Comparison of Whole Body and Segmental Bioimpedance Methodologies for Estimating Total Body Water

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Abstract
We compared the whole body (WB) and segmental bioelectrical impedance analysis (BIA) methodologies in a group of healthy adults (n= 25). It has been suggested that the segmental methodology may overcome the difficulty in generating a single algorithm to predict total body water (TBW) in all groups whether healthy or not. We measured TBW, using D2O dilution, and WB and segmental BIA parameters. Cole‐Cole analysis was used to determine the impedance at the characteristic frequency (Zc). The correlation between TBW (by D2O dilution) and segmental BIA measures (multiple regression, r= 0.90, p < 0.001, SEE = 3.1 L) was not significantly higher than the correlation between TBW (D2O dilution) and WB BIA measures (simple regression, r= 0.85, p < 0.001, SEE = 3.6 L). Others have observed this “lack of improvement” in a group of healthy subjects. The true value of the segmental BIA methodology may lie in applications involving groups with altered distributions of segmental and compartmental fluid.