[Hypercalcemia].

Calcium is pivotal for neuromuscular function, coagulation, and signal transduction. An imbalance of enteral calcium uptake, deposition in and resorption from bones, and renal calcium elimination causes hypercalcemia. The dissociation between total serum calcium and ionized calcium has important implications in diagnosing hypercalcemia. The calcium sensing receptor (CaSR) regulates parathyroid hormone release and renal calcium reabsorption. Knowing the actions of the CaSR is important for diagnosing and treating patients with hyperparathyroidism. Diuretics can cause hypercalcemia, but also provide a clinical tool to lower serum calcium.