This lab test evaluates an electrolyte that is important in many body functions and processes such as keeping the body's fluids in balance.

Sodium Overview

Reviewed: April 21, 2014

Sodium is an electrolyte which is needed by the body to work properly. It helps with the function of nerves and muscles. It also helps to keep the right balance of fluids in your body. The test is performed when the patient has symptoms of sodium imbalance or disorders associated with abnormal sodium levels. A decrease in sodium is called hyponatremia and hypernatremia is when the sodium levels are above normal.

Sodium is measured in milliequivalents per liter (mEq/L).

The normal range for sodium is 135 - 145 mEq/L


Blood draw


Fasting is not required before the test.

What the results mean

Abnormal sodium levels can be due to many different conditions.

A higher than normal sodium level is called hypernatremia and may be due to Cushing syndrome, diabetes insipidus, hyperaldosteronism, dehydration, or certain medications.

A lower than normal sodium level is called hyponatremia. This may be due to Addison's disease, overhydration, certain kidney diseases, burns, cirrhosis of the liver, or use of certain medications.