Here is a neat journalistic summary of a recent Italian study in July's Journal of Reproductive Endocrinology
and here is the article itself
I printed it off and took it to a recent referral to an NHS endocrinologist, to back up my perfectly reasonable refusal of a second go of artificial T4. I've just had a second operation of breast cancer and really don't want any more. He hadn't read it, but took it away. He'd never seen an iodine loading test either. we won't be meeting again.
I hope this is helpful. Good luck.