The physiology and disorders of calcium and phosphate metabolism, the function of vitamin D (which acts more like a hormone than a vitamin), and the formation of bone are all tied together in a common system along with 2 other regulatory hormones—parathyroid hormone (PTH) and calcitonin. Therefore, PTH, calcitonin, and vitamin D will be discussed in this chapter together with the associated disorders of calcium homeostasis.

Because aberrant calcium and phosphorus metabolism is reflected in the skeletal system, specific syndromes are presented in that section. (See also Dystrophies Associated with Calcium, Phosphorus, and Vitamin D.)

Last full review/revision July 2011 by Mark E. Peterson, DVM, DACVIM