Library · Molecule
Calcitonin
Make it clearer
Calcitonin is a hormone, that is, a chemical messenger that travels through the blood. It is made by the C cells of the thyroid, also called parafollicular cells because they sit next to the follicles, the little sacs where the thyroid stores its main hormone. The signal that triggers it is a rise in blood calcium.
What it does is bring that calcium down, and it does so in two ways at once. On the one hand it slows the osteoclasts, the cells that take bone apart and, in doing so, release calcium into the blood. On the other, it pushes the kidney to let more calcium out in the urine.
That said, it is worth putting calcitonin in its place. In humans it is not the one in charge: blood calcium is governed mainly by parathyroid hormone and vitamin D, and calcitonin's effect on how much is absorbed in the intestine is slight. It is a player on the team, not the captain.
In brief
Calcitonin is a peptide hormone secreted by the parafollicular cells, or C cells, of the thyroid when blood calcium rises.
It lowers blood calcium in two ways: it slows the bone resorption carried out by osteoclasts and increases calcium excretion by the kidney tubules.
In humans its role is less important than that of parathyroid hormone or vitamin D, and its effect on intestinal absorption is slight.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Calcium, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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