The parathyroid glands are four small (about the size of a grain of rice) glands that are located in the neck, next to the thyroid gland. The parathyroid glands produce parathyroid hormone (PTH).
PTH controls the level of calcium in the blood in three ways:
- Breaking down bone tissue to allow calcium to be released into the blood
- Increases the body’s ability to absorb calcium from food
- Increases the kidney’s ability to retain calcium rather than having it released in urine
Having the correct calcium balance is essential to the normal function of many of the body’s systems and organs, including the heart, nervous system, kidneys, and bones.
When parathyroid glands function normally, blood calcium levels are strictly controlled by releasing PTH when calcium levels are too low and by stopping the release of PTH when calcium levels are normal or too high.