Human growth hormones (GH and IGF). Reasons for the appearance of insulin-like growth factor Insulin-like growth factor 1 symptoms of abnormality

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Description

Insulin-like growth factor-1 is a hormone that regulates the process of cell growth, development and differentiation. Its chemical structure is similar to insulin. The insulin-like effect of the hormone is the participation of glucose metabolism in the body. Synonym – SOMATOMEDIN S, because is a mediator of somatotropic hormone. IGF-1 was discovered in 1978 and was successfully used in sports, but after 10 years, side effects of taking such a drug were discovered - damage to the liver and spleen and carcinogenicity. An interesting fact is that pygmies (the smallest people on Earth) have such a height due to their innate resistance to the effects of IGF-1.

The clinical significance of the analysis is to determine the cause of the growth disorder (slowing or accelerating) of the child. The main growth hormone is considered to be somatotropic hormone, but it can only exert its effect when it reacts with IGF-1. The amount of these two hormones is interrelated: a low concentration of IGF-1 indicates GH deficiency. A normal level of IGF-1 is strong evidence against GH deficiency.

IGF-1 is a diagnostic criterion for acromegaly (gigantism): the level of the hormone in the blood will be increased constantly, unlike STG. The analysis is necessary to establish the cause of dwarfism (dwarfism), since IGF deficiency is possible with normal GH levels. It also displays the effectiveness of the therapy for both diseases.

The insulin-like effect of the hormone is the participation of glucose metabolism in the body.

An increased concentration of IGF-1 becomes a risk factor for the development of cancer due to the inhibition of apoptosis - the programmed death of damaged cells.

The level of IGF-1 in the blood is increased by: insulin, androgens, estrogens, and steroid hormones. Glucocorticoids – reduces the level of IGF-1.

The reasons for changes in the amount of IGF-1 are divided into two groups:

PRIMARY:

Genetic diseases;

Diseases of the hypothalamic-pituitary system.

SECONDARY:

Starvation;

Pathology of the liver, adrenal glands;

Diabetes;

Taking hormonal drugs.

Indications

Indications for use:

Diagnosis of growth disorders;

Monitoring the treatment of acromegaly and dwarfism;

Assessment of changes in exchange status.

Interpretation of results

Insulin-like growth factor is a hormone that is similar in its chemical structure to insulin. It regulates the processes of cell differentiation, their development and growth. Also involved in glucose metabolism processes.

History of discovery

Back in the late 50s of the twentieth century, scientists suggested that there was some kind of intermediary between somatotropin (GH), which is also called growth hormone, and the cells of the body. This conclusion was suggested by the fact that GH had an effect only on a living organism, but when it was introduced into muscle cells, even if they were in a nutrient medium, no effect was observed.

In the 1970s, somatomedins were discovered as these mediators. They were called insulin-like growth factors. Initially, 3 groups of such substances were identified: somatomedin A (IGF-3), B (IGF-2), C (IGF-1). But in the 1980s, it was determined that insulin-like growth factor 2, like 3, was an experimental artifact and did not actually exist. Only the presence of IGF-1 was confirmed.

Structure

Insulin-like growth factor 1 (IGF-1) consists of 70 amino acids forming a chain with intramolecular bridges. It is a peptide that binds to blood plasma proteins, the so-called growth factor carriers. They allow somatomedin to maintain its activity much longer. It lasts several hours, while in free form the specified period is no more than 30 minutes.

The hormone is similar to proinsulin, which is why it got its name. And insulin plays a huge role in the synthesis of somatomedin. After all, it helps the liver receive all the necessary amino acids to launch the mechanism for creating IGF.

Hormone synthesis

This growth factor is considered an endocrine mediator that ensures the action of growth hormone. It is synthesized by liver hepatocytes in response to receptor stimulation. In tissues, almost all of the action of growth hormone is provided by IGF-1. From the liver it enters the bloodstream, and from there, through the mediation of carrier proteins, into tissues and organs. This hormone stimulates the growth of bones, connective tissue and muscles. Insulin-like growth factor is also synthesized independently in many tissues. If necessary, each cell can independently provide itself with this substance.

The secretion of IGF-1 by the liver increases under the influence of estrogens, androgens, and insulin. But glucocorticoids lower it. This is considered one of the reasons why these substances affect the speed of his puberty.

