The parathyroid glands are 4 small, oval-shaped glands. They are located next to the 2 thyroid gland lobes in the neck. Each gland is often about the size of a pea.
Parathyroid glands produce parathyroid hormone (PTH). This hormone plays a key role in regulating calcium levels in the blood. Precise calcium levels are important because small changes can cause muscle and nerve problems.
PTH stimulates these functions:
Release of calcium by bones into the bloodstream. This affects bone density and strength.
Calcium absorption from food by the intestines
Calcium conservation by the kidneys
Kidney cell stimulation. This changes the weaker forms of vitamin D into the form that is strongest at absorbing calcium from the intestines.