THE NORMAL METABOLISM OF γG-GLOBULIN

A group of normal subjects has been studied after careful clinical examination. Different methods of determining the intravascular γ G‐globulin concentration and of calculating the catabolism were used. The difference in the values as well as the composition of the material may well explain the divergent results published earlier. A standardization of these methods is therefore proposed. By using whole‐body counting as well, we obtained further information which showed that the plasma and the whole‐body curves are parallel, but not the plasma and the retained‐dose curves. This must signify that, if incomplete urine collection has been excluded, 131 I is eliminated by routes other than the urine. About 17% of the total daily amount of eliminated radioactivity can be estimated to be lost by routes other than the urine, which in turn means that the catabolic value will be too low when calculated by the U/P method. Possible routes of the 131 I‐elimination would be perspiration and via the saliva. Measurement of the extravascular pool by whole‐body counting showed that, in healthy active subjects, the extravascular compartment is equal in size to the intravascular.