Properties

IGF in muscle cells has growth-stimulating and insulin-like activity. It catalyzes and slows down the process of its destruction. It also shifts metabolism and promotes accelerated fat burning.

Insulin-like growth factor 1 is associated with the pituitary gland and hypothalamus. Its level in the blood depends on the release of other hormones. For example, at low concentrations, the secretion of somatotropin increases. The production also increases. But with a high level of IGF-1, the secretion of these hormones decreases.

A direct relationship has been established between somatostatin and insulin-like growth factor. As one of them increases, the concentration of the second also increases.

It is also worth noting that athletes should not use it as an anabolic steroid. The results of studies have already been repeatedly published, which report negative results from experimental use of drugs that contain insulin-like growth factor (IGF). Taking them can lead to diabetes, cardiac muscle dysfunction, neuropathy, and hormonal imbalances. In addition, this substance is one of the main catalysts for the growth of cancer tumors.

Features of the FMI

It has been noted that insulin-like growth factor 1 is reduced in old age and childhood, and is highest in adolescents. But researchers have also found that older people whose levels of this hormone are closer to the upper limit of normal for their age group live longer. In addition, they are less susceptible to heart and vascular diseases. Separately, it is worth noting that its amount increases during pregnancy.

The concentration in the blood is approximately the same throughout the day. Therefore, it is used to assess disturbances in the production of somatotropin. After all, the concentration of growth hormone in the blood changes throughout the day, the maximum level is determined at night. Therefore, it is problematic to accurately determine its quantity.

Decreased hormone concentration

IGF-1 was not discovered until 1978. Since then, quite a lot of research has been carried out, as a result of which a number of patterns have been established. Thus, its deficiency in childhood causes delays in growth and physical development of the baby. But it is also dangerous if insulin-like growth factor is reduced in adults. After all, underdevelopment of muscles, a decrease in bone tissue density, and a change in the structure of fats are noted.

IGF deficiency can be caused by a number of diseases. Among them are problems with the kidneys and liver. Often the cause of a reduced amount of IGF is a disease such as hypopituitarism. This is a condition in which the production may completely stop or noticeably decrease. But the production of somatomedin also decreases due to nutritional deficiency, or, more simply, starvation.

Increase in FMI

Despite the severe consequences that a lack of IGF-1 causes, one should not assume that increasing its amount is not so bad.

Thus, if insulin-like growth factor 1 is elevated, this will lead to acromegaly in adults and gigantism in children. In children, the disease manifests itself as follows. Their bones begin to grow rapidly. This results in not only enormous growth, but also enlargement of the limbs to abnormally large sizes.

Acromegaly, which develops in adults, leads to enlargement of the bones of the legs, arms, and face. Internal organs also suffer. This can lead to death due to cardiomyopathy, a disease that affects the heart muscle and impairs its functions.

The most common reason that insulin-like growth factor increases is a pituitary tumor. It can be treated with medications, chemotherapy, or surgery. The analysis helps determine how successful the therapy is or check how well the operation was performed. For example, if the tumor was not completely removed, then the concentration of IGF will be increased.

Conducting research

To diagnose changes in the concentration of insulin-like growth factor in modern laboratory centers, the ICL method is used. This is called chemiluminescence immunoassay. It is based on the immune response of antigens. At the stage of isolating the required substance, beacons are attached to it - phosphors, which are visible under ultraviolet light. Their luminescence level is measured using special equipment - a luminometer. It is used to determine the concentration of the isolated substance in

Preparing for the study

In order to determine the insulin-like growth factor IGF-1, it is necessary to donate blood in the morning, always on an empty stomach. You are only allowed to drink plain water. The interval between the last meal and the collection of material for research should be more than eight hours. It is important that the patient is at rest 30 minutes before the test. Venous blood is taken for testing.

Average indicators

When filling out forms in the laboratory, it is important to indicate your age correctly. After all, it determines what the insulin-like factor should be and is established for each age category individually. It is also necessary to focus not on average indicators, but on the data of the laboratory in which you took the tests. For example, in adolescents aged 14-16 years, the hormone level can range from 220 to 996 ng/ml. And in adults who are over 35 years old, it should not exceed 284 ng/ml. The older the patient, the lower the limit level of IGF should be. After 66 years, the norm is set within 75-212 ng/ml, after 80 - 66-166 ng/ml.

