Calcitonin

Where it comes from

Made in

Parafollicular C cells of the thyroid gland

Sent out by

A rise in blood calcium

Acts on

• Osteoclasts in bone
• Kidney

What it does

• Slows osteoclasts, the cells that dissolve bone
• Increases the loss of calcium in urine
• Its sibling CGRP, from the same gene, dilates vessels and carries migraine pain

In medicine

• Salmon calcitonin by injection for Paget’s disease of bone and for the high calcium of cancer ²
• The nasal spray for osteoporosis was withdrawn in Europe in 2012: across long-term trials the excess of cancer over placebo ran from 0.7 % with oral forms to 2.4 % with the spray ¹
• Calcitonin in the blood is the tumour marker of medullary thyroid cancer
• The CGRP side of the gene is the target of the newer migraine medicines

Beyond the body’s own use

• Calcitonin eases the pain of a fresh osteoporotic vertebral fracture, an effect separate from bone; pooled trials found the benefit in recent fractures and none in old ones ³
• Europe now allows injected calcitonin only in short courses, normally two to four weeks for the bone loss of sudden immobilisation and up to three months in Paget’s disease, because of that same cancer signal ¹
• An oral salmon calcitonin was taken through phase 3 in osteoporosis and in knee osteoarthritis and never reached the market