Parathyroid hormones are a natural regulator of the functioning of cells throughout the body. Parathyroid hormone, which is released into the bloodstream from an organ, quickly binds to all tissues and organs. Its main target is bone tissue. It is there that specific receptors are located, which react to the content of a substance in the plasma and accumulate or secrete mineral compounds into the intercellular space (depending on the level of concentration).
It is extremely important to know about this organ and its function, as it can be quite difficult to notice violations in their work at an early stage. However, knowing the symptoms and diagnostic methods, it is possible to identify the first symptoms that will correspond to an early stage. This will allow you to start treatment in a timely manner and reduce the number of uncomfortable manifestations.
Organ anatomy
The parathyroid glands are located on the back of the thyroid gland. They produce specific parathyroid hormones. Their number in humans varies. Most often, there are from 2 to 7 parathyroid glands. However, normally 1 and 15 can be found. It is believed that with normal functioning, the number of organs does not matter.
The work of the parathyroid glands is closely related to the function of the thyroid gland. The parathyroid glands secrete a hormone that antagonizes calcitonin. The latter is produced by special cells of the thyroid gland and regulates the level of calcium in the blood plasma, lowering it.
The glands reach several millimeters in diameter. In their macroscopic structure, the parathyroid glands are very similar to thyroid tissue. Therefore, when an indication for total thyroidectomy, it is very important not to remove the parathyroid formations during surgery. Otherwise, the hormones of the parathyroid gland will cease to be synthesized, and the level of calcium will be significantly reduced in the extracellular space, namely in the blood.
The parathyroid glands secrete a hormone called parathyroid hormone. It regulates the level of calcium in the body. A decrease in the level of this mineral in extracellular fluids and in the blood leads to the activation of the parathyroid glands. Their role is to release parathyroid hormone, which binds to bone cells and removes calcium from the bone depot into the bloodstream.
Role of the hormone
The parathyroid glands are extremely important for the body to function. Their functions are to produce parathyroid hormone and regulate the level of calcium in the blood. The normal content of this mineral ensures the functioning of all cells in the body.
Calcium is an essential mineral that regulates the autonomy of the heart muscle. Its excess or deficiency can lead to the development of arrhythmias, as well as to sudden cardiac arrest. It is this substance that ensures the regulation of the autonomic function of the heart. This means that the heart muscle will contract even without the presence of normal regulation of the nervous system (for example, in people with fractures of the cervical spine and complete paralysis of the trunk and limbs).
The main function of parathyroid hormone is to regulate the amount of calcium in the intercellular fluid. If there is an insufficient amount of calcium ions in the blood, the parathyroid glands are activated, starting to intensively synthesize and release parathyroid hormone into the bloodstream. With the blood stream, it spreads throughout the body, affecting the cells of the bone tissue. As a result, calcium ions begin to leave the bone depot into the bloodstream. In this case, the bones lose part of their mineral reserves.
Parathyroid hormone regulates the degree of bone mineralization, which is responsible for their increased fragility. The increased fragility of bones in old age is associated precisely with insufficient mineralization. This can manifest itself in the form of severe splintered fractures of the tubular bones, when a person simply easily falls on a limb or just gets out of bed in the morning.
Possible diseases
Excessive synthesis of parathyroid hormone by the glands is called hyperparathyroidism. At the same time, parathyroid hormone is constantly produced in more quantities than the body needs. Calcium is constantly washed out of the bones and bone tissue demineralization occurs. This leads to pathological fragility of bones and their possible pathological fractures.
Hyperparathyroidism also leads to the deposition of calcium salts in the glomeruli. This condition can be the cause of urolithiasis. Excessive content of the mineral in the blood leads to a decrease in the elasticity of the vascular wall and the development of hypertension. Excess calcium ions bind with mineral salts and are deposited in the internal organs, forming calcifications. In particular, this can lead to the development of calicifying pancreatitis.
Hypoparathyroidism is a condition in which there is insufficient synthesis of parathyroid hormone. This leads to excessive deposition of mineral compounds in the bones, significantly increasing their density. Hypoparathyroidism is also dangerous due to insufficient amounts of calcium in the intercellular bed. Hypocalcemia can lead to impaired muscle contractions in both skeletal and smooth muscle. It is dangerous to develop uncontrolled seizures.
Plasma hormone level
A blood test can detect abnormalities in the functioning of the parathyroid glands and the level of activity of parathyroid hormone. A blood test is the only way to know about the functioning of the parathyroid glands.
- If the parathyroid gland secretes excess hormone, its level in the blood rises. The level of ionized calcium also rises, which is reflected in the blood test.
- Hypoparathyroidism is characterized by insufficient synthesis and release of parathyroid hormone, which corresponds to a decrease in serum calcium and the hormone itself.
- An increase in the hormone osteocalcin in the blood is also an indirect indicator of hyperparathyroidism. Its concentration increases with the demineralization of bone tissue (the release of large amounts of calcium and its mineral salts from the bones).
A blood test must be performed after surgical interventions on the thyroid gland. In the postoperative period, the level of parathyroid hormone is determined to exclude the erroneous removal of the parathyroid glands together with the thyroid gland. The indicator of calcium in the blood in this case is not informative – as its level changes much later.
It is important to remember that even with the mistaken removal of the parathyroid glands, the concentration of parathyroid hormone in the blood may remain normal or even increased for the first hours. This is due not so much to the function of the organ as to the release of active substances into the blood before or during the operation. Therefore, the most informative is a blood test 12-24 hours after surgery. It is not worth focusing on the data obtained in the first 12 hours of the field of surgical intervention.
Other diagnostic methods
It is possible to indirectly determine the function of the parathyroid glands thanks to X-ray examination of bones (X-ray or computed tomography). With the help of these diagnostic methods, the level of bone mineralization is determined. The deposition of an excess amount of calcium salts in the bones (corresponds to hypoparathyroidism) is manifested in the form of a white rim in the epiphyses of tubular bones and an increase in density. The lack of minerals manifests itself in the form of a slight darkening in the epiphyses of the bone – the area becomes more hollow and does not have a clear border (corresponds to hyperparathyroidism).
An increased amount of minerals in the bloodstream can be detected by routine urinalysis. Normally, mineral salts are contained in minimal amounts, or not found at all. An increase in this indicator indicates an excessive amount of calcium in the bloodstream. Trying to regulate the level of this substance, the body tries to bring it out into the external environment. This happens when the blood is filtered through the kidneys. The substance is released into the external environment together with urine.