# From another forum. Giving iodine before i131 ??????



## Want2FeelGood (Sep 17, 2011)

Found a good post in another forum. Here we are on low iodine diets and one day before we get that i131 dose, some of us get i123. But that adds iodine to our body. Does this decrease the effectiveness of the all important i131 ?

I read that many places don't do this i123 scan the day before the i131. The i131 dose is determined by "risk factors and ultrasound" so standard doses are given. If the i123 study is not needed to determine a proper dose, then why do it ? If some famous places do not do the scan a day before i131, there must be a good reason.

Anyone have educated thoughts on this ?


----------



## Andros (Aug 26, 2009)

Want2FeelGood said:


> Found a good post in another forum. Here we are on low iodine diets and one day before we get that i131 dose, some of us get i123. But that adds iodine to our body. Does this decrease the effectiveness of the all important i131 ?
> 
> I read that many places don't do this i123 scan the day before the i131. The i131 dose is determined by "risk factors and ultrasound" so standard doses are given. If the i123 study is not needed to determine a proper dose, then why do it ? If some famous places do not do the scan a day before i131, there must be a good reason.
> 
> Anyone have educated thoughts on this ?


I am of a mind to agree with you as you want a good uptake but I "think" it may also depend on how long the i123 would stay in the system also. You know; the half-life of it?

Very good question!


----------



## Want2FeelGood (Sep 17, 2011)

Andros said:


> I am of a mind to agree with you as you want a good uptake but I "think" it may also depend on how long the i123 would stay in the system also. You know; the half-life of it?
> 
> Very good question!


http://jnumedmtg.snmjournals.org/cgi/content/abstract/47/suppl_1/324P-a

http://www.medscape.com/viewarticle/407924_4

http://www.springerlink.com/content/j35417x34r741576/

http://www.springerlink.com/content/8j3221800h7447m2/

http://en.wikipedia.org/wiki/Iodine-123

http://ahmadnour.maktoobblog.com/1042400/i-131-ablation-for-thyroid-neoplasms/

‏Daily dietary iodine intake is maintained below 50 ug/day for 7-10 days prior to therapy [63]. Patients avoid seafood, salt, iodine containing medications, iodinated contrast medium, and dairy products. These measures will decrease the extracellular iodine pool and increase uptake of radioiodine by about 2.5 times


----------



## Want2FeelGood (Sep 17, 2011)

_Just want to stress that quote from the last reference: "Daily dietary iodine intake is maintained below 50 ug/day for 7-10 days prior to therapy [63]. Patients avoid seafood, salt, iodine containing medications, iodinated contrast medium, and dairy products. These measures will decrease the extracellular iodine pool and increase uptake of radioiodine by about 2.5 times"_

Have never heard such a figure of 2.5 times. If true, then why do some doctors not recommend a low iodine diet ?


----------



## Andros (Aug 26, 2009)

Want2FeelGood said:


> _Just want to stress that quote from the last reference: "Daily dietary iodine intake is maintained below 50 ug/day for 7-10 days prior to therapy [63]. Patients avoid seafood, salt, iodine containing medications, iodinated contrast medium, and dairy products. These measures will decrease the extracellular iodine pool and increase uptake of radioiodine by about 2.5 times"_
> 
> Have never heard such a figure of 2.5 times. If true, then why do some doctors not recommend a low iodine diet ?


Because they are not informed; that is the only reason I can think of.

Thanks for all the links and research! This is awesome!


----------



## Andros (Aug 26, 2009)

Want2FeelGood said:


> http://jnumedmtg.snmjournals.org/cgi/content/abstract/47/suppl_1/324P-a
> 
> http://www.medscape.com/viewarticle/407924_4
> 
> ...


Springerlink laid it out best. 3rd. one down. Thank you so much.


----------



## Want2FeelGood (Sep 17, 2011)

You're welcome. So is it appropriate to do a I123 scan, and does the I123 interfere with the success of I131 ?

And doesn't this quote seem unusual ? 2.5 times ??? "These measures will decrease the extracellular iodine pool and increase uptake of radioiodine by about 2.5 times"


----------

