This test measures the level of parathyroid hormone (PTH) in the blood. PTH, also known as

parathormone, is made by your parathyroid glands. These are four pea-sized glands in your

neck. PTH controls the level of calcium in the blood. Calcium is a mineral that keeps your

bones and teeth healthy and strong. It's also essential for the proper functioning of your

nerves, muscles, and heart.

If calcium blood levels are too low, your parathyroid glands will release PTH into the blood.

This causes calcium levels to rise. If calcium blood levels are too high, these glands will stop

making PTH. PTH levels that are too high or too low can cause serious health problems.