Update in Anaesthesia 12 Clinical Implications for the

Calcium is an essential ion within the human body. The maintenance of a constant free ionised calcium concentration is biologically important for the function of excitable tissues. Abnormalities in serum calcium values may have profound effects on neurological, gastrointestinal and renal function. Normal calcium concentrations are maintained as a result of tightly regulated ion transport by the kidneys, intestinal tract and bone. This is mediated by calcaemic hormones, in particular parathyroid hormone and the active form of Vitamin D. Changes in calcium transport resulting in movement into or out of the extracellular fluid will lead to hypercalcaemia, respectively. In this article the mechanisms responsible for calcium homeostasis will be reviewed.