• Hyponatremia—Adult

    (Dilutional Hyponatremia; Euvolemic Hyponatremia; Hypervolemic Hyponatremia; Hypovolemic Hyponatremia)


    Hyponatremia is a condition in which the level of sodium in the blood is too low. This occurs when there is an imbalance in the amount of water and sodium in the body—too little sodium for the amount of water present. As a result, water moves into the body’s cells causing them to swell. This condition may be serious. It requires care from your doctor.
    There are different types of hyponatremia, each resulting in low sodium in the body:
    Type What Happens?
    Euvolemic hyponatremia Water level increases, but sodium level stays the same
    Hypervolemic hyponatremia Water and sodium levels increase, but the water gain is greater
    Hypovolemic hyponatremia Water and sodium levels decrease, but the sodium loss is greater


    Causes of hyponatremia include:
    Kidney Failure
    Kidney failure stones
    Kidney failure is one condition that may cause hyponatremia.
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    Risk Factors

    Risk factors include:
    • Drinking too much fluid (eg, water)
    • Taking certain medicines
    • Having certain conditions
    • Having certain medical procedures (eg, prostate surgery )
    • Participating in endurance exercise, like running marathons
    • Being of advanced age
    • IV treatment—While in the hospital, fluids may be delivered through a needle in the vein. In some cases, this may lead to hyponatremia.


    With mild hyponatremia, you may have no symptoms at all. During more severe cases, symptoms may include:
    • Headache
    • Sluggishness
    • Confusion
    • Hallucinations
    • Nausea
    • Irritability
    • Loss of appetite
    • Restlessness
    • Muscle twitching
    • Seizures
    • Unresponsiveness
    • Coma
    If left untreated, the condition may lead to death.


    Your doctor will:
    • Ask about your symptoms
    • Ask about your fluid intake
    • Take your medical history
    • Do a physical exam
    Tests may include:
    • Blood tests—to check the sodium level in your blood, as well as other blood tests to check the functioning of your organs (eg, kidneys, heart, liver)
    • Urine test—to check the sodium level in your urine


    Treatment may depend on:
    • What is causing the low sodium level
    • How long the sodium level has been low
    • How low the sodium level is
    In most cases, your doctor will want to correct the sodium level slowly. Serious complications may occur when sodium levels rise too rapidly. Treatment options include:
    • Restricting the amount of fluids consumed
    • Identifying the underlying cause and getting proper treatment
    • Taking medicines to help remove extra fluid from your body
    • Using an IV to deliver sodium and fluid to correct the balance


    To help reduce your chance of getting hyponatremia, take these steps:
    • If participating in sports, drink only as much water or sports drinks as you need to quench your thirst. Sports drinks that provide electrolytes, such as sodium, may be helpful during endurance events.
    • Work with your doctor to effectively manage any conditions that you may have.


    American Academy of Family Physicians http://www.aafp.org/

    National Institute of Diabetes and Digestive and Kidney Diseases http://www2.niddk.nih.gov/


    The College of Family Physicians of Canada http://www.cfpc.ca/

    Health Canada http://www.hc-sc.gc.ca/


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    Hyponatremia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/ . Updated July 3, 2011. Accessed August 22, 2011.

    Hyponatremia. The Merck Manual for Healthcare Professionals website. Available at: http://www.merckmanuals.com/professional/sec13/ch167/ch167a.html . Updated May 2009. Accessed August 22, 2011.

    Mayo Clinic Staff. Hyponatremia. Mayo Clinic website. Available at: http://www.mayoclinic.com/health/hyponatremia/DS00974 . Updated July 14, 2011. Accessed August 22, 2011.

    Mittal R, Sheftel H, Demssie Y. Management of hyponatraemia. Br J Hosp Med (Lond). 2011;72(2):M22-5.

    Peng K. Management of hyponatremia. Am Fam Physician.  2004;69(10):2387-2394.

    Sodium. The Merck Manual Home Health Handbook for Patients and Caregivers website. Available at: http://www.merckmanuals.com/home/sec14/ch171/ch171b.html#v1151161 . Updated August 2008. Accessed August 22, 2011.

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