1 the extent of the observations that had been made on +4+1-treated patienfs. Lthough percent uptake of the treatment dose, estimate of gland weight, and iecks of urinary excretion were often obtained, detailed data for better canding the kinetics of the 131; such as the long term sequential observatgons on shavior of 131z in the gland, the changing levels of radioactivity in the Hlood rtivity etc., were usually not available. Because neither the observationg nor the »thods of making the cbservations were uniform among the institutions, it >» Make comparisons based on fragmentary data between patients in different : therefore seemed desirable to try to discover patterns of response from complete ita on a few patients so that reasonable predictions could be made for misging data 1 otherwise similar patients on which only incomplete data were available. ‘tailed data which had been assembled in our laboratory over some years un this i contract (including the long term follow-up data) were drawn on rather vily it superficially in an effort to prepare models of kinetics in various clirfical lerapeutic Situations. Data on sequential blood levels of 1317, disap Sappearance of iodinated compounds in the circulation as they relate to tip e rates clinical ‘fect were furnished. However, time has not permitted their use. Altho eering committee has felt keenly that data where it might relate to kinetifks should : tested thoroughly where the data were available, there have not been ‘quainted with the problem nor funds available to explore this area of the udy. Dr. A. Bertrand Brill who was the USPHS physician and who originall tional study is now at Vanderbilt and particularly interested in this a tional study. To date direction of the national study has been toward le oplasm development. More will be said of this later. and e Disappearance of 131; from the Thyroid Following a Therapeutic Dose of 1B1T In general, there are three types of curves that describe the disa erapeutic dose of 131t from the thyroid: ance of a 1) A rapid decline of 131I from the gland. This is seen where very 1317 are given for the purpose of producing rapid complete destruction off ry soon after a large dose of 1317 was given (days) the giand was unable e 131I_iodide which became available from the degraded 1 1t_thyroxine in ter the loss of 181T is due to disintegration of the gland. e doses the thyroid. trap circulation Occasionally the loss of thyroid function did not follow such a precipitous cline in 131,, The serial quantitative chromatograms reveal that there occasional tients who make thyroid hormone very rapidly and release it into the ci tion so at much of the radiation effect is delivered in the circulation rather yroid. This was shown by the_very rapid disappearance of 131T from the g pearance of high levels of i3ly thyroxine circulating in the blood. in the and the There were other patients who showed a steep decline in thyroidal radigactivity t who did not show a favorable therapeutic response. In some of these sitjations eticular patient was actually found to be producing more triiodothyronine yeoxine. In this patient the serial chromatograms of urine also revealed qonsiderable sunts of triiodothyronine. It subsequently became clear that triiodothyrogine was t well bound to protein in the circulation and that considerable amounts of it spilled t through the kidney. Thus the opportunity for this 1317 to return to the Ithyroid 3 lost. The extreme example of this phenomenon was observed in a patient i therapeutic doses of I3lT (with a total of 26 quantitative chromato 2 hyperthyroidism was controlled.