The parathyroid glands are four pea sized glands located on the thyroid gland in the neck. The thyroid and parathyroid glands are entirely different glands, each producing distinct hormones with specific functions. The parathyroid glands secrete parathyroid hormone (PTH), that helps maintain the correct balance of calcium and phosphorous in the human body. Hyperparathyroidism is raised secretion of parathyroid hormone from the parathyroid glands. Abnormally raised activity of the parathyroid glands, which may be primary or secondary hyperparathyroidism. Excessive secretion of parathyroid hormone resulting in abnormally high levels of calcium in the blood can affect many systems of the body especially causing bone resorption and osteoporosis.