MULTIPLE FREQUENCY BIOELECTRICAL-IMPEDANCE FOR THE PREDICTION OF TOTAL-BODY POTASSIUM IN CYSTIC-FIBROSIS

The use of multiple frequency bioelectrical impedance analysis (MFBIA) was compared with single frequency bioelectrical impedance analysis ( SFBIA) and anthropometry to estimate the size of the body cell mass (B CM) in a paediatric cystic fibrosis population. BCM was independently determined from the accepted gold standard reference of total body pot assium (TBK). MFBIA was used to measure the impedance of the body at 2 48 frequencies from 4 kHz to 1 MHz. Data were analysed using Cole-Cole plots of reactance versus resistance, The limits of agreement procedu re was used to determine the reliability and precision of the differen t techniques to predict values for TBK, in an individual subject. The results indicate that MFBIA with a precision of 12% offers little impr ovement over single frequency BIA but is better and more accurate than anthropometry for the prediction of TBK in an individual patient.