Body water compartment measurements: A comparison of bioelectrical impedance analysis with tritium and sodium bromide dilution techniques

• Published in: Clinical nutrition (Edinburgh, Scotland) Vol. 20; no. 4; pp. 339 - 343
• Main Authors: SIMPSON, J.A.D., LOBO, D.N., ANDERSON, J.A., MACDONALD, I.A., PERKINS, A.C., NEAL, K.R., ALLISON, S.P., ROWLANDS, B.J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2001; Elsevier
• Subjects: Adult; bioelectrical impedance analysis; Biological and medical sciences; Body Composition; Body Fluid Compartments; Body Water - metabolism; Body Weight; Bromides - metabolism; Chromatography, High Pressure Liquid; Electric Impedance; Extracellular Space - metabolism; extracellular water; Female; Humans; Indicator Dilution Techniques; Injections, Intravenous; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Miscellaneous. Technology; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Sensitivity and Specificity; sodium bromide; Sodium Compounds - metabolism; Statistics as Topic; total body water; tritium; Tritium - metabolism; tritium; sodium bromide; bioelectrical impedance analysis; total body water; extracellular water; Water; Performance evaluation; Human; Dilution; Body compartment; Whole body; Measurement method; Technique; Body composition; Comparative study
• ISSN: 0261-5614; 1532-1983
• DOI: 10.1054/clnu.2001.0398

Background and Aims: This study was undertaken to assess the comparability of body water compartment estimates in healthy volunteers using single and dual frequency bioelectrical impedance analysis (BIA) with established reference methods of tritium and NaBr dilution. Methods: Total body water (TBW) was estimated in 10 healthy volunteers using single frequency (50 kHz) BIA (Bodystat 1500), dual frequency (5 and 200 kHz) BIA (Bodystat Dualscan 2005) and tritium dilution. Extracellular water (ECW) was measured with dual frequency BIA and NaBr dilution. BIA was performed using distal tetrapolar electrodes in the supine position. Venous blood was sampled for measurement of background concentrations of tritium and NaBr using a beta counter and high performance liquid chromatography respectively. 10 ml tritiated water (3.7 MBq) and 50 ml 5% NaBr solution were then injected intravenously and blood samples taken from the opposite arm every 45 min for 4.5 h for estimation of concentrations of tritium and NaBr. Results: There was good correlation (r2=0.76) between estimates of ECW using dual frequency BIA and NaBr dilution, with the former overestimating ECW by ∼1 L. However, this difference varied systematically with body weight. Although TBW measurements obtained by single and dual frequency BIA correlated well with estimates using tritium dilution (r2=0.96 and 0.95 respectively), single frequency BIA underestimated TBW by ∼1 L and dual frequency BIA by ∼5 L compared to tritium dilution. Conclusion: TBW measurements obtained using the single frequency BIA device were more accurate than those obtained using the dual frequency BIA device. Dual frequency BIA provided a reasonably accurate estimate of ECW.