noun Biochemistry.
a polypeptide hormone that participates in the regulation of calcium levels in vertebrates by inhibiting loss of calcium from bone to the blood.

1960–65; calci- + tone + -in2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To calcitonin
World English Dictionary
calcitonin (ˌkælsɪˈtəʊnɪn)
Compare parathyroid hormone Also called: thyrocalcitonin a hormone secreted by the thyroid that inhibits the release of calcium from the skeleton and prevents a build-up of calcium in the blood
[C20: from calci- + ton(ic) + -in]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
Cite This Source
American Heritage
Medical Dictionary

calcitonin cal·ci·to·nin (kāl'sĭ-tō'nĭn)
A peptide hormone, produced by the thyroid gland in humans, that acts to lower plasma calcium and phosphate levels without augmenting calcium accretion. Also called thyrocalcitonin.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source
American Heritage
Science Dictionary
calcitonin   (kāl'sĭ-tō'nĭn)  Pronunciation Key 
A peptide hormone secreted by the thyroid gland that stimulates bone formation and lowers blood calcium and phosphate levels.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
Encyclopedia Britannica


a protein hormone secreted in humans and other mammals by parafollicular cells in the thyroid gland, and in birds, fishes, and other nonmammalian vertebrates by cells of the ultimobranchial bodies, which are discrete calcitonin-secreting glands. Calcitonin lowers the concentration of calcium in the blood when it rises above the normal value. It has the opposite effect of parathyroid hormone (parathormone).

Learn more about calcitonin with a free trial on

Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
Cite This Source
Example sentences
It also produces calcitonin which is one of the regulators of calcium levels in the blood.
Medullary carcinoma of the thyroid is cancer of the thyroid gland that starts in cells that release a hormone called calcitonin.
Calcitonin is a medicine that slows the rate of bone loss and relieves bone pain.
It also releases calcitonin, which plays a role in calcium balance and will not be discussed here.
Copyright © 2014, LLC. All rights reserved.
  • Please Login or Sign Up to use the Recent Searches feature