: This study assessed the accuracy of measurements of body fat percentage in ambulatory individuals with cerebral palsy (CP) from bioelectrical impedance analysis (BIA) and skinfold equations. METHOD: One hundred and twenty-eight individuals (65 males, 63 females; mean age 12y, SD 3, range 6-18y) with CP (Gross Motor Function Classification System [GMFCS] levels I (n=6), II (n=46), and III (n=19) participated. Body fat percentage was estimated from (1) BIA using standing height and estimated heights (knee height and tibial length) and (2) triceps and subscapular skinfolds using standard and CP-specific equations. All estimates of body fat percentage were compared with body fat percentage from dual-energy X-ray absorptiometry (DXA) scans. Differences between DXA, BIA, and skinfold body fat percentage were analyzed by comparing mean differences. Agreement was assessed by Bland-Altman plots and concordance correlation coefficients (CCC). RESULTS: BMI was moderately correlated with DXA (Pearson's r=0.53). BIA body fat percentage was significantly different from DXA when using estimated heights (95% confidence intervals [CIs] do not contain 0) but not standing height (95% CI -1.9 to 0.4). CCCs for all BIA comparisons indicated good to excellent agreement (0.75-0.82) with DXA. Body fat percentage from skinfold measurements and CP-specific equations was not significantly different from DXA (mean 0.8%; SD 5.3%; 95% CI -0.2 to 1.7) and demonstrated strong agreement with DXA (CCC 0.86). INTERPRETATION: Accurate measures of body fat percentage can be obtained using BIA and two skinfold measurements (CP-specific equations) in ambulatory individuals with CP. These findings should encourage assessments of body fat in clinical and research practices.

Neuropsychological recovery and quality-of-life in children and adolescents with growth hormone deficiency following TBI: a preliminary study.

OBJECTIVE: To compare neurocognition and quality-of-life (QoL) in a group of children and adolescents with or without growth hormone deficiency (GHD) following moderate-to-severe traumatic brain injury (TBI). STUDY DESIGNS: Thirty-two children and adolescents were recruited from the TBI clinic at a children's hospital. Growth hormone (GH) was measured by both spontaneous overnight testing and following arginine/glucagon stimulation administration. Twenty-nine subjects participated in extensive neuropsychological assessment. RESULTS: GHD as measured on overnight testing was significantly associated with a variety of neurocognitive and QoL measures. Specifically, subjects with GHD had significantly (p < 0.05) lower scores on measures of visual memory and health-related quality-of-life. These scores were not explained by severity of injury or IQ (p > 0.05). GHD noted in response to provocative testing was not associated with any neurocognitive or QoL measures. CONCLUSIONS: GHD following TBI is common in children and adolescents. Deficits in neurocognition and QoL impact recovery after TBI. It is important to assess potential neurocognitive and QoL changes that may occur as a result of GHD. It is also important to consider the potential added benefit of overnight GH testing as compared to stimulation testing in predicting changes in neurocognition or QoL.

Traumatic brain injury in children and adolescents: surveillance for pituitary dysfunction.

BACKGROUND: Children who sustain traumatic brain injury (TBI) are at risk for developing hypopituitarism, of which growth hormone deficiency (GHD) is the most common manifestation. OBJECTIVE: To determine the prevalence of GHD and associated features following TBI among children and adolescents. STUDY DESIGN: A total of 32 children and adolescents were recruited from a pediatric TBI clinic. Participants were diagnosed with GHD based on insufficient growth hormone release during both spontaneous overnight testing and following arginine/glucagon administration. RESULTS: GHD was diagnosed in 5/32 participants (16%). Those with GHD exhibited more rapid weight gain following injury than those without GHD and had lower levels of free thyroxine and follicle-stimulating hormone. Males with GHD had lower testosterone levels. CONCLUSIONS: GHD following TBI is common in children and adolescents, underscoring the importance of assessing for GHD, including evaluating height and weight velocities after TBI. Children and adolescents with GHD may further exhibit absence or intermediate function for other pituitary hormones.

Anthropometric measures: poor predictors of body fat in children with moderate to severe cerebral palsy.

