Anatomy and physiology

The parathyroid glands, also called parathyroids, are four pea-sized glands located in the neck, near or attached to the back side of the thyroid gland. Occasionally, one or more of the parathyroids can be embedded in the thyroid, in the thymus, or located elsewhere around this area. In most cases, however, the glands function normally.

The parathyroid hormone (PTH) regulates calcium and phosphorus levels within the blood and bone, maintaining a balance between the mineral levels in the blood and the bone. Calcium in combination with phosphorus plays an important role in bone and tooth development, in maintaining bone strength, in nerve transmission and muscle contraction.