Parathyroid (parathyroid) glands are endocrine glands, which are usually located on the wall of the thyroid gland. Their number in a healthy person should be from 2 to 8, most often 4. Distinctive feature is a location that is possible both on back wall thyroid gland, behind the esophagus and on the surface of the spine. About these parathyroid glands ah was discovered in 1880, and at the same time it was proved that they play a huge role in the body. The parathyroid gland controls calcium and phosphorus metabolism, with the help of (calcitrin) and calcitonin, which tend to increase or decrease the level of calcium in the blood. Therefore, the absence of the parathyroid gland serves as a source of a rapid decrease in calcium, which in turn can cause paralysis and even fatal outcome. In this regard, any symptoms of a violation in its work, including adenoma, are extremely dangerous, timely and competent treatment is necessary.

First of all, phosphorus-calcium disorders in the body are affected by:

1. Genetic pathologies of the parathyroid glands or their congenital absence.
2. Complete removal during surgery.
3. Hormone secretion disorder.
4. Immunity of tissue receptors to gland hormones.

All these factors can provoke many diseases, the treatment of which always requires a careful approach.

Features associated with age

The parathyroid glands are formed in the fetus in the second month of pregnancy, at birth their weight is about 9 mg, with the growth of the child, the weight increases and amounts to:

• at the age of 1 year - from 18 to 36 mg;
• at the age of 5 years - from 36 to 70 mg;
• at the age of 10 years - from 70 to 100 mg;
• at 20 years and above - from 120 to 140 mg.

It should also be noted that the parathyroid gland in men has less weight than in women.

Major diseases

Hyperparathyroidism

Hyperparathyroidism is a pathological condition of the couple thyroid gland in which there is an excess of parathyroid hormones. The appearance of the disease can be affected by hyperplasia, some diseases of the gastrointestinal tract, kidney failure, long-term treatment with anticonvulsants. Also often given state also causes parathyroid adenoma. Typical symptoms of the disease:

Often the treatment of the disease involves surgical removal parathyroid gland, and this is considered the most radical method. Also, in some cases, special injections of ethanol are used.

Hypoparathyroidism

Inadequate functioning of the parathyroid glands leads to a decrease in the hormone, which causes a sharp decrease in calcium in the blood and an increase in the amount of phosphorus. The main factors causing hypoparathyroidism include the absence of an organ, both congenital and removed as a result of the operation, as well as underdevelopment of the glands. Symptoms accompanying the disease are as follows:

• convulsions, spasms of facial muscles;
• numbness of the limbs;
• poor condition of teeth and nails;
• development of dermatitis.

Treatment of this pathology includes several main methods. Prescribe injections of calcium and vitamin D preparations, use treatment ultraviolet rays, in parallel prescribe the intake of magnesium and sedative drugs, and also recommend that you follow a magnesium-calcium diet.

Parathyroid adenoma

Parathyroid adenoma is a rare diseases, the tumor usually forms in one of the glands, rarely occurs in several. As a rule, the disease is accompanied enhanced function glands, more often diagnosed in women. The development of adenoma leads to damage to protein cells that are responsible for the supply of calcium to the parathyroid gland, as well as its insufficient amount in the body. In addition, various injuries in the neck and radiation exposure can cause the disease. Symptoms of the disease are varied, as they affect the cardiovascular and skeletal systems, as well as the gastrointestinal tract and kidneys, the main ones are:

The only treatment that an adenoma needs is surgery. But before proceeding with the operation, an additional drug therapy with the help of hypercalcium, it helps to remove excess calcium and harmful toxins from the body. After surgery, patients are shown recovery period, in which you should follow a diet, perform special physical exercise to massage damaged joints.

As mentioned above, the parathyroid glands play a lot important role in the normal functioning of the whole organism, so any violations on their part require a thorough examination. In case of need for without fail providing quality treatment.

Parathyroid glands (parathyroid glands, epithelial bodies) are small endocrine glands of a reddish or yellow-brown color. In humans, they are usually represented by two pairs. The dimensions of each of them are approximately 0.6x0.3x0.15 cm, and the total mass is about 0.05-0.3 g. The parathyroid glands are closely adjacent to the posterior surface of the thyroid gland (Fig. 43). The upper pair of parathyroid glands, adjacent to the capsule of the lateral lobes of the thyroid gland, is located on the border between the upper and middle thirds of the thyroid gland, at the level of the cricoid cartilage. The lower pair of parathyroid glands is localized at the lower pole of the thyroid gland. Sometimes the parathyroid glands can be located in the thyroid tissue or thymus, as well as in the pericardial region.

