Sodium Blood LabTest

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Sodium Blood LabTest

A sodium blood test measures the amount of sodium in your blood. Sodium is a type of electrolyte. Electrolytes are electrically charged minerals that help maintain fluid levels and the balance of chemicals in your body called acids and bases. Sodium also helps your nerves and muscles work properly.

You get most of the sodium you need in your diet. Once your body takes in enough sodium, the kidneys get rid of the rest in your urine. If your sodium blood levels are too high or too low, it may mean that you have a problem with your kidneys, dehydration, or another medical condition.

Other names: Na test

A sodium blood test may be part of a test called an electrolyte panel. An electrolyte panel is a blood test that measures sodium, along with other electrolytes, including potassium, chloride, and bicarbonate.

Your health care provider may have ordered a sodium blood test as part of your regular checkup or if you have symptoms of too much sodium (hypernatremia) or too little sodium (hyponatremia) in your blood.

Symptoms of high sodium levels (hypernatremia) include:

  • Excess thirst
  • Infrequent urination
  • Vomiting
  • Diarrhea

Symptoms of low sodium levels (hyponatremia) include:

  • Weakness
  • Fatigue
  • Confusion
  • Muscle twitching
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
You don't need any special preparations for a sodium blood test or an electrolyte panel. If your health care provider has ordered more tests on your blood sample, you may need to fast (not eat or drink) for several hours before the test. Your health care provider will let you know if there are any special instructions to follow.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

If your results show higher than normal sodium levels, it may indicate:

  • Diarrhea
  • disorder of the adrenal glands
  • kidney disorder
  • Diabetes insipidus, a rare form of diabetes that happens when the kidneys pass an unusually high volume of urine.

If your results show lower than normal sodium levels, it may indicate:

  • Diarrhea
  • Vomiting
  • Kidney disease
  • Addison disease, a condition in which your body's adrenal glands don't produce enough of certain types of hormones
  • Cirrhosis, a condition that causes scarring of the liver and can damage liver function
  • Malnutrition
  • Heart failure

If your results are not in the normal range, it doesn't necessarily mean that you have a medical condition needing treatment. Certain medicines can increase or decrease your sodium levels. If you have questions about your results, talk to your health care provider.

  1. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Sodium, Serum; 467–8 p.
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  3. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Electrolytes: Common Questions [updated 2015 Dec 2; cited 2017 Apr 2]; [about 5 screens]. Available from: https://labtestsonline.org/understanding/analytes/electrolytes/tab/faq
  4. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Electrolytes: The Test [updated 2015 Dec 2; cited 2017 Apr 2]; [about 4 screens]. Available from: https://labtestsonline.org/understanding/analytes/electrolytes/tab/test
  5. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Sodium: The Test [updated 2016 Jan 29; cited 2017 Apr 2]; [about 4 screens]. Available from: https://labtestsonline.org/understanding/analytes/sodium/tab/test
  6. Lab Tests Online [Internet]. American Association for Clinical Chemistry; c2001–2017. Sodium: The Test Sample [updated 2016 Jan 29; cited 2017 Apr 2]; [about 3 screens]. Available from: https://labtestsonline.org/understanding/analytes/sodium/tab/sample
  7. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2017. Diseases and Conditions: Hyponatremia; 2014 May 28 [cited 2017 Apr 2]; [about 4 screens]. Available from: http://www.mayoclinic.org/diseases-conditions/hyponatremia/basics/causes/con-20031445
  8. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Addison Disease [cited 2017 Apr 2]; [about 2 screens]. Available from: https://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/adrenal-gland-disorders/addison-disease
  9. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Hypernatremia (High Level of Sodium in the Blood) [cited 2017 Apr 2]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hypernatremia-high-level-of-sodium-in-the-blood
  10. Merck Manual Consumer Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2017. Hyponatremia (Low Level of Sodium in the Blood) [cited 2017 Apr 2]; [about 2 screens]. Available from: http://www.merckmanuals.com/home/hormonal-and-metabolic-disorders/electrolyte-balance/hyponatremia-low-level-of-sodium-in-the-blood
Sodium Blood LabTest

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