Vasopressin, an antidiuretic hormone, is produced by the hypothalamus, which is located in the posterior pituitary gland (neurohypophysis). This hormone provides homeostasis in the human body, maintaining water balance. So, for example, when the body is dehydrated or massive bleeding under the influence of vasopressin, mechanisms are activated that ensure the cessation of fluid loss. Thus, antidiuretic hormone (ADH) simply keeps us from drying up.
Where is ADH synthesized?
Antidiuretic hormone is produced in large cell neurons of the supraoptic nucleus of the hypothalamus and binds to neurophysin (carrier protein). Further, along the neurons of the hypothalamus, it goes to the posterior lobe of the pituitary gland and accumulates there. As needed, from there it enters the bloodstream. ADH secretion is affected by:
- Blood pressure (BP).
- Plasma osmolarity.
- Volume of circulating blood inbody.
Biological effects of antidiuretic hormone
With high blood pressure, the secretion of antidiuretic hormone is suppressed and, conversely, with a drop in blood pressure by 40% of the norm, the synthesis of vasopressin can increase 100 times from the usual daily norm.
Plasma osmolarity is directly related to the electrolyte composition of the blood. As soon as the osmolarity of the blood falls below the minimum allowable norm, an increased release of vasopressin into the blood begins. With an increase in plasma osmolarity above the permissible norm, a person is thirsty. And drinking a lot of fluid suppresses the release of this hormone. Thus, dehydration is protected.
How does the antidiuretic hormone affect the change in the volume of circulating blood? With massive blood loss, special receptors located in the left atrium and called volomoreceptors respond to a decrease in blood volume and a drop in blood pressure. This signal goes to the neurohypophysis, and the release of vasopressin increases. The hormone acts on the receptors of blood vessels and their lumen narrows. This helps stop bleeding and prevents a further drop in blood pressure.
Disturbances in ADH synthesis and secretion
These disorders may be due to insufficient or excessive amounts of vasopressin. So, for example, in diabetes insipidus, there is an insufficient level of ADH, and in Parkhon's syndrome, its overabundance.
Non-sugardiabetes
With this disease, the reabsorption of water in the kidneys is sharply reduced. Two circumstances may contribute to this:
- Inadequate secretion of vasopressin - then we are talking about diabetes insipidus of central origin.
- Reduced kidney response to ADH - this occurs with neurogenic diabetes insipidus.
In patients suffering from this pathology, daily diuresis can reach 20 liters. Urine is weakly concentrated. Patients are constantly thirsty and drink a lot of fluids. To find out which form of diabetes insipidus the patient suffers from, an analogue of the hormone vasopressin, the drug Desmopressin, is used. The therapeutic effect of this drug is manifested only in the central form of the disease.
Parchon Syndrome
It is also called the syndrome of inappropriate ADH secretion. This disease is accompanied by excessive secretion of vasopressin, while there is a reduced osmotic pressure of the blood plasma. In this case, the following symptoms appear:
- Muscle twitches and cramps.
- Nausea, lack of appetite, possible vomiting.
- Possible lethargy, coma.
The condition of patients deteriorates sharply when fluids are ingested (intravenously or orally with drinking). With a sharp restriction of the drinking regime and the abolition of intravenous infusions, patients go into remission.
What symptoms indicate insufficient levels of vasopressin?
If the hormone is antidiureticsynthesized in insufficient amounts, a person may experience:
- Intense 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 sexual sphere. In men - a decrease in potency, in women - menstrual irregularities.
- Chronic fatigue.
- Increased intracranial pressure.
- Reduced vision.
What does a decrease in ADH indicate?
Decrease 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 increased ADH secretion?
- Decrease in daily diuresis (urine production).
- Weight gain with reduced appetite.
- Drowsy and dizzy.
- Headaches.
- Nausea and vomiting.
- Muscle cramps.
- Various lesions of the nervous system.
- Sleep disorders.
Under what conditions does an increase in ADH levels occur?
An increase in vasopressin can be observed in pathologies characterized by excessive secretion of this hormone, these include:
- Julien-Barré syndrome.
- Intermittent acute porphyria.
Also, this is possible under the following conditions:
- Tumoursbrain (primary or metastases).
- Infectious diseases of the brain.
- Vascular diseases of the brain.
- Tuberculosis meningitis.
- Pneumonia.
Antidiuretic hormone - where to donate?
One of the most effective methods for determining ADH in the blood is radioimmunoassay (RIA). In parallel, determine the osmolarity of blood plasma. The analysis can be done at any endocrinological center. Many paid clinics also do such tests. Blood is donated from a vein to test tubes without any preservatives.
Before donating blood for antidiuretic hormone, there should be a 10-12 hour break in eating. Physical and mental stress on the eve of blood donation can distort the result of the analysis. This means that the day before the test, it is advisable not to engage in hard physical labor, not to participate in sports competitions, not to take exams, etc.
Drugs that can increase ADH levels should be discontinued. If this cannot be done for any reason, then the referral form must indicate which drug was used, when and at what dose. The following drugs can distort the real level of ADH:
- estrogens;
- sleeping pills;
- anesthetics;
- tranquilizers;
- "Morphine";
- "Oxytocin";
- "Cyclophosphamide";
- "Carbamazepine";
- "Vincristine";
- "Chlorpropamide";
- "Chlorothiazide";
- "Lithium carbonate".
Antidiuretic hormone test can be taken no earlier than a week after a radioisotope or X-ray examination.
This study differentiates between nephrogenic diabetes insipidus and pituitary diabetes insipidus, as well as syndromes characterized by excessive secretion of ADH.
