Patient selection: middle-aged adults
Parameters:
(1) height in cm
(2) body weight in kilograms
(3) resistance in ohms measured by 4 electrodes (on hand and feet) at 50 kHz
(4) reactance in ohms (Xc)
extracellular water in liters =
= (0.052 * (weight in kg)) + (0.189 * (((height)^2) / (resistance in ohms))) - (0.0002 * (((height)^2) / (reactance in ohms))) + 1.03
intracellular water in liters=
= (total body water in liters) - (extracellular water in liters)
where:
• The height squared divided by the resistance is called the impedance index.
• The formula for total body water is given above.
• The resistance and reactance are the lowest values measured at the 4 electrodes.
Performance:
• R-squared was 0.884; the standard error of the estimate (SEE) was 1.01
