What hormones are related to the thyroid gland. Available words about the norm and the consequences of deviation of thyroid hormones

The thyroid gland is a significant human organ that affects many body systems through the hormones produced in it. Violations in the work of the gland are palpable physically: first of all, it suffers nervous system, heart and blood vessels, reproductive function, skin and their appendages decrease. A person may be disturbed by a rapid heartbeat or bradycardia, he becomes irritable or apathetic, dryness, flabbiness of the skin, brittleness and hair loss appear. Often, female infertility is associated with impaired functioning of the thyroid gland. All these problems are caused by a deficiency or excess production of thyroid hormones. Therefore, it is so important to know which hormones the thyroid gland produces and how to monitor their performance in blood tests.

The main task of the thyroid gland is the production of thyroid hormones that control many functions of the body:

1. Triiodothyronine (T3).
2. Thyroxine (T4).

The hypothalamus (a small structure of the brain) coordinates the work of almost all body systems, including the thyroid gland. It produces thyroid-stimulating hormone (TSH), which has an inverse correlation with the amount of thyroid hormones. TSH keeps normal T3 and T4. Due to its ability to suppress the production of thyroid hormones, they are not produced uncontrollably, which would lead to sad consequences. An unreasonably high amount of hypothalamic hormones also entails many problems, up to the extinction of thyroid function.

The maximum concentration of TSH is determined in newborns, and with age, its amount gradually decreases, reaching a stable level by maturity.

For the most part, thyroid diseases affect women (on average, the incidence is 20% higher than that of men). However, in recent years, problems with the endocrine system have been actively progressing and affect both women and the male half of the world's population.

Hormones in women are great importance for well-being and the function of procreation, affect appearance. Secreted by the thyroid gland is no exception. Therefore, failures in the work of the gland itself negatively affect the entire body.

The most common diseases of the thyroid gland are caused by a violation of its function and are associated with a deficiency or excess of hormones produced by this organ.

Autoimmune thyroiditis is chronic inflammation thyroid gland, which has an autoimmune genesis. In etiology this disease note the role of hereditary predisposition. Depending on the stage of the disease, the body may experience both a lack of thyroid hormones and suffer from their overabundance.

Another serious women's problem- infertility, is also associated with impaired thyroid function.

What causes endocrinological problems? By what signs can you understand that it's time to see a doctor? This will be discussed below.

The importance of thyroid hormones in the male body

Occurring in males, thyroid dysfunction causes similar problems, although they are 4 times less common than in women. The situation is complicated by the fact that men later apply for medical care and are prone to trigger disease. The importance of thyroid hormones for men cannot be overestimated.

Hormonal disorders in men are the cause of a number of pathologies:

• erectile dysfunction.
• Hyperplasia of the prostate.
• Testicular hypoplasia.
• Infertility associated with a decrease in sperm quality (poor sperm motility, decreased secretion).

In thyroiditis, when there is a hypothyroid state, hormone deficiency in men leads to problems in reproduction. During the thyrotoxic phase, when there are too many hormones, sexual functions are not disturbed, and there are no difficulties with fertilization.

The role of thyroid hormones

As mentioned above, the thyroid gland produces two hormones - T3 and T4. They have a very important mission. Which one exactly remains to be seen.

main processes, hormone-regulated thyroid glands:

• regulation of metabolism;
• maintenance of tissue respiration;
• control over the formation of heat in the body.

Following the advice of doctors, you need to contact an endocrinologist as early as possible, at the first sign of trouble. Any, even minimal changes in well-being, may indicate a developing pathology in the body. This is especially true for the thyroid gland. This organ is vulnerable to adverse factors external environment, under the influence of which develop serious illness thyroid glands. The further the disease has gone, the more time and effort the treatment takes.

If treatment started on early stage diseases, you can count on its maximum effectiveness. In advanced cases, with a progressive disease, recovery is delayed, despite ongoing therapeutic measures.

Levels of hormones in the blood

In the results of the examination for hormones, reference values ​​\u200b\u200bare indicated (normal limits). This is necessary for doctors to navigate the indicators, since laboratories do not use common units of measurement in the designation of quantities.

Normal hormone levels in one of the measurement systems:

Hormone	International designation	Reference values ​​(norm)
thyrotropic	TSH	0.4 - 4.2 mmol/l
Thyroxine general	T4 general	62 – 141 nmol/l
Triiodothyronine total	T3 general	1.17 - 2.18 nmol/l
thyroxine free	T4 free	9 - 25 pmol/l
Triiodothyronine free	T3 free	1.2 - 6 pmol/l

Deviations from the norm in the analyzes

When, when assessing the hormonal status of the thyroid gland, indicators are observed that go beyond the limits of the norm, certain pathological conditions in the patient can be assumed. For example, infectious thyroiditis, nodular formations, chronic autoimmune inflammation. A number of pathologies can cause disturbances in the functioning of the thyroid gland, which, in turn, can disrupt the functions of other body systems.

Among possible pathologies associated with a change in the content of hormonal substances in the blood, the main ones can be distinguished:

Hormone	Pathologies caused by changes in the concentration of the hormone
	Increased rate	Reduced rate
Thyrotropic (TSH)	Hypothyroidism (accompanied by a low T4). Hashimoto's thyroiditis. It is also observed during pregnancy, physical exhaustion, emotional stress.	Thyrotoxicosis (accompanied by high rates T4), Basedow's disease, pituitary lesion.
Triiodothyronine (T3)	Toxic goiter, nephrotic syndrome, chronic diseases liver.	Emotional stress, stress. It is observed during starvation, injuries, protein-free diets.
Thyroxine (T4)	Hyperthyroidism. thyroiditis, toxic goiter, myeloma, liver failure, obesity, immunodeficiency, renal failure.	Hypothyroidism. Endemic goiter, autoimmune thyroiditis, inflammation in the pituitary gland.

It is possible to suspect the development of hidden pathologies in the thyroid gland with a decrease TSH level and maintained within the normal range of T3 and T4.

The reliability of the study of hormonal status is affected by pregnancy, hepatitis, immunodeficiency states. This should be taken into account when evaluating indicators.

Who needs to take a blood test for hormones

All newborns still in the hospital are prescribed a blood test for hormones. It is important to assess their level in the baby's blood in order to exclude the possibility of developing a pathology such as cretinism, which manifests itself in physical and mental retardation.

Adult patients are referred for a blood test by a narrow specialist (doctor), who, based on complaints, has reason to assume that the patient has an endocrine pathology. These may include physicians in the following specialties:

• cardiologist (for complaints of interruptions in the work of the heart);
• therapist (if a patient has asthenia for no apparent reason);
• surgeon (if abnormalities are found in the organs);
• endocrinologist (if characteristic symptoms and an altered thyroid gland are detected);
• gynecologist (when deciding on the establishment of a factor of infertility);
• ultrasound doctor (if changes are detected during ultrasound of the thyroid gland).

Rules for donating blood for hormones

The content of hormones in the blood depends on gender, age, emotional state of a person, and even on the biological clock. For example, the maximum concentration of thyroid hormones is observed at night, and by morning it decreases to the minimum.

Therefore, blood sampling for analysis is carried out in the morning, before 10-00 hours. The patient is advised to come to the clinic early so that he can bring his emotional background to a stable state.

For analysis take venous blood. For this nurse the treatment room imposes a tourniquet on the patient's arm above the elbow and treats the skin of the inner surface of the elbow joint with an alcohol wipe. As soon as the vein is sufficiently filled with blood, it takes the biomaterial with a sterile catheter.

To the puncture site skin and a hematoma has not formed in the vein, the procedural nurse pulls out the needle and immediately applies a bandage to the manipulation site. If nevertheless there is a complication in the form of a hematoma or edema, then you can make a warm compress.

A relative contraindication for blood sampling is a hereditary disease associated with poor blood clotting (hemophilia). With this disease, it is very difficult to stop bleeding even from a small vessel. Such a patient is obliged to warn health workers about his illness so that they can administer hemostatic drugs to the patient in a timely manner.

The result of a blood test for hormones is usually ready the next day after the material is taken. Readiness terms may vary depending on the conditions of a particular laboratory (delays may be associated with the need to transport the biomaterial to a laboratory located in another city).

A doctor can evaluate the results of the examination (as a rule, this is an endocrinologist, but there may also be a doctor of a related specialty - a gynecologist, a family doctor). Based on the results of the tests, the doctor chooses the tactics of managing the patient: he immediately prescribes treatment or sends him for further examination.

The thyroid gland is the largest, weighing about 20 grams and a volume of not more than 18 cm3, endocrine gland in the shape of a butterfly, wrapping around the trachea. It differs not only in size, but also in a set of vital functions, for the implementation of which thyroid hormones are responsible. Highly active substances are designed to regulate the activity of all organs and systems of the human body. Let us consider in more detail what hormones the thyroid gland produces, and what duties are assigned to this main endocrine organ.

Thyroid hormones

First of all, it is important to know what hormones the thyroid gland secretes. It should produce iodothyronines, which act as the main storage of iodine. Iodine-containing thyroid hormones are called thyroxine T4, triiodothyronine T3, diiodothyronine T2, monoiodothyronine T1. Their production is assigned to the spherical A-cells of the thyroid follicles. Their synthesis is controlled by thyroid-stimulating substance (TSH) - this is the main thyroid hormone, which is produced in the pituitary gland purely for its functioning.

