The bioelectrical impedance vector migration in healthy infants.

BACKGROUND & AIMS Detecting young children with high amount of body fat is important to intervene in the development of obesity. The aim of this study is to gain inside in the bioelectrical impedance vector analysis in healthy infants. METHODS Repeated measurements of whole body reactance and resistance were assessed, using a 50kHz frequency bioelectrical impedance analysis, in 51 boys and 62 girls during infancy. Bivariate vector analysis, which can be used to determine tissue hydration and soft tissue mass, was conducted. The 95% confidence intervals of the mean vectors for different age groups and the 95%, 75% and 50% tolerance intervals were plotted, using resistance and reactance components standardized by the participant's height. RESULTS During infancy impedance vectors changed significantly: A vector migration of the Xc/H of 8.50ohm/m and the R/H of -95.68ohm/m between the age of two months and eight to twelve months (p=0.0001) was observed. Bivariate, reference tolerance intervals of the impedance vectors for healthy infants at the age of two months are presented. CONCLUSION Our results show a significant impedance vector migration during the first year of life. New reference tolerance intervals for the second month of life were constructed.