Why does thyroid hormone production remain low in a patient with adequate iodine intake but a mutation causing constitutive activation of thyroid hormone receptor (TR) in the hypothalamus?

💡 Explanation

In this case, constitutive TR activation in the hypothalamus leads to continuous negative feedback signaling, thereby inhibiting TSH secretion from the pituitary. Because TSH stimulates thyroid hormone production, its suppression results in low thyroid hormone levels; therefore, negative feedback explains the suppressed production, rather than iodine uptake or deiodinase activity.

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