The hormones T1, T2, T3 and T4 have a strong chemical similarity, their number of iodine ions in the molecules distinguishes them, which is reflected in the designation. Each triiodothyronine molecule contains three iodine atoms, thyroxine - four, diiodothyronine - two, and monoiodothyronine, respectively, one. It is these thyroid hormones that regulate energy metabolism, which is used to maintain the vital activity of the whole organism while at rest.

The thyroid gland also secretes the polypeptide hormone calcitonin, which is involved in the regulation of calcium metabolism and the formation of the skeletal system. Parathyroid hormone, calcitriol (vitamin D) and a number of other substances are involved in the complex process of calcium deposition in bones simultaneously with calcitonin. Unlike parathyroid hormone, which increases the concentration of calcium in the blood, calcitonin increases the deposition of calcium in bone beams and regulates its level and phosphorus.

Thyrocalcitonin can be synthesized not only by the endocrine glands (thymus, parathyroid glands), among which the main responsibility for its production lies with the thyroid gland, but also by other organs, such as the lungs, intestines, and others. Calcitonin has a complex chemical structure, which includes 32 chains of amino acids. Parafollicular C-cells of the thyroid gland of neuroendocrine origin are responsible for its formation.

The mechanism of formation of thyroid hormones

The regulation of hormone secretion, the formation and release of highly active iodine-containing substances into the bloodstream is produced by the pituitary gland, with the participation of thyrotropin, without which the production of triiodothyronine and thyroxine is impossible. The next important task of TSH is the role of this substance in the growth of the thyroid gland. The power of TSH release into the bloodstream is coordinated by the hypothalamus, on which the synthesis of TRH (thyrotropin releasing hormone) depends. Consequently, the formation of thyroid hormones is subject to a complex, multilevel mechanism.

The synthesis of thyroid hormones occurs due to such a mineral as organic iodine. As a result of ingestion of iodides (iodine atoms), they, moving with the bloodstream, are delivered by a carrier protein to the thyroid gland, the activity of which is controlled by TSH. There occurs the organization of iodides, that is, their oxidation. Further, after iodination of tyrosine in the thyroglobulin molecule and its condensation, thyroglobulin is transferred to the follicle colloid. Then comes the proteolysis of thyroglobulin with the formation of T4 and T3, after which the process of mutual penetration of molecules, called diffusion, T4 and T3 into the bloodstream takes place.

Purpose of thyroid hormones

All active substances produced by the thyroid gland, such as the hormones TSH, T3 and T4, are different from other elements endocrine system by the fact that they do not act locally, in particular, on the target cells of the controlled organ. And comprehensively, that is, for all organs, soft tissues and systems human body. Consider what the hormones TSH, T3, T4 of the thyroid gland affect. Their functions are very important and varied.

The effect of thyroid hormones on the body:

1. Complete formation of the brain and central nervous system.
2. Involved in the production of red blood cells.
3. Normalization of heat transfer.
4. Activation of protein synthesis required to create new cells.
5. Strengthening the release of glucose from fats and proteins and increasing its amount in the blood.
6. Stimulation of the breakdown of fats in the places of their deposition, due to which there is a rapid decrease in body weight.
7. The development of the sexual sphere, through the production of sex hormones.
8. Anabolic effect, due to which the body grows and matures, differentiation of the skeletal mass is carried out.

The correct activity of the thyroid gland in conjunction with the pituitary and adrenal glands is a guarantee of a full-fledged metabolism in the body and its speed, as well as internal homeostasis. When there is a violation of the coherence of work and the development of the prescribed norm of hormones, this inevitably affects human health. If there is a lack of thyroid hormones, the metabolism slows down.

Often this deviation is manifested by rapid and unreasonable, in terms of the amount of food intake, weight gain, which, among other things, is difficult to eliminate. Thyroid deficiency is usually corrected pharmaceutical preparations containing iodine in an easily digestible form and in the right amount. And in addition to foods rich in iodine, such as seafood, seaweed, sea salt and others.

The action of thyroid hormones directly affects the state of immunity. A protective system that reflects all adverse impacts both from the outside as pathogens, and from the inside in the form of autoimmune reactions of the body. This is due to the fact that before penetrating into the structures of the body, all infections first enter the thyroid gland.

When autoimmune diseases occur, the same sequence is observed - pathogens pass through the thyroid gland. Therefore, with frequent ailments, it is necessary to ensure the healthy functioning of this organ.

Since the thyroid gland may simply not be able to cope with the scale of aggressive environment during epidemics, for example, or internal deviations, in the event of a weakening of the body's defenses.

The role of the thyroid gland is also great for the reproductive system in women. When normalizing menstruation, you will definitely need to make sure that the failure of the cycle is not the result of a malfunction of this endocrine organ. During pregnancy and after childbirth, it is advisable to carefully monitor that hormone levels TSH thyroid glands were always normal.

The content of thyroid hormones and pathology in case of deviations from the norm

A blood test for the components of the thyroid gland determines their quantitative level. The state of normal thyroid hormones is called euthyroidism. The changing level of thyroid hormones, when elevated, provokes hyperthyroidism or thyrotoxicosis, and when reduced, hypothyroidism. Hormonal failure in the direction of increase or decrease in the blood flow is controlled by the main hormones TSH, T3, T4 of the thyroid gland. Their norm should be 0.16-4.06 mIU / l for thyroid-stimulating hormone, from 2.4 to 5.7 nmol / l for triiodothyronine, from 11.4 to 22 nmol / l for thyroxine and from 5.4 to 27 pmol/l.

Excess (hyperthyroidism) of thyroid hormones:

• Hyperthermia, which is expressed in an episodic, but fairly persistent increase in body temperature to critical levels.
• Weight loss with a stable diet.
• Sharp bursts of emotional and motor activity, manifested in the form of excessive excitement, aggressiveness. At later stages, the central nervous system shows a decrease in memory and intelligence.
• Failure of cardiac activity, violating the heart rhythm. Due to vascular hypertonicity, there is an increase blood pressure and severe tachycardia.
• Job disruption gastrointestinal tract manifested by disorders of the digestive system.
• Tremor of the upper limbs.

indicators advanced level components of the thyroid gland are TSH, T3 and T4. With hyperthyroidism, the ratio of thyroxine and triiodothyronine increases, and thyroid-stimulating hormone decreases. Depending on fluctuations in the ratios of titers between these hormones, endocrinologists make an appropriate diagnosis.

Deficiency (hypothyroidism) of thyroid hormones of the thyroid gland:

• Hypothermia, which reveals itself in a stable decrease in body temperature below normal.
• Increase in body weight with a normal diet.
• Withering and dryness of the skin, brittle nails.
• Pathological processes of the excretory system, which are expressed in swelling of the face and limbs.
• Pressure decreases (hypotension), and bradycardia is observed from the side of the heart.
• Failures in the biological rhythm - at night there are difficulties with falling asleep, and during the day it accompanies a lethargic state.

The cause of this condition may be a lack of iodine or substances involved in the synthesis of the hormone. On top of that, the culprits of endocrine disruption are pathogens that interfere with the full synthesis of thyroid hormones. Also taking some specific medications, removal of the thyroid gland or an insufficient amount of TSH. Myxedema is a dangerous condition for adults. But even more detrimental to health is hypothyroidism, when it occurs in childhood. Because it can provoke mental, physical and mental retardation of varying severity.

Analysis of thyroid hormones

The study of hormones for the thyroid gland is the determination of the quantitative content of thyroid TSH hormones, T4, T3. The blood test for thyroid hormones is carried out simultaneously with the test for antibodies to thyroperoxide (TPO) in order to obtain a full clinical picture.

Table of thyroid hormones TSH for women.

Names	Normal value	Interpretation
TSH	0.4–3.9 µIU/ml	An increase is the primary stage of hypothyroidism or the secondary degree of thyrotoxicosis. Reduction - primary or secondary stage of hyperthyroidism.
T3	2.61–5.68 pmol/l	Hypothyroidism or thyrotoxicosis.
T4	9–20 pmol/l
Antibodies (AT-TPO)	up to 30 IU/ml negative indicator	Autoimmune pathologies, postpartum thyroiditis.
	30–100 IU/ml border indicator
	more than 100 IU/ml positive effect
Antibodies (AT-TG)	up to 100 mU/l	Autoimmune diseases.
thyroglobulin	<1–2 нг/мл - тиреоидэктомия	Increase - subacute thyroiditis.
	< 50 нг/мл - норма
	< 70 нг/мл - дефицит йода

The indicator of active substances of the thyroid gland, determined during the study, depends on belonging to the male or female sex and age. Reference values ​​fluctuate throughout the day (circadian rhythm). Thus, the saturation of the pituitary gland with thyroid-stimulating hormone was recorded in the evening and at night. And the concentration of thyroid hormones thyroxine and triiodothyronine is most pronounced in the morning.

Having received a blood test, where the indicators are slightly deviated from the norm, you first need to take into account the climate, season, individual properties of the body, age and sex characteristics, and other information relevant to the examination.