The blood supply of the parathyroid glands is carried out due to the branches of the inferior thyroid artery, and the innervation is carried out by the fibers of the sympathetic nervous system from return and upper laryngeal nerves. The parathyroid glands consist of a parenchyma partitioned into lobules by connective tissue membranes with vessels. In the parenchyma, chief and acidophilic cells are distinguished. The most numerous of the chief cells are round shape, small in size, containing a small amount of watery light cytoplasm and a well-staining nucleus. This chief cell type reflects an increase in parathyroid function. Along with them, dark chief cells are isolated, which reflect the resting stage of the parathyroid glands. Acidophilic cells are located mainly on the periphery of the parathyroid glands. Acidophilic cells are considered as the involutionary stage of chief cells. They are usually larger than its main cells, with a small dense nucleus. Transitional cells are transitional forms between chief and acidophilic cells. The parathyroid glands are vital formations. When all the parathyroid glands are removed, death occurs.

The product of the intrasecretory activity of the parathyroid glands (mainly the main and to a lesser extent acidophilic cells) is parathyroid hormone, which, along with calcitonin and vitamin D (D-hormone), maintains a constant level of calcium in the blood. It is a single-chain polypeptide consisting of 84 amino acid residues (molecular weight is about 9500 daltons, half-life is about 10 minutes).

The formation of parathyroid hormone occurs on ribosomes in the form of preproparathyroid hormone. The latter is a polypeptide containing 115 amino acid residues. The preproparathyroid hormone moves to the region of the rough endoplasmic reticulum, where a peptide consisting of 25 amino acid residues is cleaved from it. As a result of this, a propathic hormone is formed, containing 90 amino acid residues and having a molecular weight of 10,200 daltons. The binding of propathic hormone and its transfer into the cisternal space of the endoplasmic reticulum is carried out by a secretory protein. The latter is formed in the main cells of the parathyroid glands. In the Golgi apparatus (lamellar complex), a polypeptide of 6 amino acid residues is cleaved from the propathic hormone. The latter ensures the transport of the hormone from the endoplasmic reticulum to the Golgi apparatus, which is the place where the hormone is stored in secretory granules, from where it enters the blood.

The secretion of this hormone is most intense at night. It has been established that the content of parathyroid hormone in the blood after 3-4 hours from the beginning of a night's sleep is 2.5-3 times higher than its average daily level. Parathyroid hormone maintains a constant level ionized calcium in the blood by affecting the bones, kidneys and intestines (via vitamin D). Stimulation of the secretion of parathyroid hormone occurs when calcium in the blood decreases below 2 mmol / l (8 mg%). Parathyroid hormone contributes to an increase in the calcium content in the extracellular fluid, as well as in the cytosol of cells of target organs (mainly kidneys, skeletal bones, intestines). It is believed that this is associated with an increased supply of calcium through the cell membrane, as well as with the transition of its mitochondrial reserves into the cytosol.

The bone consists of a protein framework - a matrix and minerals. Structure bone tissue and a constant metabolism in it is provided by osteoblasts and osteoclasts. Osteoblasts originate from undifferentiated mesenchymal cells. Osteoblasts are located in a monolayer on the bone surface, in close contact with osteoid. The waste product of osteoblasts is alkaline phosphatase. Osteoclasts are giant polynuclear cells. It is believed that they are formed by the fusion of mononuclear macrophages. Osteoclasts secrete acid phosphatase and proteolytic enzymes that cause collagen degradation, breakdown of hydroxyapatite, and removal of minerals from the matrix. The actions of osteoblasts and osteoclasts are coordinated with each other, despite the independence of their function. This leads to normal skeletal remodeling. Osteoblasts are involved in the neoformation of bone tissue and the processes of its mineralization, and osteoclasts are involved in the processes of resorption (resorption) of bone tissue. Osteoclasts do not alter the bone matrix. Their action is directed only to the mineralized bone.

With excessive production of parathyroid hormone, hypercalcemia occurs, mainly due to the leaching of calcium from the bones. Along with the demineralization of bone tissue with a prolonged excess of parathyroid hormone, destruction of the matrix occurs with an increase in the content of hydroxyproline in the blood plasma and its excretion in the urine. In the bones and kidneys, parathyroid hormone activates the mediator of the cellular effects of this hormone, cyclic adenosine monophosphate (cAMP), by stimulating adenylate cyclase, an enzyme associated with the cell membrane. The latter accelerates the formation of cAMP. The interaction of parathyroid hormone with osteoblast receptors is accompanied by an increase in the level alkaline phosphatase, the formation of new bone tissue with an increase in its mineralization. When parathyroid hormone activates osteoclasts, they increase the synthesis of collagenase and other enzymes involved in the destruction of the matrix (for example, acid phosphatase). Under the influence of parathyroid hormone, the content of cAMP in the kidneys increases and is accompanied by an increase in the excretion of cAMP in the urine. It has been established that parathyroid hormone and cAMP increase the permeability of the proximal tubules of the kidneys. Parathyroid hormone increases calcium reabsorption in the distal tubules of the kidneys, resulting in a decrease in calcium excretion in the urine.

Along with hypercalcemia, parathyroid hormone simultaneously contributes to a decrease in the content of phosphorus in the blood by suppressing its reabsorption in the proximal tubules of the kidneys. The consequence of this is an increased excretion of phosphorus in the urine. Parathyroid hormone also increases urinary excretion of chlorides, sodium, potassium, water, citrates and sulfates and causes alkalinization of urine.

