STUDIES OF PLASMA VOLUME USING HUMAN SERUM ALBUMIN TAGGED WITH RADIOACTIVE IODINE131

Abstract

The purpose of this paper is to report a method of determining plasma volume in man, using hu- man serum albumin tagged with radioactive iodine, Il8. The preparation of the tagged material and a check of its stability and physiological behavior will also be discussed. We will also give a pre- liminary report of our results using this method for the determination of plasma volume in man as compared with the plasma dye method using Evans Blue Dye, T-1824. The determination of plasma volume, using the Evans Blue Dye, T-1824 (1, 2), has become an accepted laboratory procedure in clinical investi- gation. In the course of an investigation of changes in blood volume it became apparent that repeated determinations in the same individual over a short period of time were impossible using this method. A method combining a radioactive isotope with a non-toxic vehicle seemed worthy of trial. This vehicle must of necessity be macro- molecular, to prevent rapid diffusion from the vas- cular space, freely miscible with plasma, and of a chemical nature to combine with a radioactive iso- tope. The radioactive isotope must also be non- toxic and possess a relatively short half-life.