Table 8. Results of retrospective analyses suggesting the presence of
thyroid dysfunction prior to surgery in certain exposed Marshallese (1980).
Date of
Sub ject
No
& sex
at
19M
serum
sample
22
1963
470
33F
74F
1972
83M"
C/m1)
1963
1963
1965
1966
69F
Serum TSH
1974
Normal control range:
Serum T
Est imated
thyroid dose
(units)
6.5
0.84
2
1100
1.4
0.64
4
1
1150
5.7
9.5
8.3
16.3
_
0-6.0
Age 2t
exposure
Ceg/add
6.9
8.2
22
6.7
TBGL
3.3
5-10.22
1.01
0.80
0.82
-—
0.98
(years)
(rads)
5
1000
1000
15
425
in utero
>175
0.85-1.10
*This infant's mother (No. 74) had an estimated thyroid dose of 425 rads.
Ie was of interest to measure TSH in frozen plasma samples obtained
years earlier to determine whether individuals might have had evidence of thy—
roid dysfunction prior to surgery. In many cases only one sample obtained
prior to surgery was available. The criterion used in these instances was
that serum TSH be >6 1J/ml on at least one occasion.
It was assumed, but not
proved, that TSH is relatively stable in plasma samples stored at -20°F for
prolonged periods. This conclusion was supported by resuits on subject No.
5, who had a serum TSH of 500 U/ml in a samp! obtained in 1963, but
obviously it is uncertain what that value would have been had this specimen
heen measured fresh.
Since all subjects were on T, therapy after 1963, it
should be assumed that these results might underestimate the prevalence of
presurgical hypothyroidism. In any case, six individuals exhibited biochemical evidence of mild to severe degree of hypothyroidism prior to surgery
(Table 8).
The most marked abnormality was observed in subject No. 69, in whom a
serum TSH of 470 wWU/ml was found in a sample obtained in 1963. This subject
had surgery performed in 1964.
Three individuals had modest elevations in
serum TSH, between 16 and 22 U/ml, and the remaining two had mild abnormal-
~
ities. Most but not all of these elevated serum TSH values were associated
with decreased serum tree-thyroxine indices, and all were in subjects exposed
at a young age, four receiving an estimated thyroid dose >1000 rads.
Receiving lower thyroid doses were No. 74, who was 15 at the time of expo ure,
and No. 83, who was in utero (gestational age v6 mc). These results appear to
be consistent with observation; in subjects No. 3 and 5.
In addition to the-results on the above 13 subjects in Tables 7 and 8,
which indicated primary thyroid dysfunction as a consequence of radiation
-73-
.