Re: I-131 Thyroid Uptake

[Charles Willis <caw@nrc.gov>]

Mike,

According to ICRP-30, the uptake of the thyroid from the blood is 30 percent. That is true in the regulatory world but biology is more complex.  I do not know of any good data on the question and one of my graduate students is planning to collect and make available what data he can obtain from records from nuclear medicine facilities.  We do know that the thyroid uptake is a function of the amount of stable iodine already in the person's body.  We also know that  thyroid blockage can be up to about 95 percent effective.  Of course there are individuals without thyroids, just as there are individuals with iodine-starved thyroids, so the possible uptake range is quite large.  We know that Americans consume far more stable iodine than the did before the days of fast food hamburgers and iodized salt, but we do not know  just what difference it has made.

Charlie Willis
caw@nrc.gov
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
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