Thank you for responding Frodo ..I have been on Armour thyroid for years and my problem has always been finding a doctor or endocrinologist who fully understands the Thyroid ..like the TSH hormone is a pituitary hormone that signals the thyroid ..
This is the best way I can explain it.
Testing must include ALL your Actual Thyroid Hormone levels.
Free T3 - should be in the top quarter of its Range+
Free T4 - midrange ( or slightly more)
Reverse T3 - bottom of its Range or very near
Those are your actual thyroid hormones and where they should be together to be Optimally dosed on Thyroid Replacement Hormones.
IF they are not all being tested Together, you are not being Tested properly and you are not being Treated properly.
It is VERY COMMON for those on T4-ONLY medication like Thyroxine or Synthroid to develop
1) a Low Free T3 level - your Active Hormone level , it is THIS LIEVEL, and where its at that determines how Hypo vs Hyper you are and FEEL.
2) a High Reverse T3 level - can block T3 from being used - indicates a T4 Conversion problem
These will keep your body Hypo , which can indicate you do not have enough T3 for your Heart and your Entire Cardiovascular System to function properly.
Your tsh is a pituitary hormone that responds to what hormones your thyroid is producing. If you are on proper thyroid replacement, your tsh SHOULD be suppressed. Your pituitary should be chilling out and not asking your thyroid for more of anything.
That's kind of how it works the best I can explain it. It is more intricate than that, but that is a general way to think of it.