Triiodothyronine, otherwise free T3 - what kind of hormone it is, its functions. What does it mean to increase or decrease the level of triiodothyronine in the body of women and men?

Synthesis and role of triiodothyronine

Triiodothyronine is produced in thyroid cells, peripheral tissues and blood. The main sources for its synthesis are iodine and the amino acid tyrosine. With the help of the enzyme peroxidase, the hormone thyroxine (T4), containing 4 iodine atoms, is formed from them. When one of them is cleaved under the action of the enzyme deiodinase, triiodothyronine is obtained. Its main amount is produced in the blood and peripheral tissues, and only a small part is produced in the thyroid gland.

The biological activity of triiodothyronine is 5 times higher than the activity of thyroxine. In the blood, T3 is in a free and bound state. An equilibrium is maintained between these fractions - as the free form decreases, the amount of bound form decreases, and vice versa. This helps maintain a certain concentration of the hormone. Only the free form is capable of penetrating the cell and exerting a biological effect.

The main stimulator of triiodothyronine production is thyroid-stimulating hormone (TSH) from the pituitary gland, which is under the control of the hypothalamus. TSH secretion increases as free T3 concentrations decrease. As its level in the blood increases, the TSH level drops below normal.

Triiodothyronine is responsible for the following processes:

development and growth of the body;
activation of basal metabolism;
regulation of the circulatory, respiratory, digestive, and reproductive systems.

Determination of free T3

The main indication for testing free T3 is to evaluate the functioning of the thyroid gland.

In the laboratory, the levels of total and free fractions of the hormone can be determined. The difference between total T3 and free T3 is that the first indicator reflects the content of all forms of triiodothyronine in the blood and depends on the concentration transport proteins, and the second shows the amount of only biologically available hormone. Thus, the determination of free T3 has great diagnostic significance.

The T3 test must be taken on an empty stomach, in the morning. To determine the indicator, blood is taken from a vein. In women, the study is carried out regardless of the day menstrual cycle. The test results may be affected by taking levothyroxine, thyreostatics, or iodine preparations.

Decoding the results

The norms of free T3 in humans, depending on gender and age, are presented in the table:

To assess the functioning of the thyroid gland, they always look at the concentration along with T3 free thyroxine and thyroid-stimulating hormone. Only based on the results of all three indicators can the function of an organ be determined. A decrease in the level of free T3 and T4 and an increase in TSH indicates hypothyroidism, an increase in the content of thyroid hormones in the blood and low values TSH - about hyperthyroidism and thyrotoxicosis.

Thyroid function depending on the levels of free T3, T4 and TSH:

Low free T3 levels

Causes of low hormone levels:

inflammatory diseases of the thyroid gland - thyroiditis;
condition after organ removal or radioiodine therapy;
pathology of the pituitary gland and hypothalamus, leading to hypothyroidism;
severe mental or physical illness.

Thyroiditis

Thyroiditis is a whole group of diseases that can be of an autoimmune nature or develop under the influence of radiation, while taking medications - Amiodarone, potassium iodide, lithium carbonate. As a result of damage to organ tissue, its dysfunction occurs.

The outcome of most thyroiditis is hypothyroidism - a condition in which the content of thyroid hormones in the blood is reduced. The functioning of the whole organism is disrupted - the nervous, cardiovascular, respiratory system, the skin and its appendages are affected.

Laboratory determination of TSH is elevated, and the concentration of free T3 is low.

It is necessary to treat the pathology with replacement doses of drugs containing thyroxine - L-thyroxine, Eutirox. The dosage of the medicine is selected individually, taking into account initial levels hormones, patient weight and concomitant diseases.

Removal of the thyroid gland

Hypothyroidism is also caused by surgical removal of the thyroid gland and radioactive iodine therapy. After the interventions, a persistent decrease in free T3 is observed.

To eliminate the lack of thyroid hormones, L-thyroxine or Euthyrox is prescribed. The dose of the drug depends on the extent of the operation and the degree of hypothyroidism, weight and general condition of the patient.

Central hypothyroidism

In this case, the decrease in free T3 occurs due to insufficient stimulation of the thyroid gland by thyroid-stimulating hormone. In laboratory determination, the concentrations of TSH, T3, T4 are low. The cause of the pathology is damage to the hypothalamic-pituitary zone. As a rule, together with TSH, the synthesis of hormones that control the functioning of other hormones is disrupted. endocrine glands.

To correct hypothyroidism, thyroxine preparations are used.

The main conditions leading to central hypothyroidism:

postpartum pituitary necrosis - Sheehan syndrome;
traumatic brain injuries;
tumors - pituitary adenoma, glioma, craniopharyngioma;
infections - syphilis, tuberculosis, toxoplasmosis;
hemochromatosis, sarcoidosis;
autoimmune lymphocytic hypophysitis;
irradiation and surgical interventions in the area of the hypothalamus and pituitary gland.

Low T3 syndrome

A reduced level of free T3 can be observed in severe acute and chronic diseases. In this case, the functioning of the thyroid gland is not impaired, and the TSH concentration is normal or slightly higher.

To find out the reason hormonal changes it is necessary to determine indicators in dynamics. The use of thyroxine is not indicated; the underlying pathology is treated.

High free T3 levels

Reasons for increased triiodothyronine levels:

diffuse toxic goiter;
thyroiditis in the initial stage;
decompensated functional autonomy;
a pituitary tumor that produces TSH - thyrotropinoma;
resistance to thyroid hormones;
overproduction of human chorionic gonadotropin (CG);
taking thyroxine medications.

Diffuse toxic goiter

This autoimmune disease, in which thyrotoxicosis syndrome develops. The cause of the pathology is stimulation of the production of thyroid hormones under the influence of antibodies to TSH receptors (AB to rTSH). A characteristic clinical picture- weight loss, palpitations, fever, trembling in the body and hands. Often the disease is accompanied by endocrine ophthalmopathy - eye damage associated with the circulation of antibodies to rTSH in the bloodstream.

Significantly reduced in blood test TSH level, the levels of free T3 and T4, and antibodies to rTSH are greatly increased.

Used to treat the disease medications, which block the process of hormone formation - thyreostatics (Tyrozol, Propicil). If there is no effect from taking them, use surgical intervention or radioiodine therapy.

Thyroiditis

On initial stages development of thyroiditis, thyrotoxicosis may occur. The increase in the concentration of free T3 in this case is associated with its excess entry into the blood from destroyed thyroid cells. At this time, the disease is difficult to distinguish from diffuse toxic goiter. At laboratory research TSH is reduced, T3 and T4 are above normal, and there are no antibodies to rTSH.

Thyreostatics are not used to treat this type of thyrotoxicosis. Symptomatic therapy is indicated - sedatives, drugs that reduce heart rate - beta blockers (propranolol), prednisolone. Over time, the functioning of the gland normalizes. In the future, such patients have high probability development of hypothyroidism.