In contact with

Thyroid hormones are biological substances produced in a certain amount in all people.

Deviations from the norm are accompanied by a deterioration in general well-being.

Often a person does not even suspect that the cause of fatigue, apathy and depletion of energy resources is hidden in a change in thyroid cells.

It is difficult to overestimate in the human body.

This organ has a bilobed shape and is located in the trachea. The weight of a healthy thyroid gland does not exceed 25 grams.

In children of the first months of life, hormone-producing tissue weighs 2 grams.

The thyroid gland has a vesicular structure. It contains many follicles that synthesize, store and produce hormones - substances necessary for the proper functioning of the endocrine apparatus and ensuring the vital functions of the human body.

The anatomy and physiology of the thyroid gland makes it invisible to humans. With the development of pathological processes, tissues increase, which can be seen with the naked eye.

A differential study of the thyroid gland helps to determine the causes of deviations.

Diagnostics is subject to quantitative indicators of hormones:

• thyrotropic (TSH);
• total thyroxine (T4)
• free triiodothyronine (st3);
• total triiodothyronine (T3);
• antibodies to thyroperoxidase;
• antibodies to thyroglobulin (TG).

Ensuring growth, emotional, mental and physical development are the main functions of thyroid hormones. The secretion of biological substances and their work is disturbed with a lack of iodine.

For this reason, in order to maintain normal indicators, a sufficient amount of iodine-containing substances must be supplied to the human body.

Thyroid hormones provide heat transfer, metabolic processes, organize the proper function of the cardiac, vascular, nervous, respiratory systems, increase the oxygen demand of cells, and participate in protein synthesis.

The thyroid gland and its hormones are responsible for providing the body with energy resources, maintaining metabolic processes, organizing a complex relationship between the departments of the endocrine apparatus.

The tasks of the endocrine gland can be collected in the list:

• maturation, development and maintenance of the work of all organs and systems;
• maintaining physical activity and ensuring energy exchange;
• participation in the chemical and physical processes of the body;
• blood saturation with useful microelements;
• ensuring water-salt metabolism and other metabolic processes;
• control of the pancreas, adrenal glands, sex glands and other target organs;
• organization of adaptive reactions.

If the hormones are normal, then the person feels good, and all the processes occurring in his body are debugged.

An increase and decrease in the quantitative indicators of biological substances is accompanied by a clinical picture and has certain reasons.

Excess thyroid hormones

An increase in thyroid hormones is the result of toxic goiter and hypothyroidism. Also, an increase in the concentration of T4 and T3 is determined in inflammatory diseases of the organ - thyroiditis of various etiologies.

Increased activity of the thyroid gland is observed with liver pathologies, immunodeficiency virus, postpartum hormonal changes in women, tumor processes.

Signs of an excess of thyroid substances are the following conditions:

• disruption of the ovaries in women, menstrual irregularities, lack of ovulation;
• tachycardia, arrhythmia, increased heart rate;
• an increase in the levels of hormones synthesized by the adrenal glands;
• increased sweating, sensation of a rush of heat;
• swelling of the eyelids;
• wetness of the palms and feet;
• muscle weakness;
• dyspeptic disorders;
• increased appetite and increased thirst against the background of weight loss;
• osteoporosis, frequent fractures.

Lack of hormones

Hypofunction of the thyroid gland is accompanied by a decrease in the levels of synthesized hormones.

The reasons are: hypothyroidism, thyrotoxicosis, mechanical damage to the brain, Sheehan's syndrome.

The clinical picture of autoimmune thyroiditis includes the following symptoms:

• cardiac ischemia;
• decrease in working capacity;
• increased fatigue;
• bowel dysfunction;
• liver disorders;
• atherosclerosis;
• the formation of stones in the gallbladder;
• violation of the menstrual cycle in women;
• decrease in stress resistance;
• depression.

Tables of indicators of thyroid hormones

To determine the dysfunction of the thyroid gland, it is necessary to pass an analysis. To perform the study, venous blood is taken.

The material is taken on an empty stomach with a preliminary correction of nutrition - to exclude fatty, spicy, alcohol, and medicines. On the eve of the diagnosis, you can not smoke.

A hormonal blood test is performed on any day of the menstrual cycle. The work of the gonads in women does not affect the performance of the studied biological substances.

When deciphering the result, one should rely on the reference values ​​​​of the laboratory, which differ from each other. The generally accepted tables of normal values ​​are indirect and cannot be taken as true indicators of diagnostic centers.

Determination of the main thyroid hormones is combined with ultrasound. A comprehensive assessment of the results sets the vector for further appointments.

The total and free index of thyroid-stimulating hormones are subject to examination. The latter is more significant, so it is examined more often.

In women and men, the reference values ​​differ slightly.

Statistics show that the fairer sex is more likely to suffer from thyroid dysfunction than the opposite sex.

T3 hormone triiodothyronine total, free

Included in the list of the main hormones of the endocrine gland. The biological substance is responsible for filling tissues with oxygen and ensuring the vital activity of the body.

The activity of TK is several times higher than the significance of its successor, tetraiodothyroxine.

The norms of indicators depend on the age of the patient.

Free T3 for persons from 30 to 50 years old is normally from 2.6 to 5.7 pmol / l.

T4 hormone tetraiodothyroxine total, free

- a biological compound that takes part in metabolic processes and provides thermoregulation of the human body.

In women before menopause, the levels of this substance are slightly higher than in men.

After 45-50 years, the values ​​equalize and remain in one pore.

TSH hormone thyroid-stimulating hormone

Thyroid-stimulating hormone is synthesized in the brain. This distinguishes it from previous biological substances.

Thanks to this hormone, the body breaks down proteins, fats and carbohydrates, and controls sugar levels.

Thyroid-stimulating hormone ensures the growth and development of tissues, which is especially important in childhood.

Analysis for calcitonin

Refers to thyroid hormones and provides calcium-phosphorus metabolism.

The indicators of this substance directly depend on the value of calcium in the blood, and, therefore, can be regulated by nutrition.

Permissible parameters are different for women and men.

Analysis for antibodies to thyroperoxidase

Thyroid peroxidase is an enzyme involved in the formation of T3 and T4.

Normally, the indicators of this substance do not exceed 34 IU / ml.

Deviation from the reference values ​​indicates inflammatory processes of the hormone-producing organ or is a sign of pathology, the result of which is an imbalance in the hormonal background.

For analysis, venous blood is taken exclusively on an empty stomach. Before taking the material, rest for 15-20 minutes is necessary.

Influence values

may stress, physical activity, smoking and medication.

The degree of concentration of antibodies to thyroglobulin

Thyroglobulin is a protein from which the main thyroid hormones are subsequently formed. The analysis is prescribed for the purpose of diagnosing autoimmune conditions.

Up to 10% of healthy people have a reduced concentration of antibodies to thyroglobulin.

Overestimated values, as a rule, speak of autoimmune disorders - Hashimoto's thyroiditis and, less commonly, Graves' disease.

Normally, the degree of concentration should not exceed 100 U / ml.

When should a woman check her hormone levels?

Women should determine the function of the thyroid gland and adrenal glands at any menstrual irregularities.

A change in the work of the endocrine apparatus is usually manifested by the absence of monthly bleeding or a distortion of their volume.

Necessary when planning a pregnancy.

Timely identification of problems will prevent complications in the future and correct conditions even before conception.

Thyroid examination is necessary all women over the age of 30. It is especially important to undergo a diagnosis if there have been cases of diseases of this organ in the family.

In the postpartum period A new mother needs to control hormone levels.

At this time, the baby consumes a lot of useful substances, which is often accompanied by iodine deficiency and, as a result, a violation of hormone production.

That women are more likely to experience hormonal imbalances.

Therefore, it is necessary to carry out regularly with dry skin, hair loss, poor sleep, decreased performance and other minor complaints.

How can a thyroid disease be detected by a blood test for hormones?

Primary hypothyroidism accompanied by a change in the function of the endocrine gland, resulting in a violation of hormone production: T3 decreases or remains within the reference values, T4 decreases, TSH increases.

Secondary hypothyroidism It is characterized by dysfunction of the hypothalamic-pituitary system, resulting in a change in the functioning of the thyroid gland: T3 decreases, T4 decreases, TSH decreases.

hyperthyroidism expressed by hyperfunction of the thyroid gland, laboratory studies show: increased T3 and T4, reduced TSH.

Thyroiditis autoimmune or subacute characterized by an inflammatory process that is not caused by changes in the thyroid gland. , as well as a change in T3 values ​​​​by the type of hypothyroidism or hyperthyroidism.

Thyroid hormone analysis is performed within 1 working day.

The study does not involve complex preparation, however, it can show hidden pathological processes that, over time, can lead to irreversible consequences.

It consists of two lobes and an isthmus and is located in front of the larynx. The mass of the thyroid gland is 30 g.

The main structural and functional unit of the gland are follicles - rounded cavities, the wall of which is formed by one row of cuboidal epithelium cells. Follicles are filled with colloid and contain hormones thyroxine and triiodothyronine associated with the protein thyroglobulin. In the interfollicular space are C-cells that produce the hormone thyrocalcitonin. The gland is richly supplied with blood and lymph vessels. The amount flowing through the thyroid gland in 1 min is 3-7 times higher than the mass of the gland itself.

