Total exchangeable potassium, total exchangeable sodium, and total body water were simultaneously measured by dilution of K42, Na24, and H3, respectively. Total exchangeable chloride was estimated at the same time by dilution of Br82. The concentrations of water, sodium, potassium, and chloride were measured in the serum. The subjects included three healthy young men. The remaining 65 subjects were patients, with illness associated with disorders of nutrition and of water and electrolyte metabolism ranging from cachexia to extreme obesity and from dehydration to massive anasarca. The results show that in this highly varied group of subjects, neither Nae, Ke, nor Cle was correlated at all well with total body water when considered singly. Cle, in fact, was not considered to add useful information in the absence of information regarding other anions. However, the sum of Nae and Ke correlated exceedingly well with total body water (r = .991). Additional relationships containing serum cation concentrations had even higher degrees of correlation. Furthermore, it was found that expressions capable of predicting Nae or Ke could be derived from the data. Similarly high degrees of correlation were found when these regressions were computed for data from the literature. Note: With the Technical Assistance of E. Rossmeisl, R. McLean, H. Alpert, M. Halpin, and R. Gardner total body water; total exchangeable potassium; total exchangeable sodium; total exchangeable chloride Submitted on January 24, 1963
Basic Facts of Body Water and Ions