Functional autonomy

This is a pathology caused by a lack of iodine in the body. With insufficient intake of the microelement, the synthesis of thyroid hormones, including triiodothyronine, is disrupted. To maintain their normal concentration, thyroid cells increase in size and rapidly divide, forming nodes. They acquire the ability to produce hormones regardless of TSH levels. Under the influence of provoking factors (taking iodine preparations, L-thyroxine), decompensation of functional autonomy occurs with the development of thyrotoxicosis.

In the tests, the TSH level is reduced, and the concentration of free T3 and T4 is increased. If the thyroxine level is normal, then we speak of isolated T3 toxicosis.

To stabilize the patient’s condition, the drug that provoked the pathology is discontinued and thyreostatics are prescribed. After achieving normal levels of the hormonal spectrum, surgical intervention is indicated, during which nodular formations are removed. The scope of the operation is determined individually.

Thyrotropinoma

A pituitary tumor that produces excess amounts of thyroid-stimulating hormone is called thyrotropinoma. Under the influence of TSH, hyperstimulation of the thyroid gland occurs, and thyrotoxicosis develops. An increase in TSH and free fractions of thyroid hormones is detected in the blood. To clarify the diagnosis, an MRI of the pituitary gland is indicated.

It is necessary to treat the pathology surgically. The tumor is removed using a transnasal transsphenoidal approach. At large sizes education, it is possible to perform open neurosurgical intervention. As preoperative preparation, medications are used - Octreotide, Dostinex.

Resistance to thyroid hormones

The pathology is characterized by a decrease in the sensitivity of peripheral tissues or the pituitary gland to the action of thyroid hormones. The cause of the condition is a defect in the receptors. There is an increase in the concentration of free T3 and T4 against the background normal values TSH. In some patients, pituitary resistance to hormones predominates, the mechanism of feedback, and, despite the fact that T3 and T4 are above normal, TSH may also increase.

As a rule, patients do not complain. The low sensitivity of tissues to the action of hormones is compensated by the high content of T3 and T4 in the blood.

For growth retardation in children, thyroxine is prescribed. To eliminate the manifestations of thyrotoxicosis, beta blockers are used, surgical removal thyroid gland followed by replacement therapy.

Hyperproduction of hCG

The structure of the human chorionic gonadotropin molecule is similar to thyroid-stimulating hormone. HCG can interact with TSH receptors on thyroid cells and enhance its function. High levels of gonadotropin are observed early in pregnancy, which may be accompanied by temporary thyrotoxicosis with an increase in free T3.

This condition does not require treatment. Regular monitoring required hormonal indicators until they are normalized.

An increase in gonadotropin is also possible in trophoblastic diseases:

chorionic carcinoma;
hydatidiform mole;
metastases of embryonal testicular carcinoma.

Against the background of pathologies, thyrotoxicosis also develops. Treatment - surgery, after which stabilization of the thyroid gland occurs.

Excess of thyroxine preparations

Thyroxine preparations are used to correct hypothyroidism. When they overdose, thyrotoxicosis occurs, which is accompanied by an increase in free T3 and T4, and a decrease in TSH. Reducing the dose of the drug or stopping it leads to recovery hormonal levels.

After removal of the thyroid gland in patients with cancer, high (suppressive) doses of thyroxine are indicated. This is necessary to reduce the risk of relapse of the pathology. In this case, the TSH concentration is maintained at a low level, which may be accompanied by a slight increase in T3 and T4.

Norm of free hormone indicator

T3 hormone is a hormone produced by the thyroid gland. The thyroid gland is small size an organ that consists of two identical lobes connected by a bridge.

Characteristics of the thyroid gland

The thyroid gland is shaped like a shield or a butterfly, the “wings” of which are 50-60 mm wide and 55-80 mm high. Despite its small size and light weight (up to 20 g), its function is to human body vital. The main function of the thyroid gland is to produce hormones such as thyroxine, iodotyrosine and triiodothyronine. The hormone thyroxine affects the growth and development of the body, increases the body's resistance to elevated temperatures. Thyroxine stimulates the functioning of cells, which under its influence become stronger, increasing their protective functions. Thyroxine, or T4, differs from the T3 hormone only by the presence of an extra iodine atom. Once in the body, thyroxine loses an additional atom, turning into the T3 hormone.

Free triiodothyronine is found in the body in very small quantities, since most of it is bound by special proteins. The protein-bound hormone T3 (more than 92% of it in the body) does not function, it is absolutely inactive. Takes part in many body processes, influencing the functioning of many internal organs and only T3 systems are free.

Blood test for the hormone and its function in the human body

Many negative human health conditions, long-term chronic diseases, difficult to treat, should make everyone think - what is the cause of such problems? It wouldn't hurt to go comprehensive examination internal organs and donate blood for hormones. In particular, to find out the amount of the T3 hormone, you need to donate blood for two tests:

General T3. The content of triiodothyronine in the body as a whole is checked.
Free T3. The total amount of hormones in bound and free states is summed up (the norm is up to 0.5%).

What functions does free triiodothyronine perform in the body? It turns out that its influence on the human body is colossal, since without it a person would not be able to grow and develop. Free T3 hormone affects such processes as:

stimulation of metabolism;
improving oxygen absorption by tissues;
increasing the synthesis of vitamin A in one of the most important organs of the human body - the liver;
reducing the amount of cholesterol and triglycerides in the blood;
work of the central nervous system;
increased excretion of calcium in urine;
heat exchange in the body, etc.

Deviations from the norm

Thyroid hormones are produced in the baby while still in the womb, playing an important role in further development almost all organs and their functions. Without thyroid hormones, a person would not be able to grow in height, and his mental abilities would be very limited. The human body's immune system also could not exist without thyroid hormones.

There are cases when the thyroid gland stopped functioning in a child with early age, as a result of which the already grown-up person had the appearance of a first-grader, both in physical and mental indicators, which once again confirms the importance of hormones for the body. The thyroid gland is influenced by the pituitary gland and hypothalamus, regulating the production of hormones. The pituitary gland produces thyroid-stimulating hormone, which stimulates the production of triiodothyronine, thyroxine and affects the growth of the thyroid gland itself. External factors(stressful situations, hunger, strong fear) enter through nerve impulses into the hypothalamus, where the received information is processed and analyzed. The hypothalamus sends a signal to the pituitary gland by producing hormones, and the pituitary gland, in turn, signals the thyroid gland. Under the influence of signals received from the brain thyroid is capable of producing about 300 mcg of thyroid hormones per day.

The norm for free triiodothyronine for an adult is 3-6 pmol/l, and for total triiodothyronine - 1.3-3.1 mIU/l. In boys under 8 years of age, the amount of free hormone will be slightly less than in girls, but from the age of 10 this figure will be almost the same. In adulthood, there is a tendency towards a decrease in free triiodothyronine in the body.

Signs and symptoms of an elevated rate

The reasons why T3 may be elevated are varied. Normally, triiodothyronine has positive influence on the central nervous system, therefore any deviations from the norm will inevitably affect the functioning of the central nervous system. Insufficient or excessive production of T3 will inevitably affect a person’s well-being, leading his nervous system to a state of increased excitability or, conversely, severe depression. General state in this case, it will be similar to chronic fatigue, which is what the patient will refer to, unaware of the hormonal imbalance.

