3+
population. The findings also support the program
of thyroxine replacement in the exposed Rongelap
population to prevent both clinical hypothyroidism andtheassociatedrise in plasma TSH, which
may be tumorigenic.
wassignificantly lower (6.0== 1.8 wg/dl). Thefrequencydistribution calculations (see Table 29 and
Figure 39) indicate that a substantial portion of
the Utirik population has plasma Ty concentration <3 ywg/dl. Measurements of plasma tn-
4. Thyroid Function in the Utirik and
tions in those patients with low Ty values. Plasma
Unexposed Rongelap Groups
iodothyronine (not shown) showedsimilar reduc-
During the 1973 survey, Ts and TSH concen-
40
trations were measured in plasma from 109 unexposed Rongelap and 97 exposed Utirik subjects
T
e---a Utirik
Rongelap group, 7.7 ug/dl, was the sameas in
the United States, and, as in the United States,
the plasma T, concentrations were skewed to the
Group
109 Rongelap
unexposed
97 Utirik
exposed
Subjects
4
T
Subjects
Plasma T,,
ue/dl
with value
<5.0.
with value
>113
7.7420
6%
6%
6.0% 1.8*
32%**
6%
2.5
“Significantly different, p<(0.001.
5.0
Rongelap
TBG-binding
capacity
n
pg T,/dl
TBG (RIA)
elo
yd7 Uli
/My
40;
TBG capacity
———
1
1
Rongelap
aap!!
4
I
Exposed
12
All sera
All sera*
25
22
Curik
All sera
All sera*
22
22
Unexposed
mg/dl
12.5
lap unexposed groups having given thyroxinelevels, 1973.
Thyroxine-Binding Globulin (TBG) Levels
(Mean = 5.D.) in Serum, 1973
n
10.0
Figure 39. Percentages of people in Utirik and in Ronge-
Table 30
Group
7.5
Plasma thyroxine (#g/ 100 mi)
**6% had values <3.8.
TBG by RIA
t
oa
ow
Plasma Thyroxine Concentrations (Mean = S.D.)
in Utirik and Unexposed Rongelap Populations,
March 1973
1
30
% oftotal population
Table 29
!
@o—e Rongelap
March 1973
(see Table 29). The mean Ty, in the unexposed
upper range. In the Utirik group, the mean T,
T
13
1.45240.54
14
21.54 69
1.64+0.95
1.3440.45
25°
21
23.14115
191+ 62
1.40+0.42
1.40+0.42
31
27)
189+ 78
16.4 43
1.8241.22
110
25.315.7
*Omitting sera with TBG >3 or TBG-binding capacity
>30.
Statistical comparisons revealed no significant difference ( p>0.05) between anyof the groups.
0
1
2
3 4 5
mg/dl
O
10 0 30
ug T2/dl
40 30
Figure 40. Thyroxine-binding globulin levels
in serum and TBG-binding capacity, 1973.