What Is Hypernatremia?

Medically Reviewed by Dan Brennan, MD on April 30, 2021

Hypernatremia is the medical term to describe too much sodium in your blood. Sodium is one of the body's electrolytes — found mostly in your blood — that is important for many bodily functions. However, when there's too much, it is an imbalance in your body's electrolytes and can cause serious problems.   

Why Is Sodium Important?

Sodium is an important nutrient in your body. It helps to regulate your blood volume, your blood pressure, the pH of your body, and the electrical conductivity of your cells. This means that sodium not only helps balance the amount of water that is on the inside or outside of your cells, but it's also critical for how your muscles and nerves work. Your kidneys help regulate how much sodium is in your body — most of it is removed through urine, and a small amount comes out in your sweat.

Hypernatremia: Too Much Sodium

Hypernatremia occurs when the balance of water and sodium in your blood is off: there's too much sodium or not enough water. This can happen when too much water is lost or too much sodium is gained (or accumulated) in the body. Doctors define hypernatremia as a measurement of over 145 milliequivalents per liter — a normal level is considered between 136—145 milliequivalents per liter.

In healthy people, the brain automatically balances the amount of water and sodium in your body by controlling intake and output — getting thirsty or urinating. If your brain detects that your body has elevated sodium levels, it can regulate the amount by increasing how much is removed from your bloodstream by your kidneys and can also make you drink water by making you feel thirsty.  

Hypernatremia is usually a symptom of dehydration. Most cases of hypernatremia are mild and easily corrected by fixing dehydration. Usually, when a person starts to get dehydrated and feel thirsty, they are sensing a mild case of hypernatremia and reversing it by drinking water or an electrolyte-containing sports drink. However, more moderate cases can require medical care.

Symptoms of Hypernatremia

Symptoms of hypernatremia include: 

  • Muscle weakness
  • Restlessness
  • Extreme thirst
  • Confusion
  • Lethargy
  • Irritability
  • Seizures
  • Unconsciousness

Hypernatremia can be very serious, especially in small children. It can be caused by dehydration due to diarrhea, vomiting, excessive sweating, significant burns, or other systemic problems. 

Similarly, hypernatremia can cause very serious problems in the elderly. Sometimes as the brain ages, it does not pick up on electrolyte imbalances as quickly, leading to too much sodium in your blood. Older people can also have kidney problems that can contribute to hypernatremia. 

Diagnosis and Treatment of Hypernatremia

A doctor can diagnose hypernatremia through a blood test. Sometimes, urine tests can be used as well.

The treatment for hypernatremia is to get the balance of fluid and sodium in your body back to the ideal level. If your hypernatremia is more than mild, your doctor will likely replace the fluids in your body using an IV. This will supply fluids directly into your blood system, balancing the amount of sodium that is in your blood.

In most cases, hypernatremia is fixable. However, your doctor will want to determine the underlying cause of your hypernatremia to make sure there aren't other problems in your brain or kidneys that need to be treated.

Complications of Hypernatremia

One of the most severe complications of hypernatremia is a ruptured blood vessel in your brain. Called a subarachnoid or subdural hemorrhage, this kind of bleeding in your brain can cause permanent brain damage or death.

If doctors are able to detect and begin treating hypernatremia before it gets too severe, restoring the balance of sodium and fluids in your body, they can prevent serious complications like brain damage, seizure, or death.

How to Prevent Hypernatremia

The easiest way to prevent hypernatremia is to ensure that you are well hydrated and consuming a reasonable amount of sodium. 

It is recommended that the average adult drink between four to six cups of water each day. If you are on certain medications, very active, in a hot climate, or at an elevated altitude, you should drink more to avoid dehydration and hypernatremia.

The American Heart Association recommends an ideal limit of 1,500 milligrams per day of sodium for a healthy adult. The organization notes that the average intake for an American is more than 3,400 milligrams per day — an amount that can contribute to imbalances like hypernatremia, among other serious health problems. The AHA recommends swapping prepackaged and restaurant food for homemade versions and keeping an eye on your sodium intake.

A healthy, balanced diet and proper hydration should help most people avoid hypernatremia. However, hypernatremia can be the result of an electrolyte imbalance caused by other conditions. In this case, it is a medical emergency and is manageable by doctors.

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