Increased antidiuretic hormone. Decreased hormone levels. Excess secretion of vasopressin

Antidiuretic hormone (ADH) or vasopressin is a hormone that is secreted by the pituitary gland (the central organ of the endocrine system, located on the lower surface of the brain).

Its main role in the body is reduced to the regulation of water metabolism. Vasopressin stimulates the reverse flow of fluid through the membranes of the renal tubules, i.e. carries out water retention in the body. Along with the regulation of water metabolism, it controls the osmotic pressure of blood plasma.
The lack of antidiuretic hormone leads to diabetes insipidus, a disease characterized by the release of extremely large quantities urine fluids. The main symptoms of diabetes insipidus are polyuria (increased urination) and polydipsia (abnormally increased thirst).
Not diabetes develops due to insufficient production of vasopressin (central form) or the inability of the kidneys to adequately respond to vasopressin circulating in the blood, due to the insensitivity of the renal tubules to this hormone (renal form). In the renal form of diabetes insipidus, ADH deficiency is called relative, and its plasma concentration is increased or normal.

Pregnancy insipidus (gestational diabetes mellitus) is associated with an increase in the activity of the placental enzyme vasopressinase, which destroys ADH. This form of diabetes insipidus is temporary and stops after childbirth.
With excessive production of vasopressin by the hypothalamus, a syndrome of inadequate production of vasopressin or Parkon's syndrome occurs. Parkhon's syndrome is the most common variant of impaired ADH production, characterized by a decrease in the sodium content in the blood, plasma hypoosmolarity, oliguria (decreased urine output), lack of thirst, the presence of general edema, and an increase in body weight. The patient is disturbed headache, lack of appetite or its decrease, nausea, vomiting, muscle weakness, drowsiness or insomnia, painful spasms muscles, tremor (trembling) of the limbs. This condition occurs with injuries of the skull and brain, circulatory disorders, birth defects development, inflammatory diseases central nervous system, such as meningitis, encephalitis, poliomyelitis, etc.

A significant increase in the content of ADH, which contributes to the development of Parhon's syndrome, can also cause some malignant tumors such as lung cancer, lymphosarcoma, pancreatic cancer, Hodgkin's lymphoma, cancer prostate and others, which themselves are able to synthesize vasopressin. In addition, non-tumor lung diseases often lead to an increase in ADH: pneumonia caused by staphylococcus aureus, tuberculosis, lung abscess, sarcoidosis.

The analysis determines the concentration of antidiuretic hormone (ADH) in blood plasma (pg / ml or pmol / l) and plasma osmolality (mosm / kg or mosm / l).

Method

One of the most highly sensitive and highly specific methods for determining hormones in blood serum is the RIA method (radioimmunoassay). The essence of the method is that on a special binding system (with limited number binding sites) apply serum containing the desired substance (ADH) and an excess of the same substance (ADH) in a known concentration, labeled with radionuclides (radioactive isotopes). Excess ADH and ADH from the sample (blood serum) bind competitively to the binding system, forming specific complexes (labeled and unlabeled). The number of labeled complexes is inversely proportional to the amount of unlabeled (desired) substance in the sample and is measured by special devices- radio spectrometers.

The osmolarity of blood plasma can be determined by cryoscopy, i.e., by the freezing point of the solution. Units of measurement - mosm/kg or mosm/l.

Reference values ​​- norm
(Antidiuretic hormone (vasopressin, ADH), blood)

Information regarding the reference values ​​​​of the indicators, as well as the very composition of the indicators included in the analysis, may differ slightly depending on the laboratory!

Norm:

Indications

Diagnosis of diabetes insipidus;
- diagnosis of tumors of the APUD system (ectopically producing vasopressin).

Increasing values ​​(positive result)

An increase in ADH secretion is observed in the following conditions:

Acute intermittent porphyria;

brain tumor (primary or metastases);

Pneumonia;

tuberculous meningitis;

Pulmonary tuberculosis;

Renal diabetes insipidus.

Malignant bronchogenic lung cancer;

Hodgkin's lymphoma;

prostate cancer;

malignant tumors of the pancreas, thymus, duodenum.

An increase in the concentration of ADH is also observed at night, during the transition to vertical position for pain, stress or physical activity, with increased plasma osmolality (for example, with the introduction hypertonic saline), with a decrease effective volume blood and hypotension.

