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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #246588
Title: In vivo and in vitro bromide equilibration time course in adults and sample handling effect

Author
item SCHLOSSER, KAREN - University Of Wisconsin
item TAYLOR, JOSHUA - University Of Wisconsin
item KEHAYIAS, JOSEPH - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item TEGENKAMP, MICHELLE - University Of Wisconsin
item SCHOELLER, DALE - University Of Wisconsin

Submitted to: International Journal of Body Composition Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2009
Publication Date: 12/20/2009
Citation: Schlosser, K., Taylor, J., Kehayias, J., Tegenkamp, M.H., Schoeller, D.A. 2009. In vivo and in vitro bromide equilibration time course in adults and sample handling effect. International Journal of Body Composition Research. 7:141-147.

Interpretive Summary: Body water is divided into two compartments: intracellular water, which represents the metabolic portion of the body (such as muscle), and extracellular water (ECW). The latter can change rapidly in heart disease, malnutrition, dialysis, frailty, and other diseases. Therefore, the volume of ECW has been used as an indication of nutritional and health status. Its measurement is simple. The subject is given a drink that contains bromide, then blood or urine is analyzed a few hours later. This work examines the technical details of this method in order to optimize its accuracy. It concluded that although it may take up to eight hours for the bromide to reach equilibrium after administration, measurements of blood or urine can be made reliably in half of this time. The work also compared different methods of sample preparation.

Technical Abstract: Extracellular water is a major component of body weight and an indicator of nutritional status. Bromide dilution has been used to estimate this compartment. Recent evidence, however, indicates that the bromide equilibration time is longer than the 4 hr assumed in many studies. The aim of this study was to determine in vitro equilibration time and effects of sample handling. Nineteen healthy adults (14 women and 5 men, age 18- 25yr) were orally dosed with 30 mg/kg bromide in water and blood sampling was performed at 4, 6 and 8 hr, with careful control of water intake and bromide loss to urine. We found a 4% difference between Br space at 4 and 8hr (p = 0.004), but not at 6hr. Based on this and previous studies, we suggest that equilibration requires 8 to 9 hr . Delays up to 16 hr in separating plasma and erythrocytes did not influence the bromide measurement.