but not adequate. Repetition of the detailed studies in both types of phtients hive been desired, but unfortunately the enormous investment of time ana effo to fallow a single treatment dose in one patient has been so great that it has onlp been possible to study selected patients. Thus, it has only been a chance ocfurrence that an additional therapeutic dose of radioiodine was necessary in a patient|who had beer. completely studied on the first aga ion. Partly by chance and partly by design a few patients were given a dose of +311 which was not sufficient to re the patient to a euthyroid state. A second therapeutic dose exactly equal to the fist was subsequently given in a few instances and all of the observations repeatd@d. The comparative studies of the two treatment doses have not revealed information that «as particularly informative, except that the second dose was often not takem up as well as was the first. ¥e- ert ohh ~ eX 940)0}) H4-5 in the Circulation Following « it) Li) *-+T Therapy ie odina a “Te * Ls =i ae) ie = ’ on It has been pointed out that in serial chromatograms of serum follc ing a treatment dose of there was an increased amount of radioactivity at he appiicat-- point. Paper electrophoresis was used to explore the nature of the iodinated compournx=> which remained at the application point. These observations although carfied at periodically for a number of years, did not reveal striking results excep much of the radioactivity was in the alpha globulin fraction and probably] the thyroxine-binding globulin. Ultimately when the patient reached the state, considerable 131; was in the albumin fraction. to show thay represemted frypo oid The Role of Triiodothyronine in Hyperthyroidism Since we and others had identified triiodothyronine in the circulation and its rapid and potent metabolic action had been proven, the possibility represented the principle form of thyroid hormone in thyrotoxic patients by many persons. Among other theories it was thought that thyroxine migh} ursor of triiodo ine. AS iously described, the @ mumber Chromatograms on ity.treated Was of mn that it | entertains be ea ser: pationts probably reflected basic'chysiolody of me disease immediately after the tly was passed reflected the radiation effect. given and later after hours and days had Triiodothyronine was found in the ehromareran of serum of many of the more thyrotoxic patients. The chromatograms done [pn the ery early samples of blood often showed that triiodothyronine, if present, appeared sooner and in larger quantities than thyroxine (especially in the most toxic patipnts). This observation tended to discredit the possibility that thyroxine was the prebursor >t triiodothyronine. There was in our series an occasional patient treated with 1317 for nypertinroid=- caused by a toxic adenoma. Some patients in a euthyroid state have been theated wth 1317 and studied in the sam: detailed way. In both situations <riicdothyrpnine ws oceasicnally detected, showing that triiodothyronine was not peculiar to Gheves' disease. fi