Contents
The structure, function and role of the thyroid gland in the body
The thyroid gland is an important part of the endocrine system and provides the synthesis of a number of hormones that maintain the homeostasis of the body. Disorders of the endocrine system manifest themselves as many unpleasant symptoms, but most people do not realize that the cause of all the troubles can be a small (only 4 cm in length) organ – the thyroid gland. At the same time, few people know where it is, and people who go to the doctor with swelling in the neck, when it is no longer possible to ignore the pathology, strongly trigger the disease.
The thyroid gland is a symmetrical paired organ located under the Adam’s apple (Adam’s apple) in front of the trachea. The shape resembles a butterfly, consists of the right and left parts-lobes and isthmus. The isthmus is adjacent to the trachea, and the lobes form the “wings” of a butterfly, the upper part of which is elongated in comparison with the lower.
Normally, the gland has a euthyroid state, while it is soft and almost imperceptible to palpation. However, in an inflamed state, such as with thyroiditis, it can increase in size and swell to the point of squeezing the airways, which can make breathing and swallowing difficult.
The variation in the mass of the organ from 20 to 65 g is characteristic. The size of the thyroid gland varies, depending on the age of the person and his hormonal status. So, in pregnant women, there is a slight increase in the thyroid gland, and after childbirth, the organ restores its size. During puberty, the thyroid gland becomes larger, and in old age it decreases. In all other cases, when changing the size and mass of the thyroid gland, you must consult a doctor.
The hormones synthesized in the thyroid gland are the iodine-containing thyroxine and triiodothyronine and the peptide hormone calcitonin. The synthesis of thyroxine (T4) and triiodothyronine (T3) does not occur in the absence of molecular iodine. In addition, the thyroid gland should always have a supply of thyroglobulin – a protein that contains the amino acid tyrosine necessary for the synthesis of iodine-containing hormones. Synthesis processes are localized in the apical part of the thyroid gland epithelium and are triggered only in the presence of the thyroid peroxidase enzyme.
The abbreviated names of the iodine-containing hormones T3 and T4 show how many iodine molecules are needed for the synthesis of each of them: three for triiodothyronine and four for thyroxine.
Calcitonin is produced by the C-cells of the thyroid gland, as well as by the parathyroid glands. Calcitonin regulates calcium metabolism, muscle performance, growth, regeneration of bone and muscle tissue depends on it. With an insufficient amount of this hormone (for example, due to hypothyroidism or autoimmune thyroiditis), calcium absorption from food is disrupted and problems with the musculoskeletal system arise.
Thyroid hormones regulate the vital processes of the body, are necessary for all tissues and organs. By binding to parts of the chromosome in the cell nucleus, they stimulate redox reactions, the processes of synthesis of new substances. Without thyroid hormones, the antioxidant system cannot work, cells cannot protect themselves from the negative effects of free radicals. Thyroid hormones regulate the growth, division and differentiation of cells, their programmed death (apoptosis). They also maintain the thermal balance of the body, maintain a constant temperature necessary for the work of enzymes and hormones. Without thyroid hormones, the normal functioning of the immune system, the production and activity of immune T-cells is impossible.
A lack of thyroid hormones causes growth and puberty disorders, bone tissue diseases and brain pathology in the fetus with impaired thyroid function in pregnant women.
The prevalence of thyroid disease
According to WHO, thyroid pathologies are the second most common among endocrine disorders, while diabetes mellitus is the first. One and a half billion people face health problems due to iodine deficiency conditions, 665 million go to the doctor with endemic goiter. At the same time, the number of patients increases by 5% annually.
The reasons for this prevalence of diseases may be the deterioration of the environmental situation, an inadequate diet with a low content of iodine in products, impaired absorption of iodine, and congenital pathologies of the thyroid gland.