The cardiovascular system suffers no less from an increased or decreased amount of the hormone T3, since as a result of hormonal imbalance, the work of the heart muscle increases, which begins to work at an increased rate while the body remains at its usual pace. As a result, muscle tissue does not have time to become saturated with oxygen, nutrients, and increased work of the cardiovascular system and central nervous system leads to the fact that a person feels increased fatigue, muscle pain, deterioration in health.

In general, three factors indicate a lack of the hormone T3 in the body:

poor resistance to various diseases;
the body's ability to recover various injuries and damage;
the degree of protective functions during the onset of the disease.

The dependence of the immune system on thyroid hormones was discovered by scientists relatively recently. As a result of the research, it was revealed that immune cells small receptors sensitive to triiodothyronine. Based on these and other observations, it was found that poor protective functions of the body and the presence of various immune diseases are closely related to thyroid hormones.

Thyroid hormones affect metabolism in the body. Thus, without them it would be impossible to assimilate useful substances body - vitamins, proteins, macro- and microelements. With an increase in the free T3 hormone in the body, a person may begin to lose weight sharply or, conversely, rapidly gain weight. Any corrective measures to correct weight, be it diet or exercise, are ineffective. What is happening in the body at this moment? Increased hormone T3 quickly utilizes fat in the body, further using proteins to increase energy. Symptoms of constantly irritable stomach and intestines, gastritis - all this can be associated with triiodothyronine disharmony. When the T3 hormone decreases, a person may experience constipation and poor digestion of food. As practice shows, it is joint treatment organs of the gastrointestinal tract and thyroid gland give the most positive results than just treating the organs digestive tract. This factor should definitely alert a person and prompt him to contact an endocrinologist.

If T3 is elevated, symptoms such as:

headache;
chronic heat bodies;
increased blood pressure;
tremor in the arms and upper face;
diarrhea;
insomnia;
unstable psycho-emotional state;
frequent urination;
feeling of constant hunger;
disruption of the menstrual cycle;
growth of mammary glands in males.

With a reduced level of the hormone T3, a person will experience following symptoms: muscle weakness, feeling tired, pale skin, lack of sexual desire, constipation, decreased body temperature, impaired memory and sensitivity, swelling in the extremities, etc.

Therapeutic measures

Iodine is a substance that the thyroid gland needs for normal functioning. For the hormones produced by the thyroid gland (in particular for the hormone triiodothyronine), iodine is a peculiar building material. The daily requirement of iodine for the human body is 150 mcg. Both a lack of this element and its excess are harmful to the body. A lack of iodine in a child’s body can lead to mental and physical underdevelopment. Goiter is also a common endocrine disease that occurs against the background of iodine deficiency.

Most often, disruption of hormone production is observed in women, especially before and after menopause. IN Lately dysfunction of the thyroid gland has increased several times in many people, which is associated, first of all, with bad environment, fast pace of life and poor nutrition.

The disruption of the production of the hormone T3 can also be affected by a tumor of the thyroid gland, which will put pressure on the organ itself and interfere with its normal operation. Treatment of this pathology will depend on the size of the tumor and its condition. Most often, conservative treatment is prescribed using medications and hormonal drugs. In some cases, surgery is prescribed to remove the tumor; in an extremely severe situation, it may be necessary to remove the entire organ.

The cause of menstrual irregularities and infertility can also be a lack of triiodothyronine. In order for a woman to conceive a child, all organs and systems in her body must work harmoniously, otherwise it will be almost impossible to get pregnant. To correct the situation, it is necessary long-term treatment using hormonal drugs.

In order for the thyroid gland to function well, producing the hormones necessary for the body, you need to carefully monitor not only your health by checking with doctors, but also monitor your diet, consuming foods that are important for the functioning of the thyroid gland. In particular, you need to enrich your diet walnuts, seafood (especially seaweed), iodized salt etc. Doctors do not recommend applying iodized mesh to the skin, since this releases a large amount of iodine into the blood, which can disable the thyroid gland for a long time. This is especially dangerous for those people who have thyroid disease or are genetically prone to developing thyroid dysfunction.

Free triiodothyronine, despite small amount in the body, affects many processes. Its deficiency or excess can lead to various violations, which will invariably affect a person’s quality of life. To save it normal amount in the body, it is necessary to monitor the health of the thyroid gland by healthy image life and maintaining a proper and balanced diet. Don’t ignore the symptoms that are often disguised as small organ- thyroid gland, to talk about yours possible violations and illness. Only timely diagnosis And correct treatment will help maintain the functioning of the thyroid gland, and therefore the health of the entire body as a whole.

Medicines for the treatment of the thyroid gland

Thyroid hormone preparations are usually divided by origin into two groups: synthetic and animal hormones. It is better to choose synthetic drugs for the treatment of the thyroid gland in women, despite their “unnatural” origin. Such drugs are practically devoid of impurities, their effect is completely predictable, there are much fewer side effects and cases of intolerance.

Indications

When thyroid medications or thyroid hormone medications are used:

If they are deficient due to illness, congenital absence, neck irradiation due to radiation therapy, or treatment with radioactive iodine, or surgical removal the thyroid gland, the level of its hormones cannot meet the needs of the body. In some cases, thyroid hormone medications have to be taken indefinitely, for years.

You need to temporarily “turn off” the thyroid gland. When dealing with cancer from thyroid tissue, its growth can be delayed by stopping hormonal production in the gland. Cancer growth is based on cell division, which slows down if the gland does not work. A person is given as much thyroid hormone as the body needs, or a little more. Then the stimulation of the thyroid gland stops, and it freezes - the cancer too.

For weight loss. This is what those few women dare to do, whose courage has won common sense. Thyroid hormones taken without medical prescription and control are not adequate and safe means for weight loss, as it sharply increases appetite, and in people with heart disease can cause arrhythmias, angina attacks, and acute heart failure. Thyroxine in overdose is harmful to the heart even healthy person. At long-term use or in high doses, a woman has a chance of developing pathology of the thyroid gland as well.

Contraindications

Contraindications are divided into absolute and relative. There are absolute and relative. Scroll absolute contraindications, as usual, is small - this is hyperthyroidism, when there is already an excess of thyroid hormones, and an allergy, which usually occurs to hormones of animal origin and when replaced with synthetic drug disappears.
List of relative contraindications:

Diabetes mellitus, because thyroid hormones increase blood sugar and therefore increase the need for insulin. If the administration of hormones is vital, then their doses have to be carefully selected and correlated with the residual hormonal function of the gland and the person’s current need for insulin. This is a very difficult task even for an experienced endocrinologist.
Adrenal hormone insufficiency (Addison's disease), as thyroid hormones increase the need for cortisol.
General significant exhaustion. By increasing the metabolic rate and, accordingly, energy expenditure for life support, thyroid hormones will only worsen exhaustion and lead to cachexia.
Severe forms of ischemic heart disease. There is an increase in cardiac activity, with which diseased heart may not cope, a heart attack is possible.