In children, IGF levels will also depend on age. In newborn babies who are not yet 7 days old, it should be from 10 to 26 ng/ml. But after the 16th day and up to 1 year, the norm is set at 54-327 ng/ml.

Diagnosis of diseases

By determining insulin-like growth factor, a number of diseases can be diagnosed. An increase in its level indicates not only gigantism in children or acromegaly in adults. This may be a sign of tumors of the stomach and lungs, chronic renal failure. But it is worth noting separately that it can be increased by taking dexamethasone, alpha-adrenergic agonists, and beta-blockers.

A decrease in IGF levels in children may indicate dwarfism. In adults, levels are often reduced due to hypothyroidism, liver cirrhosis, anorexia nervosa, or simply due to starvation. Another possible cause is chronic lack of sleep and taking a number of medications with high doses of estrogen.

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Optimal growth and cell division, protecting the body from aging, accelerating fat burning, activation of somatotropin, maintaining heart function and bone density - this is not a complete list of the effects of IGF - 1. What is it? Insulin-like growth factor is a hormone without which optimal development of the body is impossible.

It is important to know why the secretion of somatostatin is impaired, what negative signs indicate a decrease in the concentration or an excess of IGF-1. Factors influencing the result of the analysis, rules for preparing for the study of somatomedin levels, the dependence of the hormone concentration on gender and age indicators - these and other important nuances are reflected in the article.

general information

Somatomedin or insulin-like growth factor is an active hormone that is structurally similar to insulin. The production of IGF-1 occurs in hepatocytes (liver cells). After penetration into the bloodstream with the participation of carrier proteins, IGF-1 enters all departments and activates the growth of bone, muscle and connective tissue. Somatomedin performs the same functions as growth hormone and additionally stimulates insulin receptors.

IGF-1 is a necessary element for the activation of growth hormone. The concentration of somatomedin affects the level of somatoliberin, without which optimal secretion is impossible. The principle of feedback works: the production of hormones of the pituitary gland and hypothalamus increases with a decrease in the secretion of IGF-1 and vice versa.

The half-life of IGF-1 associated with receptors is significantly higher than that of the free fraction of the hormone: from 12 to 15 hours and 10 minutes. The active substance includes 70 amino acids. The minimum concentration of the growth regulator is in the elderly and children under five years of age.

Somatostatin is a mediator of growth hormone, but other types of hormones also have a noticeable effect on the level of IGF-1. Increase the concentration of somatostatin: both androgens and progestins. Reduce the level of IGF-1: steroids, glucocorticoids (hormones of the gonads and adrenal glands).

Activation of somatomedin secretion occurs with the consumption of protein foods, parenteral nutrition, physical activity, and high levels. Increased secretion of growth hormone also affects the increased production of IGF-1. During research, scientists have found that an excess of an important regulator often provokes and accelerates the growth of cancerous tumors.

Somatomedin deficiency negatively affects processes in the body: the rate of apoptosis (programmed cell death) increases. Lack of the hormone provokes early aging of the body against the background of insufficient division and growth of cells of internal organs, skeleton, and blood. A decrease in secretion occurs with a deficiency of growth hormone, during pregnancy (3rd trimester), with an excess of estrogens, against the background of inflammatory processes and obesity, during menopause. The synthetic hormone somatomedin is used in the complex therapy of some forms of dwarfism.

Unlike growth hormone (somatotropin), IGF is released not only with the onset of a period of rapid growth in children and adolescents, but also throughout life. After 50 years, somatomedin levels gradually decrease, but the concentration is quite high even in old age.

Effects in the body

The hormone somatomedin is needed for many processes:

• activation of growth hormone in cells and tissues. Without sufficient secretion of IGF-1, somatotropin is inactive;
• reduces the rate of apoptosis at the cellular level;
• activates specific insulin receptors, which helps to penetrate inside the cell and create a powerful energy reserve;
• stimulates the growth of cells of various departments. Somatomedin has the most active effect on the structures of bones, nerve fibers, muscle and cartilage tissue, liver, lungs, and stem cells in the blood;
• supports the functioning of the heart muscle, the ability of cardiocytes to divide and grow.

Another effect is the acceleration of protein breakdown and active fat burning. This nuance is used by unscrupulous athletes: IGF-1 is recognized as doping, and the use of the hormone to improve results during competitions is prohibited.

