Sodium Blood Test

What is the Sodium Blood Test?

The sodium blood test, also known as a serum sodium test, evaluates the concentration of sodium ions present in the blood. Sodium is an electrolyte that is essential to the proper function of the body's cells, and abnormalities in sodium levels can indicate problems in other areas of the body. The test results can help physicians diagnose medical issues like dehydration, kidney disease, and Conn's syndrome.


No special preparation is necessary for the sodium blood test. You may be asked to fast prior to the test so please consult the ordering clinic or physician's office for any instructions.


A serum sodium test is usually ordered as part of a baseline lab work panel and is collected using a regular venipuncture. For the test, collection personnel will draw a sample of your blood into a special serum separator tube. The sample is then sent off to a lab for analysis.


The most common type of sodium blood test is a serum test, which measures the amount of sodium in the blood serum, or liquid portion, of the sample. Other tests, such as urine and fecal sodium tests, measure the amount of sodium excreted in the urine and stool.


The sodium blood test isn't associated with any major risks. The venipuncture used to collect your blood sample carries a risk of minor pain, bruising, and infection.

Why Get Tested?

A sodium blood test is used to measure the amount of sodium in the body. Abnormal levels of sodium in the blood can be indicative of a variety of medical issues, including:

  • Dehydration
  • Sickle cell anemia
  • Addison's disease
  • Excessive water loss through fever, vomiting, diarrhea, burns, or diuretics
  • Kidney or Lung Disease
  • Adrenal insufficiency
  • Conn's syndrome (a rare type of adrenal gland disorder)

When To Get Tested?

Your doctor may order a sodium blood test as part of a regular work-up to check your electrolyte imbalance. It is also sometimes ordered if you present with symptoms such as confusion, fatigue, muscle cramps, or headaches.