If a patient has a mutation causing constitutive activation of thyroid stimulating hormone (TSH) receptors, why does thyroid hormone production not increase indefinitely?

💡 Explanation

Although the TSH receptor is constitutively active, negative feedback exerted by T3 and T4 on the hypothalamus and pituitary still functions. Because this feedback reduces the production of thyrotropin-releasing hormone (TRH) and TSH, it prevents indefinite thyroid hormone production, rather than iodine uptake ceasing or other regulatory proteins being solely responsible.

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