Arterial Sodium (Blood Gas)

This test measures the concentration of sodium in an arterial whole blood sample using a blood gas analyzer. Sodium is the main electrolyte in the fluid outside your cells and is essential for nerve signaling, muscle contraction, and keeping the right balance of water in your body.

It is often performed in urgent or critical settings because it provides a rapid snapshot of your electrolyte status alongside other blood gas measurements. The result reflects your sodium level at the moment the arterial sample is taken.

Your care team uses this test to quickly assess for sodium disturbances that can affect thinking, alertness, seizures, muscle cramps, and heart rhythm. It is commonly ordered during emergencies, surgery, and intensive care to guide fluids and medications.

Results can help evaluate problems related to dehydration, fluid overload, kidney or hormone disorders, and side effects from medicines that change water handling. It also helps monitor response to treatments that add or remove salt and water.

Your result is interpreted together with your symptoms, exam, and other lab findings. If the value is lower than expected, your team may look for causes such as excess water intake, losses from vomiting or diarrhea, certain medications, hormone problems, or high blood sugar. If the value is higher than expected, dehydration, salt loads, or water loss are often considered.

Because this measurement is made on arterial whole blood with a point-of-care instrument, it can differ slightly from a standard laboratory serum result. If a result does not fit your clinical picture, your clinician may repeat the test or confirm with a serum measurement. Do not change your fluids or medicines unless your care team advises you to do so.