Sodium (Na) in Blood

Blood Sodium

What To Think About

• When the sodium level changes quickly, you are likely to have more symptoms than when the level changes slowly. Symptoms of an abnormal sodium level include confusion, lack of energy (lethargy), or seizures.
• To see whether the body is passing too little or too much sodium in the urine, a value called the fractional excretion of sodium (FENa) can be found by looking at the amounts of sodium and creatinine in blood and urine. In a person with kidney failure, a low FENa may mean less blood flow to the kidneys is causing the kidney failure. A urine test for sodium may be done. For more information, see the medical test Sodium (Na) in Urine.
• Other electrolytes, such as calcium, chloride, magnesium, potassium, phosphate, blood urea nitrogen (BUN), and creatinine, may be checked in a blood sample at the same time as a blood test for sodium. For more information, see the medical tests Calcium (Ca) in Blood, Chloride (Cl), Magnesium (Mg), Potassium (K) in Blood, Phosphate, Blood Urea Nitrogen, and Creatinine and Creatinine Clearance.

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Author:	Caroline Rea, RN, BS, MS	Last Updated: September 18, 2008
Medical Review:	E. Gregory Thompson, MD - Internal Medicine Avery L. Seifert, MD - Urology
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