The functional activity of the parathyroid glands is mainly autoregulatory in nature and depends on the calcium content in the blood serum: with hypocalcemia, the production of parathyroid hormone increases, and with hypercalcemia, it decreases. Calcium (ionized calcium) plays an important role in the life of the body. It reduces the excitability of the peripheral nervous system and the permeability of cell membranes, is an important plastic material for the formation of bone tissue, is involved in the regulation of blood coagulation, etc. The main reserves of calcium and phosphorus are found in bone tissue. The amount of calcium in bone tissue is 95-99% of its content in the body, and phosphorus - 66%. The human body weighing 70 kg contains approximately 1120 g of calcium. daily requirement in calcium of adults is 0.5-1 g.

In the bones, calcium is found in the form of phosphorus-calcium compounds, which form crystals of hydroxide apatite. General content calcium in the blood healthy people is 2.4-2.9 mmol / l (9.6-11.6 mg%). Only ionized calcium has biological activity, which contains 1.2 mmol / l (5 mg%) in blood serum; 1 mmol/l (4 mg%) of calcium in the blood is protein-bound, 0.5 mmol/l (2 mg%) of calcium is not ionized. The amount of protein-bound calcium increases with a shift in the pH of the medium to the alkaline side. It has been established that parathyroid hormone regulates the content of ionized calcium and phosphorus in the blood, controlling its constituent fraction - inorganic phosphorus. The content of phosphorus in the blood serum of healthy people is 3.2-4.8 mmol / l (10-15 mg%), of which inorganic phosphorus is 0.97-1.6 mmol / l (3-5 mg%), lipid phosphorus - 2.6 mmol / l (8 mg%), phosphorus esters - 0.3 mmol / l (1 mg%).

The secretion of parathyroid hormone is stimulated by growth hormone, prolactin, glucagon, catecholamines, and other biogenic amines (serotonin, histamine, dopamine). Magnesium ions also have a regulatory effect on the secretion of parathyroid hormone and the implementation of its specific action. The concentration of magnesium in the blood serum is 0.99 mmol / l (2.4 mg%), and its ionized fraction is 0.53 mmol / l (1.3 mg%). With an increased content of magnesium in the blood, stimulation occurs, and with a reduced content, the secretion of parathyroid hormone is suppressed. It has been established that with magnesium deficiency, the synthesis of cAMP in the parathyroid glands and in the target organs of parathyroid hormone is disrupted, followed by the development of hypocalcemia.

In humans, calcitonin is synthesized, in addition to the thyroid gland, in the parathyroid glands and thymus. Calcitonin secretion stimulator is hypercalcemia (above 2.25 mmol/l), glkzhagon, cholecystokinin, gastrin. The intracellular mediator of calcitonin secretion is cAMP. An increase in the intracellular mediator - cAMP - Occurs when calcitonin interacts with receptors in bone tissue and in the kidneys.

In healthy people, parathyroid hormone and calcitonin are in dynamic balance. Under the influence of parathyroid hormone, the calcium content in the blood increases, and under the influence of calcitonin, it decreases. The hypocalcemic effect of calcitonin is associated with its direct effect on bone tissue and inhibition of resorptive processes in the bones. Along with the hypocalcemic effect, calcitonin also contributes to a decrease in the content of phosphorus in the blood. Hypophosphatemia occurs due to a decrease in the mobilization of phosphorus from the bone and a direct stimulation of the absorption of phosphorus by the bone tissue. The biological effect of calcitonin is carried out not only due to its effect on bone tissue, but also on the kidneys. The interaction of calcitonin and parathyroid hormone in bone tissue occurs mainly with osteoclasts, and with receptors in the kidneys - in various parts nephron. Receptors for calcitonin are located in the distal tubules and the ascending part of the nephron loop, and receptors for parathyroid hormone are located in the proximal tubules of the descending part of the nephron loop and the distal tubules.

Along with parathyroid hormone and calcitonin, vitamin D3 also takes part in the regulation of phosphorus-calcium metabolism. Vitamin D3 (cholecalciferol) is formed in the skin from 7-dehydrocholesterol under conditions ultraviolet irradiation. The resulting vitamin D3 initially does not have biological activity. In order to become biologically active, it undergoes two hydroxylation pathways - in the liver and kidneys. By the first hydroxylation, under the influence of the enzyme 25-hydroxylase, vitamin D is converted in the liver to 25-hydroxy-cholecalciferol (25-OH-D3). Subsequently, in the kidneys, by repeated hydroxylation under the influence of the enzyme 1-a-hydroxylase in the presence of calcitonin and parathyroid hormone, it is synthesized into 1,25-(OH)2-D3 - biologically active vitamin D3 (D-hormone). The process of hydroxylation of vitamin D3 in the kidneys can also take place in another way - under the influence of the enzyme 24-hydroxylase, as a result of which 24,25-(OH)-D is formed in the kidneys. The biological activity of the latter is below 1,25-(OH)2-D3. The process of hydroxylation of vitamin D is carried out in mitochondria. The accumulation of D-hormone in the cells of the proximal tubules of the kidneys and an increase in its content in the blood lead to inhibition of the synthesis of 1,25-(OH)2-D3 with a simultaneous acceleration of the synthesis of 24,25-(OH),-D3. This is due to the inhibitory effect of 1,25-(OH)2-D3 on the activity of the 1-a-hydroxylase enzyme and its stimulating effect on the activity of 24-hydroxylase.

