The antidiuretic hormone (ADH). The secretion of antidiuretic hormone

Vasopressin - antidiuretic hormone - is produced by the hypothalamus, which is located in the posterior lobe of the pituitary (neurohypophysis). This hormone provides a homeostasis in the human body, preserving the water balance. So, for example, with dehydration of the body or massive bleeding under the influence of vasopressin, mechanisms that ensure the cessation of fluid loss are included. Thus, the antidiuretic hormone (ADH) simply does not allow us to dry out.

Where is ADH synthesized?

The antidiuretic hormone is produced in the large cell neurons of the supraoptic nucleus of the hypothalamus and binds to the neurophysin (a carrier protein). Next, the neurons of the hypothalamus are sent to the posterior lobe of the pituitary gland and there accumulates. From there it goes into blood. The secretion of ADH is affected by:

1. Blood pressure (BP).
2. Osmolarity of the plasma.
3. The volume of circulating blood in the body.

Biological effects of antidiuretic hormone

At high arterial pressure, the secretion of the antidiuretic hormone is suppressed and, conversely, when the BP falls by 40% of the norm, the synthesis of vasopressin may increase from the usual daily norm by a factor of 100.

Osmolarity of the plasma is directly related to the electrolyte composition of the blood. As soon as the osmolarity of the blood drops below the minimum allowable rate, intensified vasopressin release into the blood begins. When the osmolarity of the plasma is raised above the permissible norm, a person is thirsty. And the use of a large amount of liquid suppresses the secretion of this hormone. Thus, protection from dehydration is carried out.

How does the hormone antidiuretic influence the change in the volume of circulating blood? With massive blood loss, special receptors located in the left atrium and called volumoreceptors react to a decrease in blood volume and a drop in blood pressure. This signal enters the neurohypophysis, and vasopressin release increases. The hormone acts on receptors of blood vessels and their lumen is narrowed. This helps to stop bleeding and prevents further drop in blood pressure.

Disturbances in the synthesis and secretion of ADH

These disorders can be associated with an insufficient amount of vasopressin or with its excess. So, for example, in diabetes insipid diabetes, an insufficient level of ADH is observed, and Parkhon's syndrome has an oversupply.

Non-diabetes mellitus

At this disease reabsorption of water in the kidneys is sharply reduced. This can be facilitated by two circumstances:

1. Inadequate secretion of vasopressin - then we are talking about diabetes insipidus of central origin.
2. Reduced renal response to ADH - this occurs with the neurogenic form of diabetes insipidus.

Patients suffering from this pathology daily diuresis can reach 20 liters. The urine is slightly concentrated. Patients are constantly thirsty and they drink a lot of fluids. To find out which form of diabetes insipidus the patient suffers, an analogue of the hormone vasopressin is used - the drug Desmopressin. The therapeutic effect of this drug is manifested only when the central form of the disease.

Parhon Syndrome

It is also called the syndrome of inappropriate secretion of ADH. This disease is accompanied by excessive secretion of vasopressin, while a reduced osmotic pressure of the blood plasma is observed. The following symptoms appear:

• Muscle twitching and cramps.
• Nausea, lack of appetite, vomiting is possible.
• Possible lethargy, coma.

The state of patients deteriorates sharply when entering the body fluid (intravenously or inward with a drink). With a sharp restriction of the drinking regime and the abolition of intravenous infusions, the patients are in remission.

What symptoms indicate an insufficient level of vasopressin?

If the antidiuretic hormone is synthesized in insufficient quantity, a person can experience:

• Strong thirst.
• Increased urination.
• Dryness of the skin, which is constantly progressing.
• Lack of appetite.
• Problems with the gastrointestinal tract (gastritis, colitis, constipation).
• Problems with the genital area. In men, there is a decrease in potency, in women, menstrual irregularities.
• Chronic fatigue.
• Increased intracranial pressure.
• Decreased vision.

What does the decrease in ADH indicate?

Reduction in the level of vasopressin in the blood can be observed in the following situations:

• Central diabetes insipidus.
• Nephrotic syndrome.
• Psychogenic polydipsia.

What symptoms indicate an increased secretion of ADH?

• Decrease in daily diuresis (urine production).
• Increased body weight with reduced appetite.
• Lethargy and dizziness.
• Headache.
• Nausea and vomiting.
• Cramps in the muscles.
• Various lesions of the nervous system.
• Sleep disturbances.

At what conditions does the increase in the level of ADH occur?

The increase in vasopressin can be observed in pathologies characterized by excessive secretion of this hormone, they include:

• Julien-Barre syndrome.
• Intermittent acute porphyria.

In addition, this is possible under the following conditions:

• Tumors of the brain (primary or metastasis).
• Infectious diseases of the brain.
• Vascular diseases of the brain.
• Tuberculous meningitis.
• Pneumonia.

Antidiuretic hormone - where to surrender?

One of the most effective methods for determining ADH in the blood is radioimmunoassay (RIA). In parallel, the osmolality of the blood plasma is also determined. The analysis can be done in any endocrinology center. Many paid clinics also do such tests. Blood is surrendered from the vein into test tubes without any preservatives.

Before donating blood to the hormone, an antidiuretic should have a 10-12 hour break in eating. Physical and mental stresses on the eve of donating blood can distort the result of the analysis. This means that the day before the test is done, it is advisable not to engage in heavy physical labor, not to participate in sports competitions, not to take exams, etc.

Drugs that can raise the level of ADH should be discarded. If this can not be done for any reason, then in the form of the referral you need to specify which drug was used, when and at what dose. The following preparations can distort the real level of ADH:

• Estrogens;
• hypnotic;
• Anesthetics;
• Tranquilizers;
• Morphine;
• "Oxytocin";
• "Cyclophosphamide";
• "Carbamazepine";
• Vincristine;
• "Chloropropamide";
• "Chlorothiazide";
• "Lithium carbonate".

Analysis for the antidiuretic hormone can be taken no earlier than a week after a radioisotope or radiographic study.

This study allows differentiating nephrogenic diabetes insipidus and hypophysial diabetes insipidus, as well as syndromes characterized by excessive secretion of ADH.