Antidiuretic hormone (ADH) is a protein substance that is produced in the hypothalamus. Its main role in the body is to maintain water balance. ADH binds to specific receptors located in the kidneys. As a result of their interaction, fluid retention occurs.

Some pathological conditions accompanied by a violation of the production of the hormone or a change in sensitivity to its effects. With its deficiency, diabetes insipidus develops, and with an excess, the syndrome of inadequate ADH secretion develops.

Characteristics and role of the hormone

The precursor of antidiuretic hormone (or vasopressin) is produced in the neurosecretory nuclei of the hypothalamus. By processes nerve cells it is carried to the posterior lobe of the pituitary gland. In the process of transport, mature ADH and the neurophysin protein are formed from it. Secretory granules containing the hormone accumulate in the neurohypophysis. Partially, vasopressin enters the anterior lobe of the organ, where it participates in the regulation of the synthesis of corticotropin, which is responsible for the work of the adrenal glands.

Hormone secretion is controlled through osmo- and baroreceptors. These structures respond to changes in fluid volume and pressure in the vascular bed. Enhance the production of vasopressin factors such as stress, infection, bleeding, nausea, pain, chorionic gonadotropin, severe lung injury. Its production is affected by the intake of certain drugs. The concentration of ADH in the blood depends on the time of day - at night it is usually 2 times higher than during the day.

Drugs that affect the secretion and action of the hormone:

Regulation of secretion and effects of vasopressin

Vasopressin together with other hormones - atrial natriuretic peptide, aldosterone, angiotensin II, controls the water and electrolyte balance. However, the importance of ADH in the regulation of water retention and excretion is leading. It promotes fluid retention in the body by reducing urine output.

The hormone also performs other functions:

• regulation of vascular tone and increase blood pressure;
• stimulation of the secretion of corticosteroids in the adrenal glands;
• influence on blood coagulation processes;
• the synthesis of prostaglandins and the release of renin in the kidneys;
• improving learning ability.

Mechanism of action

On the periphery, the hormone binds to sensitive receptors. The effects of vasopressin depend on their type and location.

Types of ADH receptors:

The structural and functional unit of the kidney, in which plasma filtration and urine formation occurs, is the nephron. One of its components is the collecting duct. It carries out reabsorption processes reverse suction) and the secretion of substances that allow maintaining water-electrolyte metabolism.

The action of ADH in renal tubules

The interaction of the hormone with type 2 receptors in the collecting ducts activates a specific enzyme, protein kinase A. As a result, the number of water channels, aquaporins-2, increases in the cell membrane. Through them, water moves along the osmotic gradient from the lumen of the tubules into the cells and the extracellular space. It is assumed that ADH enhances the tubular secretion of sodium ions. As a result, the volume of urine decreases, it becomes more concentrated.

In pathology, there is a violation of the formation of the hormone in the hypothalamus or a decrease in the sensitivity of receptors to its action. The lack of vasopressin or its effects leads to the development of diabetes insipidus, which is manifested by thirst and an increase in urine volume. In some cases, it is possible to increase the production of ADH, which is also accompanied by a water-electrolyte imbalance.

diabetes insipidus

At diabetes insipidus stands out a large number of diluted urine. Its volume reaches 4-15 or more liters per day. The cause of the pathology is the absolute or relative insufficiency of ADH, resulting in a decrease in water reabsorption in the renal tubules. The condition may be temporary or permanent.

Patients note an increase in the amount of urine - polyuria, and increased thirst - polydipsia. With adequate fluid replacement, other symptoms do not bother. If the loss of water exceeds its intake into the body, signs of dehydration develop - dry skin and mucous membranes, weight loss, drop in blood pressure, increased heart rate, increased excitability. age feature older people is a decrease in the number of osmoreceptors, so in this group the risk of dehydration is greater.