Vitamin D hydroxylation pathway? (ergocalciferol), found in plants, in the body is the same as that of vitamin D3. As a result of hydroxylation of vitamin D, 1,25-(OH)3-D2 is formed. Last by biological activity not inferior to 1,25-(OH)2-D3.

Vitamin D circulates in the blood in combination with a-globulin. The latter is synthesized by the liver. Receptors for 1,25-(OH)2-D3 are found in the intestines, kidneys, bones, skin, muscles, mammary and parathyroid glands. The biological effect of vitamin D is manifested primarily in the kidneys, intestines and bones. 1,25-(OH)2-D3 has direct action on the kidneys, contributing to increased tubular reabsorption of calcium and phosphates. In the intestines, active metabolism of vitamin D contributes to increased absorption of calcium and phosphorus. Stimulation of calcium absorption in the intestine occurs by stimulating the synthesis of calcium-binding protein. The latter is a carrier of calcium across the membrane of the cells of the intestinal mucosa. In bone tissue, the active metabolite of vitamin D contributes to the normalization of bone formation and mineralization by mobilizing calcium and using it in newly formed bone tissue. 1,25-(OH)2-D3 also affects collagen synthesis. The latter takes part in the formation of the bone tissue matrix. The active metabolite of vitamin D., therefore, counteracts, along with parathyroid hormone, a decrease in the level of extracellular calcium.

Parathyroid hormone, calcitonin and active metabolite of vitamin D3 in varying degrees stimulate the secretion of ACTH, thyroliberin, prolactip and cortisol. Calcitonin has an inhibitory effect on the secretion of growth hormone, insulin and glucagon. In addition, parathyroid hormone and calcitonin have a pronounced cardiotropic and vascular effect.

Glucocorticoids, growth hormone, thyroid hormones, glucagon and sex hormones also take part in the regulation of phosphorus-calcium metabolism. In contrast to the parathyroid hormone, these hormones have a hypocalcemic effect. Glucocorticoids reduce the function of osteoblasts and the rate of formation of new bone tissue, increase bone resorption. At the same time, the function of osteoclasts in bone tissue does not change or is somewhat enhanced. These hormones reduce the absorption of calcium into gastrointestinal tract and increase urinary calcium excretion.

Growth hormone stimulates the activity of osteoblasts and bone-parative processes in the newly formed bone tissue, increases the excretion of calcium in the urine. In previously formed bone, growth hormone stimulates osteoclast activity and bone demineralization. This hormone also enhances the absorption of calcium in the intestine directly by affecting the intestinal mucosa and indirectly by enhancing the synthesis of vitamin D.

At physiological concentrations, thyroid hormones in equally stimulate the activity of both osteoblasts and osteoclasts, i.e. act on bone tissue in a balanced way. With an excess of thyroid hormones, there is an increase in urinary calcium excretion, osteoclast activity predominates, bone resorption increases, and with their deficiency, a delay in the formation and maturation of bone tissue.

Estrogens stimulate the synthesis of parathyroid hormone and D-hormone. However, they reduce the sensitivity of bone tissue to parathyroid hormone. In addition, estrogens suppress the activity of osteoclasts by increasing the secretion of calcitonin.

Glucagon contributes to a decrease in the calcium content in the blood by direct action on the bones (reduction of resorption processes) and indirectly through stimulation of calcitonin secretion.

In the human body there is a huge number of organs and systems that perform a variety of functions. One of them is the parathyroid glands. This is a certain part of the thyroid gland, located directly on its back wall. Correct work These glands affect many processes in our body. Therefore, every person must have some information about them.

Thyroid

It is not uncommon for people to develop thyroid problems as they age. In this case, doctors often advise to take it. Is this topic so terrible, can complications arise, and how to properly diagnose the thyroid gland? Almost everyone knows where the thyroid gland is located - this is the front of the human neck. First of all, it is worth noting that the thyroid gland is Naturally, it is part of the totality of the endocrine system that the human body is endowed with. In general, the work of the thyroid gland is associated with the production of certain hormones that maintain balance in the human body.

Lobes of the thyroid gland

The thyroid gland is, first of all, a symmetrical organ, since it includes an isthmus and two identical lobes located on both sides of it. Right lobe the thyroid gland, like the left one, is located directly on the trachea, while the isthmus is located on its front part. Some physicians may also focus on the pyramidal lobe. Here we should mention such a thing as the volume of the thyroid gland. After all, sometimes, when an extra (third) share is detected, illiterate specialists begin to talk about the pathology of the development of this gland. But this is far from true. It does not affect human health in any way and is not a defect.

