My line of thought in case your interested is this:
TSH triggers hormone creation but ALSO NIS symporter creation. these are the receptors if you will that take up iodine.
The process of creating the thyroid hormones creates toxic byproducts which the body neutralizes with a selenium based enzyme.
If selenium levels are inadequate T4 cant be converted to T3 AND the toxins cant be neutralized at an optimal rate which can result in thyroid damage. If the damage taking place is preventing the body from achieving what it feels is ideal amount of NIS symporters because they are being damaged, then maybe a little more selenium will help.