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Hyponatremia—Adult

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

Definition

Hyponatremia is a potentially serious condition in which the level of sodium in the blood is too low. An imbalance is created when there is too little sodium for the amount of water in the body. As a result, water moves into the body’s cells causing them to swell.
There are different types of hyponatremia, each resulting in low sodium in the body:

Causes

Hyponatremia may be caused by:
Normal Anatomy of the Kidney
Kidney failure stones
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Risk Factors

Factors that may increase your chance of hyponatremia include:

Symptoms

People with mild hyponatremia usually don't have symptoms. As hyponatremia progresses, symptoms will appear and worsen.
Moderate to severe hyponatremia may cause:
Severe and rapid onset hyponatremia may cause seizures , coma , or death.

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Your doctor will ask you about your fluid intake and do some tests.
Tests may include:
Other tests may be done to look for any underlying causes of your hyponatremia.

Treatment

Treatment may depend on:
In cases when the sodium has been low for more than 1-2 days, your doctor will want to correct the sodium level slowly. Serious complications may occur when sodium levels rise too rapidly. It can be corrected more quickly if it has been lw for a short time.
Treatment options may include:

Prevention

To help reduce your chance of hyponatremia:

RESOURCES

American Society for Nutriton http://www.nutrition.org

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

CANADIAN RESOURCES

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

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

References

Almond CS, Shin AY, et al. Hyponatremia among runners in the Boston Marathon. N Engl J Med. 2005;352(15):1550-1556.

Ayus JC, Arieff AI. Glycine-induced hypo-osmolar hyponatremia. Arch Intern Med. 1997;157(2):223-226.

Elhassan EA, Schrier RW. Hyponatremia: Diagnosis, complications, and management including V2 receptor antagonists. Curr Opin Nephrol Hypertens. 2011;20(2):161-168.

Hyponatremia. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 9, 2014. Accessed November 6, 2014.

Mittal R, Sheftel H, et al. 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.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH). EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 15, 2012. Accessed November 15, 2013.

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