How is thyroid hormone regulated?
The hypothalamus secretes thyrotropin-releasing
hor-mone (TRH), which stimulates the release of thyroid-stimulating hormone (TSH)
by the anterior pituitary gland. The thyroid gland, in response to TSH,
releases T3 and T4 into the circulation. TSH also causes
increased uptake of iodide and increased iodination of thyroglobu-lin. Both T3
and T4 have a negative-feedback effect on the hypothalamus and