Gastrointestinal and renal regulation of calcium metabolism

Calcium is critical to human physiology for the function of excitable tissues (e.g. neuromuscular function) and is also needed for skeletal mineralization. The maintenance of a constant free ionized calcium concentration is biologically important for these functions. Regulation of calcium levels is a pre-requisite for its maintenance. In this article, calcium homeostasis is reviewed in respect to the critical organs involved; gastrointestinal tract, and the kidneys. Also reviewed is the calcium sensing receptor (CaSR) which serve as a calcium regulator (calciostat) in calciotropic tissues and regulates other biological functions in non-calciotropic tissues. The purpose of this review is to discuss the normal regulation of calcium metabolism in order to provide the clinician with basic information for the diagnosis and therapeutic management of calcium metabolism disorders as well as related pathologies.