In general, the norm of the thyroid gland in terms of volume should be determined only on the basis of an examination by a competent endocrinologist, individually for each person. By the way, you should contact him already when the first symptoms associated with your inner well-being appear. It turns out that malfunctions in the thyroid gland directly affect mood and the physical state person. The normal functioning of the thyroid gland depends on how much it receives all the necessary nutrients(oxygen, iodine, proteins, etc.). If their deficiency is detected, then the person immediately becomes aggressive and prone to depression. Also overweight and the inability to lose weight are also clear violations in hormonal balance thyroid gland. The norm of the thyroid gland in terms of volume is determined for each person individually. First, the doctor will ask you to go ultrasonography, and already then to hand over a blood on a level of hormones.

The activity of the thyroid gland: is it so important for the human body?

It should be noted that the size of the thyroid gland depends directly on the weight of the person. One can, of course, single out average value share: 20/20/40 mm. The value of the volume of the isthmus will be equal to 4 x 5 mm. The size of the lobes of the thyroid gland in this case will be from 20 to 40 g. By the way, the mass of the thyroid gland can reach a maximum of 65 g. There is another very important detail: gender and age characteristics have the most direct impact on the size of the thyroid gland. Old age reduces the volume of the thyroid gland, and the age of puberty, on the contrary, increases it. Also, the pregnancy of women stimulates a temporary increase in the volume of this gland. At the same time, the fact in question is considered the norm and is not treated in any way until the very birth.

As it has already become clear, the thyroid gland is a part of a person, therefore several hormones are constantly synthesized in it: calcitonin (a peptide hormone), triiodothyronine and thyroxine (iodine-containing hormones). They regulate the hormonal balance of the human body. These hormones affect the formation of new cells and the death of old ones, metabolism in the body. A person always needs energy to live, move, eat, sleep, etc. They do this hard work. They are also able to maintain the temperature necessary for the body. mental and physical development a person in the process of life depends on the functioning of thyroid hormones. They are responsible for the functioning of the immune system, and this is very important in the fight against infection. That is why it is necessary not only to know where the thyroid gland is located (in order to react in time when discomfort in the neck), but also to understand the importance of its correct work.

What is a parathyroid gland?

I would immediately like to note her direct involvement in all endocrine system person. At normal structure throughout the thyroid gland, the parathyroid glands are located on its posterior surface. A person has two such pairs. Remember that they can also be outside the thyroid gland. The composition of these glands includes two types of cells: oxyphilic and chief.

These cells, namely their cytoplasm, contain granules called secretory. It is very important to understand that the parathyroid gland is an organ of internal secretion, and it lives and functions completely independently. Therefore, somehow it cannot be replaced or deleted. Otherwise, even if you try to leave thyroid gland the person does not survive.

The size of the parathyroid (parathyroid) glands, their number and location

The shape of the parathyroid glands is predominantly oval (in the form of a kidney or bean, sometimes it resembles a circle, and is also flattened), and the size reaches 8 mm. Quite often, a person has various anomalies in the number and location of the parathyroid glands. Sometimes doctors diagnose their presence in the goiter or between the trachea and esophagus. An increase in the number of parathyroid glands is more common. Scientists, together with doctors, recorded cases of finding 8 and even 12 pieces. The sizes of the parathyroid glands do not differ much: thickness - 1.5-2 mm, width - 3-4 mm, length - 6-7 mm. Often the upper parathyroid glands are slightly smaller than the lower ones - this is the norm. Their weight is small, in total it reaches 0.04 g. The color of the parathyroid (another name in medicine) glands is usually yellowish-brown or pale brown. They are located in the so-called own capsule, although sometimes they can attach directly to the thyroid gland. Their blood circulation is carried out due to their own branch of the artery. Interesting fact: in all vertebrates, their number, shape, and size are significantly different.

Parathyroid glands: structure and functions

The composition of the parathyroid glands includes two types of cells, the so-called "light" (oxyphilic) and "dark" (main). The latter are usually much larger in number. The main thing is that these glands are well supplied blood vessels which allows them to take in oxygen. significantly surround the parathyroid glands. Hormones on them, as well as with the help of vein network distributed throughout the human body. Of course, the functions of the parathyroid gland are many. But one of the main ones is the regulation of the exchange of phosphorus and calcium in human body. This phenomenon occurs only with the help of the fact that the work on the synthesis of hormones is done directly by the parathyroid glands. The hormones they produce are of two types:

• calcitonin - it is he who reduces the level of calcium in the blood;
• parathyroid hormone - increases the level of calcium in the blood.

In general, the work of the parathyroid gland (another medical name) is based on the "feedback" method. The human body catches how much calcium and phosphorus it contains. And the parathyroid gland, on the basis of these data, regulates their number by releasing a certain dose of one or another hormone.

Hormones produced by the parathyroid glands

The parathyroid glands produce two hormones, the main one being parathyrin (parathormone). Indeed, with its help, a powerful regulation of calcium levels in human body. This hormone is a compound of protein, which, in turn, contains sulfur, iron and nitrogen. He stands out parathyroid gland endless. Parathyrin promotes the growth and development of the human skeleton.

