54
population. Thefindings also support the program
of thyroxine replacementin the exposed Rongelap
population to prevent both clinical hypothyroidism and the associatedrise in plasma TSH, which
was significantly lower (6.04 1.8 ug/dl). The frequencydistribution calculations (see Table 29 and
Figure 39) indicate that a substantial portion of
the Utirik population has plasma T, concentra-
4. Thyroid Function in the Utirik and
iodothvronine (not shown) showedsimilar reductions in those patients with low Ty values. Plasma.
may be tumorigenic.
Unexposed Rongelap Groups
tion <3 pg/dl. Measurements of plasma tri-
During the 1973 survey, T4 and TSH concentrations were measuredin plasma from [09 unexposed Rongelap and 97 exposed Utirik subjects
40
a---e Utirik
March 1973
Rongelap group, 7.7 ug/dl, was the sameas in
the United States, and, as in the United States,
in Utirik and Unexposed Rongelap Populations,
March 1973
Plasma Ts,
Group
ug/dl
109 Rongelap
unexposed
97 Utirik
exposed
Subjects
tw
S
Plasma Thyroxine Concentrations (Mean + S.D.)
30
% oftotal population
Tabie 29
Subjects
with value
with value
<5.0.
1L0e
>I1ES
7,742.0
6%
6%
6.0 1.8*
32%**
6%
25
*Significantly different, p<.0.001.
**6% had values <3.8.
Thyroxine-Binding Globulin (TBG) Levels
Rongelap
Exposed
Unexposed
All sera
All sera*
Uurik
All sera
All sera*
75
TBG (RIA)
(Mean = S.D.) tn Serum, 1973
Group
5.0
10.0
Plasma thyroxine (ug/100 ml}
12.5
Figure 39. Percentages of people in Utirik and in Rongelap unexposed groups having given thyroxinelevels, 1973.
Table 30
TBG by RIA
T
e——e Rongelap
(see Table 29). The mean Ty; in the unexposed
the plasma T4 concentrations were skewedto the
upper range. In the Utirik group, the mean Ty
T
TBG capacity
—
TBG-binding
capacity
n
mg/dl
n
ug T,/dl
12
13
29
22
1.45+0.54
1.82+1.22
1.64+0.95
1,340.45
14
1100
25
2b
215+ 69
25.32015.7
23.b4115
19.1> 6.2
22
22
1.4020.42
1.40+0.42
31
27)
189+ 78
16.44% 43
*Omitting sera with TBG >3 or TBG-binding capacity
> 30.
Statistical comparisons revealed no significant difference (p>>0.05) between any of the groups.
45+
q
i
!
i
i
|
I
0
1
2
3 4 5
mg/dl
O
10 20 30
pg T?/dl
/
40 30
Figure 40. Thyroxine-bindingglobulin levels
in serum and TBG-binding capacity, 1973.