Hormonal regulation of calcium homeostasis.

Several hormones play a role in calcium homeostasis. PTH and 1,25(OH)2D exert their effects on the skeleton, kidney, and gastrointestinal tract, maintaining normal levels of calcium and phosphate in both blood and extracellular fluid. Regulation of bone turnover, reabsorption of calcium and phosphate from the glomerular filtrate, and absorption of calcium and phosphate from the diet are mechanisms by which homeostasis is preserved. Calcitonin may be involved in calcium homeostasis, but its role is less well defined.