If it is vital for a person to take thyroid hormones, then they are prescribed early, but in minimally effective doses, usually in a hospital and under the cover of other medications.

Dose

For adults, the dose of the drug is not changed; for children, it is increased according to the needs of the body. The dose of thyroid drugs depends on what is being treated, but in any case, TSH is the main guideline. If thyroid drugs are prescribed for the treatment of hypothyroidism, then normalization of TSH is the criterion for the ideal dose. On the contrary, TSH must be sharply reduced if the goal of treatment is to “turn off” the thyroid gland. It is necessary to reselect the dose if:

The disease progresses and hypothyroidism worsens accordingly.
There are/have been severe stress reactions and surgeries.
A person switches to constant use of amiodarone or some other drugs. That is why, when prescribing new drugs, you must warn your doctor that you are taking thyroid hormones. Conversely, at your appointment, always tell the endocrinologist the names and doses of all the medications you are taking.
There is sudden weight loss without visible reasons, changeable mood(“now into laughter, now into tears”), blood pressure rises, and drugs in usual doses it is no longer being reduced.
Weight gain, again, without visible to that reasons, swelling, lethargy, memory impairment, constantly depressed, melancholic mood.
In diabetes mellitus, blood sugar rises for no reason.

If a woman receiving treatment with thyroid drugs becomes pregnant, they are not discontinued. In some cases, doses may need to be adjusted to suit changing needs. developing child and mother.

For adults, the correct dose of the drug is rarely changed, and for children it is gradually increased in accordance with the ever-increasing needs of the growing body.

Varieties

The most convenient and therefore popular drug from the group of thyroid hormones is levothyroxine. An analogue of thyroxine, or T4 produced in the thyroid gland. It begins to act after 3-4 days and its effect lasts about two weeks. This drug is usually chosen both for infertility in women caused by subclinical hypothyroidism and for a lack of thyroid hormones in pregnant women. Prescribed in tablets or for injection into a vein.

There is a synthetic analogue of T3, liothyronine, in the arsenal of doctors. The drug is similar to natural human triiodothyronine and chemical structure, and by biological effect. It is approximately 5 times more active than T4. This powerful medicine is used only for coma and psychosis due to a very severe deficiency of thyroid hormones.

Liothyronine is often effective in the absence of response to thyroidin and causes almost no allergic reactions. The maximum effect is within a day, the drug lasts for almost a week. Available in tablets and solution for injection into a vein.

Thyroidin is extracted from the thyroid glands of slaughter cattle. It contains T3 and T4, the effect is somewhat weaker, and the frequency of allergies is higher than that of synthetic analogues. The body's response to treatment with thyroidin is difficult to predict, because the strength of action of T3 and T4 is different, and it is impossible to standardize their ratio in this medicine.

Combinations are effective thyroid hormone with iodine preparations. Thus, iodothyrox consists of potassium iodide and levothyroxine. Thyrocomb, for example, also contains liothyronine.

The endocrine system combines the glands of the human body, which are responsible for the production of hormones and certain substances. The thyroid gland occupies a special place. It is located in the neck area and has the shape of a butterfly. This small gland weighs no more than 20 grams and produces several important hormones, including T3, T4 and TSH, as well as complex chemical substances. T3 hormone - what is it responsible for in women and why is it so important?

Hormone functions

T3 or Triiodothyronine is one of the main thyroid hormones. The effect of this substance affects literally everyone critical systems human body. T3 at the cellular level activates metabolic processes and cell nutrition, and also affects libido.

T3 hormones are biologically active substances; appropriate examination allows you to timely identify disorders in the thyroid gland and undergo treatment:

A study is prescribed if a woman begins to lose or gain weight for no apparent reason.
Abrupt change appearance women (deterioration of nails, hair loss, etc.).
Constant gastrointestinal disorders.
Problems with memory and solving simple problems that previously did not cause difficulties.
Vulnerability to colds, general decline in immunity.
Menstrual irregularities.
Constant irritability, tendency to mood swings.

Hormone functions

T3 is one of the thyroid markers; its concentration in the blood reflects the functioning of the thyroid gland. A blood test is prescribed by a doctor if indicated. Free T3 hormone is a small part from total number, about 99% of this substance is present in the body in bound form with proteins and other compounds. Hormone analysis is usually carried out comprehensively, looking at several interrelated indicators. T3 is determined in conjunction with other substances produced by the thyroid gland:

In the blood, T3 performs a regulatory function of metabolic processes. This process directly affects a woman's weight. If the thyroid gland works too intensively, “to wear out,” then a woman can eat a lot and not gain weight at all. But if the functions of the thyroid gland are suppressed, it cannot produce enough biologically active substances to stimulate metabolism. In this case, even with normal nutrition, the woman’s weight will increase.
T3 and T4, responsible for stimulating cells, also enhances amino acid transport and tissue development.
The normal concentration of T3 in the blood increases general immunity human and is responsible for the production of heat by the human body.
The T3 hormone stimulates fat metabolism and the removal of “bad” cholesterol from the body.
Triiodothyronine activates protein synthesis in the central nervous system.
The hormone ensures and improves the absorption of oxygen by the cells and tissues of the body.
Regulates the cardiovascular system. With an excess of the hormone, the heart rate increases by 20% or more.
Increased synthesis of vitamin A.

Norm

The norm for women depends on the age of the patient and her condition (pregnancy, illness, etc.). The study of a woman’s hormonal levels is carried out not only if disorders are suspected; doctors recommend regular preventive examinations.

Most often, the analysis is carried out to determine pathologies and dysfunctions of the thyroid gland.

The standards that the patient must rely on are as follows:

Always ask to show you the test results, because endocrinologists do not take into account the optimal scale of values when making a diagnosis. They tend to look only at the range as a whole.

During pregnancy, the concentration of the hormone may change slightly. The substance also depends on the hormonal medications taken. The test result should only be interpreted by a qualified physician. Many factors influence the final results, including the units of measurement used in the laboratory. The indicator can be displayed in mIU/l, pmol/l, nmol/l.

Excess T3

What is the T3 hormone responsible for in women? The functions of hormones and biologically active substances do not reflect the completeness of their influence on the body. Their quantity may be insignificant compared to the total mass of a person, but a deficiency or excess of biologically active substances often negatively affects the body.

An excess of the hormone indicates that the gland is working too intensely and causes the following negative symptoms:

A slight increase in body temperature, while the temperature does not decrease and constantly remains at the same level above normal.
Frequent urge to urinate, upset stomach.
Appetite increases, but body weight decreases.
Headaches of varying strength.
Trembling appears in the hands.
Patients suffer from psycho-emotional changes, sudden mood swings, tearfulness, etc.
Blood pressure levels rise and heart rate increases.
Women often complain of shortness of breath.
The condition of the nails deteriorates (brittleness, delamination).
Among women high level T3 hormone causes disruption of the menstrual cycle.

