Calcitonin is a hormone produced by the C cells of the thyroid gland, which influences the body's calcium balance, and more precisely it reduces the level of calcium in the blood. However, what are the exact functions of calcitonin and what are the possible therapeutic uses of this hormone?

Calcitoninis one of those hormones involved in controlling the calcium-phosphate balance in the body - it regulates it together with substances such as parathyroid hormone and calcitriol.

Basically, testing the level of calcitonin in the blood is not a routine test, but it is very valuable - determining the level of calcitonin plays a role, among others. in the diagnosis of thyroid neoplasms.

Calcitonin was discovered in 1962 - two researchers, Copp and Cheney, were behind this discovery.

Initially, it was thought that the hormone was secreted by the parathyroid glands, but over time, both the place where calcitonin actually takes place, and its exact structure and function have been discovered.

Calcitonin: structure and secretion

Calcitonin is a polypeptide hormone that consists of 32 amino acids. It is formed from the transformation of its prohormone, which is procalcitonin.

Here it is worth saying a few words about the last mentioned. Well, physiologically, the role of procalcitonin in the regulation of calcium-phosphate metabolism is small - measurements of the concentration of this substance in order to assess calcium management are rather not performed.

The situation is different, however, when it is suspected that a patient may have an infection, especially a bacterial one. In such a case, the concentration of procalcitonin may already increase significantly - therefore, the determination of its level, in addition to testing whether it is CRP or ESR, is used in the diagnosis of various infections and inflammations.

Coming back to calcitonin itself, this hormone is predominantly produced and secreted by the C cells of the thyroid gland (also called follicular cells).

The thyroid gland is the primary source of calcitonin, but cells that can produce it are also present in the nervous system, in the lungs and in the organs of the digestive system.

Calcitonin: secretion regulation

The main factor that leads to the release of calcitonin into the blood is the increase in the concentration of calcium ions in it. However, not only calcium is associated with the secretion of this hormone - it is also influenced, among others, by gastrin or glucagon.

Calcitonin: function

Calcitonin, as mentioned earlier, is primarily associated with controlling the body's calcium and phosphate metabolism.

The main action of this hormone is to lower the concentration of calcium in the blood, besides, calcitonin can also lead to a decrease in the concentration of phosphate in the blood.

In general, it can be said that calcitonin is an antagonistic (i.e. opposite) hormone to another hormone, which is parathyroid hormone secreted by the parathyroid glands.

Calcitonin basically works through two mechanisms. The primary one is the effect on osteoclasts.

These cells, present in the skeleton, deal with the breakdown of bone tissue, which is related to the release of calcium into the circulating blood.

The effect of calcitonin is to inhibit osteoclast function - thanks to this, bone resorption processes are stopped, which ultimately results in a reduced release of calcium from bone tissue into the blood.

The second mechanism by which calcitonin exerts its effects is its effect on the kidneys.

This hormone can affect the cells of the renal tubules, blocking the reabsorption of calcium and phosphates in them. The effect of this action is reduced reabsorption of the above-mentioned compounds - more calcium and phosphates are therefore excreted with the urine, which reduces their concentration in the blood.
The above are the basic effects of calcitonin, but this hormone has also other effects, quite interesting activities.

It is interesting, for example, that calcitonin protects the bones of young mothers - in them, due to breastfeeding, calcium consumption is much higher.

In this case, calcitonin is responsible for ensuring that too much calcium is not released from the bones of a nursing woman. Yet another effect of calcitonin secretion is to prevent hypercalcemia (increased blood calcium) from occurring after a meal.

Calcitonin: study

Calcitonin concentration can be determined after taking a blood sample from the patient. But what is the norm of calcitonin?

There is simply no one specific answer here - the correct level of calcitonin varies, among others, depending on gender and age.

Additionally, the calcitonin norm may differ depending on the method by which it was madeanalysis. For this reason, when analyzing the calcitonin test result, you should always take into account the standards that apply in a given analytical facility.
Calcitonin concentration in the blood can be determined as much as possible, but there is only one question here: in what situations is it ordered making such a marking?

Diseases associated with abnormal calcitonin levels

Theoretically, calcitonin could be tested in patients who may have elevated levels of calcium in the blood - after all, as mentioned earlier, hypercalcemia is the primary stimulus to increase calcitonin secretion.

The problem, however, is that with long-lasting hypercalcemia, the level of calcitonin does not have to deviate from the norm - its increased secretion lasts only for a short time, therefore, in the diagnosis of an increased level of calcium in the blood Calcitonin is simply not used.

Calcitonin can be - and it is successfully used - marked in other diseases.

We are talking about neoplastic diseases here. First of all, the calcitonin test is used in the diagnosis of medullary thyroid cancer, in which it is often possible to detect significantly elevated levels of calcitonin in the blood.

In this case, these symbols are used not only in establishing the diagnosis, but also they are helpful during and after treatment.

For example, in a patient who has undergone treatment of the above-mentioned neoplasm, monitoring of the concentration of calcitonin in the blood may be used to diagnose a possible recurrence - in a patient whose blood levels of calcitonin increase after some time after cancer treatment, this may suggest the occurrence of a relapse or the presence of neoplastic metastases in the body.

Here it should be noted, however, that the level of calcitonin may also be increased in the case of other neoplastic diseases. Examples of medical conditions that can lead to such deviations are, inter alia, lung cancer or pancreatic cancer.

Calcitonin: use in medicine

The importance of calcitonin in the diagnosis of various diseases has been described above, but apart from them, this hormone is also used in medicine.

For therapeutic purposes, patients are given salmon calcitonin - a preparation derived from animals has a structure very similar to that of the human hormone, but it is not identical - it presents some difficulties, which will be discussed later.
Calcitonin preparations - due to the effect of reducing the losscalcium from bones - they are used primarily in the treatment of diseases related to the loss of this substance from the skeleton.

This is why calcitonin is administered, among others, to patients with osteoporosis or Paget's disease.

Other uses of this hormone are bone pain associated with various cancers in the skeletal system, and the need to treat hypercalcemia.

Calcitonin, although probably only in the future, may also have other applications. It is possible that, inter alia, it will be used in psychiatry - there are studies that show that this hormone may have beneficial effects in patients suffering from bipolar disorder.

New, quite unusual - like the above-mentioned - uses of calcitonin in medicine, however, will probably only be possible in the future.

At present, a completely different problem is actually more important. Well, because salmon calcitonin is similar to, but not identical to, human calcitonin, patients treated with this agent may produce antibodies against it.

Such a result may lead to the drug's effects being weakened or even suppressed at all - due to this possibility, the work of scientists nowadays focuses not on finding new uses for calcitonin, but rather on how such a problem eliminate.

Sources:

  1. Interna Szczeklika 2016/2017, ed. P. Gajewski, publ. Practical Medicine
  2. Hirsch P.F. et al., Calcitonin, an enigmatic hormone: does it have a function ?, J Musculoskel Neuron Interact 2001; 1 (4): 299-305
  3. Materials of the Encyclopaedia Britannica, on-line access: https://www.britannica.com/science/calcitonin-hormone
  4. Sofronescu A.G., Calcitonin, Medscape, Feb 2015, online access: https://emedicine.medscape.com/article/2087580-overview

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