Our bones are the largest reservoirs of calcium, harboring most of the calcium in our bodies (about 99%) in the form of calcium hydroxyapatite. Calcium is also found in teeth, the circulatory system, extracellular fluid, muscles and other tissues. It plays crucial roles such as regulating the tone of the blood vessels, production of hormones, intracellular signaling (communication of information within body cells), muscle contraction, nerve communication, among other functions.

Because of this critical role played by calcium, its normal blood concentration is tightly controlled by the body to a level of...