An evaluation of the tritiated water method for estimating body water in small rodents

The total body water of 27 rodents (live weights less than 100 g) were estimated by a tritiated water method and by direct analysis. There was no significant difference between the values as estimated by the two methods. The 95% confidence interval for total body water as estimated by the tritiated water method was ±10% of the value estimated from direct analysis. The accuracy of the method is acceptable for most applications, however, investigators should be cognizant of the estimate error, especially when calculating other components of body composition from total body water, e.g. body fat.