Biosynthesis of thyroxine and triiodothyronine It is carried out due to iodination of the amino acid tyrosine, therefore, active absorption of iodine occurs in the thyroid gland. The content of iodine in the follicles is 30 times higher than its concentration in the blood, and with hyperfunction of the thyroid gland, this ratio becomes even greater. Absorption of iodine is carried out due to active transport. After the combination of tyrosine, which is part of thyroglobulin, with atomic iodine, monoiodotyrosine and diiodotyrosine are formed. Due to the combination of two diiodotyrosine molecules, tetraiodothyronine, or thyroxine, is formed; condensation of mono- and diiodotyrosine leads to the formation of triiodothyronine. Subsequently, as a result of the action of proteases that break down thyroglobulin, active hormones are released into the blood.

The activity of thyroxin is several times less than that of triiodothyronine, however, the content of thyroxin in the blood is about 20 times greater than that of triiodothyronine. Thyroxine can be deiodinated to triiodothyronine. Based on these facts, it is assumed that the main thyroid hormone is triiodothyronine, and thyroxine functions as its precursor.

The synthesis of hormones is inextricably linked with the intake of iodine in the body. If there is a deficiency of iodine in the region of residence in water and soil, it is also scarce in food products of plant and animal origin. In this case, in order to ensure sufficient synthesis of the hormone, the thyroid gland of children and adults increases in size, sometimes very significantly, i.e. goiter occurs. An increase can be not only compensatory, but also pathological, it is called endemic goiter. The lack of iodine in the diet is best compensated by seaweed and other seafood, iodized salt, table mineral water containing iodine, bakery products with iodine additives. However, excessive intake of iodine in the body creates a load on the thyroid gland and can lead to serious consequences.

Thyroid hormones

Effects of thyroxine and triiodothyronine

Basic:

• activate the genetic apparatus of the cell, stimulate metabolism, oxygen consumption and the intensity of oxidative processes

Metabolic:

• protein metabolism: stimulate protein synthesis, but in the case when the level of hormones exceeds the norm, catabolism prevails;
• fat metabolism: stimulate lipolysis;
• carbohydrate metabolism: during hyperproduction, glycogenolysis is stimulated, the blood glucose level rises, its entry into cells is activated, and liver insulinase is activated

Functional:

• provide development and differentiation of tissues, especially nervous;
• enhance the effects of the sympathetic nervous system by increasing the number of adrenoreceptors and inhibiting monoamine oxidase;
• prosympathetic effects are manifested in an increase in heart rate, systolic volume, blood pressure, respiratory rate, intestinal peristalsis, CNS excitability, increased body temperature

Manifestations of changes in the production of thyroxine and triiodothyronine

Comparative characteristics of insufficient production of somatotropin and thyroxine

The effect of thyroid hormones on body functions

The characteristic action of thyroid hormones (thyroxine and triiodothyronine) is an increase in energy metabolism. The introduction is always accompanied by an increase in oxygen consumption, and the removal of the thyroid gland is accompanied by its decrease. With the introduction of the hormone, the metabolism increases, the amount of released energy increases, and the body temperature rises.

Thyroxine increases the expenditure. There is weight loss and intensive consumption of glucose from the blood by tissues. The decrease in glucose from the blood is compensated by its replenishment due to the increased breakdown of glycogen in the liver and muscles. The reserves of lipids in the liver decrease, the amount of cholesterol in the blood decreases. The excretion of water, calcium and phosphorus from the body increases.

Thyroid hormones cause increased excitability, irritability, insomnia, emotional imbalance.

Thyroxine increases the minute volume of blood and heart rate. Thyroid hormone is necessary for ovulation, it helps to maintain pregnancy, regulates the function of the mammary glands.

The growth and development of the body is also regulated by the thyroid gland: a decrease in its function causes growth to stop. Thyroid hormone stimulates hematopoiesis, increases the secretion of the stomach, intestines and secretion of milk.

In addition to iodine-containing hormones, the thyroid gland produces thyrocalcitonin, reducing the amount of calcium in the blood. Thyrocalcitonin is a parathyroid hormone antagonist. Thyrocalcitonin acts on bone tissue, enhances the activity of osteoblasts and the process of mineralization. In the kidneys and intestines, the hormone inhibits calcium reabsorption and stimulates phosphate reabsorption. The implementation of these effects leads to hypocalcemia.

Hyper- and hypofunction of the gland

hyperfunction (hyperthyroidism) causes a disease called Graves' disease. The main symptoms of the disease: goiter, bulging eyes, increased metabolism, heart rate, increased sweating, motor activity (fussiness), irritability (capriciousness, mood swings, emotional instability), fatigue. Goiter is formed due to diffuse enlargement of the thyroid gland. Now the methods of treatment are so effective that severe cases of the disease are quite rare.

Hypofunction (hypothyroidism) thyroid gland that occurs at an early age, up to 3-4 years, causes the development of symptoms cretinism. Children suffering from cretinism lag behind in physical and mental development. Symptoms of the disease: dwarf growth and a violation of the proportions of the body, a wide, deeply sunken bridge of the nose, widely spaced eyes, an open mouth and a constantly protruding tongue, as it does not get in the mouth, short and curved limbs, a dull expression. The life expectancy of such people usually does not exceed 30-40 years. In the first 2-3 months of life, subsequent normal mental development can be achieved. If treatment begins at the age of one, then 40% of children who have undergone this disease remain at a very low level of mental development.

Hypothyroidism in adults leads to a disease called myxedema, or mucous edema. With this disease, the intensity of metabolic processes decreases (by 15-40%), body temperature, the pulse becomes less frequent, blood pressure decreases, swelling appears, hair falls out, nails break, the face becomes pale, lifeless, mask-like. Patients are characterized by slowness, drowsiness, poor memory. Myxedema is a slowly progressive disease that, if left untreated, leads to complete disability.

Regulation of thyroid function

The specific regulator of the activity of the thyroid gland is iodine, the thyroid hormone itself and TSH (thyroid stimulating hormone). Iodine in small doses increases the secretion of TSH, and in large doses inhibits it. The thyroid gland is under the control of the central nervous system. Foods such as cabbage, rutabagas, turnips depress thyroid function. The production of thyroxine and triiodothyronine increases sharply in conditions of prolonged emotional arousal. It is also noted that the secretion of these hormones accelerates with a decrease in body temperature.

Manifestations of disorders of the endocrine function of the thyroid gland

With an increase in the functional activity of the thyroid gland and excessive production of thyroid hormones, a condition occurs hyperthyroidism (hyperthyroidism)), characterized by an increase in the level of thyroid hormones in the blood. The manifestations of this condition are explained by the effects of thyroid hormones in elevated concentrations. So, due to an increase in basal metabolism (hypermetabolism), patients experience a slight increase in body temperature (hyperthermia). Decrease in body weight despite the preserved or increased appetite. This condition is manifested by an increase in oxygen demand, tachycardia, an increase in myocardial contractility, an increase in systolic blood pressure, and an increase in lung ventilation. The activity of ATP increases, the number of p-adrenergic receptors increases, sweating, heat intolerance develop. Excitability and emotional lability increase, tremor of the limbs and other changes in the body may appear.

Increased formation and secretion of thyroid hormones can cause a number of factors, the correct identification of which determines the choice of a method for correcting thyroid function. Among them are factors that cause hyperfunction of follicular cells of the thyroid gland (tumors of the gland, mutation of G-proteins) and an increase in the formation and secretion of thyroid hormones. Hyperfunction of thyrocytes is observed with excessive stimulation of thyrotropin receptors by an increased content of TSH, for example, in pituitary tumors, or with reduced sensitivity of thyroid hormone receptors in thyrotrophs of the adenohypophysis. A common cause of hyperfunction of thyrocytes, an increase in the size of the gland is the stimulation of TSH receptors by antibodies produced against them in an autoimmune disease called Graves-Basedow's disease (Fig. 1). A temporary increase in the level of thyroid hormones in the blood can develop with the destruction of thyrocytes due to inflammatory processes in the gland (toxic Hashimoto's thyroiditis), taking an excessive amount of thyroid hormones and iodine preparations.

Elevated levels of thyroid hormones may be thyrotoxicosis; in this case, one speaks of hyperthyroidism with thyrotoxicosis. But thyrotoxicosis can develop when an excessive amount of thyroid hormones is introduced into the body, in the absence of hyperthyroidism. The development of thyrotoxicosis due to increased sensitivity of cell receptors to thyroid hormones has been described. There are also opposite cases when the sensitivity of cells to thyroid hormones is reduced and a state of resistance to thyroid hormones develops.

Decreased formation and secretion of thyroid hormones can be caused by many reasons, some of which are the result of a violation of the mechanisms of regulation of thyroid function. So, hypothyroidism (hypothyroidism) can develop with a decrease in the formation of TRH in the hypothalamus (tumors, cysts, radiation, encephalitis in the hypothalamus, etc.). This hypothyroidism is called tertiary. Secondary hypothyroidism develops due to insufficient formation of THG by the pituitary gland (tumors, cysts, radiation, surgical removal of part of the pituitary gland, encephalitis, etc.). Primary hypothyroidism can develop as a result of autoimmune inflammation of the gland, with a deficiency of iodine, selenium, excessive intake of goitrogenic products - goitrogens (some varieties of cabbage), after irradiation of the gland, long-term use of a number of drugs (iodine, lithium, antithyroid drugs), etc.

