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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #88253
Title: HUMAN HYDROMETRY: COMPARISON OF MULTIFREQUENCY BIOELECTRICAL IMPEDANCE WITHDEUTERIUM AND BROMINE DILUTION

Author
item Ellis, Kenneth
item Wong, William

Submitted to: Journal of Applied Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The traditional way scientists have assessed a subject's body water content and its cellular distribution is to use isotope tracer techniques. This required the subject to drink a very salty solution and two blood samples to be taken about 3 hours apart. Furthermore, the lab analysis of the blood could take several weeks to complete. We wanted to see if a new method called bioelectrical impedance spectroscopy (BIS) would produce equally accurate results. This method requires no blood samples or for the subject to drink a salty solution, and the results are virtually instantaneous. We tested both methods on 469 adults and children and compared the results. BIS appears to work on a population, but not for the individual. Furthermore, the constants used with the BIS instrument for the adult measurements do not appear to apply to the measurement of children. We identified ways to improve BIS so it might work in both respects.

Technical Abstract: The traditional method of assessing total body water (TBW), extracellular water (ECW), and intracellular water (ICW) has been the use of isotopes, based on the dilution principle. Although the development of bioelectrical impedance techniques have eliminated many of the measurement constraints associated with the dilution methods, the degree of interchangeability between the two methods remains uncertain. We used multifrequency bioelectrical impedance (BIS) and deuterium (D2O) and bromine (Br) dilution to assess TBW, ECW, and ICW in 469 healthy subjects (248 males, 221 females) aged 3 - 29 y. We found that the TBW, ECW and ICW estimates were significantly correlated (r2 = 0.80 - 0.96, P<0.0001, SEEs = 2.3 - 2.7 L) between the two methods, while the volume estimates for an individual were highly method-dependent. We conclude that, on a population basis, the BIS analysis can be substituted for the D2O and Br dilution techniques. To improve the accuracy of the BIS measurement for the individual, further refinement will be needed for the various constants used with this technique.