There are the following forms of the disease:

• Central- due to a decrease in the production of vasopressin by the hypothalamus due to injuries, tumors, infections, systemic and vascular diseases affecting the hypothalamic-pituitary zone. Less commonly, the cause of the condition is an autoimmune process - hypophysitis.
• Nephrogenic- develops due to a decrease in the sensitivity of renal receptors to the action of ADH. In this case, diabetes is hereditary or occurs due to benign hyperplasia prostate, sickle cell anemia, low protein diet, lithium. Pathology can be provoked by increased excretion of calcium in the urine - hypercalciuria, and low maintenance potassium in the blood - hypokalemia.
• Primary polydipsia- occurs when overconsumption fluid and is psychogenic in nature.
• diabetes insipidus in pregnancy- a temporary condition associated with increased destruction of vasopressin by an enzyme synthesized by the placenta.

For the diagnosis of diseases, functional tests with fluid restriction and the appointment of vasopressin analogues are used. During their conduct, the change in body weight, the volume of urine excreted and its osmolarity are evaluated, the electrolyte composition of the plasma is determined, and a blood test is taken to study the concentration of ADH. Studies are performed only under medical supervision. If you suspect central shape brain MRI is shown.

Treatment of pathology depends on the variant of its course. In all cases it is necessary to use enough liquids. To increase the level of vasopressin in the body in central diabetes, hormone analogues are prescribed - Desmopressin, Minirin, Nativa, Vazomirin. The drugs selectively act on type 2 receptors in the collecting ducts and increase water reabsorption. In the nephrogenic form, the root cause of the disease is eliminated; in some cases, the appointment is effective large doses Desmopressin, use of thiazide diuretics.

The balance of fluid and electrolytes in the human body is maintained by several mechanisms. One of the regulatory factors is the antidiuretic hormone (ADH, vasopressin) of the hypothalamus. It's biologically active substance affects the kidneys smooth muscle vessels and organs, central nervous system.

Hormone structure

ADH is a peptide chemical structure. It contains nine amino acid residues.

Hormone amino acids:

• cysteine ​​(1 and 6 in the chain);
• tyrosine;
• phenylalanine;
• glutamine;
• asparagine;
• proline;
• arginine;
• glycine.

The molecular weight of antidiuretic hormone is about 1100 D.

Synthesis and secretion

Vasopressin is produced from amino acids in the cells of the hypothalamus. In the neurons of this part of the brain, the prohormone precursor is secreted. Next is chemical compound enters the Golgi cell apparatus and is modified into a prohormone. In this form, the future ADH combines with neurosecretory granules and is transported to the posterior pituitary gland. During transport from the hypothalamus, vasopressin is cleaved into the mature hormone and neurophysin (transport protein).

Both substances are deposited in the terminal extensions of axons in the posterior pituitary gland. It is from there that the hormone is released into the blood under certain stimuli.

Secretion stimulation

Antidiuretic hormone responds to changes in the electrolyte composition of the blood.

Stimuli for vasopressin secretion:

• an increase in sodium levels in the blood;
• promotion osmotic pressure extracellular fluid.

Synthesis and secretion of the hormone are enhanced by signals from two types of receptors. The first of these are the osmoreceptors of the hypothalamus. They react to the ratio of the concentration of salts and water in the blood. If this parameter changes at least by 0.5-1%, then the release of ADH increases significantly. The second are atrial baroreceptors. They rate the level blood pressure. If the pressure drops, then the synthesis and secretion of vasopressin increase.

Normally, the release of the hormone into the blood increases after:

• profuse sweating;
• physical activity;
• eating salty food;
• fluid restrictions in the diet;
• changes in body position (when standing up).

Vasopressin has certain circadian rhythms. The hormone is more produced and released at night. This pattern is especially well observed in the prone position.

The circadian rhythm of ADH production develops with age. In children under one year old, there is no significant increase in the concentration of the hormone in the blood at night. Next, a nocturnal peak of secretion is formed. If the mechanisms of growing up are late, then the child may be diagnosed with enuresis.

Receptors for ADH

Antidiuretic hormone is perceived by cells of the kidneys, smooth muscle fibers and neurons. There are two types of membrane components sensitive to this substance.

Allocate:

• V1 receptors;
• V2 receptors.

Water retention in the body under the action of ADH occurs due to V2 receptors, and an increase in vascular tone occurs due to V1 receptors.

The genes for ADH receptors have been cloned; the type V2 receptor gene is localized on the X chromosome.

V1 structures are found in vascular smooth muscle cells, liver, and brain. The affinity of vasopressin for them is quite low. The effect of the hormone is fixed only at its high concentrations.

