Accuracy of an eight-point tactile-electrode impedance method in the assessment of total body water.
OBJECTIVE
To establish the accuracy of an eight-polar tactile-electrode impedance method in the assessment of total body water (TBW).


METHODS
Transversal study.


METHODS
University department.


METHODS
Fifty healthy subjects (25 men and 25 women) with a mean (s.d.) age of 40 (12) y.


METHODS
TBW measured by deuterium oxide dilution; resistance (R) of arms, trunk and legs measured at frequencies of 5, 50, 250 and 500 kHz with an eight-polar tactile-electrode impedance-meter (InBody 3.0, Biospace, Seoul, Korea).


RESULTS
An algorithm for the prediction of TBW from the whole-body resistance index at 500 kHz (height (2)/R(500) where R is the sum of the segmental resistances of arms, trunk and legs) was developed in a randomly chosen subsample of 35 subjects. This algorithm had an adjusted coefficient of determination (r2(adj)) of 0.81 (P<0.0001) and a root mean square error (RMSE) of 3.6 l (9%). Cross-validation of the predictive algorithm in the remaining 15 subjects gave an r2(adj) of 0.87 (P<0.0001) and an RMSE of 3.0 l (8%). The precision of eight-polar BIA, determined by measuring R three times a day for five consecutive days in a fasting subject, was < or =2.8% for all segments and frequencies.


CONCLUSIONS
Eight-polar BIA is a precise method that offers accurate estimates of TBW in healthy subjects. This promising method should undergo further studies of precision and its accuracy in assessing extracellular water and appendicular body composition should be determined.


BACKGROUND
Modena and Reggio Emilia University.
Bedogni
G
G
Human Nutrition Chair, Faculty of Medicine and Surgery, University of Modena and Reggio Emilia, Modena, Italy. giorgiobedogni@libero.it
Malavolti
M
M
Severi
S
S
Poli
M
M
Mussi
C
C
Fantuzzi
A L
AL
Battistini
N
N
D000328:Adult; D000465:Algorithms; D001823:Body Composition; D001834:Body Water; D017666:Deuterium Oxide; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D017666:Deuterium Oxide