Thyroid disease
Thyroid diseases are divided into three groups depending on changes in its function or structure:
Diseases associated with excessive secretion of iodine-containing hormones triiodothyronine and thyroxine – thyrotoxicosis;
Diseases associated with impaired synthesis and insufficient secretion of thyroid hormones – hypothyroidism or myxedema;
Diseases in which the amount of thyroid hormones is normal and the function of the thyroid gland does not suffer, but its shape and structure change – hyperplasia, nodules, goiter.
Gipotireoz
Hypothyroidism or hypofunction of the thyroid gland is a condition in which the level of thyroid hormones is low, women lead in frequency of occurrence (19 cases per 1000 compared to 1 per 1000 in men). Hypothyroidism does not have pronounced symptoms, which makes it difficult to diagnose it at home. Often, hypofunction of the thyroid gland takes place against the background of a number of other concomitant diseases, which is why the wrong treatment is prescribed from the very beginning.
Hypothyroidism is characterized by a slowdown in metabolic processes due to a lack of thyroid hormones, a decrease in the production of energy and heat, and a number of other symptoms:
Fatigue and weakness, loss of strength, memory disorders and depressive states; 14% of patients diagnosed with depression actually suffer from hypothyroidism. Depression as a symptom is often observed at the initial stage of thyroid hypoplasia.
Violation of cardiac activity, slowing of the heart rate, problems with blood circulation, because of which the patient is constantly cold.
Metabolic disorders: slowdown in digestive processes, gastrointestinal problems, constipation, indigestion, difficulty in the absorption of nutrients and vitamins, obesity.
Atherosclerosis and high blood cholesterol.
The processes of synthesis of vitamins, in particular vitamin A, are disrupted, due to which a person develops symptoms of jaundice (the skin becomes amber-yellow); hair becomes brittle and dull, skin becomes dry, flaky and hypersensitive.
Early menopause and disruption of the menstrual cycle in women, polycystic ovaries.
The lymph outflow becomes difficult, the fluid is retained in the tissues, which leads to the formation of edema. Edema of the tongue and larynx, leading to a decrease in the timbre of the voice and nighttime snoring.
Hearing and twilight vision disorders.
Heat balance disorders, lowering body temperature to 30 ° C, due to which the activity of immune cells decreases, and the body becomes more vulnerable to infection.
By themselves, these symptoms do not yet speak of hypothyroidism, each of them individually can also speak of other diseases. An accurate diagnosis can only be made by an endocrinologist after a series of laboratory tests. In order not to miss hypothyroidism and not to “heal” non-existent diseases, it is recommended to conduct an annual preventive ultrasound of the thyroid gland.
Euthyroidism
Euthyroidism is a condition of the thyroid gland, when the level of thyroid hormones (T3 and T4) in the blood is normal. Euthyroidism itself is not dangerous, however, in medical practice, the concept of euthyroid pathology is distinguished – when pathological processes in the tissues of the thyroid gland can occur at a normal level of iodine-containing hormones. Then euthyroidism is considered as a temporary condition, against the background of which autoimmune thyroiditis (autoimmune euthyroidism), nodular goiter and other diseases develop.
Thyroiditis
Thyroiditis is called inflammatory diseases of the thyroid gland, which can have a different etymology. The most common forms of thyroiditis are acute, subacute, and chronic. Subacute thyroiditis is of a viral nature, tests show the presence of mumps and adenoviruses in the tissues, as well as an increased level of antibodies in the blood. The cause of the occurrence and development of subacute thyroiditis may be the causative agent of lymphoreticulosis.
The first symptoms of inflammation of the thyroid gland usually appear a few weeks after the transferred disease of an infectious nature – mumps, measles, influenza. In the region of the gland, swelling and inflammation are observed, due to which the patient is hurt by the slightest touch to the neck. Symptoms of general intoxication are chills, aches, weakness and dizziness.
