RAI question

My mom is getting ready for her RAI ablation following her TT in Oct 2012. She will be getting Thyrogen injections and my understanding was she would receive a tracer dose and scan to determine the therapy dose. I talked to a tech in the nuclear medicine department and she said since my mom will be using Thyrogen they don't do a tracer dose just a full therapy dose of 100 mil(?). She said her TSH won't stay raised long enough to do a tracer dose then a therapy dose. Does this sound correct? I have a call in to her endo to clarify.

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If your mom's doctor does not know what RAI ablation dose he wants, then he will order a tracer dose and whole body scan (WBS) prior to ablation to help him decide. If everything is scheduled appropriately it is possible to have two thyrogen injections then the WBS then the ablation but timing is critical. My protocol was done that way but many here have had to go through two sets of thyrogen injections because the timing could not be coordinated. She will also have a WBS about a week after ablation to be sure there was adequate uptake of the RAI. No additional thyrogen is given for this scan.

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The tracer dose is not necessary and can actually cause tissue stunning...just a treatment dose is needed, and the WBS about a week later will show where the uptake was.
I went hypo and still did not have a tracer dose, as per the ATA guidelines which recommend that it is only necessary if a dose really cannot be determined otherwise.

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Theresa, I have to do that tracer dose a week from friday after my 2 injections next mon and tues, pill wed then the scan fri.
They are telling me it is such a low dose I do not need to isolate myself. Is that frue for a tracer dose?
What kind of tissue stunning does a tracer do?
Now I am concerned....
He said my cancer was small enough he did not plan to to RAI but the thryroglobulin (sp) started climbing recently and the ultrasound shows activity in thyroid area.
TT was in May 2012... this is my first "scan"

Your input would be really appreciated!

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It is true that for a tracer dose isolation isn't needed- I've read advice to treat it as if you have a bad cold for 24 hours (avoid close contact w/ others).
A tracer dose can stun tissue for the uptake of subsequent RAI if given shortly thereafter but not within 72 hours - it sounds like your doctor is just trying to see what is going on, though, unless he has discussed doing a treatment dose after the tracer dose.

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thanks Theresa, yes he is trying

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My tracer dose was I 123. My WBS was done 48 hours later and my ablation dose of I 131 was administer several hours after my WBS. Stunning is not an issue if the timing is right and is also less of a concern if I 123 is used as the tracer dose.

My doctor was very uncertain as to whether or not I really needed RAI at all. My WBS done with just 1.5 miC of I 123 showed a cancerous medistinal lymph node. If your doctor has any doubts then a pre-RAI WBS is the way to go to gain very accurate information that will help determine what treatment is correct for you.

The ATA guidelines address the issue of stunning. I think they explain it very well.

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