If you keep your cycle at 5 weeks with 8 weeks pause, you will not permanently damage your thyroid. Do not go over 100mcg to be on the safe side--pyramid as I demonstrated. Here is a sad story as told by a friend of mine.
There was a Ms. Galaxy winner several years back that used T3 and Clen to cut successfully. She had a doc in her corner. the next year, she ditched the doc because she knew everything. So, she started a T4 cycle by herself. She wasn't getting any results, so she upped the dose. By the end of 12 twelve weeks and a very high dose, she finally started losing fat. After she went off the T4, she started gaining fat very quickly on "just regular eating." She went to get her thyroid tested and her T3 and T4 levels were virtually zero. She ballooned out to over 200 lbs and "she looked like a marshmellow" This is a sad story. he showed me pictures of her before (when she won Ms. Galaxy) and after.
In my opinion, drugs like T3, T4, and glucophage treat symptoms. In patients whose Test and GH levels are optimized, they have superior thyroid function and excellent insulin function. Once fat levels are reduced, then antiestrogens aren't even needed.