Total body sodium and chlorine in normal adults as determined by neutron activation analysis

Total body neutron activation analysis (TBNAA) has used to determine the absolute levels of total body sodium (TBNa) and total body chlorine (TBCl) in 81 normal adults. For the age span studied (30–90 years), the mean values of TBNa and TBCl remained relatively constant for males, but decreased slightly for females beyond sixty years of age. In order to reduce the variability in this cross-sectional study, the TBNa and TBCl values were normalized for body dimensions (weight, height, body surface area) as well as age and sex. In addition, TBNa was related to skeletal mass (total body calcium) and lean body mass (total body potassium). The quantity of body sodium in excess of the chlorine space was determined. This value, defined as sodium excess, was significantly correlated with total body calcium. The values for total body sodium, total body chlorine, and sodium excess obtained in the present study were compared with values previously reported in the literature.