Lukaski and Bolonchuk developed an equation for predicting an adult's total body water using personal information and bioelectrical impedance. The authors are from the US Department of Agriculture's Human Nutrition Research Center in Grand Forks, North Dakota.


Patient selection: middle-aged adults



(1) height in cm

(2) resistance in ohms measured by 4 electrodes (on hand and feet) at 50 kHz

(3) body weight in kilograms

(4) gender (male =1 , female 0)

(5) age in years


total body water in liters =

= (2.9 * (points for gender)) - (0.08 * (age in years)) + (0.14 * (weight in kg)) + (0.377 * (((height)^2) / (resistance in ohms))) + 4.65



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

• The resistance used is the lowest value for the 4 electrodes.



• R-squared 0.975; standard error of the estimate (SEE) 1.50.


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