Definition: Calcitonin is a hormone produced by the thyroid gland. Your body produces calcitonin when you have high levels of calcium in your blood.
Calcitonin lowers blood calcium levels in two ways. First, it prevents the action of cells that break down old bone cells (a process that releases calcium into the bloodstream). Second, it encourages cells that lay down new bone, which takes calcium out of the blood.
Also Known As: thyrocalcitonin
