How does levothyroxine suppress TSH?

The cells in the pituitary gland that produce TSH are very sensitive to the amount of thyroid hormone present in the bloodstream. In the normal state, a feedback mechanism helps to control the amount of TSH produced by the pituitary gland in order to maintain a steady level of production and release of thyroid hormone. As the thyroid gland releases thyroid hormone and the amount in the bloodstream increases, the pituitary gland senses the increase and decreases the amount of TSH it produces proportionately. When a patient takes levothyroxine for thyroid hormone suppression therapy, the dose is carefully adjusted so that there is always a higher level of thyroid hormone in the bloodstream. Sensing this, the pituitary gland will decrease the amount of TSH it produces to a lower level. With continued treatment with levothyroxine, TSH production can be continually suppressed to a lower-than-normal level.

Back to My doctor recommends thyroid hormone for my nodule