FURTHER OBSERVATIONS ON THE RELATION BETWEEN BODY FLUID VOLUME AND URINE FLOW IN MAN

Summary The factors governing the partition of fluid between the various body compartments are discussed and related to the previously expressed concept of the mechanism of control of body fluid volume. Further data are presented concerning the relationship between daily urine flow and body weight. It is concluded that within the limits of the technique used the daily urine flow is linearly related to body fluid volume, but that the relationship may be modified or obscured by changes in the partition of fluid between compartments. Changes in the non‐fluid part of body weight may likewise obscure this relationship when body weight is taken to represent body fluid volume. This discussion also indicates that control of body fluid volume can be upset in at least three ways : first, a change in the ability to excrete fluid ; secondly, a change in the partition of fluid within the body ; thirdly, a sequestration of fluid outside the influence of the control mechanism.