Acute thyroiditis is caused by a primary or secondary infection of the thyroid gland. With a primary infection, the inflammatory process immediately covers the tissues of the organ, and a secondary infection is preceded by tonsillitis, influenza, typhoid fever, or other infectious diseases. Inflammation begins with the left or right lobe of the thyroid gland and gradually spreads to the entire organ.
Chronic thyroiditis is an autoimmune disease that causes fibrosis of the thyroid tissue. As the disease progresses, the body’s own cells attack the thyroid gland, destroying its tissues. The more the organ is damaged, the more pronounced are the symptoms of hypothyroidism, which will progress in parallel with the localized autoimmune process. Diagnostics on ultrasound shows the heterogeneity of the tissue texture, its image on the screen is an alternation of dark and light spots. This picture is also characteristic of multinodular goiter, so autoimmune thyroiditis is difficult to diagnose immediately. The areas of compaction that are visible on the ultrasound image and on palpation of the gland are in fact not nodes, but are foci of inflammation.
In the absence of treatment, iron can completely atrophy. Complications of chronic thyroiditis are hypothyroidism and goiter.
Asymptomatic thyroiditis is often observed in women who have recently given birth, and, as the name implies, there are no pronounced symptoms of inflammation. The cause of the disease is considered to be autoimmune factors. Of all the forms of thyroiditis, asymptomatic is considered the easiest, because after several weeks of hormone therapy, the functionality of the thyroid gland can be restored. Relapses of the disease are possible, so the patient must follow all the recommendations of the doctor, do not miss preventive examinations and pay attention to the slightest changes in his condition.
Thyroiditis has the following symptoms:
Redness of the neck area at the location of the thyroid gland, a slight swelling, in the area of uXNUMXbuXNUMXbwhich there may be burning, itching and pain;
Increased body temperature, weakness, anemia, pain in the neck, ears, jaw;
Tachycardia, heart rhythm disturbances, tremor;
Irritability and hyperreflexia.
Thyroid enlargement
Enlargement of the thyroid gland with the formation of swelling on the neck can be observed in pregnant women, after childbirth it disappears without a trace. An increase in the mass and size of the thyroid gland may be associated with iodine deficiency or, conversely, with its excess. So, residents of coastal cities, who receive a large amount of iodine from food (seafood, algae, fish) and air, may have an enlarged thyroid gland. If the organ increases without the formation of nodes, this condition is called hyperplasia.
If the mass and volume of the thyroid gland increase unevenly, and nodular formations are felt under the skin, then nodular goiter of the thyroid gland is diagnosed.
Also, the causes of an enlarged thyroid gland can be benign or malignant tumors. Therefore, the condition of this organ must be carefully monitored and, with the slightest change, consult a doctor.
Hyperplasia
Hyperplasia is an increase in the mass and volume of the thyroid gland without the formation of nodes. Hyperplasia can be accompanied by both a state of hypothyroidism (lack of thyroid hormones), and their increased secretion or thyrotoxicosis. This disease develops gradually, structural changes in the tissues of the thyroid gland occur as a compensatory reaction due to a violation of its function. So, with iodine deficiency in the body, the synthesis of iodine-containing thyroid hormones decreases, and the thyroid tissue begins to grow.
The rate of organ enlargement depends on immunity and the general condition of the body – in a healthy person, a change in the size of the thyroid gland can remain invisible for a long time, while in a person with chronic diseases, the gland quickly increases and acts like a tumor on the front of the neck.
Thyroid reduction
Reducing the thyroid gland is a dangerous pathology that threatens human life and health. Thyroid hormones are responsible for metabolic processes, cell growth and differentiation, and provide immunity. A reduced thyroid gland cannot provide the required amount of hormones, which leads to serious health problems.
A reduction in the thyroid gland in newborns is called congenital hypoplasia and may be due to maternal hypothyroidism. Children with congenital hypoplasia are lethargic, apathetic, grow and develop more slowly than their healthy peers, and suffer from digestive disorders. Hypoplasia can manifest itself as symptoms of hypothyroidism, a lack of thyroid hormones impairs the absorption of calcium and minerals in the intestines, due to which the bones and teeth of the child become fragile and do not grow fast enough.
