The thyroid gland is located in the neck. This is an organ that synthesizes and accumulates highly active substances that regulate all metabolic and energy processes in the body. Violation of its normal functioning negatively affects the health of the individual. The synthesis of hormonal substances begins long before the baby is born. Before delivery, their concentration is much higher than in adults. Immediately after birth, hormone levels decrease.
Thyroid gland: what hormones does it synthesize?
The hormones produced by the iron are divided into two classes - calcitonin and iodothyronine. The composition of the latter includes iodine, three of its molecules are contained in triiodothyronine and four in thyroxine. Accordingly, the abbreviated name of the hormones T3 and T4. They are produced in follicular tissue. The first is several times more active than the last. Iodine deficiency disrupts their synthesis, as a result of this microelement, the body does not receive enough, as a result, the processes of energy metabolism in the body fail. Before getting into the bloodstream, hormones bind to transport proteins.
In the cell tissue, thyroxine is converted to triiodothyronine. The biological effect in the body is carried out mainly due to the last substance. The secretion of thyroid hormones is controlled by other endocrine organs. The hypothalamus, having received information about the concentration of thyroid hormones, emits special substances that affect the pituitary gland, which synthesizes thyroid-stimulating hormone acting on the thyroid gland. Stimulate or inhibit the secretion of the latter signals from the hypothalamus.
For example, any stress provokes the active release of thyrotropin and, accordingly, leads to an increase in thyroxine and triiodothyronine. Calcitonin is involved in the regulation of calcium-phosphorus metabolism and activates the formation of bone cell tissue, and is also responsible for the content of calcium in the bloodstream. Similar functions are inherent in parathyroid hormone, which is synthesized by the parathyroid gland. The insufficient production of these active substances provokes the development of osteoporosis. Thyroid hormones take part in all processes occurring in the body of the individual, and have the following effects:
- increase heat generation;
- stimulate the breakdown of fats, contributing to weight loss;
- participate in the formation of red blood cells;
- the normal development and functioning of the female and male genital organs depends on them;
- affect the maturation, growth of the body, the development of the central nervous system, including the brain;
- activate the production of protein, which is necessary for the construction of cells;
- increase the level of glucose in the blood, affecting its formation from fats and proteins.
Studies to evaluate thyroid function
To ensure the normal functioning of the body, thyroid hormones should be sufficient. What tests to test the functions of this body? During the study, not only the amount of thyroxine, triiodothyronine, thyrotropin is evaluated, but also antibodies to thyroglobulin, thyroperoxidase, and thyroid stimulating hormone receptors. This is due to the fact that in case of failures in the body's immune response, antibodies are formed not only on other organisms, but also on their own. As a result, the functions of the thyroid gland and the action of hormones are disrupted. The number of the latter is influenced by:
- iodine, which should be in sufficient quantity, since this trace element is used to produce hormones;
- signals that come from the brain, affecting the function of the thyroid gland and the amount of active substances;
- the presence and volume of healthy cells in the gland.
The norm of thyroid hormones can be found above.
Hormone deficiency
What hormones are given to the thyroid gland is now clear. Consider what troubles happen with insufficient organ function. In this case, a disease called hypothyroidism develops. The reason for its occurrence lies in iodine deficiency or the appearance of substances that disrupt the production of hormones, less often when taking certain medications, removing the gland. In regions with low iodine levels, hypothyroidism appears as an endemic goiter. At the slightest suspicion or detection of the following symptoms, you should visit a doctor who will prescribe a referral for a blood test for thyroid hormones. Their lack is manifested in the following:
- constant weakness, fatigue;
- depressed state;
- weight gain;
- menstrual irregularities;
- infertility
- low body temperature and inability to warm;
- muscle and joint pain;
- constipation
- swelling of the legs, face;
- itching, the appearance of dandruff;
- decrease in pressure and a low heart rate;
- decreased memory and response.
Hyperthyroidism
In this case, there is a hyperfunction of the organ, in which the synthesis and secretion of thyroxine and triiodothyronine increases. The analysis shows that the thyroid hormones are increased, while it increases in size, the individual has exophthalmos. The clinical picture is as follows:
- constant feeling of heat;
- fever;
- excellent appetite, but weight loss;
- weakness, fatigue;
- dryness and sagging of the dermis;
- high blood pressure;
- irregular periods;
- inability to conceive;
- decrease in reaction rate;
- palpitations are frequent;
- bad memory.
