Parathyroid hormone (PTH) promotes the formation of the hormone calcitriol, which is the active form of vitamin D. PTH stimulates the kidney enzyme 1-α-hydroxylase to convert inactive vitamin D into calcitriol, which then helps increase calcium absorption in the intestine.

Details on PTH and Hormone Formation

• PTH is secreted by the parathyroid glands in response to low blood calcium levels.
• One of PTH's key functions is to stimulate the kidneys to produce calcitriol (1,25-dihydroxyvitamin D), the active form of vitamin D.
• Calcitriol then increases calcium absorption from the intestines, working alongside PTH's actions on bones and kidneys to raise blood calcium levels.