Total-body sodium and sodium excess.

Total-body levels of sodium (TBNa), chlorine (TBCl), calcium (TBCa), and potassium (TBK) were measured by neutron activation and analysis of results by whole body counting in 66 postmenopausal women. The relationship between TBNa, and TBCl, TBK, and TBCa on the one hand, and height and weight on the other, were found to compare with those previously reported. The hypothesis that TBNa and TBCl are distributed normally could not be rejected. The sodium excess (Naes) is defined as the sodium that is present in excess of that associated with the extracellular fluid (chlorine) space; the Naes approximates nonexchangeable bone sodium. In these 66 postmenopausal women, and in patients with different endocrinopathies previously described, the values of Naes did not differ from the normal values except in the thyrotoxicosis patients, where they were decreased. A close relationship between Naes and TBCa was maintained in the endocrinopathies studied. This relationship was found in conditions accompanied by either an increment or a loss of skeletal mass. It appear