Hyperthyroidism is observed in some pathologies of the thyroid gland. In isolated cases, the reason for its development is the uncontrolled intake of thyroid drugs, drugs for weight loss, pituitary and ovarian neoplasms, an overdose of iodine preparations. In all cases, in order to monitor the patient's condition, an analysis of thyroid hormones is indicated.
Thyroxine (T4)
The thyroxin synthesized by follicular cells of the gland is excreted into the bloodstream, where most of it binds to globulin. In this state, he loses biological activity. The remaining T4 in free form performs the following functions:
- increases heat and energy metabolism;
- activates metabolic processes;
- improves cellular respiration;
- reduces the number of triglycerides and cholesterol in the blood;
- gives impetus to all processes in the central nervous system;
- responsible for the synthesis of retinol in liver cells;
- improves the condition of bone tissue.
The level of the thyroid hormone T4 in the blood is influenced by the psychological and physiological state of the individual. In pregnant women, the norm of this indicator is higher. The use of certain medications also affects the result:
- lower its level of corticosteroids, androgens, sulfanilamides, potassium iodide, penicillin;
- overestimate - thyroid drugs, estrogens, synthetic thyroxine.
High and low T4
Excess hormone accelerates the decomposition of lipids, as a result, the individual quickly loses weight. The energy released during this process negatively affects the body:
- differences in blood pressure are observed;
- increased perspiration;
- the heart functions to the limit of its capabilities;
- excessive stimulation of the central nervous system leads to neurosis and emotional instability;
- calcium begins to be washed out of bones, the risk of caries, fractures, cracks, osteoporosis and other pathologies increases.
Diseases in which an increased concentration of thyroxin is detected in analyzes for thyroid hormones:
- obesity, regardless of degree;
- diffuse goiter;
- chronic liver disease;
- myeloma
- glomerulonephritis;
- thyroiditis;
- and others.
The main signs characteristic of elevated thyroxine:
- weakness;
- fast fatiguability;
- irritability up to aggression;
- nervousness;
- tremor of limbs;
- a sharp decline in body weight;
- excessive sweating.
With insufficient organ function, a small concentration of thyroxine, a thyroid hormone, is observed, and this occurs in the following cases:
- defeat or inflammatory process in the pituitary gland, hypothalamus;
- endemic goiter;
- head surgery or traumatic brain injury;
- excess thyroid hormones as a result of taking medication;
- autoimmune thyroiditis;
- thyroid surgery.
The low level of thyroxine revealed by the results of a blood test for thyroid hormones is characteristic of a pathology that is incurable and the patient takes medications for life, that is, receives substitution therapy.
Endocrine function of parafollicular cells of the thyroid gland
Calcitonin is produced in this tissue and consists of amino acid residues; iodine is absent in it. An increase in blood calcium stimulates the secretion of calcitonin, and a lower one - on the contrary. Its level changes under the following conditions:
- thyroid neoplasm;
- anemia;
- osteoporosis;
- cancer of the respiratory, prostate or mammary glands.
A significant increase in the concentration of this hormonal substance in the blood when analyzed for thyroid hormones, a thousand times higher than the permissible values, is observed with medullary carcinoma. However, a slight increase or complete absence of calcitonin, which occurs after removal of the thyroid gland, does not lead to a violation of the state of the skeletal system and calcium metabolism. Thus, the role of this hormonal substance in the correction of calcium metabolism is not fully understood and remains incomprehensible.
Thyroid-stimulating hormone
The natural functioning of the thyroid gland depends on the concentration of this hormonal substance, which is produced in the anterior pituitary gland. The hormone TSH affects the production of triiodothyronine and thyroxine - this is its main function. An increase in thyrotropin is a manifestation of pathological processes in the body. Its level depends on the age of the individual, for example, in newborns it is high, and as they grow older and grow, the indicators change. In addition, it is affected by time of day, nervous tension, taking certain medications, and physical activity. A single jump in TSH is not a cause for concern. A persistent increase can be observed with:
- thyroid disease;
- gallbladder resection;
- lead poisoning;
- excess or deficiency of iodine;
- pathology of the respiratory, cardiovascular, digestive and urinary system;
- adrenal dysfunction;
- severe forms of gestosis in the second and third trimester;
- tumors in the lungs, mammary and thyroid gland, pituitary gland.
Risk factors are strict long-term diets, heredity, autoimmune pathologies, constant stress and physical activity. An increased concentration of TSH is observed in hypothyroidism. Initially, the disease does not give a pronounced clinical picture, which causes difficulties in detecting it at an early stage. With an increased level of thyrotropin, thyroid hormones T3 and T4 decrease. There are some features of the course of hypothyroidism:
- The male sex drive disappears, potency decreases, testosterone concentration decreases, sperm quality worsens, infertility develops.
