Gregory et al developed an equation for predicting total body water using bioelectrical impedance and body height. The authors are from the University of Dundee in England.


Reference method for total body water: H2O using 18-O oxygen isotope


Patient population: pediatric



(1) height in cm

(2) resistance in ohms measured using bioelectrical impedance (Holtain body composition analyzer with electrodes on right wrist and right ankle at 50 kHz)


total body water in kilograms =

= (0.55 * (((height in cm)^2) / (ohms))) + 0.79



• The height squared divided by the resistance is called the impedance index.


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