A reduced thyroid gland can also occur in adults with autoimmune thyroiditis, pathologies of the pituitary gland, or due to aging.
Hypoplasia
Hypoplasia is a congenital pathology of the thyroid gland, in which it develops unevenly, and its size is reduced. Hypoplasia can affect the entire organ, or it can only be in the left or right lobe of the thyroid gland. If the symptoms of hypothyroidism are observed in a newborn from the first days of life, then they are diagnosed with grade 1 hypoplasia, but if the deviations from the norm are insignificant, and hypothyroidism occurs at school age, then we are talking about grade 2 hypoplasia.
The causes of congenital hypoplasia are associated with the period of intrauterine development: if the mother had hypothyroidism during pregnancy, or there was not enough iodine in the diet, the newborn may experience underdevelopment of the thyroid gland. Treatment of iodine deficiency states and hypothyroidism with radioactive iodine can also be the cause of hypoplasia.
Hypoplasia in children has the following symptoms:
Lethargy, lethargy, lack of response to light and sound, growth retardation;
Yellowish skin tone (unlike physiological jaundice, not a temporary phenomenon, but lasts a long time);
Sleep and appetite disorders, flatulence, constipation;
Hoarseness of voice due to swelling of the tongue and larynx.
Thyrotoxicosis
Thyrotoxicosis or hyperfunction of the thyroid gland is characterized by an increase in the secretion of thyroid hormones, which leads to an acceleration of metabolic processes and increased heat production. Symptoms of thyrotoxicosis include:
An increase in body temperature, a feeling of heat, “hot flashes”, which women often confuse with the first signs of menopause, sweating.
Increased heart rate, heart rhythm disturbances.
Irritability and nervousness, insomnia and other sleep disorders.
Significant weight loss while maintaining appetite – calorie loss occurs due to increased energy production and heat production.
Goiter is one of the common symptoms of thyroid disease. This is a structural change in tissues, due to which the endocrine gland increases significantly in size. If the entire organ is enlarged, the goiter is called nodular, and if individual parts of the thyroid gland are enlarged, they speak of diffuse goiter.
In women, an enlarged thyroid gland does not always mean pathology – during pregnancy or after menopause, the organ can increase in size without compromising functionality. The same happens to women and men during adolescence.
Causes of thyroid disease
Hereditary predisposition is one of the main causes of pathologies of the endocrine system:
But there are a number of factors that contribute to the development of the disease even in a healthy person:
These include, first of all, a violation of the mineral balance of the body, a deficiency of molecular iodine, as a result of an unbalanced diet, as well as nervous stress, infections and chronic diseases that deplete the body.
Thyroid pathologies can develop due to unfavorable environmental conditions, due to high radiation (radioactive iodine accumulates in the thyroid gland, causing goiter).
The functionality of the thyroid gland can be impaired after taking certain medications.
The constant impact of external stress factors wears out the body’s defense system, in which the endocrine organs play an important role. So, to protect against infection, a large number of immune cells with increased activity are needed, and thyroid hormones take part in the regulation of their production. In chronic diseases, T3 and T4 are produced in large quantities, which, with concomitant adverse factors, can lead to “wear and tear” of the thyroid gland and a temporary deterioration in its function or structural disorders. This is how hypothyroidism or hyperthyroidism, hyperplasia, goiter and nodular formations in the tissues of the thyroid gland occur.
Diagnosis of thyroid diseases
Diagnosis of patients with thyroid pathologies is carried out in different ways, its purpose is to determine the morphological structure and functional activity of the gland, to find out the cause of the disease for proper treatment. Physical methods make it possible to detect tissue heterogeneity, nodes or foci of infection even before the first symptoms of hypothyroidism or general inflammation of the gland appear.