T3 deficiency

It should be remembered that the appearance of one or two specified symptoms, is not a clear sign of hormonal imbalance. However, feeling half or more of the listed ailments is a good reason to consult a doctor and undergo the appropriate tests. If the result of the analysis showed an amount of hormone that is significantly below the permissible norm, this reflects dysfunction of the thyroid gland:

Woman feels constant weakness, fatigue. Even during minor physical activity he gets tired quickly.
Lack of appetite, which may lead to weight gain excess weight, even food is coming in very little.
Difficulties appear with the thought process. With T3 deficiency, thinking slows down and simple tasks take longer to solve.
Swelling of the arms and legs may appear, and sometimes the face swells.
The skin becomes pale and lifeless.
During the day a person feels drowsy, but at night, on the contrary, he cannot sleep.
Convulsions may occur.
Body temperature drops below normal.
There may be a feeling of nausea (regardless of meals) and constipation.

The concentration of the thyroid hormone T3 within normal limits allows the female body to function normally. Any deviations from the natural concentration of the hormone lead to failures and disturbances. Over time, disorders develop into pathologies and serious illnesses. It is very important for a woman to maintain normal hormonal levels throughout her life.

Nutritional supplements to normalize T3

For the production of T3, the following are important:

potassium iodide;
amino acid L-tyrosine.

Potassium iodide can be purchased at pharmacies under different brands.

Amino acid L-tyrosine is a precursor to thyroxine (thyroid hormone) and powerful antioxidant. Taking this supplement often helps lower TSH, but it is also very important for T3 production.

Sometimes the problem is not the T3 hormone itself, but a problem with the conversion of the T4 hormone to T3.

To convert T4 into the active hormone T3, the following may help:

Zinc;
Selenium;
Vitamin B12;
Vitamin C;
Vitamin E.

When choosing zinc, give preference to shape picolinate, it improves the absorption of minerals. If you take calcium at the same time, then distribute it with zinc in the morning-evening mode.

Selenium is most preferred in the form selenomethionine. Remember that without vitamin E, taking selenium will not give you significant results. Start with a small dosage, increasing it if necessary.

In contact with

To ensure energy metabolism in all human cells and organs, various hormones are needed, and most of them are produced by the thyroid gland, which is controlled by a part of the brain - the pituitary gland.

Upper section The pituitary gland is responsible for the hormone that affects the production of the thyroid gland:

T3 – triiodothyronine;
T4 – thyroxine.

T4 is more active; under the influence of the enzyme thyroid peroxidase (TPO), it is converted into T3. In the blood, they are combined into protein compounds and circulate in this form, and if necessary, they leave the ligament and are released. Such free hormones T3 and T4 provide the main metabolic and biological activity. The level of free hormones in the blood is less than 1% of the total, but these indicators are important for diagnosis.

How T4 and T3 act in the body

Acting interconnectedly, iodinated polypeptide hormones affect general development body, activating all systems. As a result of coordinated work:

blood pressure stabilizes;
heat is generated;
motor activity increases;
the saturation of all organs with oxygen accelerates;
mental processes are stimulated;
is being produced normal frequency and heart rate;
the absorption of proteins is accelerated;
Hormones participate in all metabolic processes, enriching the cells and tissues of the body with energy.

Deviation from the norm of any of the hormones, more or less, leads to an imbalance and can cause various abnormalities:

decreased intellectual abilities;
disturbance of mental activity;
lowering blood pressure;
disruptions in contractions of the heart muscle;
the occurrence of body edema;
disturbances in the functioning of the reproductive system, including infertility;
the functionality of the gastrointestinal tract is impaired;
development coronary disease hearts.

If the level of T3, T4 and TSH decreases sharply during pregnancy, this can provoke a disruption in the formation of the nervous system in the fetus.

The value of tests

To diagnose the condition of the thyroid gland, the doctor will prescribe an analysis for all three hormones - T3, T4 and TSH, and quantitative indicators in the free state will be determined and general level:

TSH - regulates the production of hormones; if its level begins to increase, the thyroid gland produces T4 and T3 to a lesser extent - this deviation is called hypothyroidism;
free hormone T4 is responsible for the production of proteins in the body, its deviations from the norm indicate a malfunction of the thyroid gland;
the overall level of thyroxine is affected by the concentration of transport proteins in the blood;
Free T3 is involved in oxygen metabolism and its absorption by cells.

The free T3 hormone is formed as a result of the synthesis of T4, which differs only in one iodine atom in the molecule.

Norms of T3, T4 and TSH for different groups of people

Patients	TSH, µIU/ml	T3 SV	T3 general	T4 SV	T4 general
Adults	0,4–3,9	2,6–5,5	0,9–2,7	9,0–19,0	62,0–150,7
Pregnant	0,1–3,4	2,3–5,2	1,7–3,0	7,6–18,6	75,0–230,0
Children:
1–5 years	0,4–6,0	–	1,30–6,0	–	90,0–193,0
6–10 years	0,4–5,0	–	1,39–4,60	10,7–22,3	82,0–172,0
11–15 years	0,3–4,0	–	1,25–4,0	12,1–26,8	62,0–150,7

The norm for women is the same as for men.

Why there may be an imbalance of T4 and T3

The consequences of a lack or excess of T4 T3 hormones affect all systems of the body, and the causes of imbalance are abnormalities in the functioning of the thyroid gland or pituitary gland:

toxic goiter (or forms);
toxic adenoma;
pituitary tumor;
oncological diseases of the thyroid gland.

During pregnancy occurs hormonal imbalance and the production of T4 and T3 may be impaired, most often the level of 3T is reduced, especially in the first and second trimester. For the normal development of the fetus, it needs iodine, and since its own thyroid gland is not yet formed, it draws supplies from the mother’s body. To compensate for the deficiency, the thyroid gland begins to produce T3 to a greater extent, while the secretion of TSH by the pituitary gland sharply decreases. If the deviation from the norm in a pregnant woman is close to zero, then this indicator should be alarming and requires a more detailed study.

The problem of diagnosing hormone levels in pregnant women is due to the fact that the symptoms are very similar to toxicosis and many women, and even doctors, do not pay due attention to them.

What do deviations from the norm of the T3 hormone indicate?

The main thing that the T3 hormone is responsible for is metabolic processes in the body, so its deficiency will contribute to:

frequent illnesses;
reduction of the body's protective functions;
inability of tissues to recover after injury.

You can determine that T3 levels are low by the following signs:

pale skin;
decreased body temperature;
memory impairment;
constipation;
poor digestion of food.

A decrease in T3 levels is observed in the following diseases:

anorexia nervosa;
liver pathologies;
thyroiditis;
eclampsia (in pregnant women).

When triiodothyronine levels are low in children, it can lead to mental retardation

If free T3 is elevated, this may be evidence of the following diseases:

toxic goiter;
choriocarcinoma;
myeloma;
peripheral vascular resistance;
thyroiditis.

You can determine whether the norm has been exceeded in men by several signs:

decreased potency;
lack of sexual desire;
formation of a female-type figure (enlarged mammary glands, the appearance of a fatty layer in the lower abdomen).

If the hormone is in excess in women, it can provoke:

painful and irregular menstruation;
frequent increases in temperature;
sudden weight gain or, conversely, weight loss;
mood swings, emotional outbursts;
trembling fingers.

