Description

Yamada et al reported equations for estimating appendicular lean mass (ALM) using bioelectrical impedance analysis (BIA). The authors are from the National Institute of Health and Nutrition and TANITA Body Weight Scientific Institute in Tokyo.

Patient selection: age from 18 to 86 years of age

Parameters:

(1) impedance at 50 kHz in Ohms

(2) impedance at 250 kHz in Ohms

(3) impedance at 5 kHz in Ohms

(4) height in centimeters

(5) sex

impedance index at 50 kHz =

= ((height)^2) / (impedance)

ALM in kg in male =

= (0.6947 * ((height)^2) / (impedance at 50 kHz)) - (55.24 * ((impedance at 250 kHz) / (impedance at 5 hHz)) - (10940 / (impedance at 50 kHz)) + 51.33

ALM in kg in female =

= (0.6144 * ((height)^2) / (impedance at 50 kHz)) - (36.61 * ((impedance at 250 kHz) / (impedance at 5 hHz)) - (9332 / (impedance at 50 kHz)) + 37.91

where:

In the human body reactance is less than 10% of resistance and the correlation between impedance and resistance is > 0.99. Therefore, the impedance index and resistance index at 50 kHz are interchangeable.