Tritium dilution space measurement is not modified by a doubling in fluid intake

The purpose of this study was to examine the effects of a doubling in water intake on the total body water measured by the tritium dilution technique. Overdrinking was obtained by presenting tap water and sweet water to the rats. Total body water was measured twice, tritium dilution vs. dessication. Body water volumes differed between the two methods but not between the two groups. Thus the isotopic dilution technique can be used to measure total body water regardless of the flux of fluid through the subject.