A child may have elevated hormones if:

heavy metal poisoning;
neuropsychic disorders;
due to excessive physical stress on the body;
development

What is the effect of low and high T4 levels?

T4 hormone, responsible for protein synthesis and delivering it to cells, also has big influence on female body– reproductive function depends on it.

If the T4 hormone level is reduced, women may experience the following symptoms:

high fatigue;
tearfulness;
muscle weakness;
hair loss;
weight gain;
heavy menstruation;
ovulation failures.

If free T4 is elevated in men, they may feel:

weakness and increased fatigue;
irritability;
increased heart rate;
sweating;
weight loss;
tremor of fingers.

When the T4 norm is exceeded, this may indicate the following diseases:

porphyria;
toxic adenoma;
thyrotropinoma;
tumor diseases of the pituitary gland;
hypothyroidism;

Most often, T4 is elevated in a child with toxic goiter, when it occurs and greatly increases in volume. In second place among the reasons is taking medications, such as:

levothyroxine;
propranolol;
aspirin;
tamoxifen;
furosemide;
valproic acid.

The total T4 hormone can increase only when the child has been taking these drugs for a long time. If such medications are prescribed to a child, they should be given strictly as prescribed by the doctor.

T3, T4 free and general - what's the difference?

Both hormones circulate in the blood in two states:

free;
related transport proteins.

The general indicator is the totality of free and bound hormones.

The effects of total and free T4 on the body are very different. The overall indicator may be outside the normal range, but the amount of free hormone will be greatly reduced. Therefore, information about free T4 and T3 is important for adequate analysis. When bound to protein, thyroxine and triiodothyronine have no effect on the body. They can circulate through the bloodstream for months and accumulate. But if the breakdown process is disrupted, then there will be a shortage of free hormones. That is why an analysis is necessary to determine free T4 and T3, as well as their total level.

It is difficult to determine which indicator is more important: total or free T4. The most revealing analysis is during pregnancy. At this time, the amount of protein in the blood, which concentrates thyroxine, greatly increases in the woman’s body, so its overall indicator may be normal, but the free form of the T4 hormone will be lacking, which will negatively affect the development of the fetus.

How to determine hormone levels

To evaluate the functioning of the thyroid gland or if there are one or more symptoms of hormone imbalance, the endocrinologist will prescribe. Before taking a test for the hormone T4, T3, TSH, you need to prepare:

stop taking it in a month;
two days before eliminating medications that contain iodine;
exclude physical exercise in two days;
try not to be nervous;
Stop eating 12 hours before and drink only water
You need to take a hormone test on an empty stomach, in the morning;

A dynamic analysis of free T4 will be more revealing; it must be taken once a month for six months.

Triiodothyronine (referred to as T3 for simplicity) and thyroxine (tetraiodothyronine or T4) are the most important hormones produced by the thyroid gland. These hormones influence almost all processes in the human body.

They are involved in metabolism, reducing cholesterol, normalizing calcium metabolism, growth and mineralization of bones, formation muscle tissue, the work of the cardiovascular system and nervous system, regulation of the activity of other endocrine glands, etc.

All diseases of the thyroid gland (TG), accompanied by a violation of its function, manifest themselves in a bright, specific clinical symptoms(metabolic disorders, damage to the nervous system, cardiovascular system, etc.).

If a thyroid dysfunction is suspected, a hormonal profile study is mandatory.

Laboratory assessment of thyroid function includes:

TZ general (total triiodothyronine);
TZ free (triiodothyronine free);
total tetraiodothyronine (T4);
T4 free;
calcitonin;
TSH (thyroid-stimulating hormone is synthesized by the pituitary gland, but it plays an important role in regulating the activity of the thyroid gland);
antibodies to thyroglobulin, thyroid peroxidase, etc.

Attention. The study of thyroid hormones should be carried out comprehensively; a diagnosis cannot be made based on changes in the level of one hormone.

enlarged gland, difficulty swallowing;
tremor of the limbs,
heart rhythm disturbances;
hair loss, thinning;
brittle nails;
dry skin or severe hypersecretion of the sebaceous glands, as well as increased sweating;
poor tolerance to heat and cold;
rapid obesity or, conversely, weight loss;
increased nervous excitability, irritability, aggressiveness or lethargy, lethargy and drowsiness;
menstrual irregularities in women, decreased potency in men;
swelling, puffiness of the face;
decreased memory and intelligence;
ocular symptoms (widened palpebral fissure, rare blinking, inability to fix gaze, shiny eyes, etc.);
developmental delay (in children);
disruption of the gastrointestinal tract (constant abdominal pain, constipation or diarrhea), etc.

What are triiodothyronine and tetraiodothyronine

The thyroid cells secrete so-called iodinated hormones - the hormone triiodothyronine (T3) and thyroxine (T4 or tetraiodothyronine), as well as non-iodized calcitonin. The parathyroid glands, located on the posterior surface of the thyroid gland, secrete parathyroid hormone.

The main components used for the synthesis of thyroid hormones are iodine and tyrosine (amino acid). main feature iodinated hormones T4 and T3 - this is the presence of an iodine molecule.

Important. A sufficient intake of iodine into the body from food is one of the most important factors necessary for the full synthesis of thyroid hormones.

T3 is an iodine-containing thyroid hormone containing three iodine molecules, triiodothyronine. And T4 is a thyroid hormone containing four molecules of iodine - tetraiodothyronine.

In addition to the fact that triiodothyronine is produced by the follicular cells of the thyroid gland, it is also formed in peripheral tissues due to deiodination (detachment of the iodine molecule) of T4.

Triiodothyronine is much more active than tetraiodothyronine, although it is found in the blood at higher levels. low concentrations. The production of T3 occurs under the control of thyroid-stimulating hormone.

The free T3 hormone is part of the total triiodothyronine, which is found in the body in a state associated with transporter proteins. The free hormone is approximately 0.2-0.5% of the total concentration.

For reference. When diagnosing thyroid function, free T3 is usually studied; the level of total triiodothyronine is checked upon receipt dubious result to free T3.

T3 hormone - functions in the body

Triiodothyronine is capable of:

have a stimulating effect on gas exchange processes in organs and tissues, increasing oxygen consumption and CO2 release;
increase the synthesis of retinol (vitamin A) in the liver;
normalize the absorption of vitamin B12 in the intestines;
activate glycolysis processes and increase peripheral glucose utilization by tissues;
normalize thermoregulation and increase heat production and body temperature;
maintain normal lipid balance, reducing the level of “bad” cholesterol (lipoproteins NP and SNP) and triglycerides in the blood;
accelerate protein metabolism processes (triiodothyronine can both enhance and inhibit protein synthesis, depending on the needs of the body);
intensify calcium metabolism V bone tissue, increase the excretion of calcium in the urine;
increase the strength and frequency of heart contractions;
have a stimulating effect on the central nervous system;
stimulate the processes of growth, development and differentiation of tissues;
stimulate growth and mental development in children.

