Low Sodium

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What is low sodium?

Low sodium, medically known as hyponatremia, is a lack of balance between the water and salt (sodium) levels in your body. A correct level of sodium is important for the proper function of your muscles and nerves.

Low sodium is a common electrolyte disorder in the U.S. population. Electrolytes are important chemical substances that are present in the body, such as sodium and potassium. When dissolved in water, these substances become ions that are capable of conducting electricity. Electrolytes are critical for proper functioning of all body systems.

There are three types of hyponatremia: euvolemic, hypervolemic and hypovolemic. Euvolemic hyponatremia occurs when your body’s water content is normal but your sodium level declines. Hypervolemic hyponatremia is when water is increased relative to sodium levels. Hypovolemic hyponatremia happens when both water and sodium decrease, but more sodium is lost than water.

There are several common causes of sodium loss leading to low sodium levels, including diarrhea, excessive sweating, and vomiting. Medications that are prescribed to treat high blood pressure or fluid retention, called diuretics, can lead to low sodium levels. Kidney diseases, congestive heart failure (deterioration of the heart’s ability to pump blood), burns, cirrhosis of the liver, and the effects of cancer treatment also can bring on low sodium levels. High endurance athletes, such as marathon runners, may experience low sodium levels if fluids and electrolytes are not adequately replaced.

Seek immediate medical care (call 911) if you have serious symptoms of low sodium, such as a change in mental status (confusion or hallucinations); a change in level of consciousness, such as passing out or unresponsiveness; chest pain or pressure; convulsions; muscle spasms; muscle cramps; muscle weakness; nausea with or without vomiting; rapid heart rate (tachycardia); and vomiting.

What are the symptoms of low sodium?

Common symptoms of low sodium

You may experience low sodium symptoms daily or just once in a while. At times any of these low sodium symptoms can be severe:

  • Abdominal pain or cramping
  • Bloating
  • Body aches
  • Changes in mood, personality or behavior
  • Difficulty with memory, thinking, talking, comprehension, reading or writing
  • Dizziness
  • Headache
  • Impaired balance and coordination
  • Malaise or lethargy
  • Muscle spasms
  • Nausea with or without vomiting

Serious symptoms that might indicate a life-threatening condition

In some cases, low sodium can be life threatening. Seek immediate me dical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

What causes low sodium?

There are several common causes of low sodium, including diarrhea, excessive sweating, and vomiting. Medications that are prescribed to treat high blood pressure or fluid retention, called diuretics, can lead to low sodium levels.

Causes of low sodium

A number of medical conditions or circumstances can lead to low sodium levels including:

  • Adrenal gland disease

  • Burns

  • Certain medications such as diuretics

  • Cirrhosis (scarring) of the liver

  • Congestive heart failure

  • Dehydration (loss of body fluids and electrolytes, which can be life threatening when severe and untreated)

  • Diarrhea or vomiting

  • Excess water consumption

  • Extreme exercise

  • Kidney diseases

  • Profuse sweating

  • Syndrome of inappropriate anti-diuretic hormone (SIADH), a condition that causes the body to retain excess water

What are the risk factors for low sodium?

A number of factors increase the risk of developing low sodium. Not all people with risk factors will get low sodium. Risk factors for low sodium include:

  • Advanced age

  • Excessive exercise, particularly outdoors in hot weather

  • Hot climate

  • Kidney disease

  • Liver failure

  • Medication side effects

Reducing your risk of low sodium

If your exercise routine contains demanding physical activity, it is important to stay properly hydrated by drinking electrolyte-containing beverages.

You may be able to lower your risk of low sodium by:

  • Drinking electrolyte-containing fluids, such as sports drinks to replenish fluids and electrolytes when participating in sports

  • Maintaining proper hydration

How is low sodium treated?

In an emergency setting, low sodium is most often treated with the introduction of a sodium chloride solution into the bloodstream through intravenous (IV) delivery. Additional treatment will depend on the underlying causes of low sodium levels.

For more moderate cases of low sodium, your health care provider may suggest restricting your water intake or prescribing medications that treat low sodium.

If you are taking diuretic medications for high blood pressure or for other reasons, your health care provider will check your sodium levels on a regular basis and may suggest changes in your medication regimen if you develop mild hyponatremia.

What are the potential complications of low sodium?

Complications of untreated or poorly controlled low sodium can be serious, even life threatening in some cases. You can help minimize your risk of serious complications by following the treatment plan you and your health care provider design specifically for you. Complications of low sodium include:

  • Brain damage
  • Impaired balance and coordination
  • Seizures and tremors
  • Unconsciousness and coma
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 16
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  3. Hyponatremia. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/hyponatremia/symptoms-causes/syc-20373711