IN MEDICAL PRACTICE moderate dehydration is usually diagnosed by observing the turgor of the skin and the fullness of the tongue. Laboratory data have been found to be of little value in determining the presence of dehydration, particularly when the patient first appears for examination in a state of dehydration and with impaired renal function. The physician, after making the diagnosis of dehydration, is often unable to determine the volume of fluid to be replaced since there is little data in the literature1,2 to guide him. The work of Coller and Maddock1 has been quoted widely as the basis for the statement that an adult must lose 6% of body weight in water before dehydration is present.
The purpose of the present study was to investigate further the amount of fluid that must be lost from the adult human before dehydration becomes apparent on physical examination. Also, an