The secretion of parathyroid hormone is controlled by the concentration of
A) calcium bound to citrate anions
B) calcium in the diet
C) calcium inside of the bone matrix
D) ionized calcium in the blood

Question

Quizplus · Accepted Answer

Parathyroid hormone secretion is primarily controlled by the concentration of ionized calcium in the blood. When ionized calcium levels decrease, the parathyroid gland secretes more PTH, which acts to increase calcium levels in the blood through actions on the bone, kidneys, and intestines.

The Secretion of Parathyroid Hormone Is Controlled by the Concentration