Measurement of total body water in children using bioelectrical impedance: a comparison of several prediction equations

Background: Body composition evaluation by bioelectrical impedance analysis in children makes use of different group-specific population-derived equations. The present study was conducted to attempt to validate the use of population-independent physical model-derived equations in children. Methods: The validity of bioelectrical impedance analysis for the measurement of total body water in children was evaluated by comparing results of two physical model-derived and two population-derived equations with those of deuterium dilution as reference method in a group of 38 heterogeneous children. Results: Means +/- standard deviation (in liters) for total body water measured with deuterium dilution and the physical model 1-derived equation were 18.4 +/- 4.7 L and 18.1 +/- 4.4 L, respectively. This difference is not significant, whereas significant differences were found for all other tested equations. Significant smaller absolute differences between the model 1 equation and deuterium reference results were found when compared with the results of the other three tested equations. Conclusion: When compared with results of the reference deuterium method the physical model 1-derived equation was the only one that provided reliable total body water results by bioelectrical impedance analysis in children.