Extracellular and intracellular space measured by total body neutron activation

Although total body neutron activation analysis (TBNAA) has been use primarily to measure total body calcium and nitrogen composition, the present study emphasizes the potential application of total body chloride data for determining the volumes of body water compartments. Because of the good correlation with more conventional iosotope dilution methods, the range of studies to which TBCl can be applied is vastly extended. The determination of extracellular space by TBNAA has the advantage over conventional isotope dilution in that it is a direct, noninvasive measure with small error. Further, the equilibrium of all elements is assured, and non-specific isotope exchange need not be considered