V2 structures are located in the kidney. They are responsible for the main action of ADH. Receptors are found on the cell membranes of the distal tubules and collecting ducts. Even low concentrations vasopressin in the blood affect the receptors.

Hormone and receptor genetics

Vasopressin is encoded in the gene on the twentieth chromosome (20p13). It carries information about the prohormone and its precursor. The gene has a complex structure: three exons and two introns.

The vasopressin receptor genes have been cloned. It has been proven that the type V2 receptor is located on the tenth chromosome.

Action of ADH

Vasopressin has several effects. His main biological action- antidiuretic. If ADH is not synthesized, then the kidneys stop concentrating urine. Its density becomes as low as that of blood plasma. Up to 20 liters of urine can form per day.

If the antidiuretic hormone is present in the blood plasma, then it binds to receptors in the kidneys (type V2). This reaction stimulates adenylate cyclase and protein kinase A. Then the aquaporin-2 protein gene is expressed. This substance is embedded in the membrane of the renal tubules and forms channels for water.

As a result, there is a reuptake of water from the tubules. Urine becomes more concentrated and its volume decreases.

In plasma, on the contrary, osmolarity decreases. The volume of circulating blood and tissue fluid increases.

Other effects of ADH:

• stimulation of glycogen synthesis in the liver;
• increased tone of smooth muscle fibers;
• vasoconstrictor effect;
• reduction of mesanglial cells;
• regulation of platelet aggregation;
• regulation of the release of adrenocorticotropin, prolactin endorphins.

Until now, the effect of vasopressin on the central nervous system has not been fully studied. It is believed that the hormone is partially responsible for behavioral reactions (aggression, attachment to offspring, sexual behavior). ADH can be the cause of depression and other psychiatric illnesses.

Disturbances in the synthesis and secretion of ADH

Lack of synthesis or sensitivity to vasopressin (type V2 receptors) is the cause of diabetes insipidus.

This disease is of two types:

• central form;
• renal form.

Patients with diabetes insipidus develop profuse diuresis. The volume of urine per day is significantly higher than normal (1-2 liters). Complaints of patients are associated with dehydration (hypotension, dry skin and mucous membranes, weakness).

Inadequate secretion of the hormone occurs with another disease - Parhon's syndrome. This rare disease has a severe clinical picture: convulsions, lack of appetite, nausea, loss of consciousness.

Insufficient release of vasopressin into the blood at night is observed in childhood. If this situation persists after 4 years, then enuresis is likely to develop.

Norm ADH

Normal values ​​of vasopressin depend on the level of plasma osmolarity. At an osmolarity of 275–290 mosmo/L, ADH should be between 1.5 ng/L and 5 ng/L. For accurate diagnosis diabetes insipidus and Parkhon's syndrome, stress tests are recommended.

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Vasopressin is one of the hormones of the hypothalamus. It is formed in large-celled neurons of this part of the brain. Further, vasopressin is transported to the neurohypophysis, where it accumulates.

The role of vasopressin in the body

Vasopressin has a major effect on water exchange. Another name for this substance is antidiuretic hormone (ADH). Indeed, an increase in the concentration of vasopressin leads to a decrease in the volume of urine excreted (diuresis).

The main biological action of ADH:

• increased reabsorption of water;
• decrease in sodium levels in the blood;
• increase in blood volume in the vessels;
• an increase in the total volume of water in the tissues of the body.

In addition, antidiuretic hormone affects the tone of smooth muscle fibers. This effect is manifested by an increase in vascular tone (arterioles, capillaries) and blood pressure.

It is believed that ADH is involved in intellectual processes (learning, memory) and forms some forms social behavior (family relationships, paternal attachment to children, control of aggressive reactions).

Release of ADH into the blood

The antidiuretic hormone accumulated in the neurohypophysis is released into the blood under the influence of two main factors: an increase in the concentration of sodium and other ions in the blood and a decrease in the volume of circulating blood.

Both of these conditions are a manifestation of dehydration. For early detection life-threatening fluid loss, there are special sensitive receptor cells. An increase in plasma sodium concentration is detected by osmoreceptors in the brain and other organs. A low volume of blood in the vessels is detected by volomoreceptors of the atria and intrathoracic veins.

