Radioactive iodine given for chest scan - can this damage my thyroid?

I am hypo-thyroid, Hashimoto's. I just had to have a chest CAT ? Scan in which they injected radioactive iodine into my blood. I was advised it can give you strange sensations and I felt it in my thyroid area as well as elsewhere. I'm a bit concerned now as I see that Radioactive iodine treatment is used to kill off over-active thyroid. Does anyone have any info on this? Is the dose for CAT scan minimal? :-(

Thanks :-)

12 Replies

  • Sue_b, the trace amount of radioactive iodine injected for the CAT scan won't damage your thyroid. Quite high doses of radioactive iodine are required to ablate the thyroid gland and are delivered in a capsule, not by injection.

  • Thanks Clutter, I was beginning to freak out a bit <3

  • Sue I have had quite a few CT scans with contrast solution over the last 2 years & as far as I am aware the contrast is a nonradioactive iodine. Each time the sensation starts in my ears & works its way down to neck, chest, stomach then a feeling of passing urine although you are not passing urine it is just a sensation. I have always had everything explained so I know what to expect.

  • Contrast agents are just that - they enhance the contrast of tissues in the images produced. No reason whatsoever for them to be radio-active.

    There are various radio-active substances used in some imaging and tracing processes, but they use the emissions of that radio-active substance - not X-rays.

    Further, there are two forms of radio-active iodine used in medicine:

    Iodine-123 (half-life 13 hours) for imaging the thyroid gland

    Iodine-131 (half-life 8 days) for destroying (wholly or partially) the thyroid gland

  • Hi helvella

    mine was to look at my lungs, same stuff I guess.


  • Hi Dusty2, yes, that is what they told me I would experience.

    thanks :-)

  • Js iodine better then that other crap they flush into your body

  • When I told the consultant that was doing the CT scan of my heart of my concerns re my thyroid he said that as I had active Graves it would be advisable not to have the injection.

    This has come up before and I commented then and also put a link to the information.

    I know in this case with Hashimoto it may be different but I'm a bit surprised by some of the replies on this site sometimes!

  • OOh, Silver_Fairy,

    so best to tell them about the Hashi's then. I'll bear what you say in mind, thank you :-)

  • Hi - I have long-standing undiagnosed and pretty much untreated hypothyroid for several years and look and feel like death. Last year, I was referred onward from an NHS Endo (more a diabetes specialist, which is one thing that - I think - I don't have) to a Resp. Consultant due to increasing shortness of breath (this was last summer, and I am even worse now....); the latter requested a CT scan with contrast to show up the vessels that couldn't be seen by the "clear" X-ray (same day). The Technician did, as mentioned above, warn me about sensation as the contrast passes through very quickly - and indeed it was very strange and focused most definitely and immediately in the area of the thyroid - anyway, this is my long-winded way of letting you know that it did have a rather negative effect on me - and studies have been done into adverse reactions for those with thyroid troubles. Of course, when you feel like c**p anyway, it might not really be noticeable but, in my case (and I am sure everyone responds differently) it seemed to make me feel a whole lot worse...... :o(

    (I blame myself, as I had not researched the procedure but then it was all done at the one and only appointment, so I had no time. Oh -and the "diagnosis"? DEPRESSION --------- of course).


  • Blimey, blame yourself??? I don't think so and as you say, how were you supposed to prepare for a day full of surprises ? We all know that alongside thyroid dysfunction comes depression/anxiety and we all know that GP's seem incapable of ruling out a physical cause for depression before they recommend anti-depressants.

    As all the wonderful admin on here would say, post your blood test results if you have some. If you haven't got them ask your GP for them, they can't refuse. Someone may be be to point you towards some information that will enable you to find a way of helping yourself.

    all the very best :-)


  • Thank you Sue :o)

    I do think - based on some reports that were linked to me when I questioned it on here last year - and on the basis of my experience, that you they should really be made aware of your condition. I refuse to believe that it has zero effect on the thyroid - which is anyway sensitive to radio-activity and in general is the engine of the body; how can it not I wonder? :o/

    I do and have posted on here with results and have had lots and lots of help, support and wisdom imparted to me for which I am so thankful :o) I do read so much that I become utterly confused and end up in the grip of some weird inertia, not knowing what do, afraid that I will suffer every ill-effect that everyone else does..... The problem for me now is that I am sinking so fast that I can hardly make sense of things anymore.

    I may of course have been unique in feeling as bad as I did - or - I guess it could all have been "in my head" *sigh* - and there could be no harmful effects for you; I certainly hope so. And of course, that they get something useful from the scan for it's intended purpose.... I know that the Hippocratic oath states to "First do no harm...." but I wonder if that really applies with the treatments and investigations that cause as many, or more, problems than they solve.



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