Norm for adults and children

Optimal indicators of somatomedin (measurement in mg/l):

• age from 0 to 2 years: girls - from 11 to 206, boys - from 31 to 160;
• age from 2 to 15 years: girls - from 286 to 660, boys - from 165 to 616.

Adolescence and youth:

• girls - from 398 to 709;
• boys - from 472 to 706.

Adult women and men:

• from 20 to 30 years old - from 232 to 385;
• from 40 to 50 years - from 140 to 310;
• after 60 years - from 94 to 269.

The level of somatomedin changes throughout life; in females and males, IGF-1 indicators are different. Acceptable values ​​vary slightly between laboratories. When assessing the results of the analysis, the doctor takes into account the gender and age of the patient. The concentration of somatomedin is stable throughout the day, in contrast to somatotropin, the level of which increases at night.

Indications for somatomedin analysis

The endocrinologist refers adults and children to the laboratory in the following cases:

• very tall or short height of the child;
• to assess the functionality of the pituitary gland;
• with a significant change in appearance and growth of certain parts of the body (limbs, thickening of the hands, nose, ears) in adults;
• with symptoms of pathologies associated with abnormalities in the secretion of growth hormone;
• if you suspect osteoporosis;
• in the process of treating gigantism and dwarfism, to assess the dynamics of growth hormone production;
• against the background of a noticeable discrepancy between the actual age of the patient and the condition of the bone tissue.

Note! The results of studying the level of IGF provide an indirect idea of ​​the secretion of growth hormone (somatotropin) in children and adults.

Features of the study

Preparation:

• on the day before the somatostatin test, you should not exercise intensively in the gym, it is advisable to remain calm;
• in consultation with your doctor, it is important to stop taking medications for 1-2 days, with the exception of vital ones;
• Do not drink alcohol or smoke during the day;
• blood is donated strictly on an empty stomach, necessarily after fasting for 8-10 hours;
• You need to take the test early in the morning (from 7 to 10 o'clock).

It is imperative to take a test not only for somatomedin, but also to determine the level of growth hormone (GH). To find out the reasons for deviations in the level of IGF-1 and the causes of pathological processes, the doctor additionally prescribes other types of studies. The patient must donate blood for pituitary and thyroid hormones, sex regulators. A blood test (general and biochemical type), urine test, kidney tests, and clarification of the level of total protein and albumin are required.

Causes and symptoms of deviations

Temporary changes in the secretion of somatomedin are associated with natural factors and conditions (age-related changes, pregnancy), bad habits (smoking) and pathological processes of various kinds. If symptoms appear that indicate a deficiency or excess of an insulin-like substance, you should visit. It is important to pay attention to manifestations of gigantism or dwarfism in children while growth plates are open in order to correct hormonal levels in time.

Look at the list of gonadotropins, and also learn about their role in the human body.

The page is written about deviations and normal levels of insulin in the blood of women on an empty stomach and after meals.

On the page, read about the likely consequences and complications of radiation therapy in oncology for breast cancer.

IFR - 1 increased

Manifestations:

• painful sensations in the joints;
• enlarged spleen, heart, liver;
• creating prerequisites for the formation in children and adults, development;
• children are much taller than their peers. It is important to determine hormonal status to differentiate gigantism from hereditary tall stature;
• fatigue, severe headaches, excessive sweating;
• increased blood pressure without obvious causes or provoking factors;
• the feet and hands, facial bones enlarge (the most noticeable changes are in the area of ​​the brow arches and the mandibular area);
• impaired vision and smell;
• erectile dysfunction, decreased libido.

Causes:

• excessive secretion of somatotropin in children, while growth plates are open, development of gigantism;
• against the background of a tumor producing somatotropin;
• hypopituitarism is hyperfunction of the pituitary gland, against the background of which the secretion of regulators increases.

Decreased hormone levels

Negative symptoms in children:

• slow mental and physical development in early and teenage years;
• late puberty;
• As boys and girls grow older, their faces remain “childish,” “doll-like”;
• muscle weakness;
• significant growth retardation.

In adults:

• sagging and muscle weakness;
• development of osteoporosis;
• lipid profile disorder.

Provoking factors and diseases:

• pituitary dwarfism;
• starvation, anorexia due to nervousness;
• chronic diseases of the liver and excretory system;
• - decrease in the functional activity of an important endocrine organ - the thyroid gland;
• insufficient protein intake when following certain types of diet;
• Laron syndrome: patients exhibit somatotropin insensitivity at the level of IGF - 1;
• improper absorption of substances in the intestines (malabsorption syndrome).