Normally, the antidiuretic hormone vasopressin is secreted in sufficient quantities to maintain a constant internal body fluid.

Especially a lot of vasopressin enters the vascular bed during injuries, pain syndrome, shock, massive blood loss. In addition, some drugs and mental disorders can trigger the release of ADH.

lack of vasopressin

Insufficient levels of ADH in the blood leads to the development of the central form of diabetes insipidus. In this disease, the function of reuptake of water in the renal tubules is inhibited. A lot of urine is excreted. During the day, diuresis can reach 10-20 liters. characteristic feature is the low specific gravity of urine, which is almost equal to the specific gravity of blood plasma.

Patients with diabetes insipidus suffer intense thirst, constant dryness mouth, dryness skin and mucous membranes. If a patient is deprived of the opportunity to drink water for any reason, then dehydration quickly develops. The manifestation of this condition is sudden loss body weight, lowering blood pressure (less than 90/60 mm Hg. Art.), dysfunction of the central nervous system.

Diabetes insipidus is diagnosed using urine, blood, Zimnitsky's test. In some cases, it is required to limit fluid intake for a short period of time with monitoring of blood composition and urine density. Analysis for vasopressin is uninformative.

The reason for the decrease in secretion of antidiuretic hormone may be genetic predisposition, traumatic brain injury, meningitis, encephalitis, hemorrhage in functional fabric tumor of the pituitary or hypothalamus. This disease often develops after surgery or radiation treatment neoplasms of the brain.

Quite often, the cause of diabetes insipidus cannot be established. This decrease in ADH secretion is called idiopathic.

Treatment of the central form of diabetes insipidus is carried out by an endocrinologist. Synthetic antidiuretic hormone is used for therapy.

Excess secretion of vasopressin

Excessive secretion of the hypothalamic hormone vasopressin occurs in Parhon's syndrome. This is a fairly rare pathology.

The syndrome of inappropriate secretion of antidiuretic hormone (Parchon's syndrome) is manifested by low blood plasma density, hyponatremia, and the release of concentrated urine.

Thus, excess ADH provokes electrolyte loss and water intoxication. Under the action of vasopressin, water is retained in the body, and trace elements leave the bloodstream.

Patients are concerned about the small volume of diuresis, weight gain, great weakness, convulsions, nausea, loss of appetite, headache.

AT severe cases coma and death occur as a result of cerebral edema and depression of vital functions.

The cause of inadequate secretion of antidiuretic hormone is some forms of cancer (in particular, small cell lung tumor), cystic fibrosis, bronchopulmonary pathology, diseases of the brain. Parkhon's syndrome may be a manifestation of individual intolerance to some medicines. For example, opiates, barbiturates, nonsteroidal drugs, psychotropic drugs, etc.

Excess levels of antidiuretic hormone are treated with vasopressin antagonists (vaptans). It is important to limit the amount of fluid you drink to 500-1000 ml per day.

Antidiuretic hormone (ADH) is a protein substance that is produced in the hypothalamus. Its main role in the body is to maintain water balance. ADH binds to specific receptors located in the kidneys. As a result of their interaction, fluid retention occurs.

Some pathological conditions are accompanied by a violation of the production of the hormone or a change in sensitivity to its effects. With its deficiency, diabetes insipidus develops, and with an excess, the syndrome of inadequate ADH secretion develops.

Characteristics and role of the hormone

The precursor of antidiuretic hormone (or vasopressin) is produced in the neurosecretory nuclei of the hypothalamus. Through the processes of nerve cells, it is transferred to the posterior lobe of the pituitary gland. In the process of transport, mature ADH and the neurophysin protein are formed from it. Secretory granules containing the hormone accumulate in the neurohypophysis. Partially, vasopressin enters the anterior lobe of the organ, where it participates in the regulation of the synthesis of corticotropin, which is responsible for the work of the adrenal glands.

Hormone secretion is controlled through osmo- and baroreceptors. These structures respond to changes in fluid volume and pressure in the vascular bed. Enhance the production of vasopressin factors such as stress, infection, bleeding, nausea, pain, human chorionic gonadotropin, severe lung damage. Its production is affected by the intake of certain drugs. The concentration of ADH in the blood depends on the time of day - at night it is usually 2 times higher than during the day.

