Hypernatremia

Hypernatremia is always associated with hyperosmolarity. When the a-molarity of the plasma becomes higher than 290 mos / l, an increase in ADH secretion by the posterior lobe of the pituitary gland is observed. A decrease in the volume of extracellular fluid enhances this reaction, whereas an increase can weaken it. The kidney reaction to ADH is aimed at preserving free water in the body and consists in reducing diuresis.

Hypernatremia( sodium concentration in the serum above 150 mmol / l) can cause:

■ dehydration during water depletion( increased water loss through respiratory tract during shortness of breath, fever, tracheostomy, artificial lung ventilation in conditions of insufficient moistening of the respiratory mixture, usenon-moistened oxygen, open treatment of burns, prolonged sweating without adequate water compensation);it is generally believed that an excess of

of every 3 mmol / L of sodium in the serum above 145 mmol / l means a deficiency of 1 liter of extracellular water;

■ Saline body overload( feeding through the probe with concentrated mixtures without adequate water injection for prolonged unconsciousness, after operations on the brain, due to obstruction of the esophagus, feeding through the gastrostomy);

■ diabetes insipidus( decreased sensitivity of kidney receptors to ADH);

■ renal diseases occurring with oliguria;

■ hyperaldosteronism( excessive secretion of aldosterone by adenoma or adrenal tumor).

Primary water losses compared to sodium lead to an increase in plasma osmolality and sodium concentration, due to a decrease in the volume of circulating blood, blood flow in the kidneys decreases and aldosterone formation is stimulated, which leads to sodium retention in the body. At the same time, hyperosmolarity stimulates the secretion of ADH and reduces the excretion of water with urine. Depletion of water reserves is quickly restored if sufficient water is supplied to the body.

Depending on the water balance disorders that always accompany hypernatremia, the following forms are distinguished:

■ hypovolemic hypernatremia;

■ euvolemic( normovolemic) hypernatremia;

■ hypervolemic hypernatremia.

Hypovolemic hypernatremia may result from a predominant loss of water compared to sodium loss. Loss of sodium with any body fluid, with the exception of intestinal and pancreatic juice, leads to hypernatremia( the total sodium content in the body decreases).The consequences of hypotonic fluid loss include hypovolemia( due to loss of sodium) and increased osmotic pressure of body fluids( due to loss of free fluid).Hypovolemia is a serious complication, which can lead to hypo-lemic shock.

Euvolemic hypernatremia occurs in diabetes insipidus and loss of water through the skin and respiratory tract. Loss of water without loss of sodium does not lead to a decrease in the volume of fluid in the intravascular bed. In addition, hypernatremia does not develop unless the patient's water intake decreases.

There are two main variants of excess water diuresis( eu-lemic hypernatremia) - central diabetes insipidus and non-frogogenic diabetes insipidus.

In most patients with progressive chronic kidney disease, the ability of the kidneys to gradually concentrate urine is gradually impaired. With CRF of any etiology, it is possible to develop a decreased sensitivity to ADH, which is manifested by the release of hypotonic urine. In the treatment of such patients who are still able to "form" urine, it is very important to remember that consumption of a certain amount of liquid is necessary for them, since it allows to influence the daily osmosis of

by a non-invasive method. Restriction of fluid intake in such patients can lead to the development of hypovolemia.

Hypervolaemic hypernatremia, as a rule, develops as a result of the introduction of hypertonic solutions( for example, 3% sodium chloride solution), as well as correction of metabolic acidosis with intravenous sodium bicarbonate infusions.

Clinical manifestations of hypernatremia as such - thirst, trembling, irritability, ataxia, muscle twitching, confusion, convulsive seizures and coma. Symptoms are pronounced with a sharp increase in the concentration of sodium in the blood serum.