Rice. 1. Diffuse enlargement of the thyroid gland in a 12-year-old girl with autoimmune thyroiditis (T. Foley, 2002)

Insufficient production of thyroid hormones leads to a decrease in the intensity of metabolism, oxygen consumption, ventilation, myocardial contractility and minute blood volume. In severe hypothyroidism, a condition called myxedema- mucous edema. It develops due to the accumulation (possibly under the influence of elevated TSH levels) of mucopolysaccharides and water in the basal layers of the skin, which leads to facial puffiness and pasty skin, as well as weight gain, despite a decrease in appetite. Patients with myxedema may develop mental and motor retardation, drowsiness, chilliness, decreased intelligence, tone of the sympathetic division of the ANS, and other changes.

In the complex processes of thyroid hormone formation, ion pumps are involved that ensure the supply of iodine, a number of enzymes of a protein nature, among which thyroperoxidase plays a key role. In some cases, a person may have a genetic defect leading to a violation of their structure and function, which is accompanied by a violation of the synthesis of thyroid hormones. Genetic defects in the structure of thyroglobulin may be observed. Autoantibodies are often produced against thyroperoxidase and thyroglobulin, which is also accompanied by a violation of the synthesis of thyroid hormones. The activity of the processes of iodine uptake and its incorporation into thyroglobulin can be influenced by a number of pharmacological agents, regulating the synthesis of hormones. Their synthesis can be influenced by taking iodine preparations.

The development of hypothyroidism in the fetus and newborn can lead to the appearance cretinism - physical (short stature, violation of body proportions), sexual and mental underdevelopment. These changes can be prevented by adequate thyroid hormone replacement therapy in the first months after the birth of a child.

The structure of the thyroid gland

It is the largest endocrine organ in terms of mass and size. It usually consists of two lobes, connected by an isthmus, and is located on the anterior surface of the neck, being fixed to the anterior and lateral surfaces of the trachea and larynx by connective tissue. The average weight of a normal thyroid gland in adults ranges from 15-30 g, but its size, shape and topography of the location vary widely.

A functionally active thyroid gland is the first of the endocrine glands to appear in the process of embryogenesis. The laying of the thyroid gland in the human fetus is formed on the 16-17th day of intrauterine development in the form of an accumulation of endodermal cells at the root of the tongue.

In the early stages of development (6-8 weeks), the rudiment of the gland is a layer of intensively proliferating epithelial cells. During this period, the gland grows rapidly, but hormones are not yet formed in it. The first signs of their secretion are detected at 10-11 weeks (in fetuses about 7 cm in size), when the gland cells are already able to absorb iodine, form a colloid and synthesize thyroxine.

Single follicles appear under the capsule, in which follicular cells are formed.

Parafollicular (near-follicular), or C-cells grow into the thyroid rudiment from the 5th pair of gill pockets. By the 12-14th week of fetal development, the entire right lobe of the thyroid gland acquires a follicular structure, and the left one two weeks later. By the 16-17th week, the fetal thyroid gland is already fully differentiated. The thyroid glands of fetuses of 21-32 weeks of age are characterized by high functional activity, which continues to grow up to 33-35 weeks.

Three types of cells are distinguished in the parenchyma of the gland: A, B and C. The bulk of the parenchyma cells are thyrocytes (follicular, or A-cells). They line the wall of the follicles, in the cavities of which the colloid is located. Each follicle is surrounded by a dense network of capillaries, into the lumen of which thyroxine and triiodothyronine secreted by the thyroid gland are absorbed.

In the unchanged thyroid gland, the follicles are evenly distributed throughout the parenchyma. With a low functional activity of the gland, thyrocytes are usually flat, with a high one they are cylindrical (the height of the cells is proportional to the degree of activity of the processes carried out in them). The colloid filling the gaps of the follicles is a homogeneous viscous liquid. The bulk of the colloid is thyroglobulin secreted by thyrocytes into the lumen of the follicle.

B cells (Ashkenazi-Gurtl cells) are larger than thyrocytes, have eosinophilic cytoplasm and a rounded centrally located nucleus. Biogenic amines, including serotonin, were found in the cytoplasm of these cells. For the first time B-cells appear at the age of 14-16 years. In large numbers, they are found in people aged 50-60 years.

Parafollicular, or C-cells (in the Russian transcription of K-cells), differ from thyrocytes in their lack of ability to absorb iodine. They provide the synthesis of calcitonin, a hormone involved in the regulation of calcium metabolism in the body. C-cells are larger than thyrocytes, they are located, as a rule, singly in the composition of follicles. Their morphology is typical for cells synthesizing protein for export (there is a rough endoplasmic reticulum, the Golgi complex, secretory granules, mitochondria). On histological preparations, the cytoplasm of C-cells looks lighter than the cytoplasm of thyrocytes, hence their name - light cells.

If at the tissue level the main structural and functional unit of the thyroid gland are follicles surrounded by basement membranes, then one of the proposed organ units of the thyroid gland can be microlobules, which include follicles, C-cells, hemocapillaries, tissue basophils. The composition of the microlobule includes 4-6 follicles surrounded by a membrane of fibroblasts.

By the time of birth, the thyroid gland is functionally active and structurally completely differentiated. In newborns, the follicles are small (60-70 microns in diameter), as the child's body develops, their size increases and reaches 250 microns in adults. In the first two weeks after birth, the follicles develop intensively, by 6 months they are well developed throughout the gland, and by the year they reach a diameter of 100 microns. During puberty, there is an increase in the growth of the parenchyma and stroma of the gland, an increase in its functional activity, manifested by an increase in the height of thyrocytes, an increase in the activity of enzymes in them.

In an adult, the thyroid gland is adjacent to the larynx and the upper part of the trachea in such a way that the isthmus is located at the level of the II-IV tracheal semirings.

The mass and size of the thyroid gland change throughout life. In a healthy newborn, the mass of the gland varies from 1.5 to 2 g. By the end of the first year of life, the mass doubles and slowly increases by puberty up to 10–14 g. The increase in mass is especially noticeable at the age of 5–7 years. The mass of the thyroid gland at the age of 20-60 years ranges from 17 to 40 g.

The thyroid gland has an exceptionally abundant blood supply compared to other organs. The volumetric rate of blood flow in the thyroid gland is about 5 ml/g per minute.

The thyroid gland is supplied with blood by the paired superior and inferior thyroid arteries. Sometimes the unpaired, lowest artery (a. thyroideaima).

The outflow of venous blood from the thyroid gland is carried out through the veins that form plexuses in the circumference of the lateral lobes and isthmus. The thyroid gland has an extensive network of lymphatic vessels, through which lymph takes care of the deep cervical lymph nodes, then to the supraclavicular and lateral cervical deep lymph nodes. The efferent lymphatic vessels of the lateral cervical deep lymph nodes form a jugular trunk on each side of the neck, which flows into the thoracic duct on the left, and on the right into the right lymphatic duct.

The thyroid gland is innervated by postganglionic fibers of the sympathetic nervous system from the upper, middle (mainly) and lower cervical nodes of the sympathetic trunk. The thyroid nerves form plexuses around the vessels that go to the gland. It is believed that these nerves perform a vasomotor function. The vagus nerve is also involved in the innervation of the thyroid gland, carrying parasympathetic fibers to the gland as part of the upper and lower laryngeal nerves. The synthesis of iodine-containing thyroid hormones T 3 and T 4 is carried out by follicular A-cells - thyrocytes. Hormones T 3 and T 4 are iodinated.

Hormones T 4 and T 3 are iodinated derivatives of the amino acid L-tyrosine. Iodine, which is part of their structure, makes up 59-65% of the mass of the hormone molecule. The need for iodine for the normal synthesis of thyroid hormones is presented in Table. 1. The sequence of synthesis processes is simplified as follows. Iodine in the form of iodide is taken from the blood with the help of an ion pump, accumulates in thyrocytes, is oxidized and included in the phenolic ring of tyrosine as part of thyroglobulin (iodine organization). Thyroglobulin iodination with the formation of mono- and diiodotyrosines occurs at the border between thyrocyte and colloid. Next, the connection (condensation) of two diiodotyrosine molecules is carried out with the formation of T 4 or diiodotyrosine and monoiodotyrosine with the formation of T 3 . Part of thyroxin undergoes deiodination in the thyroid gland with the formation of triiodothyronine.

Table 1. Norms of iodine consumption (WHO, 2005. by I. Dedov et al. 2007)

Iodized thyroglobulin, together with T 4 and T 3 attached to it, is accumulated and stored in the follicles in the form of a colloid, acting as depot thyroid hormones. The release of hormones occurs as a result of pinocytosis of the follicular colloid and subsequent hydrolysis of thyroglobulin in phagolysosomes. The released T 4 and T 3 are secreted into the blood.

