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Normal values of the bioelectrical impedance vector in childhood and puberty
T De Palo1, G Messina, A Edefonti
1Division of Pediatric Nephrology and Dialysis, "Giovanni XXIII" Hospital, Bari, Italy.
Insights
This study established reference intervals for the whole-body impedance vector in Italian children aged 2-15 years. These findings provide crucial data for assessing body composition and identifying potential health concerns in pediatric populations.
Area of Science:
- Pediatric Health
- Body Composition Analysis
- Biophysics
Background:
- Assessing pediatric body composition is vital for monitoring growth and health.
- Whole-body impedance vector analysis offers a non-invasive method for body composition assessment.
- Establishing normative data is essential for interpreting impedance vector measurements in children.
Purpose of the Study:
- To determine reference, bivariate, and tolerance intervals for the whole-body impedance vector in Italian children.
- To establish age- and sex-specific impedance vector trajectories from childhood to adolescence.
- To provide a normative dataset for evaluating body composition in children using impedance vector analysis.
Main Methods:
- Cross-sectional, multicenter study involving 2044 healthy Italian children (ages 2-15 years).
- Whole-body impedance vector measured using standard tetrapolar analysis at 50-kHz frequency.
- Resistance and reactance components standardized by height; age-specific intervals and mean vector trajectories plotted.
Main Results:
- Established age-specific 95% confidence intervals for mean impedance vectors and 95%, 75%, and 50% tolerance intervals for individual measurements.
- Identified a statistically significant sex effect on vector distribution in adolescents (14-15 years).
- Observed a progressive vector shortening from age 2 to 15 years, moving towards adult vector positions.
Conclusions:
- The study successfully established the trajectory of the mean impedance vector in children aged 2-15 years.
- Reference, bivariate, and tolerance intervals for the impedance vector by age were obtained for healthy children.
- These established intervals can be used to test impedance vectors from children with altered body composition.
Abstract:
The purpose of this study was to determine the reference, bivariate, and tolerance intervals of the whole-body impedance vector in Italian children. This was a cross-sectional, multicenter study, and participants were chosen from the general school population. The impedance vector (standard, tetrapolar analysis at 50-kHz frequency) was measured in 3110 subjects, ages 2 to 15 y, and 2044 healthy children (1014 male and 1030 female) with weight and height within the 95th percentile were selected for the analysis (resistance-reactance graph method). The age-specific 95% confidence intervals of mean vectors and the 95%, 75%, and 50% tolerance intervals for individual vector measurements were plotted using resistance and reactance components standardized by the subject's height. Mean vectors from both sexes with separate 95% confidence ellipses were considered as representative of eight different age groups, from 2 to 13 y. There was a statistically significant sex effect on vector distribution from boys and girls in the age group of 14 to 15 y. The impedance vector distribution of children was also compared with healthy adult subjects (354 male and 372 female, age 15 to 85 y). There was a progressive, statistically significant vector shortening from age 2 to 15 y toward the adults' vector position. In conclusion, we established the trajectory followed by the mean impedance vector in children over ages 2 to 15 y and also obtained the reference, bivariate, and 95%, 75%, and 50% tolerance intervals of the impedance vector by age for healthy children, with which the vectors from children with altered body composition can be tested.