Thyroxine (tetraiodothyronine)
A) is more potent than triiodothyronine in peripheral tissues
B) is deiodinated in target cells to the biologically more potent triiodothyronine
C) has no biological activity and is a form of hormone removed by kidneys
D) is a transport protein for thyroid hormones

Question

Quizplus · Accepted Answer

Thyroxine is deiodinated in target cells to the more biologically potent triiodothyronine. This is known as peripheral conversion, and it allows for the fine-tuning of thyroid hormone activity in individual tissues. While both thyroxine and triiodothyronine are important thyroid hormones, triiodothyronine is generally considered to be more potent in peripheral tissues. Thyroxine is not a transport protein for thyroid hormones, nor is it a form of hormone removed by the kidneys.

Thyroxine (Tetraiodothyronine)