Female control values are significantly lower (confirmed by others).
Experinentral
~~ al
Liked o ?
animals whose thyroids had been meticulously removed or deliberately destroyed with
131; ranged as high as 3,500 ng/mg.
A series or about 300 surviving radiated male rats of one exper nment were sacrificed 14 to 16 months after a range of small doses of i Sly.
As per routine, all animals
were individually identified and all data was collected including th e rad dose of 1 31,
originally received by the thyroid.
direct heart puncture.
laboratory.
The animals were anesthetized é nd exsanguinated by
The serum was frozen until the IRA was full) operational’ in our
Information was subsequently assembled regarding the pi resence of micro-
scopic neoplasms in each thyroid.
The results of TSH assays among
hose animals that
had developed neoplasms and those that had no neoplasms are the bas ls for a report in
manuscript form.
neoplasms.
The levels of TSH in general were higher among
1s which developed
The incidence of neoplasms in this series was 79.7%.
elevation in serum
TSH was often found in rats whose thyroids had been irradiated wit
131, and also had
become the site of one or more growing neoplasms.
er, numerous in-
There were, how
stances of neoplasms having developed without accompanying elevati
of TSH.
From this
Study it may be concluded that both elevation in TSH and neoplasm
mation results
from irradiation but may not have a cause and effect relationship.
TSH elevation was
not often found until the rad dose received by the thyroid was 3,0§0 rads or more.
Thyroid neoplasms were, however, readily produced by doses between 1,500 and 2,000
rads.
As a preliminary conclusion, it may be said that 131 I radia’ lion in the thyroid
May result in a rise in TSH and may also initiate changes that res
t in neoplas™
formation but it cannot be:assumed that the rise in TSH resulting fran irradiation
initiates neoplasms.
On the other hand, once a neoplasm is initia red, TSH may be a
growth promoting factor.
Another group of 450 female rats were given small doses of Ly
The details of
preparation and observations on these animals followed the plan pr eViously used.