THE USE OF BIOELECTRICAL-IMPEDANCE ANALYSIS TO PREDICT TOTAL-BODY WATER IN PATIENTS WITH CANCER CACHEXIA

The applicability of bioelectrical impedance analysis (BIA) to predict total body water (TBW) was assessed in 16 underweight [< 95% of ideal body weight (IBW)] and 25 normal-weight (> 95% of IBW) cancer patients. Although height(2)/resistance (ht(2)/R) proved to be a strong single predictor of TBW measured by deuterium dilution in both groups (normal-weight patients: r(2) = 0.85, SEE 2.16 L; underweight patients: r(2) = 0.86, SEE 2.24 L), TBW would be significantly overestimated in the underweight group if the prediction formula developed in the normal-weight group was used [bias 1.67 L (5%), 95% CI 0.20-3.15 L]. A systematic overestimation of TBW in the underweight patients was also found when TBW was predicted in our two patient groups by several previously published BIA formulas developed in normal-weight individuals. We conclude therefore, that although a similar relationship is found between ht(2)/R and TBW in normal-weight and underweight cancer patients, single-frequency BIA overestimates TBW in underweight patients when prediction formulas are used that have been developed in normal-weight subjects.