It's really common that we're doing cases of hypo and hyperthyroidism we get stuck when we're trying to explain to a patient why your TSH is high in hypothyroid and why your TSH is low in hyperthyroid and we all talk positively about negative feedback loops and things and it gets very confusing one really simple way to explain to a patient is at an elevation of the brain is constantly talking to the thyroid all the time is talking to it and how loud the brain is talking is reflected by your TSH level.
So without an underactive thyroid or hypothyroidism, your thyroid gland down here is not working very well so your brain is starting to shout really loud to it remember is shouting loud.
so your TSH level goes up and that's why in an underactive thyroid you don't raise TSH level if you look at hyperthyroid where your thyroid gland is already working really fast your brain starts to become really quiet because the thyroid overworking so it stops talking it becomes quiet and that people TSH level goes down or low so it's worth thinking about until the patient of the brain is constantly talking to the thyroid and depending on how fast this is working your brain either gets really loud I know underactive thyroid or it goes really quiet in an overactive fire and that relates to your TSH level helps.
If you have any doubts, let me know ...