title: Estimation of total body and extracellular water using single- and multiple-frequency bioimpedance.
abstract: OBJECTIVE
  To determine the precision and bias of single- and multiple-frequency bioimpedance estimates of total body water (TBW) and extracellular water (ECW) volumes in comparison with the true values for these volumes established by gold standard dilution techniques.
  
  
  METHODS
  Controlled, prospective, open-label investigation.
  
  
  METHODS
  Private, not-for-profit university-affiliated, acute care hospital.
  
  
  METHODS
  Normal, healthy men (n = 8) and women (n = 6) volunteers, 25-46 years of age.
  
  
  METHODS
  A single oral dose of a mixture of deuterium oxide 10 g and bromine 30 mmol; bioimpedance analysis pre- and three hours postmixture administration.
  
  
  METHODS
  TBW and ECW volumes established by deuterium oxide and bromine dilutional spaces (gold standards), respectively, and single- and multiple-frequency bioimpedance estimates of those same volumes.
  
  
  RESULTS
  The mean multiple-frequency bioimpedance (MFB) and single frequency bioimpedance (SFB) estimates of TBW, 41.2 and 42.1 L, respectively, were not statistically different (NS) from the 41.2 L deuterium oxide value. Although the two methods had similar precision (NS), MFB was less biased. For ECW, the mean MFB and SFB values of 19.5 and 24.8 L, respectively, were significantly different from the bromine value of 18.8 L (p = 0.013 and p = 0.001, respectively). MFB was the more precise and less biased predictor of ECW.
  
  
  CONCLUSIONS
  Compared with SFB, the MFB approach is a more precise and less biased predictor of TBW and ECW volumes in young, healthy adults, and may offer more accurate assessment in subjects with aberrant physiology.
authors.affiliation: Department of Pharmacy Services, Henry Ford Hospital, Detroit, MI 48202.
authors.forename: R V
authors.initials: RV
authors.lastname: Patel
authors.forename: J R
authors.initials: JR
authors.lastname: Matthie
authors.forename: P O
authors.initials: PO
authors.lastname: Withers
authors.forename: E L
authors.initials: EL
authors.lastname: Peterson
authors.forename: B J
authors.initials: BJ
authors.lastname: Zarowitz
mesh_terms: D000328:Adult; D001834:Body Water; D001966:Bromine; D017666:Deuterium Oxide; D017097:Electric Impedance / Q000145:classification; D005110:Extracellular Space / Q000737:chemistry*; D005260:Female; D006785:Hospitals, University; D006788:Hospitals, Voluntary; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results
chemical_list: D017666:Deuterium Oxide; D001966:Bromine