Serum or plasma oxygen saturation (SaO₂)

What This Test Measures

Oxygen saturation (SaO₂) reflects the percentage of hemoglobin molecules carrying oxygen in your blood. A lower than expected result may suggest conditions like poor lung function, anemia, or other circulatory problems. This test is often used alongside other measures like pulse oximetry to guide medical decisions.

Why It’s Done

Your healthcare provider may order this test if you have symptoms like shortness of breath, fatigue, or if you have a known condition that affects oxygen transport in your blood, such as chronic lung disease or heart problems. It can also be part of routine monitoring for certain medical treatments.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate serum or plasma, which is then analyzed to determine oxygen saturation levels. This test is usually performed quickly and may be part of a broader blood workup.

Common Conditions Monitored

Low oxygen saturation can signal conditions like chronic obstructive pulmonary disease (COPD), pulmonary embolism, anemia, or severe infections. High levels may be seen in rare cases of polycythemia (overproduction of red blood cells) or certain metabolic disorders.