Calcitonin

Indications for use

According to the attached instructions, Calcitonin has the following indications for use:

Systemic skeletal diseases - Paget's disease, aseptic necrosis of the femoral head, osteogenesis imperfecta, spontaneous bone resorption;
Osteoporosis;
Fibrous dysplasia;
Delayed healing of fractures after traumatic bone injury;
Osteomyelitis;
Periodontal disease;
Familial hyperphosphatemia;
Hypercalcemia;
Thyrotoxicosis;
Hypervitaminosis D;
Myeloma;
The need for long-term immobilization.

The condition of any organ can be assessed by its function. As for the endocrine glands , an indicator of their work and health is the concentration of hormones in the blood that they produce. The thyroid gland produces thyroid hormones (triiodothyronine and thyroxine). But in the thyroid gland, in addition to A and B cells, which produce thyroid hormones, there are parafollicular cell structures, C cells, which synthesize a hormonal substance called calcitonin . Although this hubbub does not affect thyroid homeostasis, unlike T3 and T4, it is an important indicator, changes in the concentration of which are used in the diagnosis of a number of pathological conditions, among which the most important place is given to medullary thyroid cancer.

The role of calcitonin in the body and in diagnosis

The physiological role of the hormone calcitonin has not yet been precisely established.
This substance is classified as a regulator of phosphorus-calcium metabolism in the human body. Its synthesis by C cells and, accordingly, its concentration in the blood depend on the level of calcium in the blood. As calcium increases, calcitonin levels also increase. For this hormone, there are receptors on osteoclasts (bone tissue cells), due to the influence of calcitonin, these cells are activated and calcium is transferred from the blood into compact bone substance, while bone resorption is inhibited at the same time. Thus, the leaching of calcium from bones and the development of osteoporosis are inhibited. Calcitonin is a direct antagonist of parathyroid hormone, which activates the resorption of calcium from bones into the blood.

But it is also necessary to clarify that the amount of calcitonin in the blood is so minute, in contrast to parathyroid hormone, that there is probably another mechanism for maintaining calcium-phosphorus metabolism without its participation.

calcitonin in the blood of a healthy body ; most often it is not even detected by conventional methods. But, if the level of the hormone is elevated , then this immediately causes concern among specialists, because there are very few conditions that are accompanied by this and the number one cause is medullary thyroid cancer.

Thus, the main diagnostic value of calcitonin is that it is a tumor marker and, moreover, quite specific. Medullary carcinoma is a malignant tumor of the thyroid gland that grows from parafollicular cells, which synthesize calcitonin. Therefore, with a neoplasm, the concentration of the hormone in the blood increases significantly. Moreover, the degree of increase in calcitonin can be used as an indicator of tumor size, its prevalence, the presence of metastases and the prognosis for the patient (the higher the level, the worse the prognosis).

Features of the calcitonin test

To determine
calcitonin levels, venous blood is collected on an empty stomach.
The study is carried out by chemiluminescence immunoassay. Different laboratories conduct such research on different generations of analyzers (there are three so far). Third generation analyzers are the most accurate and almost never make errors. Therefore, if you decide to donate blood for calcitonin, ask what generation of analyzer your laboratory uses. Often the usual determination of calcitonin in the blood is supplemented with a pentagastrin test. After the introduction of pentagastrin into the body, the level of the hormone will increase in all patients with medullary thyroid carcinoma, which can be used as a differential diagnostic sign. In some patients, intravenous administration of calcium gluconate may be used as stimulation.

Evaluation of results

lower limit of normal for calcitonin , and this is not so important, since only its increase has diagnostic significance.
If, with a routine determination of calcitonin, its level exceeds 100 pmol/l, then the probability of medullary carcinoma reaches almost 100%. Each laboratory has its own standards, which depend on the determination method and equipment. In any case, an increase in calcitonin concentration should be a reason for further and detailed examination for medullary thyroid cancer.

Directions for use and dosage

According to the instructions, Calcitonin should be used intranasally or parenterally - subcutaneously, intramuscularly, intravenously, depending on the indications and form of the drug.

In emergency situations, the drug is diluted in 500 ml of isotonic sodium chloride solution and administered intravenously at the rate of 5-10 IU/kg per day.

For chronic pathologies, Calcitonin is used in the form of subcutaneous or intramuscular injections, dosage – 5-10 IU/kg during the day in 1-2 doses.

The drug in aerosol form is administered intranasally, 100-400 IU per day.

The duration of treatment depends on the patient's condition and the effectiveness of the therapy.

Where to go if calcitonin is elevated?

We encourage all patients whose blood analysis has revealed high calcitonin to contact the clinics of the North-Western Endocrinology Center

, who has the greatest experience in Russia in the treatment of medullary thyroid cancer. Specialists at the Northwestern Center will conduct clarifying studies and either reasonably exclude the diagnosis of C-cell cancer, or confirm it and perform surgery on you using the most modern technologies.

