‘exclude that diagnosis. Nevertheless,the clinical evaluation required to establish a diagnosis is associated with its own morbidity. Prominent in this morbidity is thyroid surgeryitself, a procedure that requires general anesthesia and results in a cosmetic defect and the unavoidable removal of some normalthyroid tissue. C. Hypothyroidism, postsurgical: In 1972 to 1974 it was noted that 11 of 20 exposed persons from Rongelap who underwent surgery for removalof thyroid nodules had elevated levels of thyroid-stimulating hormone (TSH). Because this evidence of postsurgical hypofunction was morefrequent than expected it was surmised that thyroid insufficiency might be developing in the exposed Rongelap population as a whole, rather than being limited to the two hypothyroid children diagnosed some ten yearsearlier (Sutow et al., 1965). Such an event was likely to be clinically inapparent becauseall of that group had been placed on suppressive doses of thyroxin since 1965 to prevent thyroid neoplasia. Therefore, after temporarily discontinuing thyroxin, a survey of thyroid function was undertaken, and twelve persons were found to have biochemical evidence of thyroid insuffi- B. Thyroid hypofunction, radiation-induced: Overt hypothyroidism was diagnosed in two Rongelap boys who wereinfants at the time of exposure (Sutowet al., 1965). In addition, subclinical hypothyroidism unrelated to thyroid surgery was confirmed in twelve other Rongelap persons (Larsen et al., 1982). In 1987 a Utirik man was diagnosed as biochemically hypothyroid. He was two years of age at the time of exposure, and he is the first exposed person from Utirik to have this diagnosis. THYROID DISEASE vs. RADIATION DOSE 100 -— & gob ! | 2 [7] BENIGN NODULES S 80 [X) HYPOTHYROIDISM S 70 | - | 77 THYROID CANCERS 3 eb ] Z yZ = YN (IN YN Y, Y S 40+ = of - A Z :5LT a yWo 44~ N- AW W- = Y & YN ) 5S ak "» Ava Arm ZLAVA SL 1-250 251-500 501-1000 Y, VAY 1001-2000 YIN IN UY VIN TAS LR UN - ZN GIN A VANA PIAS 2001-3000 3001-4000 4001-5000 REM Fig. 5: TMGabsorbed radiation dose vs. benign thyroid nodules, carcinoma, and hypofunction. wt co oe ~ ren) cm 15