Main functions of the thyroid gland:

When is it necessary to test triiodothyronine levels?

identifying diseases of the thyroid gland (with the development of symptoms of its hypo- or hyperrecretion);
suspected congenital hypothyroidism;
carrying out differential diagnosis of thyroid pathologies (thyroiditis, thyroid cancer, etc.);
selection of hormone replacement therapy for hypothyroidism;
control of treatment for hyperthyroidism;
diagnosis of relapses of hyperthyroidism;
pituitary tumors (TSH, secreted by the pituitary gland, is involved in the regulation of the secretion of thyroid hormones);
hyperthyroidism or hypothyroidism in pregnant women.

Triiodothyronine norm

Normal levels of triiodothyronine largely depend on the age of the patient. Sex differences in free hormone levels are observed only from 12 to 19 years of age.

Free T3 norms for women and men after 19 years of age differ little, however, among the fair sex, the levels are usually five to ten percent lower than among men.

Attention. In pregnant women, normal levels of triiodothyronine gradually decrease. The maximum decrease in the hormone occurs in the third trimester. Within a week after birth, triiodothyronine levels in women are completely normalized. This condition is normal and does not require treatment.

The exception is a sharp change in hormone levels, accompanied by corresponding clinical symptoms.

The presence of seasonal fluctuations is also indicative of triiodothyronine levels. Its peak level occurs at autumn period(from September to the end of November), and minimal for summer time.

FT3 (T3 free, normal) by age:

T3 general, norm by age

How to donate blood for triiodothyronine

Used for research deoxygenated blood. The collection of material should be carried out in the morning, on an empty stomach. It is allowed to drink non-carbonated water.

On the eve of the study, it is necessary to exclude smoking and drinking alcohol, physical and emotional overload, overheating or hypothermia.

Medicines containing iodine must be excluded 5-7 days before the test.

Taking thyroid hormones or others hormonal drugs excluded for a month, provided that the endocrinologist has not given other instructions (an exception may be quality control of the replacement therapy, etc.).

Important! If it is impossible to discontinue hormonal therapy, laboratory staff should be notified about the medications the patient is taking.

What may affect the results of the study?

estrogen preparations,
contraceptive tablets,
levothyroxine.

Reduce T3 levels:

administration of radiopaque iodine-containing agents,
antithyroid drugs,
taking anabolic steroids,
beta-blockers (metoprolol, propranolol),
glucocorticosteroids,
NSAIDs,
hypolipidemic mean.

When is elevated triiodothyronine detected?

Free T3 is increased when:

thyrotropinomas (rare benign hormone-secreting tumors of the pituitary gland);
diffuse toxic goiter;
isolated T3 toxicosis;
thyroiditis;
thyrotoxic adenoma;
T4-resistant hypothyroidism;
syndrome of resistance to iodine-containing thyroid hormones;
TSH – independent thyrotoxicosis;
postpartum thyroid dysfunction;
chorionic carcinomas (a rare type of malignant tumor developing from chorionic villi);
a decrease in thyroxine-binding globulins;
some myelomas;
after hemodialysis;
chronic liver pathologies.

When is low T3 detected?

decompensation of primary adrenal insufficiency;
severe exhaustion of the body (recovery after long-term illnesses, severe concomitant pathologies);
various hypothyroidisms;
artificial thyrotoxicosis, which developed as a result of self-administration of T4 or correction of the recommended dose of the hormone by the patient;
long-term low-protein and low-calorie diets;
exhausting physical activity;
sudden decrease in body weight.

How to normalize triiodothyronine levels

It is extremely important to understand that independent correction of hormone levels is unacceptable and can lead to severe and irreparable consequences for health.

Very important!! Only an endocrinologist should prescribe treatment after a thorough examination, in accordance with test results. By trying to influence T3 levels on your own, you are extremely dangerous actions, the consequences of which cannot be predicted!

All therapy is carried out under laboratory control of the hormonal profile.

If triiodothyronine levels are low, depending on the cause and level of its decrease, the following may be prescribed:

iodine preparations,
potassium iodide,
thyroxine preparations,
L-thyroxine (thyrocomb, iodothyrox, etc.).

For thyroid hyperfunction the following is prescribed:

thyreostatics (mercazolyl, tyrosol),
glucocorticosteroid preparations,
beta blockers.

For reference. If necessary, radioactive iodine preparations can be used. If conservative therapy is ineffective, surgical treatment is used.

When examining the thyroid gland, patients are often interested in why they should donate T3 free hormone - what it is. Another name for the substance is triiodothyronine. It is synthesized by the thyroid gland and is the biologically active form of thyroid hormones. Some substances enter the blood in the form of T3, the rest - as T4 (thyroxine). In peripheral tissues, low-active thyroid hormone loses one molecule of iodine and turns into triiodothyronine.

Why a T3 free hormone test is prescribed - what it is and what its purpose is, the doctor who issued the referral for the test will tell you.

Triiodothyronine circulates in the blood in 2 states - bound and free. The first is formed as a result of interaction with transport proteins that carry it to its destination. The second remains unchanged and circulates in the blood, having a pronounced effect on a person’s metabolism and well-being. Total T3 consists of bound and free hormone.

The activity of triiodothyronine is ten times higher than that of thyroxine due to the release of one iodine atom.

T3 purposes:

energy metabolism management;
normalization of cardiac activity;
control over the work of the central nervous system;
regulation of the formation of new bone tissue and destruction of old;
participation in retinol production;
providing oxygen supply to tissues, accelerating their growth;
decline bad cholesterol.

With a deficiency or excess of a substance, multiple disorders are observed:

the rate of contraction of the heart muscle changes;
psychoneurological abnormalities develop;
appearance deteriorates (condition of hair, nails, skin);
immunity decreases;
the risk of growth of benign and malignant tumors increases;
the functioning of the gastrointestinal tract and other things are upset.

Indications for the study are as follows:

Differential diagnosis of thyroid diseases accompanied by hypo- or hyperthyroidism.
Evaluation of the effectiveness of therapy with thyreostatics and drugs based on levothyroxine.
Deviations in the results of other tests (TSH, T4, AT-TPO, etc.).

Endocrinology doctors know why T3 free hormone is needed, what it is and what its norms are. For them, this indicator is of diagnostic value along with the results of other studies.

When free T3 is normal, this means that its value is in the range of 2.6–7.5 pmol. Laboratories use different units of measurement, so the numbers on the forms are different.

The level of the hormone varies depending on the age and gender of the patient.

The table of normal values looks like this:

The result of the study is influenced by:

Season. In summer, the T3 indicator is lower, and with the onset of cold weather it increases.
Taking medications. This list includes thyreostatics, levothyroxine preparations, sacylates, iodine, dexamethosone and others.
Excessive load on the body. The result is distorted by intense training and severe stress on the eve of the analysis.
Nutrition. The concentration of FT3 is affected by the consumption of heavy foods (fried, fatty).
Bad habits. The use of alcohol, drugs and smoking can distort the hormone level.
Medical staff training. Negligence of laboratory technicians or equipment malfunction sometimes lead to errors, so if the result turns out to be suspicious, it is better to retake the blood in another laboratory.

