Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Disorders of calcium metabolism occur when the body has too little or too much calcium. In the human body, the amount of calcium is closely regulated within a limited range. Extracellular calcium levels are maintained within a tight range through the actions of parathyroid hormone, vitamin D and the calcium sensing receptor. The disorders in calcium metabolism can result into hypocalcemia – decreased plasma levels of calcium – or hypercalcemia – elevated plasma calcium levels. Learn more about calcium, the disorders that may be caused by a shortage or an excess of calcium in the body, and the dietary sources of calcium with the help of this book.