Study note

Regulation of the pituitary–thyroid axis

THE CONTEXT

Thyroid hormone synthesis and release are regulated by anterior pituitary thyroid-stimulating hormone and hypothalamic input.

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Thyroid-stimulating hormone (TSH) from the anterior pituitary controls thyroid hormone synthesis and release.

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Thyrotrophin-releasing hormone (TRH), produced in the hypothalamus, also regulates TSH secretion.

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TSH secretion depends on circulating thyroid hormone levels through negative feedback.

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TSH production is suppressed in hyperthyroidism and stimulated in hypothyroidism.

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