Sodium and water amounts in the body are very strictly balanced to be able to balance normally. The concentration of sodium is higher in the blood than in the cells.

Regulatory mechanisms help control and maintain sodium levels.


hormone aldosterone synthesized by the adrenal glands and the antidiuretic hormone /vasopressin/ secreted by the pituitary gland control how the kidneys maintain sodium and water and thus maintain long-term adequate amount of water and sodium in the body.

Water in the body is closely related to where the sodium concentration is higher. If sodium levels in the bloodstream are too high, water from the cells will move into the bloodstream in an attempt to dilute it and lower the sodium concentration.

Conversely, if blood sodium levels are too low, water from the bloodstream will enter the cells and increase their volume.

Hypoatremia is a term used to describe low levels of sodium in the blood. It exists in 2 forms, acute and chronic.

In the acute case, sodium levels fall too quickly, and in the chronic case, its concentration decreases gradually over days or weeks.

The chronic form is in most cases well tolerated by the body and there is a chance to adapt to it.

What are the symptoms?

Symptoms in most affected are neurological. Condition is manifested by headache, nausea and vomiting, drowsiness and confusion.

If the sodium concentration drops rapidly to critical levels, the affected person may lose consciousness, fall into a coma and, if urgent measures are not taken, death may occur.

What are the causes?

The condition hyponatremia is caused by an imbalance between water and sodium in the body. Most often this occurs when excessive amount of water dilutes the sodium in the body or when the amount is not enough. The general classification of the condition is based on the total amount of water in the body.

• With a normal amount of water in the body /euvolemia/

Although the amount of water in the body is normal, antidiuretic hormone is not secreted properly – a syndrome of inadequate ADH secretion from the pituitary gland. This form of the condition is seen in patients with pneumonia, small cell lung cancer, brain hemorrhage, or brain tumors.

• Increased amounts of water in the body /hypervolemia/

Too much water in the body dilutes sodium and lowers concentration. It is most often observed in heart and kidney failure, liver disease such as cirrhosis.

• Insufficient amount of water /hypovolemia/

The amount of water in the body is too low, as can happen with dehydration. In such cases, the secretion of the ADH hormone is stimulated, which suppresses the release of urine from the kidneys, thus ensuring the retention of water in the body. The organism falls into such a state during excessive sweating or physical exertion in very hot water.

Treatment of hyponatremia

The way of treatment is determined by the condition of the patient, whether he has seizures or has been unconscious for a long time. In such a case, measures are taken to stabilize it.

The acute form of the condition is rare, in which case the goal is to normalize blood sodium levels to prevent cerebral hemorrhage and death.

In most patients, if the source of the excessive amounts of water is eliminated, the kidneys usually correct sodium levels on their own.

However, if the patient is unconscious or comatose, then the infusion of 3% hypertonic sodium chloride solution may be necessary.

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