Table 7. Results of serum analyses in exposed Marshallese subjects with at least two TSH assays >6 W/ml (1980). Sub ject No. & sex Date of sample Serum TSH ( wu /m1) 3M 5M 4M 1977 1963 1972 1974 69 500 6.0 7.0 1979 6.5 16M 34F VIF 78F 32M 1969 1974 1979 1974 1977 1 1 38 1150 1150 335 0.89 39 135 2.5 0.5 7.3 5.4 0.95 0.7] -0.82 4.9 0.91 6.3 8.3 7.1 8.0 -0.74 45 335 27 335 6.1 0.82 37 335 3 1050 4.2 5.2 8.8 7.3 Normal control range: Estimated thyroid dose (rads) 4.4 6.6 1979 1980 Age at exposure 6.3 10 7 1977 / TBGI (units) Serum Ty, (ug/d1) 0-6.0 -0.98 7.6 5.1 0.68 0.89 5.0-10.2 0.85-1.10 observation of elevated 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 stimulation tests had been performed earlier. Both had Tyg increments of “1 Ug/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 patient 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 WU/ml, which is the 97.5% confidence interval for mean normal responses in the Marshallese. 40 £ *% a Z 20 74 734 uy < 4, . * 10 a BASAL AFTER TRH Figure 5. Basal plasma TSH and TRH- stimulated TSH in euthyroid Marshallese and in four exposed subjects with biochemical evidence of impaired thy. . roid function. . Plasma was obtained 20 min after infusion of 500 Ug TRH. The upper limits of the normal range are indicated by the shaded bars. -72-