Download Calcitonin

By: Narjes lavasani
• Calcitonin is peptide hormone
• CT Synthesized and Secreted by the c cells (Clear
cell)or Para follicular cells of thyroid gland
• CT reduce calcium blood level opposed to parathyroid
hormone
•
Calcitonin Gene-Related Peptide (CGRP) is an alternative
product of the calcitonin gene that CGRP does not bind to the
calcitonin receptor. CGRP in thyroid, heart, lungs, GI tract, and
nervous tissue act as a neurotransmitter, not as a regulator of
Ca.
Calcitonin secreted by
Parafollicular cells
• A polypeptide chain of 32 amino acids
• An intramolecular disulfide bridge between the cysteine
residues at positions 1 and 7 make a circular shape,
In hormonal regulation of calcium and phosphate
concentration in the body, three hormones are involved:
1. Parathyroid hormone= Increase the concentration of calcium in the plasma
2. Calcitonin=Decrease the concentration of calcium in the plasma
3.Vitamin D= Increase the calcium and phosphate concentration
Calcitonin is involved in helping to regulate the level of calcium
and phosphate in the blood against the action of parathyroid
hormone. If the body sense high concentration of calcium in the
plasma this stimulate the thyroid gland to secrete calcitonin
 Calcitonin reduces the blood calcium level by acting
on:
• Bones
• Kidneys
• Intestine

In response to high concentration of blood
calcium, calcitonin released.
•
Calcitonin directly inhibits the activity of
osteoclasts(resorb bone), and stimulating
osteoblast(bone forming) directly reduces
the amount of calcium released into the
blood.
Calcitonin hormone receptor is G protein
Use cAMP pathway
•
• It decrease the calcium reabsorption in the kidney, and
leading to lower blood calcium levels by increasing the
calcium excretion in the urine.
• Gastrointestinal hormones (gastrin and cholecystokinin)
release calcitonin during digestion of food with calcium
calcitonin Inhibit calcium absorption by the intestine
Calcitonin is degraded by liver, and is
cleared from the blood by the kidney
I
Negative feedback mechanism
• Calcitonin blood test is a preventive measurement for
screening of people who have a family history of
medullary thyroid cancer.
• Normal Plasma level of Calcitonin is less than
14pg/ml(female) less than 19pg/ml(male)
An injection of manufacture
form of calcitonin can be given
to the patients with
postmenopausal
osteoporosis(low estrogen),
hypercalcemia (high calcium
levels in the blood) and Paget's
disease (bone). and Paget's disease
(bone).
Intramuscular or subdermal
http://www.biosupply.co.uk/content/14-calcitonin-aregulator-of-calcium-metabolism
https://www.ncbi.nlm.nih.gov/pubmed/7588259
https://www.ncbi.nlm.nih.gov/pubmed/17114906
http://www.yourhormones.info/hormones/calcitonin.aspx