Basal daily secretion by the thyroid gland is about 80 μg T 4 and 4 μg T 3 At the same time, thyrocytes of the thyroid gland follicles are the only source of endogenous T 4 formation. Unlike T 4 , T 3 is formed in thyrocytes in a small amount, and the main formation of this active form of the hormone is carried out in the cells of all tissues of the body by deiodination of about 80% of T 4 .

Thus, in addition to the glandular depot of thyroid hormones, the body has a second - extra-glandular depot of thyroid hormones, represented by hormones associated with blood transport proteins. The role of these depots is to prevent a rapid decrease in the level of thyroid hormones in the body, which could occur with a short-term decrease in their synthesis, for example, with a short-term decrease in iodine intake. The bound form of hormones in the blood prevents their rapid excretion from the body through the kidneys, protects cells from uncontrolled intake of hormones. Free hormones enter the cells in quantities commensurate with their functional needs.

Thyroxin entering the cells undergoes deiodination under the action of deiodinase enzymes, and when one iodine atom is cleaved, a more active hormone, triiodothyronine, is formed from it. In this case, depending on the deiodination pathways, both active T 3 and inactive reverse T 3 (3,3,5 "-triiodine-L-thyronine - pT 3) can be formed from T 4 . These hormones are converted by successive deiodination into metabolites T 2 , then T 1 and T 0 , which are conjugated with glucuronic acid or sulfate in the liver and excreted in the bile and through the kidneys from the body. Not only T3, but also other thyroxin metabolites can also exhibit biological activity.

The mechanism of action of thyroid hormones is primarily due to their interaction with nuclear receptors, which are non-histone proteins located directly in the cell nucleus. There are three main subtypes of thyroid hormone receptors: TPβ-2, TPβ-1 and TPa-1. As a result of interaction with T3, the receptor is activated, the hormone-receptor complex interacts with the hormone-sensitive DNA region and regulates the transcriptional activity of genes.

A number of non-genomic effects of thyroid hormones in mitochondria, the plasma membrane of cells, have been revealed. In particular, thyroid hormones can change the permeability of mitochondrial membranes for hydrogen protons and, by uncoupling the processes of respiration and phosphorylation, reduce ATP synthesis and increase the generation of heat in the body. They change the permeability of plasma membranes for Ca 2+ ions and affect many intracellular processes carried out with the participation of calcium.

Main effects and role of thyroid hormones

The normal functioning of all organs and tissues of the body without exception is possible with a normal level of thyroid hormones, since they affect the growth and maturation of tissues, energy metabolism and the metabolism of proteins, lipids, carbohydrates, nucleic acids, vitamins and other substances. Allocate metabolic and other physiological effects of thyroid hormones.

Metabolic effects:

• activation of oxidative processes and an increase in basal metabolism, increased oxygen uptake by tissues, increased heat generation and body temperature;
• stimulation of protein synthesis (anabolic action) in physiological concentrations;
• increased oxidation of fatty acids and a decrease in their level in the blood;
• hyperglycemia due to the activation of glycogenolysis in the liver.

Physiological effects:

• ensuring normal processes of growth, development, differentiation of cells, tissues and organs, including the central nervous system (myelination of nerve fibers, differentiation of neurons), as well as the processes of physiological tissue regeneration;
• strengthening the effects of SNS through increased sensitivity of adrenergic receptors to the action of Adr and NA;
• increased excitability of the central nervous system and activation of mental processes;
• participation in ensuring reproductive function (contribute to the synthesis of GH, FSH, LH and the implementation of the effects of insulin-like growth factor - IGF);
• participation in the formation of adaptive reactions of the body to adverse effects, in particular, cold;
• participation in the development of the muscular system, increasing the strength and speed of muscle contractions.

The formation, secretion, and transformation of thyroid hormones are regulated by complex hormonal, nervous, and other mechanisms. Their knowledge allows diagnosing the causes of a decrease or increase in the secretion of thyroid hormones.

The hormones of the hypothalamic-pituitary-thyroid axis play a key role in the regulation of thyroid hormone secretion (Fig. 2). Basal secretion of thyroid hormones and its changes under various influences are regulated by the level of TRH of the hypothalamus and TSH of the pituitary gland. TRH stimulates the production of TSH, which has a stimulating effect on almost all processes in the thyroid gland and the secretion of T 4 and T 3 . Under normal physiological conditions, the formation of TRH and TSH is controlled by the level of free T 4 and T in the blood based on negative feedback mechanisms. At the same time, the secretion of TRH and TSH is inhibited by a high level of thyroid hormones in the blood, and at their low concentration it increases.

Rice. Fig. 2. Schematic representation of the regulation of the formation and secretion of hormones in the axis of the hypothalamus - pituitary gland - thyroid gland

Of great importance in the mechanisms of regulation of hormones of the hypothalamic-pituitary-thyroid axis is the state of sensitivity of receptors to the action of hormones at various levels of the axis. Changes in the structure of these receptors or their stimulation by autoantibodies may be the cause of impaired thyroid hormone formation.

The formation of hormones in the gland itself depends on the receipt of a sufficient amount of iodide from the blood - 1-2 micrograms per 1 kg of body weight (see Fig. 2).

With insufficient intake of iodine in the body, adaptation processes develop in it, which are aimed at the most careful and efficient use of the iodine present in it. They consist in increased blood flow through the gland, more efficient capture of iodine by the thyroid gland from the blood, changes in the processes of hormone synthesis and secretion of Tu. Adaptive reactions are triggered and regulated by thyrotropin, the level of which increases with iodine deficiency. If the daily intake of iodine in the body is less than 20 micrograms for a long time, then prolonged stimulation of thyroid cells leads to the growth of its tissue and the development of goiter.

Self-regulatory mechanisms of the gland in conditions of iodine deficiency provide for its greater capture by thyrocytes at a lower level of iodine in the blood and more efficient recycling. If about 50 mcg of iodine is delivered to the body per day, then by increasing the rate of its absorption by thyrocytes from the blood (iodine of food origin and reutilizable iodine from metabolic products), about 100 mcg of iodine per day enters the thyroid gland.

The intake of 50 micrograms of iodine per day from the gastrointestinal tract is the threshold at which the long-term ability of the thyroid gland to accumulate it (including reutilized iodine) is still preserved in quantities when the content of inorganic iodine in the gland remains at the lower limit of the norm (about 10 mg). Below this threshold intake of iodine into the body per day, the effectiveness of the increased rate of iodine uptake by the thyroid gland is insufficient, the absorption of iodine and its content in the gland decrease. In these cases, the development of thyroid dysfunction becomes more likely.

Simultaneously with the inclusion of the adaptive mechanisms of the thyroid gland in iodine deficiency, a decrease in its excretion from the body with urine is observed. As a result, adaptive excretory mechanisms ensure the excretion of iodine from the body per day in amounts equivalent to its lower daily intake from the gastrointestinal tract.

The intake of subthreshold iodine concentrations (less than 50 mcg per day) leads to an increase in TSH secretion and its stimulating effect on the thyroid gland. This is accompanied by an acceleration of iodination of tyrosyl residues of thyroglobulin, an increase in the content of monoiodotyrosines (MIT) and a decrease in diiodotyrosines (DIT). The ratio of MIT/DIT increases, and, as a result, the synthesis of T 4 decreases and the synthesis of T 3 increases. The ratio of T 3 /T 4 increases in the gland and blood.

With severe iodine deficiency, there is a decrease in serum T 4 levels, an increase in TSH levels and a normal or elevated T 3 content. The mechanisms of these changes are not precisely elucidated, but most likely, this is the result of an increase in the rate of formation and secretion of T 3 , an increase in the ratio of T 3 T 4 and an increase in the conversion of T 4 to T 3 in peripheral tissues.

An increase in the formation of T 3 in conditions of iodine deficiency is justified from the point of view of achieving the greatest final metabolic effects of TG with the smallest of their "iodine" capacity. It is known that the effect on the metabolism of T 3 is approximately 3-8 times stronger than T 4, but since T 3 contains only 3 iodine atoms in its structure (and not 4 like T 4), then for the synthesis of one T 3 molecule only 75% of iodine costs are needed, compared with the synthesis of T 4 .

With a very significant iodine deficiency and a decrease in thyroid function against the background of a high level of TSH, the levels of T 4 and T 3 decrease. More thyroglobulin appears in the blood serum, the level of which correlates with the level of TSH.

Iodine deficiency in children has a stronger effect than in adults on metabolic processes in the thyrocytes of the thyroid gland. In iodine-deficient areas of residence, thyroid dysfunction in newborns and children is much more common and more pronounced than in adults.

When a small excess of iodine enters the human body, the degree of iodide organization, the synthesis of triglycerides and their secretion increase. There is an increase in the level of TSH, a slight decrease in the level of free T 4 in serum, while increasing the content of thyroglobulin in it. Longer excess iodine intake can block TG synthesis by inhibiting the activity of enzymes involved in biosynthetic processes. By the end of the first month, an increase in the size of the thyroid gland is noted. With chronic excess intake of excess iodine in the body, hypothyroidism may develop, but if the intake of iodine in the body has returned to normal, then the size and function of the thyroid gland may return to its original values.

