Hyponatremia (patient information)

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Hyponatremia
Overview
What are the symptoms?
What are the causes?
Who is at highest risk?
Diagnosis
When to seek urgent medical care?
Treatment options
Where to find medical care for Hyponatremia?
Prevention
What to expect (Outlook/Prognosis)?
Possible complications
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Hyponatremia is a metabolic condition in which there is not enough sodium (salt) in the body fluids outside the cells.

What are the symptoms of Hyponatremia?

Common symptoms include:

• Abnormal mental status
  • Confusion
  • Decreased consciousness
  • Hallucinations
  • Possible coma
• Convulsions
• Fatigue
• Headache
• Irritability
• Loss of appetite
• Muscle spasms or cramps
• Muscle weakness
• Nausea
• Restlessness
• Vomiting

What causes Hyponatremia?

Sodium is found mostly in the body fluids outside the cells. It is very important for maintaining blood pressure. Sodium is also needed for nerves and muscles to work properly.

When the amount of sodium in fluids outside cells drops, water moves into the cells to balance the levels. This causes the cells to swell with too much water. Although most cells can handle this swelling, brain cells cannot, because the skull bones confine them. Brain swelling causes most of the symptoms of hyponatremia.

In hyponatremia, the imbalance of water to salt is caused by one of three conditions:

• Euvolemic hyponatremia -- total body water increases, but the body's sodium content stays the same
• Hypervolemic hyponatremia -- both sodium and water content in the body increase, but the water gain is greater
• Hypovolemic hyponatremia -- water and sodium are both lost from the body, but the sodium loss is greater

Hyponatremia is the most common electrolyte disorder in the United States.

Causes of hyponatremia include:

• Burns
• Congestive heart failure
• Diarrhea
• Diuretic medications, which increase urine output
• Kidney diseases
• Liver cirrhosis
• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
• Sweating
• Vomiting

Diagnosis

The health care provider will perform a complete physical examination to help determine the cause of your symptoms. Blood and urine tests will be done.

The following laboratory tests can confirm hyponatremia:

• Comprehensive metabolic panel (includes blood sodium)
• Osmolality blood test
• Urine osmolality
• Urine sodium