Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/19/1999
Publication Date: N/A
Technical Abstract: Various empiric formulas have been developed for estimating total body water (TBW) from bioelectrical impedance (BIA) using young, healthy volunteers. The validity of using these equations is questionable when applied to older adults. TBW calculated from BIA using two equations from Kotler et al. (E1 and E2) and a third from Goran (E3) were validated against TBW derived from doubly labeled water (DLW) in 15 male and 13 female community-dwelling older adults (Age 66-81 yrs): E1: Height** / (Impedance ** * 4.53) E2: 0.79[Height** (Impedance ** *4.53)] + (0.20 * Weight) 5.65 E3: 0.19(Height* / (Resistance) + (7.678 * Gender) + (0.23 * Weight) + 5.02 All three equations generated TBW estimates that were highly correlated with TBW from DLW (r = 0.96,0.96, 0.93, respectively). On average, E1 under-estimated TBW by 1.7L (range -4.8 to 4.1), E2 over-estimated by 4.8L (range -8.5 to 0.1), and E3 over-estimated by 9.3 L (range 5.2 to 14.0). A plot of regression residuals vs. predicted values suggests that the simplest of these equations, E1, is the most accurate for estimating TBW from BIA among older adults. Funded in part by the Agricultural Research Service.