Please note: I'd like to preface this question by stating that this is neither homework nor me seeking medical advice. I am simply trying to understand the biological, physiological root etiology behind various thyroid-related structures.
This question shows research and is not a duplicate.
My undertanding of the pituitary gland is that it will produce TSH when it senses total T4 (not free T4) is low. So if both total T4 and TSH are low, this implies two things:
- There is some underlying reason why T4 is low; but moreover...
- There is some other (or related) reason as to why TSH is low
In all the literature I can find, the main antagonist in this scenario is a malfunctioning pituitary gland.
So I ask: if the pituitary gland is deemed functional and non-diseased, are there any other root causes for both a low total T4 and a low TSH? Biologicaly/physiologically, how do they work to produce this low level of hormone production?