AIM: This purpose of our study was to assess and compare anthropometric measures of adiposity and direct measurement of percentage body fat by dual emission X-ray absorptiometry (DXA) in children with cerebral palsy (CP). We also compared our results in children with CP with results from a national sample of typically developing children from the National Health and Nutrition Examination Survey. METHOD: Anthropometry and DXA were obtained from 58 participants with CP (25 females, 33 males; Gross Motor Function Classification System levels III-V; mean age 13 y 1 mo [SD 3 y], range 8-18 y). Height was estimated from knee height, which was measured with knee height calipers; weight was measured on a sitting scale. The relation between percentage body fat measured by DXA and z-scores of each of the anthropometric measures (body mass index, mid-upper arm circumference, triceps skinfold, and mid-upper arm fat area) was assessed by linear models. Agreement analysis was performed to assess the ability of each anthropometric measure to predict percentage body fat by DXA. RESULTS: None of the anthropometric measures were adequately associated with percentage body fat by DXA. All anthropometric methods tended to underestimate percentage body fat in children with CP. INTERPRETATION: Single anthropometric measures do not perform well in predicting percentage body fat in children with or without CP. Further work is needed to develop clinically useful and simple assessments that will predict percentage body fat and to determine the relation between percentage body fat and health to guide clinical practice.

Assessment and correction of skinfold thickness equations in estimating body fat in children with cerebral palsy.

AIM: To assess the accuracy of skinfold equations in estimating percentage body fat in children with cerebral palsy (CP), compared with assessment of body fat from dual energy X-ray absorptiometry (DXA). METHOD: Data were collected from 71 participants (30 females, 41 males) with CP (Gross Motor Function Classification System [GMFCS] levels I-V) between the ages of 8 and 18 years. Estimated percentage body fat was computed using established (Slaughter) equations based on the triceps and subscapular skinfolds. A linear model was fitted to assess the use of a simple correction to these equations for children with CP. RESULTS: Slaughter's equations consistently underestimated percentage body fat (mean difference compared with DXA percentage body fat -9.6/100 [SD 6.2]; 95% confidence interval [CI] -11.0 to -8.1). New equations were developed in which a correction factor was added to the existing equations based on sex, race, GMFCS level, size, and pubertal status. These corrected equations for children with CP agree better with DXA (mean difference 0.2/100 [SD=4.8]; 95% CI -1.0 to 1.3) than existing equations. INTERPRETATION: A simple correction factor to commonly used equations substantially improves the ability to estimate percentage body fat from two skinfold measures in children with CP.

Puberty, statural growth, and growth hormone release in children with cerebral palsy.

OBJECTIVE: Children with cerebral palsy (CP) are smaller than normally growing children.. The association between the growth hormone (GH) axis and growth in children with CP during puberty is unknown. We compared growth and markers of the GH axis in pre-pubertal and pubertal children with moderate to severe CP and without CP over a three-year period. STUDY DESIGN: Twenty children with CP, ages 6-18, Gross Motor Function Classification System levels III-V, were compared to a group of sixty-three normally growing children of similar age. Anthropometry, Tanner stage, bone age, and laboratory analyses were performed every six months for three years. Laboratory values included spontaneous overnight GH release, fasting IGF-1 and IGFBP-3. Repeated measures models were used to evaluate interactions among Tanner stage and group (children with CP vs. reference children), taking into account gender, age, and nutritional status. RESULTS: Children with CP grew more slowly than those without CP at all Tanner stages (p<0.01). Patterns of IGF-1 and GH secretion in children with CP were similar to those of the reference group; however, the concentrations of IGF-1 (p<0.01) and GH (p<0.01) were lower in girls with CP, with a similar trend for boys (p=0.10 and 0.14, respectively). CONCLUSIONS: Diminished circulating IGF-1 and GH concentrations may explain the differences in growth between the two groups.

Growth and nutrition disorders in children with cerebral palsy.

Growth and nutrition disorders are common secondary health conditions in children with cerebral palsy (CP). Poor growth and malnutrition in CP merit study because of their impact on health, including psychological and physiological function, healthcare utilization, societal participation, motor function, and survival. Understanding the etiology of poor growth has led to a variety of interventions to improve growth. One of the major causes of poor growth, malnutrition, is the best-studied contributor to poor growth; scientific evidence regarding malnutrition has contributed to improvements in clinical management and, in turn, survival over the last 20 years. Increased recognition and understanding of neurological, endocrinological, and environmental factors have begun to shape care for children with CP, as well. The investigation of these factors relies on advances made in the assessment methods available to address the challenges inherent in measuring growth in children with CP. Descriptive growth charts and norms of body composition provide information that may help clinicians to interpret growth and intervene to improve growth and nutrition in children with CP. Linking growth to measures of health will be necessary to develop growth standards for children with CP in order to optimize health and well-being.