30 thyroid lesions 1s more recent, has not been on treatment long enough for evaluatton. The in utero case was not placed on thyroxine treatment until after nodules had been detected. Thyroid lesions developed in several persons who were presumably taking their thyroid medication regularly and who appeared to be euthyroid with normal thyroxinelevels: on the other hand, thyroid nod- ules disappeared in two cases (Nos. 53 and 40) during thyroxine treatment(in the latter case, they recurred and were surgically removed). 1. Follow-up Careful follow-up studies on the subjects who had cancer, including whole-body scansat Tripler Army Medical Center, have shown nosignsofrecurrence. No clear-cut evidence has been seen of further development of nodularities in the thyroid remnants in the benign cases. Because papillary thyroid carcinoma progresses very slowly, long continued follow-up observation is necessary. No deaths or acute illnesses have been associated with the thyroid abnormalities. Morbidity has been related to the development of reduced thyroid function resulting in varying degrees of hypothyroidism and in one case of hypoparathyroidism following thyroidectomy. The lack of strict compliance with the thyroid treatment program in the operated cases involves the potential danger that serious hypothyroidism may develop,particularly in patients living on the outer islands and therefore less frequently seen. roid function has been greatly improved bythe use of radioimmunoassay techniques for measuring T4, T3 (triiodothyronine), and TSH.88.89 Studies of serum iodoproteins, which had resulted in artifactual elevations in the serum PBI in the Nlarshallese, are discussed below, as are more re- cent measurementsof thyroxine-binding proteins and serum thyroglobulin. Studies of thyroid function havealso included tests of radioiodine uptake and excretion on several occasions. In the field these were done with a somewhat primitive apparatus (Figure 38). 132] was used to minimize the dose to the thyroid. More extensive and sophisticated tests were done on patients brought to BNL for evaluation pnorto surgery elsewhere. These included tests of thyroid radioiodine uptake and scans (technetium-99m) before and after TSH stimulation; determination of basal metabolism rate, cholesterol, antithyro- globulin antibody levels; and a variety of clinical chemistry tests. In a number of cases a small amountof !3!I was administered prior to surgery and the function of excised thyroid lesions and surrounding tissues was studied by autoradiography. One 48-year-old man (No. 40) briefly developed acute thyroiditis after TSH administration. 2. Studies of Exposed Rongelap People With Thyroid Abnormalities Evidenceof thyroid hypofunction and reduced reserve wasseen in a fewof the children prior to surgery (Nos. 2, 20, 33, and 65) and to a greater degree in the two boys who developed myxedema E. STUDIES OF THYROID FUNCTION* 1. Procedures Measurementof circulating thyroid hormone has been an importantpart of the evaluation of thyroid function in these surveys. Duringthefirst 10 years it was done by PBI analysis and subsequently by ion-exchange chromatography(thyroxine by column). Since 1972 evaluationof thy*Thyroid uptake studies were done at Rongelap in 1965 and 1971 by Dr. J.E. Rall and in 1966 and 1972 by Dr. J. Robbins. At BNL thyroid function studies were done by Dr. H.L. Atkins. PBI determinations were madeby the Clinical Chemistry Section at BNL and byBio Science Laboratories, Van Nuys, Calif., who also did other serum iodine analyses. T, and T; by RIA, and dia- lyzable Ty, TSH, and TBG by reverse-flow electrophoresis were analyzed by Dr. P.R. Larsen at the University of Pittsburgh and more recently at the Peter Bent Brigham Hospital, Boston. TGB anatysis by RIA was done by Drs. M. Gershengorn and J. Robbins, and TG analysis by Drs. M. [zuma and J.-L. Baulieu. Figure 38. Thyroid function testing underfield conditions, 1966.