Antidiuretic hormone and its functions in the body
The content of the article:
-
Antidiuretic hormone - what is it?
- Where is synthesized
- How does
- The hormone vasopressin: functions
- Analyzes
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The hormone vasopressin: disruption of production
- Parhon's syndrome
- Diabetes insipidus
- Video
Antidiuretic hormone is one of the peptide hormones that is produced in the hypothalamus. In the human body, it affects water metabolism - it increases the fluid content in peripheral tissues, the volume of circulating blood, and reduces osmolarity. The antidiuretic hormone has an additional effect on blood vessels and the brain (regulates behavior). The secretion of the hormone can be disrupted upward or downward. The result of such a violation is the development of the corresponding diseases - diabetes insipidus or Parkhon's syndrome.
Vasopressin, or antidiuretic hormone, regulates water exchange in the body
Antidiuretic hormone - what is it?
Antidiuretic hormone (ADH, vasopressin) is a peptide that consists of 9 amino acids. ADH is present not only in humans, but also in most mammals.
Where is synthesized
The site of ADH synthesis is the supraoptic nucleus of the hypothalamus. Despite the place of secretion, vasopressin is often regarded as a pituitary hormone. This is due to the fact that in the hypothalamus vasopressin is only produced, then the hormone through the portal system of the pituitary gland enters its posterior lobe - the neurohypophysis.
In the neurohypophysis, vasopressin is activated and accumulated, and, if necessary, is released from there into the blood. In the blood it is found in two forms: free and bound to proteins.
How does
Vasopressin acts through receptors that are located in the vascular wall, renal tubules, liver, and brain. In total, the human body contains 4 types of receptors, the activation of each of them leads to different effects.
The hormone vasopressin: functions
Vasopressin affects the kidneys, heart and blood vessels, as well as the brain. Its main function is to reduce the excretion of urine, and its additional function is to increase blood pressure.
| Target organ | Act |
| Kidney |
The main action of ADH is to increase the permeability of the collecting ducts of the kidneys. This leads to increased reabsorption (i.e. reabsorption) of water. Sodium reabsorption also increases. All this causes fluid retention in the body - the water content in peripheral tissues increases, and the volume of blood in the vessels increases. |
| Heart and blood vessels |
By stimulating the muscle layer, vasopressin increases the tone of the vascular wall. Ultimately, an increase in blood pressure is observed (both due to the vasoconstrictor effect and due to an increase in the volume of circulating blood). |
| central nervous system |
Additionally, ADH affects the brain: • regulates behavior; • participates in memory processes; • stimulates the secretion of ACTH in response to stress. |
Analyzes
To diagnose violations of ADH production, laboratory tests are used - the level of the hormone in the blood plasma is examined. The rate of vasopressin in the blood is not defined by international standards. Results depend on the methods and reagents used in the laboratory.
In addition to determining the concentration of ADH in the blood, other studies are carried out for diagnosis.
| Study | Explanation |
| General urine analysis |
Determines the daily urine output (the volume of urine excreted per day). Diuresis depends on the amount of fluid consumed, normally this value is about 1.5 liters. Another important indicator is the specific gravity of urine. With diabetes insipidus, it is reduced, with Parkhon's syndrome - increased. |
| Osmolarity of blood | With diabetes insipidus, the osmolarity of the blood is lowered, with Parkhon's syndrome - increased. The normal blood osmolarity is 280-300 mosm / l. |
| Osmolarity of urine | With diabetes insipidus, urine osmolarity is increased, with Parkhon's syndrome - decreased. |
| Biochemical blood test (the amount of sodium is determined) | Hypernatremia is observed with a lack of ADH, hyponatremia - with its excess. |
For the diagnosis of diabetes insipidus, a dehydration test (dry eating test) and a Desmopressin test are also used. To distinguish diabetes insipidus from diabetes mellitus, you need to determine the level of glucose in the blood.
The hormone vasopressin: disruption of production
Changes in ADH production are reflected, first of all, in water-electrolyte metabolism. Insufficient secretion leads to diabetes insipidus of central origin, excess is characteristic of Parkhon's syndrome (syndrome of inappropriate secretion of ADH). Both diseases lead to disturbances in the exchange of water and sodium in the body, which is accompanied by the development of various symptoms.
Parhon's syndrome
Parkhon's syndrome is a disease characterized by increased production of vasopressin. The causes of the development of the disease are associated with damage to the pituitary gland or ectopic production of vasopressin:
- tumors, including metastatic lesions;
- infectious or vascular diseases of the brain;
- lungs' cancer;
- side effects of certain medications.
In Parkhon's syndrome, there is an increased absorption of water in the kidneys. Clinically, this is manifested by the following symptoms:
- Decreased urine output.
- Signs of water intoxication: headache, general weakness, lethargy, drowsiness.
- In severe cases, cerebral edema develops. This is manifested by vomiting, convulsions, impaired consciousness.
Specific treatment is the use of drugs from the vaptan group (for example, Tolvaptan). They block the action of vasopressin in the kidneys, which leads to the normalization of water and electrolyte metabolism.
Also, the use of liquid is limited (up to 1 liter per day), diuretics can be used for symptomatic treatment.
Diabetes insipidus
Diabetes insipidus is a disease that is caused by a violation of the secretion of vasopressin. The disease is rare. Diabetes insipidus can be associated with damage to the brain (central) or kidney (nephrogenic). The main causes of diabetes insipidus of central origin include:
- tumors of the pituitary gland or hypothalamus;
- traumatic brain injury;
- surgical interventions in the hypothalamic-pituitary zone;
- genetic abnormalities.
With the disease, the reabsorption of water in the kidneys decreases, clinically this is manifested by the release of a large amount of urine, the development of symptoms of dehydration. The following symptoms are characteristic:
| Symptom | Explanation |
| Polyuria | Increased production and excretion of urine. More than 3 liters of urine are excreted from the body per day. In severe cases, the volume of urine excreted can reach 10-15 liters. |
| Polydipsia | Due to the increased excretion of urine, a person is very thirsty and drinks a lot of water. |
| Signs of dehydration |
Due to the fact that water is not retained in the body, symptoms of dehydration occur: • dry skin and mucous membranes; • dry mouth (due to decreased salivation); • reduction of sweating; • tachycardia. |
Treatment is substitutional. A synthetic analogue of ADH, Desmopressin, is prescribed. You need to take the drug for a long time, more often for life.
Video
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
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