Renal homeostasis of calcium.

Calcium is critical for many metabolic functions. While 99% of body calcium is found as part of the structure of bone and teeth, 1% found in plasma and body cells is crucial for such functions as blood clotting, nerve impulse conduction, and muscle contraction. The homeostasis of calcium is complex because the gastrointestinal tract, the bones, and the kidneys all affect calcium balance. This manuscript reviews the functions, homeostasis, and renal handling and regulation of calcium. The major sites of renal tubular reabsorption and the related cellular mechanisms are described.