Hypernatremia is a disorder of the body's electrolyte balance. Hypernatremia is associated with increased levels of sodium in the blood. The normal concentration of sodium in the blood is between 135 and 145 millimoles per liter (mole is used to indicate the amount in chemical reactions). If the content is increased to a value of over 145 millimoles per liter, one speaks of hypernatremia. Normally, even slightly increased sodium concentrations trigger a feeling of thirst in our body. In most cases, the hypernatremia is compensated for relatively quickly by the supply of fluids.

Learn more about the Causes and consequences of electrolyte imbalances.


The most common cause of increased sodium levels in our blood is something called a hypovolemic hypernatremia. This leads to an increase in the sodium concentration dehydration. So the body loses too much water. Known causes are more permanent diarrhea, Vomit, heavy sweating or medication, like Drainage tablets. Also a special form of diabetes, the so-called Diabetes insipidus, leads to hypernatremia through extremely high fluid loss. A dysregulation in the brain or the kidneys is the cause.

Read more about the topic here Diabetes insipidus

The body loses the ability to remove water from the in the kidney produced primary or fore-urine. As a result, the body secretes enormous amounts of urine, in between 5 to 25 liters per day, out. If too little fluid is supplied to the body from the outside, this also ends in a Dehydration with hypernatremia. This concerns especially the elderlybecause of their decreased feeling of thirst often forgot to drink.

The opposite of hypovolemic hypernatremia is hypervolemic hypernatremia. This can be done, for example, by the Drinking salty sea water or as part of a medical Infusion therapy With Saline solution can be triggered. Another possible cause is the so-called Conn syndrome, a disease of the adrenal cortex that causes hypernatremia. Here the Adrenal gland too much Aldosterone, which ensures that the kidney is the primary. or the pre-urine removes sodium. This dysregulation thus restricts the excretion of sodium and leads to hypernatremia.


The symptoms of hypernatremia are usually unspecific and persist general weakness, fatigue, Difficulty concentrating or feeling thirsty. The cell begins to shrink due to the fluid shift at cell level, from the inside to the outside. This mainly triggers malfunctions in the nerve cells in the brain. Affected suffer from States of confusion, convulsions up to coma.

In the case of hypernatremia due to severe fluid loss, the risk of a Thrombosis. It comes to one Formation of clots within the bloodstream, which increases the risk of blockage due to increased blood viscosity. The faster the hypernatremia develops, the more severe the symptoms.


The above-mentioned causes of hypernatremia, such as Vomit or diarrhea can be requested. The doctor will then do a physical exam. This includes checking the Tongue dampness, as well as the Mucous membranes. You also test the so-called Skin turgor. Here the State of tension the skin is checked by the examiner lifting a fold of skin between the thumb and forefinger. If this skin fold remains due to a lack of fluid, the test is positive.

In addition, the so-called Serum sodium of the blood determined. In addition, the urine volume per unit of time can be determined. In states of thirst, the body holds back more fluid and the amount of urine excreted decreases. If diabetes insipidus is suspected, it will Antidiuretic hormone, ADH for short, determined in the blood.


Depending on the underlying disease or trigger of the hypernatremia, for example through Vomiting, diarrhea, or sweating, the sodium balance is balanced by hydration. This is done either by drinking copiously or, in the case of complicated processes, by a doctor using a Infusion solution. Treatment of severe hypernatremia should, however only under medical supervision be treated. Here is namely the slow compensation of the fluid deficit to be observed under regular electrolyte control.

A rapid decrease in sodium levels can be achieved with life threatening complications accompanied. In the case of hypervolemic hypernatremia, due to an uncontrolled high sodium intake, the person concerned becomes Glucose solution, mostly in combination with a Drainage tablet, administered to flush out fluids.


If fluids are administered intravenously, a sodium-free infusion solution choose. Instead of Saline solution, which is normally used clinically to compensate for fluid deficits, a Glucose or sugar solution used. The sodium particles in the blood combine with the sugar particles in the infusion solution and thus enable sodium to be expelled from the body. It is excreted in the urine.

Brain edema

When treating hypernatremia with an infusion solution, the sodium content in the blood is important slowly lower. Due to the permanently increased sodium concentration, the cells adapt to this condition by slightly increasing their own sodium content. Is the infusion in the context of a hypernatremia too fast administered, the liquid flows into the cells due to the concentration gradient. As a result, these swell and can become a Brain swellingcause what is known as brain edema.

Due to the restricted expansion capacity of the skull bone, the brain mass is compressed. A displacement of the brain matter in the direction of the bony canal, above the Cervical spine, can often be observed. Many important structures run in this opening, like this Spinal cord, Nerves and vessels with vital tasks for circulatory and respiratory regulation. Symptoms like Headache, nausea and dizziness can be the first signs of cerebral edema. The brain edema, as a result of the hypernatremia, should always be treated by a doctor. Therapeutic approaches are one Upper body elevation by 30 degrees, as well as drug-based drainage therapy Mannitol (Sugar substitute). If left untreated, brain edema can lead to death.

Cardiac arrhythmias

Fluctuations in the so-called electrolyte balance can lead to dangerous heart rhythm disorders. This also includes the aforementioned hypernatremia. The voltage across the cell membrane, the membrane potential, collapses and the Cell function is lost. Using the example of myocardial cells, it can life-threatening arrhythmias that should definitely be treated by a doctor with an appropriate electrolyte balance.

Read more about the topic here Cardiac arrhythmias