Studies of I-131-albumin catabolism and distribution in normal young male adults.

Studies of I13'-albumin catabolism and distribution are appearing in rapidly increasing numbers in current literature. The data for normal human subjects reported from various laboratories differ considerably in mode of analysis and in results obtained. In normal subjects the observed "half-life" of I'31-albumin has ranged from below 10 to above 20 days (1-15), and the ratio of the amount of albumin contained extravascularly to that present in the plasma has been calculated as ranging from 1 to 4.5 (6, 7, 15-17). Although these wide variations are due to many factors, the major causes appear to be these: 1) variable degrees of denaturation incurred during the preparation of the protein and its radioisotopic labeling, perhaps detectable only through biological testing; 2) variable lengths of study periods, many being too short to allow metabolic trends to be fully realized; and 3) differing mathematical approaches to the analysis of data, each requiring assumptions of variable validity. With the availability of improved I131-albumin preparations, it can be anticipated that greater efforts will be directed toward the investigation of albumin catabolism and distri-