Issues that I am trying to understand… Some of the following is fact and some is me trying to put the pieces together. Do not take this is run with it. I am hoping that there will be some discussion that will help me understand.
I am just starting to understand rT3. There are caused to be considered and addressed. But when rT3 is elevated, there is too much T4–>rT3. The short term solution is to reduce or eliminate T4 if using thyroid meds and go with T3 meds only. This will lower rT3. While that is going on, one can address adrenal and other issues.
There is a concern that iodine will lead to higher T4 levels for a few that will reduce the effect of the above strategy. For those who are not thyroid med dependent, they are still making their own hormones.
Someone who makes enough of their own T4 who has elevated rT3 does not have the option of stopping a T4 med. If they take T3, they may feel some relief, but T4–>rT3 will continue. I do not know how one would address that. This is where the ?speculation? that high dietary intake of iodine might be counter productive.
Can one reduce dietary intake of iodine? Yes, but perhaps not to any advantage. If the TSH-T4 axis is otherwise functioning well, TSH will increase to maintain T4 levels even if iodine intake is reduced.
In theory, larger amounts of iodine that might increase T4 would cause the TSH-T4 axis to reduce TSH and that would reduce T4 gains. There are some that imply that there can be open loop production of T4 that increases with more iodine. However, that sounds like a degree of hypothyroidism… and that is a whole other world of concerns.
For me, the question is, if one takes T3 meds, how does this act on the TSH-T4 axis as a negative feedback agent. As the ratio of T3:T4 is normally small, one might not be able to manipulate the TSH-T4 axis greatly.