A few weeks ago I posted an abstract about using topical thyroid hormone.
Topical L‐thyroxine: The Cinderella among hormones waiting to dance on the floor of dermatological therapy?
healthunlocked.com/thyroidu...
On that thread, jimh111 made the very good point that it might actually be a better idea to try T3 than T4. (Thank you, Jim.)
I mulled this over and decided to email Ralf Paus - who has now responded:
To be perfectly honest, I have not considered carefully the liothyronine (T3) alternative, since most of our own relevant preclinial experiments were performed with T4 - not the least since it is, as you know, the medically most widely prescribed thyroid hormone therapy and would therefore be most likely to be embraced by dermatologists for off-label indications. Also, just as others in the literature before us, we had noted that T4 may unfold some functional effects of its own, presumably independent of its conversion to T3.
But your points about T3 being much better soluble, potentially showing better skin penetration, and direct action without conversion are all well taken: in future wound healing experiments (=our current focus), we will definitely consider to run an additional test group with topical T3.
I have copied your email to my lab chief, Dr. Cheret, and welcome further feedback & thoughts from your group/forum.
Our main problem at this time is identifying adequate funding for research into topical wound healing applications of thyroid hormones. Suggestions where we might wish to try our luck would therefore be particularly helpful.
It appears possible that Jim's suggestion and my email have together prompted at least thoughts about T3.