at Table 7. Results of serum analyses in exposed Marshallese subjects with at least two TSH assays >6 \/ml (1980). Age at exposure Est imated thyroid dose (rads) 0.95 0.71 — 1 1 38 1150 1150 335 0.89 0.91 39 135 _ 45 335 _ 27 335 37 335 3 1050 Subject No. & sex Date of sample Serum TSH (10/m1) Serum Ty, Cg/d1) 3M 5M 4M 1977 1963 1972 69 500 6.0 2.5 0.5 7.3 16M 1969 1979 6.3 6.5 4.4 4.9 1979 8.3 8.0 0.74 5.2 6.1 7.6 5.1 0.98 0.82 0.68 0.89 34F 7iF 78F 32M 1974 7.0 1974 6.3 1974 10 1977 1977 1979 1980 7 6.6 8.8 7.3 Normal control range: 0-6.0 5.4 7.1 4.2 5.0-10.2 TBGI (units) 0.82 0.85-1.10 observation of elcvated TSH in the individuals Listed in Table 7 cannot be attributed to age alone. No. 4 and No. 78 were among those in whom TSH stimu- lation tests had been performed earlier. Both had Tyg increments of “1 Hg/dl 24 hours following 10 units TSH administration, a clearly subnormal response showing that these thyroids had no capacity to respond to increased demand. To evaluate the pituitary/thyroid axis more completely, TRH studies were done in some individuals. Results on subjects No. 4, 71, and 78 are given in Figure 5. Data from subject No. 74, discussed below, are also shown. ‘This pa~tient had surgery subsequent to the test and is therefore categorized separately (Table 8). Subjects No. 4, 71, and 78 all were hyperresponsive to TRH stimulation, with serum TSH values at 20 min >22 W/ml, which is the 97.52 con- fidence interval for mean normal responses in the Marshallese. . "| , * 40 5 = en g 20 < ret Inq ,, * 10 o & BASAL AFTER Figure 5. Basal plasma TSH and TRH- stimulated TSH in euthyroid Marshallese and in four exposed subjects with biochemical evidence of impaired thyroid function. Plasma was obtained 20 min after infusion of 500 | TRH. The upper limits of the normal range are indicated by the shaded bars. TRH -72-