The maximum concentration of triiodothyronine is observed in newborns. The numbers decrease with age. After 65 years, the thyroid gland begins to function worse, which is associated with age-related changes and the level of thyroid hormones decreases.

To find out whether T3 free hormone is normal or not, visit an endocrinologist who will give the appropriate direction. It is not worth going to the laboratory on your own, because in some cases this analysis is unnecessary and is not suitable as a primary screening of thyroid function.

A thyroid examination is not included in the list of mandatory diagnostic procedures during pregnancy. If pathology is suspected, a thyroid-stimulating hormone (TSH) test is taken. If the latter shows deviations, then the examination continues.

Usually, increased level FT3 against the background of normal thyrotropin and thyroxine does not have diagnostic value. IN in rare cases this indicates genetic pathologies. For this reason, a healthy woman who has no complaints is not prescribed a study.

At 1–2 weeks of pregnancy, the level of the substance increases slightly, which is normal and does not require treatment. Often the ratio of free T3 to T4 changes proportionally, so a pronounced difference between the indicators may indicate an error.

The FT3 norm in pregnant women does not differ from those of older women, with the exception of the first weeks after conception.

An increase in triiodothyronine and thyroxine indicates a phenomenon such as thyrotoxicosis. If the readings are slightly higher than normal, but TSH is within acceptable values, then treatment is not required.

Lack of therapy for severe imbalance leads to severe consequences.

The mother experiences:

heart failure;
eclampsia;
childbirth on early stages, miscarriages.

The fetus has an increased risk of:

development of thyrotoxicosis and hypothyroidism (with treatment with thyreostatics);
developmental defects;
low birth weight;
death in the womb.

With a lack of thyroid hormones, the following are possible:

various complications pregnancy (placental abruption, intrauterine fetal death, miscarriages);
the birth of a baby with congenital malformations (cretinism, autism, epilepsy and other pathologies of the central nervous system and other organs).

The functioning of the thyroid gland has a pronounced effect on reproductive function and pregnancy, therefore it is recommended to search for problems and treat them at the planning stage.

The doctor decides whether it is necessary to conduct a blood test for free T3. If there is such a need, then he gives a referral for blood tests, including TSH, FT4, AT-TPO and FT3. This is a classic examination scheme for suspected serious disorders of the thyroid gland ( Graves' disease, nodular, toxic goiter and others).

When collecting biomaterial, the following features are taken into account:

the last meal is taken 8 hours before the procedure;
You can only drink water;
physical and psycho-emotional stress is eliminated in 1–2 days;
if the patient takes medications, their list is discussed with the doctor;
blood is donated before starting therapy or 1–4 weeks after.

The results may be false if the patient the day before:

had an acute illness viral infection;
came to the laboratory with elevated temperature bodies;
I did x-rays, ultrasounds, MRIs, etc.

The duration of the study is 1 day. After receiving the form from the laboratory, you need to contact an endocrinologist, because without having medical education It is impossible to evaluate the data, make a diagnosis and prescribe treatment.

If free T3 is low, then this may be a consequence of hypofunction of the thyroid gland, which developed under the influence of the following factors:

autoimmune thyroiditis;
diffuse goiter;
thyreostatics or radioactive iodine;
prolonged fasting, anorexia;
adrenal insufficiency;
systemic diseases(scleroderma, rheumatoid arthritis, lupus erythematosus and others);
previous operations, injuries, large blood loss.

If, along with free T3, the total indicator increases, this may indicate:

removal of the thyroid gland;
preeclampsia, eclampsia;
heavy liver failure;
severe iodine deficiency.

Signs of triiodothyronine deficiency include:

violation of thermoregulation, chilliness;
slowing or speeding up heart rate;
baldness, focal alopecia;
drowsiness, weakness;
decrease in body temperature, blood pressure;
psychoneurological disorders (apathy, depression, panic attacks);
dizziness, headaches;
problems at work gallbladder;
constipation, flatulence, etc.

Such complaints are made by patients who have been diagnosed with hypothyroidism. If free T3 is greatly reduced, and other hormones are normal, then the tests need to be retaken; most likely, it was a mistake.

Timely therapy will help quickly bring hormones back to normal and improve the quality of life.

Often free T3 is increased simultaneously with thyroxine. This condition is called thyrotoxicosis - poisoning by thyroid hormones.

The following pathologies can lead to it:

goiter of toxic origin;
thyroxine and triiodothyronine resistance syndrome;
tumors, injuries, infectious lesions pituitary gland and hypothalamus;
rare forms oncologies that develop mainly during pregnancy (choriocarcinoma);
myeloma (cancer that develops from plasma);
severe liver damage.

Excess thyroid hormones leads to the following complaints:

accelerated heartbeat, atrial fibrillation, atrial flutter;
absence normal sleep;
nervousness, aggressiveness;
hyperactivity;
fast weight loss;
impaired concentration;
acceleration of speech, thought processes, mental abilities;
increased blood pressure (often a rise in systolic);
dry eyes, protrusion of eyeballs (exophthalmos);
heat intolerance, rise in body temperature, heavy sweating;
increased appetite (rarely total loss);
muscle fatigue;
osteoporosis and so on.

In 5% of patients, free T3 hormone is elevated in isolation. This pathology is called T3 toxicosis. She is accompanied by everyone typical signs hyperthyroidism, and if untreated leads to an increase in T4.

Often it is impossible to normalize the FT3 level on your own, because various factors lead to it pathological conditions, occurring in the body. To restore hormonal levels, it is necessary to eliminate primary cause disease and correct T3 levels using medication, surgery, and physiotherapeutic methods.

If T3 is elevated and leads to hyperthyroidism, then it is treated with drugs from the group of thyreostatics and radioactive iodine. IN severe cases resort to removal of the thyroid gland (complete or partial).

If the triiodothyronine level is significantly reduced, then the patient is indicated replacement therapy drugs based on levothyroxine. The duration of therapy is determined individually. Often you have to take pills throughout your life, periodically adjusting the dose.

To eliminate the symptomatic manifestations of the disease, use:

a-blockers;
choleretic agents;
antispasmodics;
antidiarrheal or laxative drugs and more.

The effect of using thyreostatics and Levothyroxine does not occur immediately. Often, your health improves within 1–2 weeks from the start of treatment. The effectiveness is assessed after a month, and the dose is adjusted if necessary.

Purpose hormonal pills(L-thyroxine, Euthyrox) is absolutely safe during pregnancy and has no toxic effect on the fetus. The synthetic components are identical to natural thyroxine produced by the follicular cells of the thyroid gland.

Drugs that suppress the activity of thyroid hormones must be selected with caution, because most are contraindicated for expectant mothers. Despite this, therapy is still required.

You should not test for free triiodothyronine yourself. In most cases this is not necessary, it is not cheap ( average price for Moscow 438 rubles) and spoils the mood if the result does not fall within the normal range. An endocrinologist should prescribe such a study. If a patient has doubts about the qualifications of a doctor, then it is better to turn to another than to take unnecessary tests on their own and invent non-existent diagnoses.