To normalize the level of somatotropin, you need to review the diet, adjust the dosage of hormonal drugs, eliminate sleep deficiency, stabilize the functioning of the adrenal glands, thyroid gland, and gonads. After identifying a hormonally active tumor, doctors prescribe surgical treatment. If there is a deviation in growth in children, you should not hesitate to visit a specialized specialist: after the final formation of the skeleton, it is difficult to influence the development of bone tissue. All actions to change hormonal levels when IGF-1 indicators deviate must be coordinated with an endocrinologist.

One of the hormonal substances vital for the human body is insulin-like growth factor - IGF-1. This chemically complex substance is produced in microscopic quantities, but indirectly acts as a regulator of many life processes: differentiation, growth and development of cells of tissues and organs, protein synthesis, lipid metabolism, etc. The functions of the hormone in the body are multidirectional and diverse, therefore insufficient or excessive production IGF-1 can cause serious disruptions in its functioning and provoke the development of many diseases.

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What it is?

Insulin-like growth factor (IGF-1, somatomedin C) is a peptide that gets its name due to its chemical affinity for insulin. The substance is synthesized mainly by liver hepatocytes with the direct participation of insulin: the hormone ensures the production of all the necessary 70 amino acids to trigger the synthesis of somatomedin. IGF-1 is then transported through the bloodstream by carrier proteins to all organs and tissues. Somatomedin can also be synthesized independently in other tissues of the body.

Three-dimensional image of IGF-1

In the 70s of the last century, scientists discovered it as an intermediary substance that ensures communication between the growth hormone - somatotropin (GH) and the cells of the body. Almost all of the action of growth hormone in tissues is provided by IGF-1. To maintain its activity for up to several hours, it binds to special carrier proteins in the blood plasma. Necessary for the normal growth of children; in adults it is responsible for the growth of muscle tissue (plays the role of an anabolic hormone).

Stimulators of IGF-1 synthesis are:

• HGH - growth hormone;
• protein food;
• estrogens;
• androgens;
• insulin.

On the contrary, glucocorticosteroids inhibit the secretion of somatomedin. Since IGF-1 normally stimulates the growth of bones, connective and muscle tissue, this is one of the proven facts of the adverse effect of glucocorticosteroids on the rate of growth of the body, its development and puberty.

Unlike growth hormone, which is produced more intensely at night, the concentration of somatomedin is stable. Produced by the body throughout life, and not just during periods of active growth.



Basic functions in the body

Chemists and biologists continue to research the substance, but several mechanisms of action have already been confirmed by scientific research:

1. 1. Somatotropic hormone on its own practically does not interact with the cells of the peripheral tissues of the body. IGF-1 is the main primary messenger required for growth hormone to enter cells.
2. 2. Somatomedin stimulates the growth, differentiation and development of skeletal muscle cells, connective, nervous and bone tissue, blood stem cells and cells of such important internal organs as the liver, kidneys, and lungs.
3. 3. IGF-1 slows down apoptosis - genetically and physiologically programmed cell death.
4. 4. Accelerates protein synthesis and slows down its destruction.
5. 5. IGF-1 increases the ability of heart cells - cardiomyocytes - to divide, thereby increasing the performance of the heart muscle and protecting it from aging. It has been proven that older people with high levels of IGF-1 suffer less from cardiovascular diseases and live longer.
6. 6. Able to activate insulin receptors, due to which glucose enters the cell and creates an additional energy reserve.



Of great interest is recent research into the role of somatomedin in oncological processes. Recent clinical trials have shown the possible oncogenic activity of elevated levels of the substance in the body and the relationship between the occurrence of tumors and high levels of IGF-1.



Symptoms of IGF-1 deficiency and excess

The lack of somatomedin secretion in the child’s body manifests itself as follows:

• short stature, dwarfism;
• slow physical and mental development;
• decreased muscle tone;
• a specific “doll” face;
• absence or severe delay of puberty.



Dwarfism

In adult patients, osteoporosis, a more or less pronounced decrease in muscle mass, changes in the lipid profile are observed - potentially dangerous changes in fat metabolism.

