If a patient with a thyroid tumor that autonomously secretes T4 receives an injection of exogenous TSH, which consequence follows?

💡 Explanation

Because the tumor secretes T4 autonomously, high levels of T4 exert negative feedback on the hypothalamus and pituitary gland. Therefore, injecting TSH does not affect T4 production from the tumor; rather than stimulating the thyroid, the increased T4 from the tumor will decrease peripheral deiodinase activity.

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