Parathyroid glands are tiny glands that are located behind the thyroid (which is a butterfly shaped gland in the neck). Part of the endocrine system, the four parathyroid glands control the amount of calcium that is present in our bones and in our blood. Calcium is essential to our body providing energy to our nervous and muscular systems along with providing strength to our skeletal system. Calcium regulation is so important that it is the only nutrient that has its own dedicated system for its regulation. This is the only function of the parathyroid glands - although they are located near the thyroid their functions are not involved with one another. Issues with the parathyroid gland include problems with calcium regulation - too little is called hypoparathyroidism and too much is hyperparathyroidism.