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 he alth of the individual. The synthesis of hormonal substances begins long before the birth of the baby. Before delivery, their concentration is much higher than in adults. Immediately after birth, hormone levels decline.
The thyroid gland: what hormones does it synthesize?
The hormones produced by the gland are divided into two classes - calcitonin and iodothyronines. 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 the follicular tissue. The former is several times more active than the latter. Iodine deficiency disrupts their synthesis, as a result, the body receives less of this microelement, as a result, the processes of energy metabolism in the body fail. Before entering the bloodstream, hormones bind to transportproteins.
In the cell tissue, thyroxine is converted into triiodothyronine. The biological action in the body is carried out mainly due to the latter substance. The secretion of thyroid hormones is under the control of 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 that acts on the thyroid gland. Stimulate or inhibit the release of the latter signals from the hypothalamus.
For example, any stress provokes an active release of thyrotropin and, accordingly, leads to an increase in thyroxine and triiodothyronine. Thyrocalcitonin 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. Insufficient production of these active substances provokes the development of osteoporosis. Thyroid hormones are involved in all processes occurring in the body of the individual, and have the following actions:
- 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 female and male genital organs depends on them;
- affect maturation, body growth, 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, there must be enough thyroid hormones. What tests to take to check the functions of this body? During the study, not only the amount of thyroxine, triiodothyronine, thyrotropin, but also antibodies to thyroglobulin, thyroperoxidase, and thyroid-stimulating hormone receptors are evaluated. This is due to the fact that in case of failures in the body's immune response, antibodies are formed not only on foreign organisms, but also on one's 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 functions of the thyroid gland and the amount of active substances;
- presence and volume of he althy cells in the gland.
You can see the norm of thyroid hormones above.
Lack of hormonal substances
What hormones are given to the thyroid gland, now it's 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 productionhormones, less often when taking certain drugs, removing the gland. In regions with low iodine levels, hypothyroidism manifests itself in the form of endemic goiter. At the slightest suspicion or detection of the following symptoms, you should visit a doctor who will write a referral for a blood test for thyroid hormones. The lack of them is manifested in the following:
- constant weakness, fatigue;
- oppressed state;
- weight gain;
- menstrual disorder;
- infertility;
- low body temperature and inability to warm up;
- pain in muscles and joints;
- constipation;
- swelling of the legs, face;
- itching, dandruff;
- low blood pressure and slow heart rate;
- decrease in memory and reaction.
Hyperthyroidism
In this case, there is a hyperfunction of the organ, in which the synthesis and secretion of thyroxine and triiodothyronine increase. The analysis shows that the thyroid gland hormones are elevated, while it increases in size, the individual has exophthalmos. The clinical picture is as follows:
- constant feeling of heat;
- fever;
- great appetite but weight loss;
- weakness, fatigue;
- dryness and flabbiness of the dermis;
- high blood pressure;
- irregular periods;
- inability to conceive;
- decrease in reaction rate;
- heartbeat is 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, weight loss agents, neoplasms of the pituitary gland and ovaries, and 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)
Thyroxine synthesized by follicular cells of the gland is excreted into the blood, where most of it binds to globulin. In this state, it 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 bone he alth.
The level of thyroid hormone T4 in the blood is influenced by the psychological and physiological state of the individual. In pregnant women, the norms of this indicator are higher. The use of certain medications also affects the result:
- reduce its level of corticosteroids, androgens, sulfonamides, potassium iodide, penicillin;
- overestimate - thyroid drugs, estrogens, synthetic thyroxine.
T4 high and low
Excess hormone accelerates the decomposition of lipids, inAs a result, the individual rapidly loses weight. The energy released during this process negatively affects the functioning of the body:
- blood pressure drops;
- sweat production increases;
- heart functions at its limit;
- excessive stimulation of the central nervous system leads to neurosis and emotional instability;
- calcium begins to leach out of the bones, increasing the risk of caries, fractures, cracks, osteoporosis and other pathologies.
Diseases in which an increased concentration of thyroxine is detected in tests for thyroid hormones:
- obesity, regardless of degree;
- diffuse goiter;
- chronic liver disease;
- multiple myeloma;
- glomerulonephritis;
- thyroiditis;
- and others.
Main signs of increased thyroxine:
- weakness;
- fatigue;
- irritability up to aggression;
- nervousness;
- limb tremor;
- a sharp drop in body weight;
- excessive sweating.
In case of insufficient organ function, a low concentration of thyroxin, a thyroid hormone, is observed, and this occurs in the following cases:
- damage or inflammation in the pituitary gland, hypothalamus;
- endemic goiter;
- head surgery or traumatic brain injury;
- excess thyroid hormones inas 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, i.e. receives replacement therapy.
Endocrine function of parafollicular thyroid cells
Thyrocalcitonin is produced in this tissue and consists of amino acid residues, iodine is absent in it. An increased amount of calcium in the blood stimulates the secretion of calcitonin, and a reduced one does the opposite. Its level changes under the following conditions:
- Thyroid neoplasm;
- anemia;
- osteoporosis;
- respiratory, prostate or breast cancer.
