MULTIFREQUENCY BIOELECTRICAL-IMPEDANCE ESTIMATES THE DISTRIBUTION OF BODY-WATER

Multifrequency bioelectrical impedance analysis was used to estimate t he ratio of extracellular water (ECW) to total body water in subjects with end-stage renal disease. The body's resistance was measured at fr equencies ranging from 1 kHz to 1 MHz. The impedance index (height(2)/ resistance) determined at low frequency (5 Mit) correlated most closel y with ECW (r = 0.886) using sodium bromide dilution as the standard o f comparison. In contrast, the ratio of height squared to resistance d etermined at high frequency (500 kHz) correlated most closely with tot al body water (r = 0.974) using deuterium oxide dilution as the standa rd of comparison. The ratio of resistance at 500 kHz to resistance at 5 kHz was directly correlated (r = 0.767) with the ratio of ECW to tot al body water. Multifrequency bioelectrical impedance analysis may ass ist in the evaluation of body water distribution in end-stage renal di sease and other clinical disorders of fluid volume and/or distribution .