ess (attributed to increased dictary bodine in hike)! Phe main purpose of the later study, haw. ever, Was losce whether the exposed individuals in the intermediate age group might be developing Uiyroid failure despite the absence of thyroid hocules: its resulis indicated no evidence for this. in 1974, as deseribed below. how showing evidenee of redaccd fume tian oa the 3. Thyroid Status of Exposed Rongelap People Without Apparent Thyroid Lesions (awever, as discussed below, some exposed Kane uclop people without lived abnoraialies are basis of response ta PSE stinmulatien.) Kadivitauatmcassays CLA) for Ty and TSH have been carted out sipee 1972 on the exposed Rongelap croup and on other people who have had thyroid surgery. Phe results on subjoets with knows thyroid lesiqus ace presented in Table 27, OH the 2 subjects tested. 17 of 3.50 Tad at lease ane VST Jevel above the upper limits of norinal (these are in bobdfiace a Pable 27). Vhese findings Hidieate thatthe residual thyroid tissue is inadequate tosustula cothseeddism in Uhese cases and abo aefleet inadequate adherence te the pres wtibed Vy replacement regimen. Liadeqiuaate VP, replacement is apparently a chrome problern for corttin patients (Nas. 3, 24, 45.605. and 721, Elevilions of plastia PSE) have been abser ed alse Ina huimber of exposed peaple without known Hivcoid lesions (the USED Conceutration wits D> 10 RU aaboaly a subyects Now Tb and 7a = sco Table Void Appeadis ty. Presatiibly these subjects, aswell as several others with plasma US Hl con contrition 225 but Ob oml (Nos. 4.16, 34, Voda Fe. re et recaraigg the Py therapy ms reguiarly as hod been boped. Ta dhe Rongelap comtiel group plasma Py comecutrations were dee feremined i TOG suibajeets. Tn those with Py <5 peg/ Gp O° al thiose tested) UST] was determined: ae elevated fovels were found: (datas net shown), Only PotOO Utirik sabjeets tested bias bad ins clevated seraia UStt devel (Ne. 22825. These notinal tindings in the unexposed and Uiirtk groups suggest thatin the inradiated Ron. gelip grogp there is dapatced thyroid function Withow! palpable lesions which could became sviiptoniiiie ithe farare. Vhe test results prob. In preparation for TSU) testing of reserve thyroid function, prophylactic Vy tiedication wass dis- continued for 2 months before the 17d survey in all exposed subjects without recagnieed lesions, During the survey, plasiia samples were obtained before and 24 he after intramuscular injecion of 10 unis of bavine (PSE (Thyrotropar, Armour, Both sets were analyaed for Ty and the first set also for TSED Vhe results, and thyeroxine- binding Wlobulin-bindinig capacities CP BG-binding capaci lies) insame cases, are given in Table 28. The mean increment in plasma Py followiig VSPb was 2.35 = L2 pg dl Qniean 2 SD). Phe mean Ty prior to VSD D injection was 6.02 0.7 yeu di. Similar teste on 1d subjects atthe University of Piteburgh showed a mean increment in plisma Vy of 4.7 Lage db and a baseline plasma Ty of 7yg dl which is not significantly different from cia ofthe exposed Rongelap group being tested. Thus, the Ty response to USL is significantly less (<< 0.001) iW this wreaup af 26 expescd Rougebip subjeets than inthe group of Ls subjects frome the United States. Secauec ab the possebility Chat che sanaller aver: ment in plasawa Py 2b he afier Psi in the exposed subjects was duc to factors other thaa deercased thyroidal reserve. TSED stinvularion tests were done on LO cuthvraid uaesposed Rongelap and Ciiik people during a subsequent survey. Vhe near initial plasuaa Ty in this group was 0s 1.7 fe dis and the mean increment 2b he after PS yccuor was 42 bya dll. significantiv greater (P<COL0KE) than in the exposed subjects. These results and the finding of clowated phasis TST} levels suuaest that there is underlying, ¢lini- af impaired thyroid function, since presumably cally dhapparent thyroid damage i the ox pased Rongclap population, While itis conceivable that the “Vy replacement prograa may have led to de- directed. Te shold be noted thatitis the peesanal need for continued close follow-up of the es posed ably least te underestimation of the true incidence Hoan of the paticuts are taking Ube medication as creased thyroid resceve, the test results indicate a pee ee ee Ai tates ee TRRSG t «Puy ee guvwras creasing thyroid iodine uptake as du North Aimere experience of many of the thyroidologists involved in this studythat it is extremely difficult ta make a clinical diagnosis of hypothbyraidism in this population. This difficulty emphasizes the iinportance of the plasma TSE! measurement, which is now recognized as the most sensitive indicator af primary thyroid dysfunction. Vhe status of thyroid function in expascd people without apparent divs roidlesions was further tested with exogenous PSI aenen who had been exposed at age 10 to 20 years, gave results sainilar te (hose obtained in bbs. Thus the Rongclapese do not showa trend toward de- ae Be at 3