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Dr. Andrea Pinto Lopez

Sep 19, 20227 min read

Hyponatremia Everything You Need to Know

The information provided herein does not constitute an expert or medical advice, nor intended to replace such advice.


Have you ever heard the term “hyponatremia” and wondered what it means? Do you know what your sodium levels should be?

Hyponatremia is a condition in which the amount of sodium in your blood is too low. But why does it happen, and what are its symptoms? This condition can become dangerous very quickly, so it’s important to be able to spot warning signs quickly.

Read this article to learn everything you need to know about hyponatremia.

Hyponatremia meaning

Hyponatremia literally means “low” (hypo) “blood sodium” (natremia). Hyponatremia is defined as having low concentrations of the electrolyte sodium in your blood. The symbol used to represent sodium is Na+, which is why you may see your sodium results reported using this symbol. 

Sodium is extremely important to regulate different processes in the human body. Levels of sodium that are too low or too high can both lead to serious consequences, and your system is constantly regulating sodium and fluid levels to prevent this. 

According to the Harvard T.H. Chan School of Public Health, your body uses sodium to:

  • Regulate the balance between fluid and minerals
  • Conduct nerve impulses throughout the body
  • Contract and relax muscle cells
  • Maintain your blood pressure levels

Hyponatremia is more common among babies and infants, older adults, people who take certain medications or who suffer from chronic diseases, and people who engage in intense physical activities.

Normal sodium levels

Under normal circumstances, your serum sodium levels should always be stable and within a specific range. According to the National Kidney Foundation, good blood sodium levels should be between 135-145 milliequivalents/liter (mEq/L).

Hyponatremia happens when your blood sodium levels fall below 135mEq/L. You can also have hypernatremia, in which sodium levels are higher than 145mEq/L.

Causes of hyponatremia

There are two main ways in which you can develop hyponatremia: it can happen as a result of having too much water in your body, which dilutes the sodium; or it can happen if you’re experiencing significant sodium losses.

Theoretically, it’s also possible to develop hyponatremia if your sodium intake is too low, but this is extremely rare in real life and practically never happens. According to the Cleveland Clinic, most cases of hyponatremia are caused by having too much fluid in your system.

According to the Mayo Clinic, some of the most common causes of hyponatremia include:

  • Heart, kidney, and liver diseases: heart failure, along with certain conditions that affect the liver and kidneys, can lead to significant fluid retention. The additional fluid dilutes the sodium levels in your blood, causing hyponatremia.
  • Certain medications: some medications can affect your fluid and electrolyte levels. This can be caused by diuretics, and certain antidepressants and pain medications. 
  • Severe dehydration: some of the most common causes of severe dehydration include chronic or severe diarrhea and/or vomiting. These conditions cause fluid and electrolyte loss that can lead to hyponatremia. Excessive sweating can also lead to dehydration.
  • Syndrome of inappropriate antidiuretic hormone (SIADH): this condition causes your body to produce excessive amounts of antidiuretic hormone, which tells your kidneys to release less water through urine. This results in fluid retention that can lead to hyponatremia.
  • Drinking too much water: excessive water intake can lead to dilutional hyponatremia if your kidneys can’t eliminate the excess fluid quickly enough. 
  • Hormonal changes: some hormonal imbalances and conditions, such as Addison’s disease, can affect your body’s ability to regulate fluid and sodium levels.
  • Some recreational drugs: Ecstasy, in particular, can lead to severe cases of hyponatremia.

Chronic sodium deficiency

Chronic hyponatremia happens when your sodium levels drop progressively over a period of 48 hours or more. This type of hyponatremia usually causes milder symptoms and complications, but it should still be treated as quickly as possible.

Hyponatremia symptoms

According to the MSD Manual, the signs and symptoms of hyponatremia can include:

  • Lethargy
  • Fatigue
  • Confusion
  • Headache
  • Nausea and vomiting
  • Increased reflexes
  • Drowsiness
  • Irritability
  • Muscle cramps
  • Muscle weakness
  • Seizures
  • Coma

Hyponatremia risks

The effects of low sodium levels in the body can range from mild to severe, and in some cases, hyponatremia can even be fatal. The risks associated with hyponatremia will largely depend on its severity.

According to Medscape, some of the complications of hyponatremia can include:

  • Rhabdomyolysis, a condition that causes the destruction of muscle cells
  • Seizures
  • Attention deficit
  • Osteoporosis
  • Fractures
  • Permanent neurological damage
  • Respiratory arrest
  • Death

Hyponatremia prevention

Fortunately, hyponatremia is relatively rare among healthy individuals. There are certain steps that you can take to prevent hyponatremia, including:

  • Consider taking sports drinks if you’re going to engage in physical activities, especially if they’re high-intensity, prolonged, or if the weather is warm.
  • Keep chronic health conditions under control and take your medications as prescribed by your physician.
  • Educate yourself on the signs of hyponatremia, especially if you have other conditions that can increase your risk.
  • Don’t drink water excessively. Make sure you’re drinking enough water to stay hydrated, but not excessively so in order to prevent electrolyte imbalances.

You can learn more about many other health conditions by visiting STDWatch.com now.


Salt and Sodium - hsph.harvard.edu

What is hyponatremia? - kidney.org

Hyponatremia - my.clevelandclinic.org

Hyponatremia - mayoclinic.org

Hyponatremia - msdmanuals.com

What are the possible complications of hyponatremia? - medscape.com

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