title: Use of multi-frequency bioelectrical impedance analysis for the estimation of extracellular fluid.
abstract: Thomasset (Lyon Medicine (1962): 207, 107-118; (1963): 209, 1325-1350; (1965): 214, 131-143) and others suggested that low-frequency impedance measurements could be used to estimate extracellular fluid and that high-frequency measurements could be used for the assessment of total body water. It was the purpose of this study to examine the relationship between body fluid compartments and multi-frequency bioelectrical impedance analysis (MF-BIA). Total body water (TBW) and extracellular fluid (ECF) were measured using deuterium and sodium bromide dilution procedures. Intracellular fluid volume (ICF) was calculated as the difference between TBW and ECF. A tetrapolar arrangement of surface electrodes was used to measure whole-body resistance (R), reactance (Xc), impedance (Z), and phase angle (P) at 25 frequencies ranging from 1 kHz to 1.35 MHz. Subjects (n = 60; 40 male and 20 female) were between the ages of 19 and 65 years. Mean ratios (+/- SEM) of ECF/ICF and ECF/TBW were 0.83 +/- 0.021 and 0.45 +/- 0.011, respectively. Individuals with the largest fat-free mass (FFM) had the highest ECF value. Whole-body resistive index values most correlated to ECF were at 224, 300, 400, 548 and 1 kHz with correlations ranging from 0.93 to 0.84. All possible subset regression analysis was used to develop a prediction equation for ECF: R2 = 0.924 and SEE = 1.061: ECF = 5.17753 + (0.09989*RI224) + (0.09322*WT) - (1.3962*SEX), where RI = resistive index (HT2/R) at the specific frequency of 224kHz; WT = weight in kilograms; sex was dummy-coded, males = 0, females = 1.
authors.affiliation: United States Department of Agriculture/ARS/WHNRC, Presidio of San Francisco, CA 94129.
authors.forename: M D
authors.initials: MD
authors.lastname: Van Loan
authors.forename: P L
authors.initials: PL
authors.lastname: Mayclin
mesh_terms: D000328:Adult; D000368:Aged; D001825:Body Fluid Compartments / Q000502:physiology*; D001834:Body Water / Q000737:chemistry; D001965:Bromides; D003903:Deuterium; D004553:Electric Conductivity; D004594:Electrophysiology / Q000379:methods; D005110:Extracellular Space / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012964:Sodium; D017670:Sodium Compounds
chemical_list: D001965:Bromides; D017670:Sodium Compounds; D012964:Sodium; D003903:Deuterium; C027938:sodium bromide