The parathyroid glands secrete a hormone which regulates the level of what substance in the blood?
The parathyroid glands secrete PTH, a substance that helps maintain the correct balance of calcium and phosphorus in the body. PTH regulates the level of calcium in the blood, release of calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine.he parathyroid glands constantly measure calcium levels in your blood. If the calcium level gets too high, the normal glands sense this and stop production of PTH. This lowers the calcium in your body and returns your calcium levels to normal. Abnormal glands cannot regulate calcium balance.