obyns, B.M.: The Failure of Radioiodine Therapy Presumably Owing to Hi viiedothyronine Production in a Patient with Severe Graves' Disease. Unpbblished. These observations prompted an analysis of data from those patients here had been triiodothyronine found in the serial chromatograms. At thag f 52 patients studied had triiodothyronine in the circulation early in bservation. Most of these were Graves' disease. which time 27 period of Most were classified asJhaving ore severe clinical manifestations of thyrotoxicosis and almost all displdyed a very apid conversion of iodide to thyroxine. Triicdothyronine was also found a case of oxic adenomatous goiter; in two patients there was a small functioning t of hyroid tissue after an almost total thyroidectomy had been performed; and[two euthyroid atients were treated for angina pectoris. ublication. enua, R.S., Dobyns, B.M., and Ninmer, A.: reated with Radioactive Iodine. J. Clin. ovember, 1955. These findings were sunmarized|in a Triiodothyronine in the Serum d f Patients Endocrinol. & Metab. iS: 1367-13478, Another cause for rapid decline of 1311 from the thyroid is the prese surces of 127] which will dilute the 111 when it is returned to the circ tudy of this phenomenon was carried out by the deliberate administration ases following the treatment dose. Contrary to expectation it did not alwhys produce 1e steep decline that was observed in some of the_patients who failed to spond. ibsequent. observations suggest that although the isly may be released the g apidly and diluted out of the circulation by an excess of 127, | the exces 127 Low the actual release of hormone from the gland in Graves' disease. The pver-all 2) ayroid. A high uptake followed by a very slow gradual decline of 1311 £ This was the natural disappearance curve that represents the biolpbgical imnoveor of iodine. This suggested that there was no disintegration of the] thyroid com thyroxine . that has been used by the peripheral tissues. In spite of Low type of disappearance curve, many thyrotoxic patients with this patt yer quite a number of months. A prompt dramatic clinical improvement, fol son after by hypothyroidism, was seldom seen following this curve. 3) A well sustained 131; level in the thyroid for 7 to 12 days foll creak in the curve and a sharp decline. This pattern in almost allinstanc o3rrelated with a fairly precipitous subsequent decline in thyroia function rial quantitative chromatograms in such cases suggested that the change i ? the curve represented a failure of the gland to retrap iodide. A varie isappearance curves are shown in Figure 6. Apparently following the breakfin the mve, 13812 was not recycled back into the thyroid. When this break in the ki irve was Clearly demonstrable, the incidence of myxedema was noticeably in 1ese observations and others were described in a publication. nua, R.S., and Dobyns, B.M.: Iodinated Campounds in the Serum, Disappear idioactive Iodine from the Thyroid, and Clinical Response in Patients Trea idioactive Iodine. J. Clin. Endocrinol. & Metab. 15: 118-130, January, 1