MEASUREMENT OF TOTAL-BODY WATER IN PREGNANT-WOMEN USING DEUTERIUM DILUTION - VALIDATION OF THE PLATEAU METHOD

Deuterium dilution was used to assess total body water (TBW) from the plateau period and from the intercept of the isotope-disappearance curve in pregnant women. With the aim of determining the equilibration time for deuterium in saliva two experiments were designed using the plateau method (PM). In a third experiment, the intercept method (IM) was used to validate the equilibration period of the PM, throughout comparison of TBW values in women with and without leg oedema. Results indicated that time for homogeneous distribution of deuterium within the body water is about 2.5 hours. There was better agreement of TBW values obtained at 2.5 hours than those at 3 hours. Plotting of differences between the mean of both TBW PM and IM values showed that the two methods of measurement can be used interchangeably. The possible influence of leg oedema in the time of homogeneous distribution was not apparent.