Laboratory methods help determine the concentration of thyroid hormones, which allows drawing conclusions about the functionality of the thyroid gland. The most common of these is enzyme immunoassay, which is carried out using standard tests.
An additional urinalysis may also be required to determine the excretion of iodine, from which conclusions can be drawn about the iodine deficiency state. Test to determine the level of iodine in the body.
Instrumental methods – computed tomography, ultrasound, scintigraphy (a marker drug is injected into the patient and gamma radiation is recorded) and thermography. Thus, it is possible to determine the size of the organ, the structure of its tissues and the nature of the accumulation of the contrast agent in different parts of the thyroid gland.
Express diagnostics is carried out using tests for T3 and T4 hormones, a test for the presence of antibodies to thyroglobulin and thyroid peroxidase.
Treatment of Thyroid Disease
Hypothyroidism and hyperthyroidism of the thyroid gland are often treated with medications – synthetic analogues of natural hormones or drugs that suppress the synthesis of thyroid hormones. So, with reduced secretion, hypofunction of the thyroid gland, thyroxine and triiodothyronine preparations are prescribed, sometimes they are combined with inorganic iodine supplements (thyreot, iodothyrox).
Compensation for the deficiency of one’s own hormones with their synthetic analogues is called hormone replacement therapy and is widely used in Russia for the treatment of hypothyroidism. However, this method of treatment has a huge drawback – the synthesis of its own thyroid hormones is disturbed, the thyroid gland ceases to produce them in the same amount, and after discontinuation of the drug, the patient’s condition becomes worse than before treatment. Thus, hormone replacement therapy makes a person dependent on the pill for the rest of his life.
Additional hormones may be contraindicated due to side effects – some patients experience allergic reactions, nervous system disorders and arrhythmias after taking the drugs.
Surgical treatment of the thyroid gland (hemithyroidectomy, thyroidectomy, resection) is used only in extreme cases, when the enlarged gland grows so much that it interferes with breathing or swallowing during meals. Operations to remove part of the thyroid gland with tissues of a pathological structure are carried out to avoid the risk of a malignant tumor. Surgery can lead to serious complications, up to 10% disability – loss of voice due to traumatic nerve damage, removal of the parathyroid gland. After removing part of the thyroid gland, the functionality of the organ can be so impaired that a person is forced to depend on pills for the rest of his life.
With hyperfunction of the thyroid gland (thyrotoxicosis), thyreostatics are prescribed – drugs that partially block the synthesis and release of thyroid hormones into the blood. These include: tyrosol, mercazolil and other thiamazole derivatives, propicil and diiodotyrosine.
Among the side effects of such treatment are allergies, impaired hematopoiesis and liver function, and nausea. In the long term, thyreostatics can cause pathologies in the tissues of the thyroid gland, disrupt its functional activity, due to which the synthesis of thyroid hormones completely stops and the need for hormone replacement therapy arises.
Promising drugs for the treatment of the thyroid gland
Due to a number of side effects and undesirable consequences of the use of the above drugs, there is a need for other drugs for the treatment of the thyroid gland. Modern preparations are made on the basis of vegetable raw materials and are used as dietary supplements for iodine deficiency, impaired function or structure of the thyroid gland.
Depending on the composition, these drugs are divided into three groups:
The first group consists of preparations containing iodine in organic or inorganic form.
The second group is represented by a complex of iodine and plant components.
The third group contains exclusively herbal ingredients to normalize the state of the thyroid gland.
Biological additives do not give such serious complications as the use of thyreostatics or hormone replacement therapy, however, their effectiveness is low. It is difficult to check the quality of a bioadditive or an iodine-containing complex, often the manufacturer deliberately cheats, including in the tablet those parts of plants where the accumulation of biologically active substances does not occur, in order to increase the mass and volume of the product and reduce the cost of production. Naturally, the effect of the drug will be subtle, if any.