What happens to thyrotropin-releasing hormone (TRH) secretion when exogenous thyroid hormone (T4) is administered, mimicking hyperthyroidism?

💡 Explanation

When exogenous T4 is administered, the increased thyroid hormone levels trigger negative feedback on the hypothalamus and pituitary, because this reduces the need for endogenous thyroid hormone production. Therefore, TRH secretion decreases significantly, rather than remaining unchanged or oscillating wildly due to this negative feedback loop.

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