What Causes Low Sodium and Chloride Levels in the Blood?

A long, sweaty workout can put you at risk for low sodium and chloride levels if you don't rehydrate properly.
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Sodium and chlorine are two electrolytes — minerals with an electric charge — that are required for the proper functioning of your cells. There are a range of conditions and medications that can cause abnormally low chloride and sodium levels in the blood.


Sodium and chloride levels can be measured through a blood test. According to the U.S. National Library of Medicine, normal blood sodium levels are between 135 to 145 milliequivalents per liter (mEq/L). When levels fall lower than that, it is called hyponatremia.

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Per the U.S. National Library of Medicine, normal chloride levels are between 96 to 106 mEq/L, and lower-than-normal levels are called hypochloremia.

What Causes Hyponatremia?

According the Cleveland Clinic, most cases of hyponatremia result from having too much water in your body, which dilutes the concentration of sodium in the blood. Less commonly, hyponatremia can occur if you lose a large amount of sodium from your body.

"People who are at risk of hyponatremia are people who, for whatever reason, are either taking in a whole lot of water or people who can't get rid of water," explains Daniel Weiner, MD, FASN, an associate professor at Tufts University School of Medicine and a member of the American Society of Nephrology's Quality Committee.


A range of health conditions can cause hyponatremia, according to the Mayo Clinic, including:

  • Heart, kidney and liver problems
  • Hormonal problems like Addison's disease or thyroid problems
  • Syndrome of inappropriate anti-diuretic hormone (SIADH), a condition in which elevated levels of this hormone cause your body to retain water instead of excreting it normally in your urine


People with burns across a large area of the body may also develop hyponatremia as well, notes the U.S. National Library of Medicine.

Read more:What Are the Dangers of Low Sodium Levels?

Certain medications can also lead to low blood sodium levels, including some antidepressants, MDMA (Ecstasy), pain medications and thiazide diuretics, which are commonly used to treat high blood pressure, according to the Mayo Clinic.


Hyponatremia may result from rapidly drinking excessive amounts of water. People who've lost a lot of water and sodium through vomiting, diarrhea or excessive sweating during prolonged exercise can also develop hyponatremia, especially if they consume a lot of water without simultaneously replacing their lost sodium, per the Cleveland Clinic.


"You need a certain amount of salt to get rid of water," says Dr. Weiner. "So if you're taking in a lot of electrolyte-free water, you can dilute out what remains because you can't get rid of the water unless you have some electrolytes."


Proper rehydrating after a workout means replacing lost water as well as electrolytes.
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Common Causes of Hypochloremia

Hyponatremia frequently goes hand-in-hand with hypochloremia. Conditions that cause low sodium levels in the blood usually also cause decreased levels of chloride, per the U.S. National Library of Medicine.


In addition, hypochloremia can result from metabolic alkalosis or chronic respiratory acidosis, conditions that affect the acidity level of the blood, Dr. Weiner says.

There are also certain genetic conditions that can cause hypochloremia, but those "would be exceedingly rare," Dr. Weiner says.

Read more:What's the Best Way to Raise Low Blood Sodium Levels?


When to Seek Treatment

Treatment for hyponatremia and hypochloremia depends on the underlying cause, as well as the severity of symptoms, so it's important to see a health care provider to determine what is causing your low sodium or chloride levels.

The Mayo Clinic recommends you seek emergency medical attention right away if you experience any of the severe symptoms of hyponatremia, such as:

  • Nausea
  • Vomiting
  • Confusion
  • Seizures or loss of consciousness

In acute cases, hyponatremia is a potentially life-threatening condition that, if left untreated, can cause brain damage, coma or death. According to the Cleveland Clinic, most patients with moderate to severe hyponatremia require treatment in a hospital setting.




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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