Parathyroid hormone (PTH) is released by the parathyroid glands. The 4 tiny parathyroid glands are located in the neck, near or attached to the back side of the thyroid gland. The thyroid gland is located in the neck, just above where your collarbones meet in the middle.PTH controls calcium, phosphorus, and vitamin D levels in the blood. It is important for regulating bone growth