My experience
may 2014. I had been on synthetic T4 for years before I started taking iodine. I was taking 137 mcg T4 at the end. My TSH was so low they couldn’t measure it anymore ( << 0.01). I am now taking 1 grain of Thiroyd, which is made from pigs thyroid. One grain contains T3 at 8.31 microgram; T4 at 35 microgram. So that is substantially lower then the 137 mcg I was taking before.
Read http://www.stopthethyroidmadness.com/t4-only-meds-dont-work/ to see why synthetic hormones didn’t work for me.
See http://www.stopthethyroidmadness.com/armour-vs-other-brands/ for information on natural thyroid hormones.
When I started taking iodine I kept taking my synthetic T4 and T3 (at 18 mcg). I started taking more and more iodine and at some point I got hyperthyroid. I lowered my T4, but got hypothyroid again, so I upped it to the original dosage again. The lesson to learn here is not to lower too fast. I had a few more disappointing adventures where I lowered my dosage too fast (or too soon). After that I changed my tactics.
I waited until I had been hyper for at least a week before lowering my T4. I didn’t lower my T3, because it helped me greatly with brain function. I then lowered my T4 by about 1/5 and waited at least 6 weeks. After 6 weeks the new blood levels of T4 are stable (T4 has a half time of about a week in your blood), so only then can you really compare.
After those 6 weeks I again waited until I had been hyper for more than a week. Etcetera. By repeating this over and over again, I was able to get off the synthetic hormone without too much discomfort.
I also stopped taking the T3.
During that time I noticed that high levels of SSKI were better at staving off those hypothyroid symptoms than low ones. High being above 1 gram of iodide, low being 100 mg of iodide (both are really high compared to the RDA which is only 150 mcg).
After a few months I noticed that some hypothyroid symptoms would still creep up. Not too bad, but annoying enough to make me stop and think. Sometimes my voice would be hoarse, I would sometimes feel cold and sluggish. It was usually when I had had a tough week at work, or in winter or when I went to bed too late. I ordered some Thiroyd (natural thyroid hormone) to try and have been on 1 grain a day ever since. It is only very little, but just enough to keep my body happy.
There are a lot of things that influence the working of the thyroid. Bromide for instance blocks it. High levels of estrogen as compared to progesterone also slow the thyroid down. So any time I felt some hypothyroid symptoms come back, I took a good look at what I was eating and how I was feeling. I now know that I have estrogen dominance, so I need to monitor that (I take progesterone cream for that). I’m also low on magnesium a lot. Magnesium is necessary for ATP production, which is needed for thyroid hormone production.