- In women, the periodicity of menstruation is violated, they become long and plentiful, uterine bleeding and yellowish-white discharge from the mammary glands, not associated with breastfeeding, are possible, difficulties arise in conception.
- In babies with a congenital disorder, edema appears, the umbilical wound heals for a long time, there is a protracted jaundice, the sucking reflex is weak. The children are slowly gaining weight, inactive, the skin is pale, muscle tone is weak. Lack of therapy leads to irreversible changes in the central nervous system, mental disorders, deafness, mental retardation and bone deformation.
- Preschoolers and older children experience a lag in intellectual and physical development, constant drowsiness, lack of concentration, impaired thermoregulation.
- In adolescents, puberty is inhibited, there is obesity, depression, low academic performance.
A decrease in thyrotropin concentration provokes the development of hyperthyroidism. It is characteristic of him:
- gastrointestinal upset;
- tachycardia;
- weight loss, despite the excellent appetite;
- increased emotionality.
In addition to analysis for TSH, the norm of which in adults ranges from 0.3 to 4 μMU / L, a test for antibodies to its receptors is shown. It is the latest study that is considered key in the diagnosis of pathological conditions of the thyroid gland.
In what cases is a test prescribed?
A blood test for thyroid hormones is a study that demonstrates the condition of the main organ of the endocrine system of an individual. Malfunctions in the thyroid gland are reflected throughout the body. Diseases of this organ often occur without vivid symptoms, and a person may not suspect the presence of pathological changes. However, you should consult a doctor if you find the following symptoms:
- increased sweating;
- weight loss with normal or increased nutrition;
- at rest, a rapid heartbeat of up to 120 beats per minute;
- jumps in blood pressure;
- arrhythmia;
- body tremor, tremor of the upper limbs;
- nervousness and irritability;
- constant lethargy, fatigue;
- fever unrelated to colds;
- bad sleep;
- hair loss
- lack or decrease in sexual desire;
- polyuria;
- the appearance of goiter, which is visible with the naked eye;
- male impotence;
- gynecological problems;
- infertility;
- the appearance of fibrocystic mastopathy.
To make an accurate diagnosis of the above symptoms, the doctor will recommend a thyroid hormone test - donate blood. In addition, with a certain frequency, it is recommended to take the biomaterial for analysis to people who are predisposed to thyroid pathology, and for prevention to people over 45 years of age. In the case of an initial test, i.e., when an individual first complains, thyroid-stimulating hormone (TSH), free triiodothyronine and thyroxine, antibodies to thyroid peroxidase (anti-TPO) are examined. In secondary and during pregnancy, a test for antibodies to TSH is added to those listed.
Analysis preparation
To obtain the most accurate results for the delivery of thyroid hormones, you must first prepare:
- Thirty days before the date of testing, hormones taken to treat endocrine pathology are stopped. Self-medication withdrawal is not recommended, this issue is agreed with the attending doctor.
- For seven days, stop drinking alcohol, smoking, attending sports training.
- For a week try to avoid stressful, conflict situations.
- Three days before the examination, do not take iodine-containing products.
- Conducting instrumental research methods in the form of MRI, ultrasound, x-rays and others should be postponed before a blood test, since they affect the results.
- If you have a malaise or any acute illness, the study must be canceled and wait for a full recovery.
- On the eve of testing, if possible, refuse to take all medications, including vitamin and mineral complexes. Otherwise, notify the doctor.
- Dinner before the test should be easy, it is recommended to give preference to sour-milk and vegetable products.
- From the last meal, including water, to the time of delivery of the biomaterial, a minimum of 12 hours must elapse.
- In the morning, on the day of testing, do not brush your teeth.
- 20-30 minutes before entering the laboratory calm down, relax.
- Biomaterial is taken until 10 a.m. It is noted that the highest activity of some thyroid substances occurs in the morning period from 7.30 to 8.00 hours.
The reliability of the tests and the adequacy of therapy depend on compliance with the above rules. Incorrectly prescribed treatment can lead to irreversible consequences. It is important for the fair sex to monitor the level of hormonal substances, since the ability to conceive, endure and give birth to a healthy baby depends on their concentration. The rules for preparing for examination for thyroid hormones in women are described above, they do not depend on the menstrual cycle.