This is due to the fact that calcium is bound by phosphates and proteins. Also, the hormone parathyrin has the opposite effect on the skeleton - bone resorption with age. In general, this process is called - the normalization of calcium levels.

The mechanism of action of parathyrin or its main effects

Of course, if this hormone has such a powerful effect on the calcium-phosphate composition in the human body, then several main organs and tissues have been noticed that are peculiar targets for it:

1. Kidneys: Some calcium is known to be excreted from the human body in the urine. This process requires regulation, which occurs due to the hormone parathyrin.
2. Bone tissue: normalizes the amount of calcium in it, so that the human skeleton is able to develop and grow.
3. Gastrointestinal tract: This is where parathyrin helps calcium to be absorbed.

In turn, the parathyroid glands, producing the hormone parathyrin, have a direct impact on the work of all body cells.

Diseases associated with abnormal functioning of the parathyroid gland

Like any other organ, tissue or whole system in the human body, the parathyroid gland is able to function incorrectly. This usually leads to its hypofunction or hyperfunction, which contributes to the development of many diseases. You can already determine this ailment on the basis of the occurrence of some symptoms. At the same time, you need to quickly contact qualified specialists and, on their recommendation, conduct appropriate examinations and pass the necessary tests.

Hypothyroidism

This disease is characterized by an incorrect amount of parathyrin produced, namely its deficiency. Usually, this can be noticed already on the basis of the patient's complaints about numbness of the limbs, chills, muscle spasms, brittle nails, hair, and more. The doctor examines a person, namely his thyroid gland, prescribes general analysis blood test, blood test for hormones, urinalysis, ECG. Usually, these studies show significant changes that will lead to further conclusions and the appointment of the correct treatment.

Hyperfunction of the parathyroid gland

Such a disease is expressed in an increase in the production of parathyrin, which is directly produced by the parathyroid glands. Hormones of this type (their excess) can disrupt the functioning of the human gastrointestinal tract, cause brittle bones and joint pain, distort the spine and chest lead to irritability and depression. Sometimes excess calcium leads to significant changes in kidney function. Therefore, if the above symptoms occur, you should immediately contact an endocrinologist to prescribe the appropriate treatment. And to confirm the hyperfunction of the parathyroid gland, ultrasound, X-ray, biochemical analysis blood. Based on the research, the doctor is able to make the correct diagnosis.

Treatment of disorders in the work of the parathyroid gland

Of course, parathyroid hypofunction is much easier to diagnose and easier to treat. In the end, it is only necessary to normalize the calcium-phosphate composition in the human body, by taking certain drugs, special diet, unlimited sun exposure for better assimilation calcium. Treatment of parathyroid hyperfunction is possible only by surgical intervention. And then therapy with special means is already prescribed.

Measures to prevent diseases of the parathyroid gland

As it has already become clear, the thyroid and parathyroid glands are very closely interconnected. Therefore, their work, as well as the problems in it, have a direct impact on each other. In order to never have problems with these internal secretion organs in your body, try to do an ultrasound of the thyroid gland at least once a year for the purpose of prevention. Any competent specialist, having identified minor changes in it, will offer you additional research to exclude various pathologies.

Understand that normal work of any organ or system in the human body directly depends on its lifestyle. How much he eats correctly and balanced, he leads active image life or not and more. Therefore, monitor your health, conduct preventive examinations and contact highly qualified doctors in a timely manner.

A person has two pairs of small oval-shaped glands.

Sometimes parathyroid glands can be located outside the thyroid gland. Their location, number and shape in vertebrates are very different. They contain 2 types: main and oxyphilic. The cytoplasm of both cell types contains secretory granules.

The parathyroid gland is an independent organ of internal secretion. After its removal, while maintaining the thyroid gland, convulsions and death occur.

The parathyroid hormone parathyroid hormone, or parathyroid hormone, is a protein compound (albumose) containing nitrogen, iron and sulfur, which acts only when administered subcutaneously, as it is destroyed by proteolytic agents, but can withstand heating up to 100 ° C. The hormone is released continuously. It regulates the development of the skeleton and the deposition of calcium in the bone substance, as it promotes the binding of calcium by proteins and phosphates. At the same time, the hormone stimulates the function of osteoclasts that absorb bones. This leads to the release of calcium from the bones and an increase in its content in the blood. As a result normal level the calcium content in the blood is 5-11 mg%.

The bones contain 99% total body calcium, 85% of all inorganic bone compounds are composed of calcium phosphate. The hormone maintains at a certain level the content of the enzyme phosphatase, which is involved in the deposition of calcium phosphate in the bones.

The hormone reduces the content of phosphate in the blood and increases their excretion in the urine. This causes the mobilization of calcium and phosphorus from the bones. After the removal of the glands, the ability to remove calcium phosphate from the bones sharply decreases.

