Definition: The parathyroid glands are part of the endocrine system. Located on the back of the thyroid, these four small glands produce parathyroid hormone which regulates blood calcium, magnesium, and phosphorus levels in the blood and bones. The parathyroid glands help regulate the functions of the nervous and muscular systems. Hyperparathyroidism is the most common disease of the parathyroid glands and is caused by overactive parathyroid glands.
