Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands, which are small glands located behind the thyroid gland in the neck. PTH plays a crucial role in regulating the body's calcium levels. When calcium levels in the blood are low, PTH is released to increase calcium concentration by stimulating the release of calcium from bones, enhancing calcium absorption in the intestines, and promoting calcium reabsorption in the kidneys. PTH also works in conjunction with calcitonin, a hormone produced by the thyroid gland, to maintain calcium balance. While PTH raises calcium levels, calcitonin lowers them when they are too high. This delicate balance is essential for various bodily functions, including muscle contraction, nerve function, and bone health.