Hypercalcemia

Calcium (Ca) homeostasis is maintained by the action of two hormones on three organ systems. The majority of Ca is stored in bone as hydroxyapatite, a compound that helps maintain structural integrity. Although the intravascular concentration of Ca is small, an imbalance can produce life-threatening symptoms. In plasma, 50% of Ca is unbound or ionized, whereas the remainder is bound to albumin. A change of 1 gm/ dl in serum albumin is associated with a 0.8mg/dl change in total serum calcium. Serum phosphate levels vary inversely with calcium, maintaining a normal concentration product between 30 and 40.