It should be noted that thyroid operations for residents of Russian regions are performed free of charge by the North-Western Endocrinology Center, within the framework of the federal quota program, or under a compulsory health insurance policy.

So, if your calcitonin is elevated, we are waiting for you

. Do not put off the examination for the future, it can be dangerous.

Side effects

In accordance with the attached instructions, Calcitonin can cause allergic reactions, including angioedema, anaphylactic shock.

When administering the drug parenterally, the following are likely:

Dizziness, headache;
Nausea, perversion of taste, vomiting, loose stools, pain in the epigastric region;
Myalgia, increased fatigue;
Cough, pharyngitis, flu-like symptoms;
Visual impairment;
Polyuria;
Hyperemia and pain at the injection site.

When using Calcitonin as an intranasal spray, the following may occur:

Dryness, swelling, erosion of the nasal mucosa;
Rhinitis;
Sinusitis;
Nosebleed.

When calcitonin is elevated

Any situation where a patient has high calcitonin, regardless of the degree of its increase compared to the norm, is very serious and requires an in-depth examination with the participation of specialists with sufficient experience in diagnosing and treating medullary thyroid cancer.

It is important to understand that if a calcitonin level is detected that exceeds 100 pg/ml, the probability of the patient having medullary cancer is almost 100%. The higher the level, the more advanced the tumor, the higher the likelihood of detecting its metastases in the lymph nodes and distant organs, and the worse the prognosis for the patient.

If in a patient with thyroid nodules, according to fine-needle biopsy, all nodes are benign, and calcitonin in the blood is elevated, you should trust the analysis more, since the likelihood that this indicator is “lying” is small. If the hormone level is really high (i.e., exceeds 100), surgical treatment including complete removal of the thyroid gland with central cervical lymph node dissection (i.e., removal of the lymph nodes surrounding the thyroid gland) must be carried out without fail. You can understand for yourself how accurate the calcitonin test must be - after all, in such cases, the patient’s thyroid gland is removed based on the results of only one laboratory test! The situation with the treatment of such tumors is similar to flying an airplane in fog using instruments, when you can’t see anything around, and decisions about where to fly have to be made only on the basis of instrument readings in the cockpit...

It is worth mentioning another important feature of medullary cancer - in 30% of cases it has a hereditary distribution, and can be inherited by the patient’s children in 50% of cases. In these situations, the thyroid gland is removed in children under 5-7 years of age (and in some cases, during the first month of life!), when the tumor is just beginning to develop, and the calcitonin level is barely elevated. And in this case, only an accurate test for calcitonin can add confidence to doctors and the child’s parents that they are doing everything correctly.

The most difficult cases in diagnosing medullary thyroid cancer are associated with situations where the hormone is only slightly elevated - that is, the level is above normal, but below the number 100. In cases where there is a slight increase, we can talk about the presence of medullary cancer of a very small size (3-4 mm), and about the absence of a tumor - in this case, calcitonin is increased due to other reasons not related to cancer.

Both in cases where calcitonin is clearly and clearly increased, and in cases of questionable, insignificant increase, you should contact a specialized endocrinology center, where specialists will conduct additional clarifying studies, including:

fine-needle biopsy of nodes under ultrasound control with determination of the calcitonin level in the washout from the puncture needle;
conducting a stimulated calcitonin test with intravenous administration of calcium gluconate.

In this article, we will not discuss all aspects of diagnosing medullary cancer, since it is wrong for patients to independently identify it - this is fraught with mistakes, the cost of which can be life. The rules that you need to remember after reading this material are simple:

calcitonin is a tumor marker
, this is its main significance
;
A blood test for the hormone calcitonin must be taken in all patients with
thyroid nodules;
the analysis should be taken in a specialized laboratory
that uses 3rd generation immunochemiluminescent analyzers and has sufficient experience in diagnosing medullary cancer;
any increase in the level of calcitonin in the blood should be a reason to contact a specialized endocrinology center
.

special instructions

Before starting to use Calcitonin, it is necessary to conduct a skin test for sensitivity to the drug, as well as determine the calcium level in the blood.

When the drug is first administered, severe hypocalcemia with tetanic syndrome may develop, which requires emergency medical care.

During the treatment period, systematic monitoring of calcium levels in the blood and periodic examination of urine sediment are recommended.

Intranasal use of the drug requires regular examination of the nasal mucosa.

In the treatment of osteoporosis, vitamin D and calcium supplements are prescribed in parallel with Calcitonin.

During treatment, care should be taken when driving vehicles and other complex machinery.

Calcitonin is normal

When testing blood for calcitonin and assessing the results of this analysis, it should be remembered that there is no lower limit of normal for this hormone

. If its level in the blood is zero, this is also normal. It is important that it does not rise above those limits that are designated as the upper limit of normal for this particular analyzer and this particular set of reagents.

It doesn’t make much sense to indicate any specific norm for calcitonin here, since laboratories now use very diverse models of analyzers - this leads to the fact that the concept of norm in this case should not even be discussed. When you take a calcitonin test in a high-quality modern laboratory, the norm will be indicated on the same form - this rule is followed very strictly by good laboratories.

