Definition
Parathyroid glands are small glands located behind the thyroid in the neck. Usually, there are four of them. Their main job is to regulate calcium levels in the blood. They secrete parathyroid hormone (PTH), which increases calcium levels when they're too low. Calcium is vital for bone health, nerve function, and muscle contraction. Think of the parathyroids as the body's calcium managers. They make sure everything is balanced for your body to function properly. If blood calcium is the water level of a pool, parathyroids maintain that level.