Therefore, an increase in the content of calcium in the blood is due to increased excretion of phosphates in the urine.

Parathyroidin does not act directly on calcium metabolism, but through the liver. When the liver does not function, the introduction of parathyroidin into the blood does not increase the concentration of calcium in the blood. After removal of the parathyroid glands, the process of deamination and the ability of the liver to convert ammonia into urea are impaired. Therefore, animals whose parathyroid glands have been removed do not tolerate protein foods well.

In the glands, the hormone calcitonin is also formed, which reduces the content of Ca in the blood. Excreted in hypercalcemia.

The parathyroid glands are innervated by sympathetic nerves and branches of the recurrent and laryngeal nerves.

Reflex regulation of the function of the parathyroid glands and their relationship with others endocrine glands not studied enough. After denervation of the glands, their function does not noticeably change. Better studied neurohumoral regulation. The main regulator of parathyroidin secretion is the level of calcium in the blood. An increase in the calcium content in the blood inhibits, and a decrease in it stimulates the secretion of parathyroid hormone. big magnification parathyroid glands observed with a diet poor in calcium.

After removal of the pituitary gland, the parathyroid glands atrophy. This allows us to conclude that the pituitary hormone enhances their function.

Hypofunction and hyperfunction of the parathyroid glands

Hypofunction of the parathyroid glands causes in humans tetany(convulsive disease). Increased excitability of the nervous system individual groups muscles appear fibrillar contractions, which turn into prolonged convulsions. Convulsions can seize all the muscles of the body and, due to convulsive contraction of the respiratory muscles, death by suffocation can occur. In cases of slowly developing tetany, disturbances in the development of teeth, hair and nails, and digestive disorders are observed.

In the parathyroid glands during tetany can be detected degenerative changes or hemorrhage. A decrease in the calcium content in the blood from 10 to 3-7 mg% is constantly observed. With tetany in the blood and urine, the amount of toxic cleavage products (guanidine and its derivatives) increases due to the depletion of the body in calcium, which leads to impaired protein cleavage. Guanidine is found in meat. In chronic hypofunction of the glands, due to increased excretion of calcium in the urine and insufficient release of calcium from the bones, its content in the blood is significantly reduced. On the contrary, the excretion of phosphorus in the urine decreases, and its content in the blood increases. Overexcitation of the nervous system turns into its inhibition. With hyperfunction of the glands, the calcium content in the blood increases to 18 mg% or more, and the phosphorus content decreases.

When the concentration of calcium in the blood becomes higher than 15 mg%, apathy and sleep occur, associated with the phenomenon of poisoning. Parathyroidin and vitamin D work in the same direction to maintain a constant level of calcium in the blood. Avitaminosis D is often accompanied by hypertrophy of the parathyroid glands with their hyperfunction. In this case, an increase in parathyroidin intake compensates for vitamin D deficiency.

With chronic hyperfunction of the glands, the calcium content in the bones decreases, they are destroyed and become brittle, cardiac activity and digestion are upset, muscles are reduced.

With the growth of the tissue of the glands associated with their hyperfunction, excessive ossification appears and at the same time an increase in the calcium content in the blood (hypercalcemia), as well as vomiting, diarrhea, cardiac disorders, a decrease in the excitability of the nervous system, apathy, and in severe cases, death occurs. The excitability of the cerebral hemispheres temporarily increases, and then inhibition intensifies.

With prolonged administration of large amounts of parathyroid hormone to young animals, their bones soften due to the transfer of calcium from bone tissue to.

The parathyroid or parathyroid gland is a cluster of round bodies located on the back wall of the thyroid gland. Their number can be different - from two to seven or eight, in most cases - four, 4-8 mm long, and they are located in pairs (hence the name) along the upper and lower poles of the thyroid gland. The mass of all bodies usually does not exceed 1.2 grams.

In contrast to the thyroid, the parathyroid gland has a lighter color - pale pinkish in children and yellowish in adults. It is separated from the surrounding organs by its own fibrous tissue.

Functions of the parathyroid gland

This body owns essential function regulation of phosphorus-calcium balance in the body through the production of a certain hormone. The functioning of the motor, nervous and skeletal systems organism.

When falling below acceptable level The parathyroid gland, through receptors sensitive to this element, begins to intensively secrete the so-called parathormone, or parathyrin, into the blood, which, in turn, stimulates the release of a deficient microelement from bone tissue. Therefore, the main purpose of the parathyroid gland is the production of a hormone, the main catalyst for calcium balance in the body.

Signs of pathologies

The body reacts to malfunctions in the work of the parathyroid glands by disturbances in the work of all its organs and systems. The first manifestations of violations of the optimal secretion of parathyroid hormone are, as a rule, pathologies of calcium-phosphorus metabolism in the body, which are manifested by symptoms characteristic of endocrine diseases:

• depression of the nervous system;
• persistent fatigue;
• appetite disorders;
• weakness;
• headaches;
• convulsive contractions of skeletal and smooth muscles due to insufficient production of parathyrin;
• increased muscular and nervous excitability.

