40 T T T T T 20+ KCI Og ‘ ooo) ¥ + 1 a L . x a coke , 4 _— &> 10h r % 7 l~-g—a Sf z J an e ~ age A . L l 2 4 a 4 | 6 HOURS Figure 30. Neck accumulation of ‘*?I in subjects with thyroid abnormality. Values are gross neck counts as % of dose, uncorrected for blood backgroundfollowing oral ad- ministration of '*71. Computer analysis of these data indicates that 7% of the extrathyroidal iodide poo!is “seen”’ by the neck counter. At the vertical lines, 500 mg KCIO, was given by mouth. a, Subject No. 54; m, subject No. 2 (partial thyroidectomy); 0, subject No. 65; @, subject No. 3; 0, subject No. 3; a, subject No. 69 (partial thyroidectomy). and 20) hadlittle or no response to TSH. The other patients had apparently normal thyroid accumulation rates, and several (Nos. 33, 42, 59, 61, 64+, and 65) responded to TSH. Urine excretion ——s rates were variable and, in someinstances, very low, probably because of incomplete urine collection. Following TSH,in manyinstances the urine excretion rate was lower than the control. Thereason for this is unknown. The theoretical thyroid fraction following TSH was sometimeselevated despite a fall in thyroid accumulation rate because of a relatively greaterfall in urine excretion rate. Incomplete urine collection probably accounts for the very high thyroid fraction in some cases. The thyroid accumulationrate, on the other hand,is relatively unaffected by inaccurate urinecollection. From the data in Tables 20 and 21 it is evident that several of the children who developed thyroid nodules but werenotclinically hypothyroid had evidence that their thyroid glands were stimulated by elevated endogenous TSH production, and two of these children were unable to respond further to exogenous TSH. Results of Thyroid Hormone Therapy Althoughit is too soon to evaluate completely the results of thyroid hormonetreatment, there are definite indications of beneficial effects. In one adult a nodule could not be palpated 6 months after treatment was begun. In September 1966, thyroid examinations showedthat 4 children with nodules (Nos. 19, 36, 54, and 72) noted previously had evidenceofslight regression of the nodules, and it was decidedto re-evaluate their cases in March 1967, after another 6 monthsof therapy. The curves for stature and boneage before and after thyroid hormone administration, plotted for the two most retarded boys (Nos. 3 and 5) in Fig- ure 31, show a definite spurt in growth subsequent to treatment. This acceleration is very prominent for bone developmentin subject No. 3. Figure 324 shows the remarkable change in appearance of No. 3 after thyroid hormone therapy for 6 months. Figure 32B shows the improvementin bone maturation in wrist bones of No. 3 after | year of ther- apy - compare with Figure 28. These findings indicate that the growth retardation noted among the boys was attributable to functional hypothyroidism. Supporting this assumption is the appearance of epiphyseal dysgenesis in one ofthese children. Figure 29 showsthis dysgenesis in the heads of the humeri. Until 1965, the serum proteinboundiodine (PBI) determinations had yielded results in the euthyroid range. It is possible, however, that the PBI levels actually represented dis- proportionately high amounts of physiologically inactive serum iodoprotein and inadequate amounts of active hormone. Theforthcomingsurveyin 1967 will be importantin assessing further growth stimulation from thyroid hormone treatment. Discussion of Thyroid Findings The development of abnormalities of the thyroid glands in the exposed Marshallese people be- ginning9 years after fallout is consistent with the known etiological relationship ofirradiation of the thyroid gland with the developmentof such ab- normalities. Though the exact mechanism involved in the pathogenesis of such lesions is not clear, it is known that adenomasand cancers of _ the thyroid gland can be produced in laboratory animais by a variety of agents or regimens which interfere with the ability of the gland to synthesize thyroid hormone. Both benign and malignant neo- plasms have been shown to be produced byiodine deficiency,** agents that chemically inhibit thyroxine synthesis such as thiouracil,*°~** x irradiation of the gland, °°** and irradiation of the gland with '3'T.°3-°> Furthermore, subtotal thyroid-