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The thyroid is an inconspicuous and invisible to the naked eye gland located in the anterior-lower part of the neck, which is one of the few odd endocrine glands. Only when it starts to fail do we notice how much depends on it. What is the role of the thyroid gland?

The thyroid glandproduces threehormones : triiodothyronine (T3), thyroxin (T4), and calcitonin. Although it is a very small gland (weighs only 30-60g), it plays a very important role in the functioning of the nervous system, circulation and movement. They also determine the level of protein synthesis and the degree of oxygen consumption in cells and the body's calcium-phosphate balance.

The thyroid gland - how is it built?

The thyroid gland is surrounded by a capsule made of two layers of connective tissue. The gland's flesh is made of tiny vesicles, the wall of which is made of a single-layer, flat and cubic epithelium. The proportions between the shape of the epithelium depends on the functional state of the gland. The squamous epithelium is a resting form - hormones are not secreted. The cubic epithelium is the active form - hormones are synthesized. The thyroid gland is the only human gland whose cells store the hormones they produce so abundantly. Before they are released into the bloodstream, they are stored in a transient form in a gel that fills the vesicles.

Thyroid and thyroid hormones - role in the body

The thyroid itself, however, does not determine the way it functions. Its proper operation is subject to double regulation. On the one hand, the production of metabolic hormones is controlled by the hypothalamic-pituitary system in the brain, which works on the principle of negative feedback - the secretion of thyroid hormones inhibits the secretion of hypothalamic hormones that stimulate the thyroid gland. On the other hand, thyroid hormones are produced as a result of the stimulating effect of the nervous system, which takes place in stressful situations, with the intensification of the body's defensive reaction. The concentration of the third thyroid hormone, calcitonin, depends on the level of calcium in the blood. When the thyroid gland secretes too much or too little hormones, it is said to be an overactive or underactive gland.

Biological functions of thyroid hormones:

  • development of the central nervous system
  • increased metabolic processes
  • bone mineralization (growth)
  • liver (increased lipogenesis, glycogenolysis, gluconeogenesis)
  • are responsible for the heart rhythm

Hyperthyroidism

An overactive thyroid gland is an excess of circulating hormones produced by the thyroid gland. The disease affects about 2% of the population and is four times more common in women than in men. It occurs when the thyroid gland is stimulated by a group of its own antibodies (autoantibodies) or the presence of an adenoma that secretes thyroid hormones independently of the regulation of the brain. Sometimes hyperthyroidism is associated with viral thyroiditis. It can also appear as a result of administering high doses of thyroid hormones for therapeutic purposes, but this is extremely rare. Symptoms of hyperthyroidism are: rapid weight loss, increased sweating, nervous excitability, sleep disturbances, trembling hands. A sick person complains of an accelerated heart rate. Heart rhythm disturbances, coronary insufficiency may appear. Many people also have problems with their eyes - they are red, irritated, dry and swollen. There is increased pressure on the optic nerve and orbital tissues, causing the eye to open out. Sometimes mental illnesses or neuroses manifest themselves in hyperthyroidism. The mainstay of treatment of hyperthyroidism is pharmacotherapy, possibly treatment with radioactive iodine. Patients are not advised to drink alcohol, black coffee, use the steam room and sunbathe.

Important

Radioiodine therapy is a method of treating thyroid diseases (some types of hyperthyroidism and cancer) with the use of the isotope - iodine-131. The doses of radioiodine used in treatment are much higher than those used in the course of diagnostic tests (e.g. in thyroid scintigraphy). Orally administered radioiodine accumulates in the thyroid tissue and acts locally within a radius of about 4 mm, sparing the surrounding tissues.

Hypothyroidism

The diagnostic symptom of hypothyroidism is the deficiency of thyroid hormones circulating in the blood. The source of hypothyroidism may be a disease of the thyroid gland itself, lying in its abnormal structure, a malfunction of the pituitary or hypothalamus, which directly affects the functioning of the thyroid gland. The disease may also be the result of an abnormal functioning of the immune system (Hashimoto's disease), as well as radioiodine treatment of hyperthyroidism or surgery. Hypothyroidism mainly affects women between the ages of 40 and 60, and is a transient dysfunction in 5% of post-pregnancy women. People with hypothyroidism gain weight, have a lowered body temperature, which is very intensethey feel cold. Patients complain about a decrease in the effectiveness of short-term memory, appearing depressive thoughts. Hypothyroidism is also accompanied by skin problems and deteriorating hair condition. Hypothyroidism requires quick treatment because it increases the risk of hypothermia, the appearance of atherosclerotic and coronary lesions. Pharmacotherapy is aimed at supplementing the deficiency of hormones in tablets. Sometimes it is recommended to supplement the diet with iodine.

Thyroid goitre

Increasing the size of the thyroid gland is popularly called goiter. The gland may be evenly enlarged (simple goitre) or have nodules in the flesh (nodular goitre). The nature of the nodules is assessed with the help of specialized laboratory hormonal tests, ultrasound, scintigraphy and fine needle biopsy.

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