Normal level of calcitonin in blood plasma

Different sources interpret the calcitonin norm in their own way. This is probably due to the fact that each laboratory, using different methods, relies on its own reference values. Some reference books do not separate the norm for women and men, noting only that it should range from 5.5 to 10.0 pmol/l or be below 50 pg/ml. However, in addition to this, some authors indicate that in women the level of calcitonin in the blood is 4 times lower, but during pregnancy it increases and approaches the norm of men. The concentration of this hormone decreases according to the years lived, that is, the older a person is, the less calcitonin is in his blood, so osteoporosis is the lot of older patients.

Thus, some laboratories give narrower limits of values, for example:

The norm for women is from 0 to 5.0 pg/ml;
In men – from 0 to 8.4 pg/ml.

Others push the boundaries of the norm:

In women, the norm is from 0.07 to 12.97 pg/ml;
In men, normal values do not leave the limits: 0.68 – 32.26 pg/ml.

Of course, it is difficult to figure it out, therefore, if a person has already gone to get tested for this hormone, then, having received the results, he should be guided by the reference values of the laboratory that studied his blood.

Recommendations before analysis

Calcitonin is usually tested by ELISA (enzyme-linked immunosorbent assay). The test uses blood taken with an anticoagulant (EDTA, heparin).

In order to obtain the correct result, the patient must follow the recommendations regarding preparation for the analysis, which, in principle, are suitable for all biochemical tests:

A month before the study, women part with oral contraceptives;
Three days before taking blood samples, a person stops active physical exercise and excludes sports training;
does not touch alcohol for 24 hours, even if there is a serious reason for this;
12 hours in advance, excludes all food in order to come to the laboratory on an empty stomach;
An hour before the test, he no longer remembers cigarettes;
Within half an hour, a person who comes to the laboratory calmly sits down, relaxes and rests.

The analysis can be done in one day, but the ELISA system is not designed for one person, so the patient must be warned about this. Perhaps the answer will be in a couple of days, or perhaps you will have to wait longer.

Physiological role of calcitonin in the body

Back in 1962, it was confirmed that this peptide hormone is a regulator of calcium metabolism, but it was mistakenly assumed that the production of calcitonin is due to the parathyroid glands. In fact, it is produced in the parafollicular cells (C cells) of the thyroid gland, although other organs (such as the lungs) may also be involved in its production, albeit to a lesser extent.

The main task of calcitonin is to resist the action of parathyroid hormone, which also takes part in the regulation of calcium metabolism, increasing its concentration in plasma.

The physiological role of thyrocalcitonin is to suppress the activity of the main cells directly involved in the destruction of bone tissue - osteoclasts. Thus:

Calcitonin, preventing calcium from leaving bone tissue, promotes its mineralization;
Inhibits the absorption of calcium and phosphorus in the intestinal tract;
Enhances the excretion of calcium through the kidneys;

Calcitonin in the body acts as a hypocalcemic factor that prevents bone degradation. In addition, this hormone plays a very important role during the period of active growth and puberty of the body; it promotes calcification of the skeletal system, strengthening it. Due to the fact that calcitonin blocks the path of calcium ions (when leaving bone tissue), it is used in the form of a pharmaceutical agent to treat osteoporosis.

The main purpose of calcitonin in laboratory diagnostics

A blood test for thyrocalcitonin, along with other laboratory tests, is used to assess calcium metabolism. However, it should be noted that this is not why it is popular in laboratory diagnostics of various pathologies. With its help, you can determine the presence of a serious oncological process. The earlier detection of a malignant and rather dangerous tumor of the thyroid gland, medullary carcinoma, is largely due to the determination of this indicator, where it acts as a tumor marker. And not only does an analysis for this hormone make it possible to establish a diagnosis, it also helps in subsequent stages:

Assess how successful the tumor removal surgery was;
Carry out monitoring after surgery;
Examine (by screening) the closest relatives of a patient diagnosed with medullary cancer.

Why medullary carcinoma? The fact is that this tumor is directly related to the malignant transformation of parafollicular cells (C-cells) into cancer cells. The content of calcitonin in such cases is increased at first, and continues to increase as the oncological process progresses.

However, it happens that calcitonin is elevated, but not so much as to suspect medullary cancer.

In such cases, stimulating tests are envisaged, where calcium gluconate and/or pentagastrin act as stimulants. After introducing one of them (or two at once), the situation becomes clearer either in favor of the tumor or in the opposite direction.

With the active development of medullary carcinoma after the introduction of stimulants, the level of this hormone in the patient’s blood will noticeably increase; in the absence of a tumor, there will be no special reaction. Meanwhile, it should be noted that the reaction to the administration of calcium gluconate in women and men, regardless of their age, is different. The thyroid gland of men responds more actively to the stimulant, therefore, calcitonin will be increased in the male analysis earlier and more.