Hi, there can be all sorts of things going wrong! Mysterious resistances, gland failures, conversion disorders, broken pituitary, broken hypothalamus, faulty deiodinase enzymes, etc. All potentially inherited or acquired. We really do seem to have no idea how this complicated system works or what it's all for, or what can cause it to go wrong.

But I would have thought that if there was widespread 'central hypothyroidism', someone would have twigged by now, since that form does show up if you do a full panel of hormone tests.

Or I would have thought that when I wrote this. By now I am in such despair about the pitiful state of medical research that I wouldn't be surprised if they'd never thought to look, so maybe it is all just perfectly obvious from blood tests and the fools have ignored it.

And the question of 'what is the optimal treatment' is bound to be tricky. I'm just trying to demonstrate that the problems exist and are widespread and thus worth looking at!

Although Skinner certainly thought 'clinical hypothyroidism' could usually be fixed by bunging enough T4 at the problem. He does mention in his book that he sometimes used T3 or NDT, but he doesn't go into details. Various other people say 'mostly T4 with a bit of extra T3', but no-one has particularly clear ideas on what works and what doesn't or why.

Thanks for the reference to Ray Peat, I hadn't heard of him before. Can you link to the best expression of his thoughts?