COMPARISON OF SULFOCYANATE WITH RADIOACTIVE CHLORIDE AND SODIUM IN THE MEASUREMENT OF EXTRACELLULAR FLUID

Abstract

In 3 dogs under varying conditions of hydration the absolute magnitude of the apparent vol. of distribution of sulfocyanate always exceeded that of radioactive Na, which in turn exceeded that of radioactive Cl. In the hydrated normal dogs, Cl38, Na24, and SCN were distributed through approx. 25%, 28% and 36% of the body wt. respectively. In spite of these differences in the absolute magnitude, changes in the vol. of the extracellular fluid as measured by each of the 3 substances and by Cl and Na balances were usually of about the same magnitude; occasionally unexplained discrepancies appeared. The vol. of distribution of sulfocyanate is therefore not a satisfactory absolute measure of the vol. of the extracellular fluid. Under most conditions, however, it may be a useful relative measure, i.e., changes in its vol. of distribution may reflect changes in extracellular fluid.