Sources of iodine that can cause excess intake of iodine are often iodized salt, complex multivitamin preparations containing mineral supplements, foods, and certain iodine-containing drugs.

The thyroid gland has an internal regulatory mechanism that allows you to effectively cope with excess iodine intake. Although the intake of iodine in the body may fluctuate, the concentration of TG and TSH in the blood serum may remain unchanged.

It is believed that the maximum amount of iodine that, when taken into the body, does not yet cause a change in thyroid function, is about 500 mcg per day for adults, but there is an increase in the level of secretion of TSH in response to the action of thyrotropin-releasing hormone.

The intake of iodine in amounts of 1.5-4.5 mg per day leads to a significant decrease in serum levels, both total and free T 4 , an increase in the level of TSH (the level of T 3 remains unchanged).

The effect of excess iodine suppression of thyroid function also takes place in thyrotoxicosis, when by taking an excess amount of iodine (in relation to the natural daily requirement), the symptoms of thyrotoxicosis are eliminated and the serum level of triglycerides is lowered. However, with prolonged intake of excess iodine into the body, the manifestations of thyrotoxicosis return again. It is believed that a temporary decrease in the level of TG in the blood with an excessive intake of iodine is primarily due to the inhibition of hormone secretion.

The intake of small excess amounts of iodine into the body leads to a proportional increase in its uptake by the thyroid gland, up to a certain saturating value of absorbed iodine. When this value is reached, the uptake of iodine by the gland may decrease despite its intake in the body in large quantities. Under these conditions, under the influence of pituitary TSH, the activity of the thyroid gland can vary widely.

Since the level of TSH rises when excess iodine enters the body, one would expect not an initial suppression, but an activation of the thyroid function. However, it has been established that iodine inhibits an increase in the activity of adenylate cyclase, inhibits the synthesis of thyroperoxidase, inhibits the formation of hydrogen peroxide in response to the action of TSH, although the binding of TSH to the thyrocyte cell membrane receptor is not disturbed.

It has already been noted that the suppression of thyroid function by excess iodine is temporary and function is soon restored despite the continued intake of excess amounts of iodine into the body. There comes an adaptation or escape of the thyroid gland from the influence of iodine. One of the main mechanisms of this adaptation is a decrease in the efficiency of iodine uptake and transport into the thyrocyte. Since it is believed that the transport of iodine across the thyrocyte basement membrane is associated with the function of Na+/K+ ATPase, it can be expected that an excess of iodine may affect its properties.

Despite the existence of mechanisms for the adaptation of the thyroid gland to insufficient or excessive intake of iodine, iodine balance must be maintained in the body to maintain its normal function. With a normal level of iodine in soil and water per day, up to 500 μg of iodine in the form of iodide or iodate, which are converted into iodides in the stomach, can enter the human body with plant foods and, to a lesser extent, with water. Iodides are rapidly absorbed from the gastrointestinal tract and distributed into the extracellular fluid of the body. The concentration of iodide in the extracellular spaces remains low, since part of the iodide is quickly captured from the extracellular fluid by the thyroid gland, and the rest is excreted from the body at night. The rate of iodine uptake by the thyroid gland is inversely proportional to the rate of its excretion by the kidneys. Iodine can be excreted by the salivary and other glands of the digestive tract, but is then reabsorbed from the intestine into the blood. About 1-2% of iodine is excreted by the sweat glands, and with increased sweating, the proportion of iodine excreted with iodine can reach 10%.

Of the 500 μg of iodine absorbed from the upper intestine into the blood, about 115 μg is captured by the thyroid gland and about 75 μg of iodine is used per day for the synthesis of triglycerides, 40 μg is returned back to the extracellular fluid. The synthesized T 4 and T 3 are subsequently destroyed in the liver and other tissues, while the iodine released in the amount of 60 μg enters the blood and extracellular fluid, and about 15 μg of iodine conjugated in the liver with glucuronides or sulfates are excreted in the bile.

In the total volume, blood is an extracellular fluid, which in an adult makes up about 35% of body weight (or about 25 liters), in which about 150 micrograms of iodine are dissolved. Iodide is freely filtered in the glomeruli and approximately 70% passively reabsorbed in the tubules. During the day, about 485 micrograms of iodine is excreted from the body with urine and about 15 micrograms with feces. The average concentration of iodine in the blood plasma is maintained at a level of about 0.3 μg / l.

With a decrease in iodine intake in the body, its amount in body fluids decreases, excretion in the urine decreases, and the thyroid gland can increase its absorption by 80-90%. The thyroid gland is able to store iodine in the form of iodothyronines and iodinated tyrosines in quantities close to the 100-day requirement of the body. Due to these iodine-sparing mechanisms and deposited iodine, TG synthesis in conditions of iodine deficiency in the body can remain undisturbed for up to two months. A longer iodine deficiency in the body leads to a decrease in the synthesis of triglycerides despite its maximum uptake by the gland from the blood. An increase in the intake of iodine in the body can accelerate the synthesis of triglycerides. However, if the daily intake of iodine exceeds 2000 mcg, the accumulation of iodine in the thyroid gland reaches a level where iodine uptake and hormone biosynthesis are inhibited. Chronic iodine intoxication occurs when its daily intake into the body is more than 20 times the daily requirement.

The iodide entering the body is excreted from it mainly with urine, therefore its total content in the volume of daily urine is the most accurate indicator of iodine intake and can be used to assess the iodine balance in the whole organism.

Thus, a sufficient intake of exogenous iodine is necessary for the synthesis of triglycerides in amounts adequate to the needs of the body. At the same time, the normal realization of the effects of TG depends on the effectiveness of their binding to the nuclear receptors of cells, which include zinc. Therefore, the intake of a sufficient amount of this microelement (15 mg/day) is also important for the manifestation of the effects of TH at the level of the cell nucleus.

The formation of active forms of TH from thyroxine in peripheral tissues occurs under the action of deiodinases, the presence of selenium is necessary for the manifestation of their activity. It has been established that the intake of selenium in the body of an adult in amounts of 55-70 μg per day is a necessary condition for the formation of a sufficient amount of T v in peripheral tissues.

The nervous mechanisms of regulation of thyroid function are carried out through the influence of the neurotransmitters ATP and PSNS. The SNS innervates the vessels of the gland and glandular tissue with its postganglionic fibers. Norepinephrine increases the level of cAMP in thyrocytes, enhances their absorption of iodine, the synthesis and secretion of thyroid hormones. PSNS fibers are also suitable for the follicles and vessels of the thyroid gland. An increase in the tone of the PSNS (or the introduction of acetylcholine) is accompanied by an increase in the level of cGMP in thyrocytes and a decrease in the secretion of thyroid hormones.

Under the control of the central nervous system is the formation and secretion of TRH by small cell neurons of the hypothalamus, and consequently, the secretion of TSH and thyroid hormones.

The level of thyroid hormones in tissue cells, their conversion into active forms and metabolites is regulated by a system of deiodinases - enzymes whose activity depends on the presence of selenocysteine ​​in the cells and the intake of selenium. There are three types of deiodinases (D1, D2, DZ), which are differently distributed in various tissues of the body and determine the pathways for the conversion of thyroxine into active T 3 or inactive pT 3 and other metabolites.

Endocrine function of parafollicular thyroid K-cells

These cells synthesize and secrete the hormone calcitonin.

Calcitonip (Thyrocalcitoin)- a peptide consisting of 32 amino acid residues, the content in the blood is 5-28 pmol / l, acts on target cells, stimulating T-TMS-membrane receptors and increasing the level of cAMP and IGF in them. It can be synthesized in the thymus, lungs, central nervous system and other organs. The role of extrathyroidal calcitonin is unknown.

The physiological role of calcitonin is the regulation of the level of calcium (Ca 2+) and phosphates (PO 3 4 -) in the blood. The function is implemented through several mechanisms:

• inhibition of the functional activity of osteoclasts and suppression of bone resorption. This reduces the excretion of Ca 2+ and PO 3 4 - ions from bone tissue into the blood;
• reducing the reabsorption of Ca 2+ and PO 3 4 - ions from primary urine in the renal tubules.

Due to these effects, an increase in the level of calcitonin leads to a decrease in the content of Ca 2 and PO 3 4 ions in the blood.

Regulation of calcitonin secretion carried out with the direct participation of Ca 2 in the blood, the concentration of which is normally 2.25-2.75 mmol / l (9-11 mg%). An increase in the level of calcium in the blood (hypscalcismia) causes an active secretion of calcitonin. A decrease in calcium levels leads to a decrease in hormone secretion. Stimulate the secretion of calcitonin catecholamines, glucagon, gastrin and cholecystokinin.

An increase in the level of calcitonin (50-5000 times higher than normal) is observed in one of the forms of thyroid cancer (medullary carcinoma), which develops from parafollicular cells. At the same time, the determination of a high level of calcitonin in the blood is one of the markers of this disease.

An increase in the level of calcitonin in the blood, as well as the almost complete absence of calcitonin after removal of the thyroid gland, may not be accompanied by a violation of calcium metabolism and the state of the skeletal system. These clinical observations suggest that the physiological role of calcitonin in the regulation of calcium levels remains poorly understood.

Thyroid gland - hormones and their functions are essential for the human body. Together with the immune system and the nervous system, the thyroid gland is involved in the regulation of the activity of all internal organs of a person.