Excess IGF-1 production also leads to the development of various pathologies:

• Gigantism in children, manifested by intense bone growth, which leads not only to abnormally high body growth, but also to an increase in arms and legs to enormous sizes;
• in adulthood, there is a pathological increase in the facial bones, especially the lower jaw and brow ridges, as well as the hands and feet;
• increased sweating, chronic fatigue, headache, joint pain appear;
• a more or less pronounced increase in internal organs (heart, liver, spleen) may be observed;
• dysfunction of smell and vision;
• in men I diagnose decreased libido and erection;
• significant impairment of glucose tolerance and development of diabetes mellitus;
• persistent increase in blood pressure.



Gigantism



Features of preparation for analysis

Blood sampling for analysis for IGF-1 is carried out in the morning from 7 to 10 o'clock, on an empty stomach, after at least 8-12 hours of fasting. You are allowed to drink still water. To obtain a reliable result, two days before and on the day of the test, it is prohibited to consume alcohol and tobacco products, or take potent medications (with the exception of vital drugs). Intense physical activity the day before and on the day of blood collection is prohibited.

The IGF-1 test does not replace the test for growth hormone (GH) levels in the blood. To obtain a reliable picture of the pathology, both studies are performed!

Indications for control

There are a number of medical indications for periodic or continuous monitoring of IGF-1 levels in the blood. It is recommended to take the analysis if:

• various pathologies associated with excess or deficiency of growth hormone;
• excessively short or, on the contrary, high growth in a child;
• a sharp increase in individual parts of the body in an adult and corresponding changes in appearance;
• discrepancy between bone age and biological age;
• diagnostic assessment of pituitary function;
• testing the effectiveness of treatment with growth hormone drugs.

Content standards for IGF-1

Hormone levels always depend on age and gender, with physiologically normal minimum levels of somatomedin observed in children under 5 years of age and the elderly. The norms for somatomedin content (mg/l) depending on age and gender are shown in the table.

Age (years)	Boys (men)	Girls (women)
0-2	31-160	11-206
2-15	165-616	286-660
15-20	472-706	398-709
20-30	232-385	232-385
30-40	177-382	177-382
40-50	124-310	124-310
50-60	71-263	71-263
60-70	94-269	94-269
70-80	76-160	76-160

The levels of IGF-1 in the blood are not established by international standards, and therefore directly depend on the research methodology and the reagents used in the laboratory. In laboratory test forms, the norm is indicated in the “reference values” column.

The test results may be affected by a number of patient-specific factors or conditions. Secretion can be increased by:

• protein food;
• dairy products;
• stress;
• high physical activity;
• parenteral (via IV) nutrition;
• testosterone.

In turn, the indicator may be lowered due to:

• high doses of estrogens;
• xenobiotics (heavy metals, pesticides, petroleum products, synthetic surfactants, etc.);
• pregnancy - with a decrease to 30% in the first trimester and a gradual subsequent increase;
• overweight in the obesity stage;
• climacteric processes;
• various inflammatory processes.

Causes of pathological increase and decrease in IGF-1

The reason for the decrease in the concentration of the indicator can be both external and internal factors:

• pituitary dwarfism (deficit in the production of growth hormone by the pituitary gland), easily overcome with the replacement administration of growth hormone;
• individual insensitivity of IGF-1 to growth hormone at the level of IGF-1;
• mutation of GH receptors (SHP2 and STAT5B);
• anorexia and starvation of nervous etiology;
• acute lack of protein in food during extreme diets;
• chronic liver and kidney diseases;
• disturbances in the absorption of nutrients in the intestine (malabsorption), which occurs during chronic pancreatitis, surgical removal of parts of the intestine;
• hypofunction of the thyroid gland (hypothyroidism).

Increased secretion of the indicator is caused by pathological conditions of the pituitary gland:

• adenohypophysis (acromegaly, pituitary tumor) - dysfunction of the anterior pituitary gland;
• gigantism (macrosomia) - increased secretion of growth hormone by the pituitary gland until the closure of bone growth zones;
• hyperpituitarism - increased hormonal function of the pituitary gland.

The human body is a complex integral system, where disruption of the normal functioning of one organ immediately causes a chain reaction of various pathological changes, especially with regard to hormones - the main regulators of life. Therefore, established deviations from normal limits in somatomedin indicators help to diagnose and carry out timely treatment of many diseases.