The sole purpose of the parathyroid glands is to control calcium within the blood in a very tight range between 8.5 and 10.5. In doing so, parathyroid glands also control how much calcium is in the bones, and therefore, how strong and dense the bones are. Although the parathyroid glands are intimately related to the thyroid gland anatomically, they have no related function. The thyroid gland regulates the body’s metabolism and has no effect on calcium levels while parathyroid glands regulate calcium levels and have no effect on metabolism. More information can be had from here.
