The parathyroid glands are four pea-sized glands found behind the thyroid gland in the neck. They are responsible for producing parathyroid hormone, which controls calcium levels in the blood. When low calcium levels are detected, the parathyroid gland releases parathyroid hormone, which causes our bones to release calcium and our kidneys to reduce calcium lost through urine. Parathyroid hormone can also promote activation of vitamin D, increasing calcium absorption from the gut.You and Your Hormones from the Society for Endocrinology. (2018). Parathyroid glands. [online] Available at: http://www.yourhormones.info/glands/parathyroid-glands/ [Accessed 26 Nov. 2018].