Simultaneous Measurement of Body Sodium and Potassium Using Na22 and K42

Journal/Book: Reprinted from METABOLISM Vol. 9 No. 6 June 1960 Printed in U.S.A.. 1960;

Abstract: From the Radioisotope Laboratory and Fluid Balance Unit Department of Medicine The Jewish Hospital of Brooklyn and Downstate Medical Center State University of New York. We are indebted to Mr. Harry Rubin and Mr. Anthony Rubino for their technical assistance. Received for publication July 8 1959. A new technic is described for simultaneously measuring total exchangeable K (KE) utilizing Na22 and K42. Ten ml. of a mixture containing approximately 125 microcuries of K42 and 10 microcuries of Na22 are administered intravenously using a single syringe. Total radioactivity is determined an samples of blond and urine shortly after collection and again 6 to 12 hours later. The differential decay of K42 a short-lived isotope and Na22 a relatively long-lived isotope permits calculation of the amount of radioactivity contributed by each of the isotopes. NaE; and KE were determined by this method in 5 normal subjects and 13 patients-5 with decompensated heart diseases 5 with renal insufficiency 2 with cirrhosis and 1 with primary aldosteronism. Normal values for NaE ranged from 36.8 to 43.8 mEq. per Kg. and for KE from 38.5 to 50.4 mEq. per Kg. which is in agreement with the values obtained by other methods. The chief advantage of this method of simultaneous Spate determinations is its simplicity. ___MH

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