A significant increase in the concentration of this hormonal substance in the blood when analyzing thyroid hormones, thousands of times higher than the permissible values, is observed in medullary carcinoma. However, a slight increase or complete absence of calcitonin, which occurs after the 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 adjustment of calcium metabolism is not fully understood and remains unclear.
Thyrotropic hormone
The natural work of the thyroid depends on the concentration of this hormonal substance, which is produced in the anterior pituitary glandglands. The TSH hormone 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 mature and grow, the indicators change. In addition, it is influenced by the time of day, nervous tension, taking certain medications, physical activity. A single jump in TSH is not a cause for concern. A persistent increase can be seen at:
- thyroid diseases;
- gallbladder resection;
- lead poisoning;
- too much or too little of iodine;
- pathologies of the respiratory, cardiovascular, digestive and urinary systems;
- adrenal dysfunction;
- severe forms of preeclampsia in the second and third trimester;
- tumors in the lungs, mammary and thyroid gland, pituitary gland.
The risk factors are strict long-term diets, heredity, autoimmune pathologies, constant stress and exercise. An increased concentration of TSH is observed in hypothyroidism. Initially, the disease does not give a pronounced clinical picture, which makes it difficult to detect at an early stage. With an increased level of thyrotropin, the levels of thyroid hormones T3 and T4 decrease. There are some features of the course of hypothyroidism:
- Sex drive disappears in males, potency decreases, testosterone concentration decreases, sperm quality deteriorates, developsinfertility.
- Women have irregular periods, they become long and heavy, uterine bleeding and yellowish-white discharge from the mammary glands are possible, not associated with breastfeeding, there are difficulties with conception.
- Babies with a congenital disorder develop edema, the umbilical wound heals for a long time, there is prolonged jaundice, the sucking reflex is weakly expressed. Children slowly gain weight, are 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 deformities.
- In preschoolers and older children there is a lag in intellectual and physical development, constant drowsiness, lack of concentration, impaired thermoregulation.
- Teens have delayed puberty, obesity, depression, poor academic performance.
Reducing the concentration of thyrotropin provokes the development of hyperthyroidism. Characteristic for him:
- disorder of the gastrointestinal system;
- tachycardia;
- weight loss despite excellent appetite;
- heightened emotionality.
In addition to the analysis for TSH, the norm of which in adults ranges from 0.3 to 4 μIU / l, a test for antibodies to its receptors is indicated. It is the latter study that is considered key in the diagnosis of pathological conditions of the thyroid gland.
When is a test ordered?
Analysisblood test for thyroid hormones is a study that demonstrates the state of the main organ of the endocrine system of an individual. Thyroid problems affect the entire body. Diseases of this organ often occur without vivid symptoms, and a person may not be aware of the presence of pathological changes. However, you should contact your doctor if you experience any of the following symptoms:
- excessive sweating;
- weight loss with normal or increased nutrition;
- resting heart palpitations up to 120 beats per minute;
- blood pressure jumps;
- arrhythmia;
- body tremor, upper limb tremor;
- nervousness and irritability;
- constant lethargy, fatigue;
- fever unrelated to colds;
- bad dream;
- hair loss;
- lack or decreased sex drive;
- polyuria;
- appearance of a goiter that is visible to the naked eye;
- male impotence;
- gynecological problems;
- infertility;
- appearance of fibrocystic mastopathy.
To make an accurate diagnosis when the above symptoms appear, the doctor will recommend taking a test for thyroid hormones - donating blood. In addition, with a certain frequency, it is recommended to take biomaterial for analysis to persons with a predisposition to thyroid pathology, and for prevention purposes to people over 45 years of age. In the case of a primary test, i.e.when the individual complains for the first time, thyroid-stimulating hormone (TSH), free triiodothyronine and thyroxine, and antibodies to thyroid peroxidase (anti-TPO) are examined. In the secondary and during pregnancy, a test for antibodies to TSH is added to the above.
Preparing for analysis
To get the most accurate results for the delivery of thyroid hormones, you must first prepare:
- Thirty days before the test date, stop taking hormonal drugs taken to treat endocrine pathology. It is not recommended to cancel medications on your own, this issue is agreed with the attending doctor.
- For seven days, give up drinking alcohol, smoking, attending sports training.
- For a week, try to avoid stressful, conflict situations.
- Do not take iodine-containing products three days before the examination.
- Instrumental research methods in the form of MRI, ultrasound, X-ray and others before a blood test should be postponed, as they affect the results.
- If you feel unwell or have any acute illness, the study should be canceled and a full recovery awaited.
- 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 light, it is recommended to give preference to fermented milk and vegetable products.
- From the last meal, including water, to the moment of surrenderbiomaterial must pass at least 12 hours.
- Don't brush your teeth on test day in the morning.
- 20-30 minutes before entering the laboratory, calm down, relax.
- Biomaterial sampling is carried out until 10 am. It is noted that the greatest activity of some substances of the thyroid gland falls on the morning period from 7.30 to 8.00 hours.
The reliability of 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 he althy baby depends on their concentration. The rules for preparing for a thyroid hormone test for women are described above, they do not depend on the menstrual cycle.