Every cell and tissue in the body needs thyroid hormones. Failure of thyroid function entails serious consequences.

The structure of the thyroid gland

The thyroid gland is considered an organ of internal secretion, its main functions are the production and interaction with all systems. thyroid hormones and functions closely related to some parts of the brain: hypothalamus and pituitary gland that affect its function and vice versa. The organ also has a second name - thyroid gland.

The thyroid gland is located on the front of the neck, slightly below the Adam's apple. The iron is shaped like a butterfly. The mass of the thyroid gland in each person is 30-60 g.

Interesting! The weight and size of the thyroid gland is dependent on nutrition, medication and age. For example, in the case of accumulation of hormones, the thyroid gland increases in size, as happens in women during periods of menstruation or pregnancy.

The gland consists of three parts:

• right lobe;
• left lobe;
• isthmus .

The fourth part, the pyramidal lobule, is also part of the thyroid gland, but only in 1/3 of the world's population. The lobule is the remnant of the organ on the basis of which the gland developed in the process of human evolution.

On the back of the thyroid gland are two paired glands. The parathyroid gland is oval in shape and weighs no more than 1 g.

Connecting with the larynx, the gland can move when swallowing or with a tilt of the head. The thyroid gland is the fastest in the body to receive blood. The role of the thyroid gland in the existence of people is of great importance, which is why a person at birth has a fully formed organ.

What is the thyroid gland made of? The thyroid gland has a complex structure. The thyroid gland consists entirely of follicles, small vesicles filled with a thick fluid - a colloid. On the edges of the follicles are cells - thyrocytes.

Iodized hormones produced by these cells accumulate in the colloid to immediately enter the blood when needed. Parafollicular cells are located between the cells and follicles that fill the thyroid gland.

Interesting! The location of the thyroid gland does not depend on sexual characteristics. Therefore, despite the different physiology in women and men, the thyroid gland is located in one place.

What hormones does the thyroid gland produce?

The gland produces two types of hormones:

• iodinated hormones;
• thyrocalcitonin.

Calcitonin, a substance produced by parafollicular cells, is involved in the regulation of calcium and phosphorus metabolism. The hormone is responsible for removing calcium from the bone tissue.

The iodinated hormones are triiodothyronine and thyroxine. The first hormone produced by the gland consists of 3 molecules of iodine, and the other hormone - of 4, respectively, they are defined as T3-hormone and T4-hormone.

In the body, the function of hormones does not occur if it receives less iodine. That is why it is necessary to consume iodine-containing foods. The amino acid tyrosine, supplied with food, is important for thyroid function, as it contributes to the formation of the hormones T3 and T4.

The activity of the thyroid gland

The hormones secreted by the thyroid gland, as well as their functions, are monitored by the hypothalamus and pituitary gland. What are these parts of the brain responsible for? The first controls the level of hormones. If there is a deficiency of thyroid hormones, then it begins to produce thyrotropin-releasing hormone (TRH).

TRH acts on the pituitary gland, which produces thyroid-stimulating hormone, which regulates thyroid function and stimulates the synthesis of T3 and T4. When thyroid hormones are biologically active, the parts of the brain inhibit their production and function.

Functions of iodinated thyroid hormones:

1. Through food, the body receives iodine, which is absorbed in the intestines.
2. When iodine reaches the thyroid gland, it dissolves in its cells.
3. The gland produces a special prohormone thyroglobulin, which is necessary for the successful formation of the hormones T3 and T4, which then enter the bloodstream.

The thyroid gland is interconnected with all systems of the human body. Without the function of the thyroid gland, the internal organs cannot work.

The main functions of thyroid hormones:

1. Actively involved in the creation of red blood cells.
2. Control energy metabolism. Hormones normalize metabolism, heat levels.
3. Promote the metabolism of proteins, fats and carbohydrates. As a result, a person does not gain weight.
4. Responsible for the reproductive system. Thyroid hormones affect the functions of germ cells, which is very important during sexual development, conception, and childbearing.
5. Regulate cellular metabolism of calcium and phosphorus. This function affects the development of bone tissue. For example, in various bone injuries, calcitonin serves as an engine: it helps calcium act on the problem.
6. Influence the functions of the central nervous system. Lack of any thyroid hormone is noticeable in children who are lagging behind in development: intelligence decreases, cretinism develops.
7. Depend on the emotional state of a person: excitability, irritability, insomnia.

Interesting! Human growth and development is regulated by the thyroid gland. With a decrease in its function, growth stops.

Functional disorders of the thyroid gland

Dysfunction in the work of the thyroid gland is characterized by the degree of functional activity of its hormones:

• euthyroidism;
• hypothyroidism;
• hyperthyroidism.

Structural changes in the gland

When reversible changes occur in the structure of an organ without affecting its functions, then it occurs. With a structural modification of the thyroid gland, all internal organs and systems work as expected, without visible failures. Euthyroidism is characterized by the growth of thyroid tissue, however, the amount of hormones remains normal.

This state of a person does not speak of his absolute health, since a violation of the structural functions of the thyroid gland is considered a borderline position. At any time, an increase or decrease in the amount of hormones can occur.

In such a situation, it is important to watch for signs of thyroid dysfunction. Euthyroidism lasts a short time and is manifested by the following symptoms:

• insomnia, weakness upon awakening;
• increased emotional imbalance: irritability, excitability;
• disorders of the pumping function of the heart;
• weight loss for no apparent reason;
• neck compression.

When Thyroid Hormones Are Not Enough

Decreased thyroid hormone function is characteristic of hypothyroidism. The function of the thyroid gland is weakened when the human body receives little iodine or substances that destroy the action of thyroid hormones.

In rare cases, hypothyroidism occurs due to certain drugs or the removal of the thyroid gland. In childhood, hypofunction of the gland affects growth and development: there is growth retardation and mental development , disproportionate growth , cretinism .

A decrease in the function of the thyroid gland and its hormones has the following external manifestations:

• weight gain that is not affected by diet or exercise;
• increased fatigue, general weakness;
• depression: a person is nervous and worried a lot;
• changes in the menstrual cycle, inability to conceive;
• body temperature is below normal;
• dry skin, dandruff, itching, swelling of the skin, legs and face;
• decreased heart rate;
• constantly cold extremities even in a warm room;
• muscle and joint pain;
• decreased memory and responsiveness.

Increased production of hormones

Increased production of thyroid hormones is associated with hyperthyroidism. Excessive secretion of the thyroid gland is characterized by the following conditions:

• displacement of the eyeballs (bulging eyes, exophthalmos);
• weight loss with increased appetite;
• changes in the menstrual cycle;
• heart palpitations and high blood pressure;
• dry skin;
• hair loss;
• diarrhea;
• constant nervous excitement.

Interesting! Diseases such as toxic and (Basedow-Graves disease, Plummer disease), viral and autoimmune thyroiditis, as well as an excess of hormonal or iodine-containing drugs are characterized by hyperfunction of the thyroid gland.

Diagnostic study

The level of gland hormones can be determined using a blood test. To make a correct diagnosis and prescribe treatment, the doctor must examine the patient, send him to x-rays and ultrasound.

Given the severity of the patient, the endocrinologist may prescribe to the patient an additional examination of changes and functions of the thyroid gland using computed or magnetic resonance imaging. CT and MRI make it possible to determine the location of the gland, its size and the presence of nodes.

Thyroid hormone levels

Thyroid problems are more common in women than in men. This comes from the fact that the female body works in a cyclic mode: birth, feeding, raising children. The ovaries, uterus, mammary glands and thyroid gland work simultaneously with these processes. Therefore, the norm of gland hormones in the sexes is different.

The figures in this table may vary slightly, as different laboratories carry out their own methods of analysis.

Table of the norm of hormones in women:

Thyroid disorders can be treated if you see a doctor in a timely manner. The appointment of special medications and regular monitoring of laboratory parameters will help restore the previous functions of the thyroid gland.

Causes of thyroid dysfunction and preventive measures

The syndrome of insufficient thyroid function occurs for several reasons:

• heredity;
• nervous excitement;
• adverse environmental factors;
• nutrition.

It is those foods that a person consumes daily directly affect the function of the thyroid gland. Deficiency of iodine, selenium and fluorine in the air, water, food affects the function of the gland. Modified and additives, stabilizers in food, negatively affect the general condition of the thyroid gland.

In order to prevent the development of an imbalance of hormones in the thyroid gland, you need to monitor nutrition: it should be complete and fortified.

The daily requirement of iodine for an adult is 150 micrograms.

Iodine is found in seafood, fresh vegetables and fruits, juices, pure water, sunflower oil. Tyrosine in sufficient quantities can be found in milk, peas, eggs, peanuts, and beans.

At the same time, it is important to use honey instead of sugar, if allowed, to eat cereals, wholemeal bread.

And limit consumption:

• smoked and canned foods;
• fatty foods;
• hot spices and seasonings;
• alcoholic and carbonated drinks.

Natural red wine in moderation has a beneficial effect on the body and the thyroid gland in particular.

A complete and balanced diet helps to normalize the activity of the thyroid gland, prevent the risk of disease and serious consequences.