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Hyponatremia

• Overview
• Symptoms
• Treatment
• Prevention

Alternative Names:

Dilutional hyponatremia; Euvolemic hyponatremia; Hypervolemic hyponatremia; Hypovolemic hyponatremia

Symptoms:

When sodium levels drop in the fluids outside the cells, water will seep into the cells in an attempt to balance the concentration of salt outside the cells. The cells will swell as a result of the excess water. While most cells can accommodate this swelling, brain cells cannot, because the skull confines them. Therefore, most symptoms of hyponatremia will result from brain swelling.

Common symptoms include:

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

Signs and tests:

Hyponatremia is confirmed through the following laboratory studies:

• Serum sodium
• Serum osmolality
• Urine osmolality
• Urine sodium

In addition to laboratory studies, a complete physical examination will be done to find the underlying cause of this condition. During this examination, your doctor may order additional tests.

References:

Braunwald E, Fauci AS, Kasper DL, et al., eds. Hyponatremia. In Harrison's Principles of Internal Medicine. 15th ed. New York, NY: McGraw-Hill; 2001:274-76.

• Review Date: 9/13/2005
• Reviewed By: Robert Mushnick, M.D., Assistant Clinical Professor, SUNY Downstate Health Center, Brooklyn, NY. Review provided by VeriMed Healthcare Network.

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