Drugs that affect the secretion and action of the hormone:

Regulation of secretion and effects of vasopressin

Vasopressin together with other hormones - atrial natriuretic peptide, aldosterone, angiotensin II, controls the water and electrolyte balance. However, the importance of ADH in the regulation of water retention and excretion is leading. It promotes fluid retention in the body by reducing urine output.

The hormone also performs other functions:

• regulation of vascular tone and increased blood pressure;
• stimulation of the secretion of corticosteroids in the adrenal glands;
• influence on blood coagulation processes;
• the synthesis of prostaglandins and the release of renin in the kidneys;
• improving learning ability.

Mechanism of action

On the periphery, the hormone binds to sensitive receptors. The effects of vasopressin depend on their type and location.

Types of ADH receptors:

The structural and functional unit of the kidney, in which plasma filtration and urine formation occurs, is the nephron. One of its components is the collecting duct. It carries out the processes of reabsorption (reabsorption) and secretion of substances that allow maintaining water-electrolyte metabolism.

Action of ADH in the renal tubules

The interaction of the hormone with type 2 receptors in the collecting ducts activates a specific enzyme, protein kinase A. As a result, the number of water channels, aquaporins-2, increases in the cell membrane. Through them, water moves along the osmotic gradient from the lumen of the tubules into the cells and the extracellular space. It is assumed that ADH enhances the tubular secretion of sodium ions. As a result, the volume of urine decreases, it becomes more concentrated.

In pathology, there is a violation of the formation of the hormone in the hypothalamus or a decrease in the sensitivity of receptors to its action. The lack of vasopressin or its effects leads to the development of diabetes insipidus, which is manifested by thirst and an increase in urine volume. In some cases, it is possible to increase the production of ADH, which is also accompanied by a water-electrolyte imbalance.

diabetes insipidus

With diabetes insipidus a large amount of diluted urine is excreted. Its volume reaches 4-15 or more liters per day. The cause of the pathology is the absolute or relative insufficiency of ADH, resulting in a decrease in water reabsorption in the renal tubules. The condition may be temporary or permanent.

Patients note an increase in the amount of urine - polyuria, and increased thirst - polydipsia. With adequate fluid replacement, other symptoms do not bother. If the loss of water exceeds its intake into the body, signs of dehydration develop - dry skin and mucous membranes, weight loss, drop in blood pressure, increased heart rate, increased excitability. The age feature of the elderly is a decrease in the number of osmoreceptors, so this group is at greater risk of dehydration.

There are the following forms of the disease:

• Central- due to a decrease in the production of vasopressin by the hypothalamus due to injuries, tumors, infections, systemic and vascular diseases affecting the hypothalamic-pituitary zone. Less commonly, the cause of the condition is an autoimmune process - hypophysitis.
• Nephrogenic- develops due to a decrease in the sensitivity of renal receptors to the action of ADH. In this case, diabetes is hereditary or occurs against the background of benign prostatic hyperplasia, sickle cell anemia, adherence to a low-protein diet, and lithium preparations. Pathology can be provoked by increased excretion of calcium in the urine - hypercalciuria, and a low content of potassium in the blood - hypokalemia.
• Primary polydipsia- occurs with excessive fluid intake and is psychogenic in nature.
• diabetes insipidus in pregnancy- a temporary condition associated with increased destruction of vasopressin by an enzyme synthesized by the placenta.

For the diagnosis of diseases, functional tests with fluid restriction and the appointment of vasopressin analogues are used. During their conduct, the change in body weight, the volume of urine excreted and its osmolarity are evaluated, the electrolyte composition of the plasma is determined, and a blood test is taken to study the concentration of ADH. Studies are performed only under medical supervision. If a central form is suspected, an MRI of the brain is indicated.

Treatment of pathology depends on the variant of its course. In all cases, a sufficient amount of liquid must be consumed. To increase the level of vasopressin in the body in central diabetes, hormone analogues are prescribed - Desmopressin, Minirin, Nativa, Vazomirin. The drugs selectively act on type 2 receptors in the collecting ducts and increase water reabsorption. In the nephrogenic form, the root cause of the disease is eliminated, in some cases it is effective to prescribe large doses of Desmopressin, the use of thiazide diuretics.