With the aggravation of conditions, the symptoms only increase due to damage to the organs and tissues of the body: musculoskeletal system suffering from myopathy and gout, visual system cataracts and the deposition of calcium salts in the cornea threaten, and problems from cardiovascular system are manifested by calcification of blood vessels and the heart, coupled with the progression of arrhythmias and hypertension.

A characteristic symptom is kidney damage with the presence of thirst, the development of urolithiasis. A feverish state and an insufficient level of hemoglobin in the blood also indicate problems with this gland.

External manifestations of hormonal disorders are jaundice and dry skin, fungal infections, brittle and dull hair, eczema or psoriasis, loss of eyelashes and eyebrows, sometimes cataracts, thinning nails, subcutaneous calcifications in the area auricles, myositis, lesions of the teeth.

Diseases of the parathyroid gland

Hyperparathyroidism- a disease that occurs with excessive secretion of parathyrin, as a result of which hypercalcemia develops in the body. Gland hyperactivity is a very threatening disease. High concentration hormone leads to elevated content calcium in the blood and, accordingly, to a decrease in its content in bone tissue, resulting in a risk of osteoporosis, kidneys suffer.

The trigger mechanism for this disease is tissue hyperplasia, adenoma or oncology of the parathyroid glands, as well as other conditions that disrupt normal functioning organ, such as long-term calcium deficiency, chronic renal failure, long-term vitamin D deficiency. Treatment this disease surgical, the prognosis is favorable in the vast majority of cases.

Hypoparathyroidism- a disease in which the an insufficient amount parathyrin, which entails a decrease in calcium in the blood and contributes to the growth of neuromuscular excitation, up to psychosis.

Often, hypoparathyroidism occurs when damage or accidental removal during surgery on this organ, with a hemorrhage in the neck, or with an inflammatory process occurring in the gland. Also, this disease can provoke a lack of vitamin D in the body, improper absorption of calcium in the intestines, exposure to radiation or carbon monoxide poisoning.

The very first sign is muscle cramps aggravated by stress, hypothermia or physical activity. Treatment of the disease is mainly hormonal.

Timely diagnosis

To identify pathological conditions glandular tissues are laboratory and instrumental diagnostic methods. The laboratory includes:

• determining the level of calcium in the urine;
• serum calcium and its ionized forms;
• the amount of phosphates;
• parathyroid hormone concentration.

However, the leading role in diagnosis today belongs to more accurate instrumental methods. Let's consider them in more detail.

1. Ultrasound examination is a safe, highly accurate and painless technique, which in the vast majority (approximately 60-70 percent of cases) allows us to ascertain the enlargement of the glands. Actively used in surgical interventions. However, when the size of the gland is unchanged, it is ineffective.
2. Computed tomography with contrast - more sensitive method, allows you to see violations in the parathyroid gland in 90% of studies.
3. MRI is a method in which nuclear magnetic resonance is visualized. This survey is quite effective in view of high sensitivity, and the absence of ionizing radiation makes it very attractive for safety reasons.
4. Subtraction scintigraphy is the most accurate imaging technique available today. During the study, the patient is injected with radioactive isotopes, the radiation from which is converted by high-tech devices into information about the degree of pathology. The sensitivity of the method makes it possible to evaluate the effectiveness of the therapy in short periods of time, however, it is not recommended for use for lactating and pregnant women and with severe conditions patients.
5. X-ray methods of research. They are mainly used to study the state of bone tissue and failures of the cardiovascular system.

It should be added that each of the diagnostic methods has both advantages and disadvantages, however, it is recommended to use several methods, especially when making the initial diagnosis or choosing a treatment. Each case of the disease must be approached individually.

In case of questionable results of ultrasound or laboratory research, which are attractive for their safety and low cost, scintigraphy should be resorted to.

Calcium is subject to parathyroid hormone

The main function of the parathyroid gland for the body is the production of periotioid hormone, or paratinin. When the level of calcium in the blood drops to a critical level, hormone receptors that are sensitive to this begin to intensively produce this hormone. Further, the hormone activates osteoclasts, which in turn extract calcium from the bone tissue. As a result, the concentration of calcium ions in the blood increases, but the bones lose their rigidity and may begin to deform when calcium-phosphorus metabolism is disturbed.

The hormone is the main regulator of maintaining calcium ions in the blood at the proper level through its effect on the bones, intestines and kidneys.

How less level calcium ions in the blood, the more intensively this hormone is secreted by the parathyroid gland, and vice versa.

During the day, its concentration in the body is different - during the greatest activity in daytime, when metabolic processes accelerated, it is maximum and, accordingly, at night it is minimum.

Did the symptoms take you by surprise?

At the first sign of a problem in parathyroid gland it must be borne in mind that the lack of timely treatment can not pass without a trace for the state of health. Great risks of development severe complications such as osteoporosis, bone fractures, kidney stones, cardiovascular disease.

Pregnant women are at particular risk of developing fetal abnormalities. Only an urgent visit to the endocrinologist is the right beginning of a return to health.