Synthesis and Release of Thyroid Hormones

• Thyroid hormone (TH) made by

  follicular cells - stimulated by TSH from anterior pituitary gland
• Follicular cells bind iodine to

  thyroglobulin proteins in colloid
• Intermediaries are combined to form

  T3 (triiodothyronine) and T4 (tetraiodothyronine) - T4 commonly known as thyroxine
• TSH stimulates release of

  T3 and T4 from follicular cells when necessary