II. THE SIMULTANEOUS MEASUREMENT OF EXCHANGEABLE BODY SODIUM AND POTASSIUM UTILIZING ION EXCHANGE CHROMATOGRAPHY

Abstract

A simple and efficient method is presented for simultaneous measurement of exchangeable body sodium and potassium utilizing a cation exchange resin, Dowex 50, for separation of radioactive sodium and potassium in the serum in combination with the isotope dilution technique. Successive measurements made in normal subjects at intervals of 1 to 2 weeks and longer have indicated that the method presented gives reproducible results. Exchangeable body sodium and potassium measurements obtained in normal young adult subjects are given and correspond well with data acquired by other investigators. Because of the wide range of normal values, it is suggested that body electrolyte measurements will yield the most accurate information when used in a serial fashion to study patients and that the ratio of exchangeable body sodium to exchangeable body potassium may provide a valuable index of body electrolyte composition.