Calcitonin

Examples of Calcitonin in the following topics:

• Thyroid Gland

  • The thyroid gland, the largest endocrine gland, is responsible for the production of the hormones T3, T4, and calcitonin.
  • Another hormone produced by the thyroid gland, thyrocalcitonin, or calcitonin, decreases the concentration of calcium in the blood.
  • Calcitonin is produced by parafollicular cells of the thyroid, either releasing hormones or inhibiting hormones.
  • Calcitonin functions to help regulate calcium concentrations in body fluids.
  • The location of the thyroid gland is in the neck below the larynx and in front of the trachea; it is the largest endocrine gland in the body, producing T3, T4, and calcitonin.

• Action of Thyroid Hormones

  • The primary function of the thyroid is production of the hormones triiodothyronine (T3), thyroxine (T4), and calcitonin.
  • Calcitonin is another hormone released by the thyroid gland which is responsible for modulating blood calcium levels in conjunction with parathyroid hormone, which is released from the parathyroid.

• Parathyroid Hormone

  • PTH works in concert with another hormone, calcitonin, which is produced by the thyroid to maintain calcium homoeostasis.
  • Parathyroid hormone acts to increase blood calcium levels, while calcitonin acts to decrease blood calcium levels.
  • This interaction between parathyroid hormone and calcitonin is also an important part of bone remodeling.

• Bone and Calcium Homeostasis

  • Calcitonin stimulates incorporation of calcium in bone.
  • When blood calcium concentration rises, the parafollicular cells of the thyroid gland increase calcitonin secretion into the blood.
  • The resulting high levels of calcitonin in the blood stimulate the bone to remove calcium from the blood plasma and deposit it as bone.
  • When the blood calcium level is too low, calcitonin secretion is inhibited and PTH secretion is stimulated.

• Hormonal Control of Blood Calcium Levels

  • The hormone calcitonin, which is produced by the parafollicular (or C) cells of the thyroid, has the opposite effect on blood calcium levels as PTH.
  • Calcitonin decreases blood calcium levels by inhibiting osteoclasts, stimulating osteoblasts, and stimulating calcium excretion by the kidneys.
  • Calcitonin is most important in children (when it stimulates bone growth), during pregnancy (when it reduces maternal bone loss), and during prolonged starvation (because it reduces bone mass loss).
  • In healthy, nonpregnant, unstarved adults, the role of calcitonin is unclear.

• Parathyroid Glands

  • PTH opposes the effect of thyrocalcitonin (or calcitonin), a hormone produced by the thyroid gland that regulates calcium levels.
  • PTH and calcitonin work in opposition to one another to maintain homeostatic calcium levels in body fluids.

• Overview of the Parathyroid Glands

  • PTH has effects antagonistic to those of calcitonin by increasing blood calcium levels by stimulating osteoclasts to break down bone and release calcium.

• Overview of Endocrine Glands

  • The thyroid also produces and releases the hormone calcitonin (thyrocalcitonin) which contributes to the regulation of blood calcium levels.
  • Thyrocalcitonin or calcitonin decreases the concentration of calcium in the blood, from where most of it is stored in the bones.
  • Calcitonin, a hormone produced by the thyroid gland that also regulates ECF calcium levels, serves to counteract the calcium-producing effects of PTH.

• Overview of the Thyroid Gland

  • The thyroid also produces calcitonin, which plays a role in calcium homeostasis.

• Paget's Disease

  • Although there is no cure for Paget's disease, medications (bisphosphonates and calcitonin) can help control the disorder and lessen pain and other symptoms.