Calcitonin

Calcitonin, (thyrocalcitonin, CT), is a peptide hormone produced by the parafollicular (C-cells) of the thyroid gland. Its concentration increases with hypercalcemia. It lowers the level calcium ions in the blood and thus represents an antagonist to the parathormonu produced by the main cells of the parathyroid bodies. Parathormon and calcitonin stimulate reabsorption in the ascending part of the loop of Henle, where calcium is reabsorbed transcellularly and paracellularly Parathormone reduces the resulting concentration of calcium in the urine, calcitonin increases it. In the distal part of the nephron, in addition to parathyroid hormone and calcitonin, calcitriol also participates in reabsorption of calcium.

Effects of calcitonin

 * Bone: retains Ca + P
 * kidney: reduces reabsorption of Ca + P
 * intestine - no direct effect (calcitonin most likely reduces the formation of calcitriol in the kidneys).

Benchmarks
men, normal laboratory value: 3-26 ng/l women, normal laboratory value: 2-17 ng/l

Related articles

 * Calcium
 * Calcium phosphate metabolism
 * Procalcitonin

Other links

 * Kalcitonin (česká wikipedie)
 * Calcitonin (anglická wikipedie)