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I-131 vs I-123 for thyroid uptake scan

I have been recently diagnosed with hyperthyroid and am set to have a thyroid uptake scan.  The radiology department uses I-131 as the tracer for the scan.  My question:  Is I-131 more dangerous than I-123?  From what I've read, most people get scanned (RAIU) with I-123 and treated (RAI) with I-131, because the I-123 has less radioactivity.   Obviously I want the least exposure with this test and I'm wondering if I should schedule somewhere else to get the scan with I-123 as opposed to the I-131.
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Avatar universal
Thanks you very much for the information.  
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Avatar universal
For future reference of anyone reading this -

You can use I-131 or I-123 for uptake.  The uptake AND scan can be done with I-123.  Each department/radiologist prefer different methods.

If an uptake and scan is ordered and the department uses I-131 for the uptake, the scan will be performed with technetium.  As a nuclear tech for the past 8 years, I prefer the images of technetium and the uptake with I-131.  

I-123 imaging takes much longer, lower resolution, and can miss smaller hot nodules if you have multinodular goiter, etc.  However, I-123 is typically the new standard due to relatively lower overall radiation dose to the patient.  
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1425146 tn?1282761884
There is a great article from the ATA regarding exactly this issue from this week, October 20, 2010 :

http://www.thyroid.org/patients/ct/ct_patients_v39.pdf

I hope this provides some clear, advanced, and upbeat news for you considering radiation therapy in addition to totals for microscopic or early detected cancers.

The only bad news, just as we know, the NUMBERS of cancers are growing almost at an out of control pace. But that's another job.

Best
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Avatar universal
No I have no eye problems and have been checked for TED (thyroid eye disease) with an Opthamologist every year.
All Negative.
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393685 tn?1425812522
We all no that communication errors happen and when it depends on your health and future I am a firm believer in the saying, "Better safe that sorry."

What happened to you does seem odd. Even if the I-131 as they say - given in a "scan" dosage is true. For me - that does not make sense at all.

It doesn't sound like the symptoms of Graves is rearing in you at this time to be forced to make a quick decision. Graves needs to be taken serious - but I think getting a review of information could be helpful here at the next appointment.

It would be good to for you to understand the "express thyroid 101" before this appointment.

Make sure you have the free tests. Not just the FT4 - but also the FT3. It must be done.
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Avatar universal
Thanks for all the posts.  Here is some more info on my situation.  My TSH= 0.1 and FT4=2.7 (0.8-1.8), so my family physician sent me to the endocrinologist.  The endocrinologist drew for thyroid antibodies and told me to schedule an iodine uptake scan.  He then wanted me to come back in 2 wks to go over the results of the blood test and the scan to decide treatment.  

When I called to schedule the scan the scheduler said the order the doctor put in the computer was for I-131??  I told her that the order should just be for the scan (I-123).  She said it IS for the scan.  I asked why she said I-131 because that is for RAI ablation.  She said its just the scan.  I was a little nervous after that because I was imagining going in thinking I'm getting a scan, and then they ablate my thyroid!  I asked if I could talk to radiology and they said they use I-131 and Technitium? for the scan, but it is only a small amount and is not for the ablation treatment, just for the scan.  

I go back tomorrow for the appt with the endocrinologist to get my blood results.  I did NOT end up doing the scan after all that confusion.  I'm thinking the scan may not be necessary if the my Thyroid Stimulating AB titer is positive, right?

Smilerdeb- I am glad the RAI worked for you.   Did you have any eye problems after RAI?
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Avatar universal
Basically each person is different......and a TSI test should be run to rule out Graves Disease.
Hyperthyroidism can be managed by ATDS and the person can control the hyperthyroidism but if Graves Disease antibodies are there, it is much harder to control the antibodies that attack the thyroid causing hyperthyroidism.

I have always stated that NEVER rush into anything permanant unless there is no other solution.
As for me...2 1/2 years Post RAI.....I have never ever regretted having RAI. There has never been ONE DAY that I have regretted it.
But that is ME...others may feel different.
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Avatar universal
Some people have no choice when they have Graves and Thyca.......as for RAI, it saved my life.
Sometimes Hyperthyroidism is present without Graves Disease but it is also worth noting that long term use of anti-thyroid meds can cause Liver damage.
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1425146 tn?1282761884
There's a great article on this weeks ATA newsletter about this you may want to review:

http://www.endocrinetoday.com/view.aspx?rid=70416

Keep asking questions and Good Luck!
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Avatar universal
The most important question is...have you had a TSI test done for Graves Disease?
And I wouldnt let anyone do anything permanant until I knew the answer to that one.

The hyperthyroidism may be treatable with anti-thyroid medications if Graves is not involved.

I had I-123 used for an uptake scan and would not have I-131 used for RAIU (radioactive iodine uptake).
Are you sure your not being sent for RAI  (permanent abaltion).
I have never known a Nuclear Dept. to use !-131 for an uptake scan.

I think you have a few questions to ask and I wouldnt go ahead with anything until you know the answers.
Maybe a visit to the Nuclear Dept. is in order.
With !-131 they have to order it in....they dont have to with !-123.

Hope that clarifies things a bit better.
Let us know how you go :o)
Helpful - 0
1425146 tn?1282761884
Have you had a simple sonogram/ultrasound yet?

What reasons for the hyperthyroid diagnosis were you given.

Do you have blood test results?

What symptoms did you present when you went for the diagnosis?

Sorry for all the questions, I am at odds with an uptake scan before simpler tests are fully conducted, sometimes on a multiple basis.
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393685 tn?1425812522
actually the I-123 will be used to do the uptake scan.. the I-131 will ablate the gland if the hyper warrants that.
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