+0) adult a nodule could not be palpated 6 months after treatment was begun. In September 196b, thyroid examinations showed that 4 children with nodules (Nos. 19, 36, 54, and 72) noted previously NECK UPTAKE (%)} had evidence of slight regression of the nodules, and it was decided to re-evaluate their cases in March 1967, after another 6 months of therapy. mAOURS Figure 30> Neck accumulation of © -[in subjects with thyroid abnormality. Values are gross neck counts as‘ of dose, uncorrected for blood background following oral administranon of ''-1 Computer analysis of these data indicates that 7% of the excrathvroidal iodide pool is “seen” by the neck counter Atcthe vertical lines, 300 mg ACIO, was given ov mouth ~, Subject No 54 @, subject No 2 partial thyroidectomy), _, subject No. 65, @. subject No 9. , subject No. 3: a, subject No. 69 (partial thyroidectomy } and 20) had little or no response to TSH. The other patients had apparently normal thyroid ac- cumulation rates, and several (Nos. 33, +2, 59, 61, 6+, and 65) responded to TSH. Urine excretion rates were variable and, in some instances, very low, probably because of incomplete urine collection. Following TSH, in manyinstances the urine excretion rate was lower than the control. The reason for this is unknown. The theuretical thyroid fraction following TSH was sometimes elevated despite a fall in thyroid accumulation rate because of a relatively greater fall in urine excretion rate. Incomplete urine collection probably accounts for the very high thyroid fraction in some cases. The thyroid accumulation rate, on the other hand, ts relatively unaffected by inaccurate urine collection. From the data in Tables 20 and 21 it is evident that several of the children who developed thyroid nodules but were not clinically hypothyroid had evidence thai their thyroid glands were stimulated by elevated endogenous TSH production, and two of these children were unable t. respond further to exogenous TSH. Results of Thyroid Hormone Therapy Although it is too soon to evaluate completely the results of thvroid hormone treatment, there are definite indications of beneficial effects. In one The curves for stature and bone age before and after thyroid hormone administration, plotted for the two most retarded boys (Nos. 3 and 5) in Figure 31, show a definite spurt in growth subsequent to treatment. This acceleration is very prominent for bone development in subject No. 3. Figure 324 shows the remarkable change In appearance ol No. * after thyroid hormone therapy for 6 months. F.guve 32B shows the improvement in bone maturauon in wrist bones of No. 3 after 1 vear of therapy ~ compare with Figure 28. These findings indicate that the growth retardation noted among the boys was attributable to functional hypothy- roidism. Supporting this assumption is the appearance of epiphyseal dysgenesis in one of these children. Figure 29 showsthis dysgenesis in the heads of the humen. Until 1965, the serum proteinbound iodine (PBI) determinations had yielded results in the euthyroid range. It is possible, however, that the PBI levels actually represented disproportionately high amounts of physiologically inactive serum lodoprotein and inadequate amounts of active hormone. The forthcomingsurvey in 1967 will be important in 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 beginning 9 vears after fallout is consistent with the known etiological relauionship of irradiation of the thyroid gland with the development ot such abnormalities. Though the exact mechanism involved in the pathogenesis of such lesions is not clear, itis known that adenomas and cancers of the thyroid gland can be produced in laboratory animals bya variety of agents or regimens which interfere with the ability of the gland to synthesize thyroid hormone. Both benign and malignant neoplasms have been shownto be produced byiodine deficiency,'' agents that chemically inhibit thvroxine synthesis such as thiouracil,'” '' x irradiation of the gland, “** and irradiation of the gland with ''T.' *" Furthermore, subtotal thvyroid-