Total Antioxidant Capacity of Plasma (ORAC-like measurement)

What Does This Test Measure?

This test evaluates the total antioxidant capacity (TAC) of plasma, which reflects the combined ability of various antioxidants (like vitamins, enzymes, and other molecules) to neutralize harmful free radicals. Free radicals are unstable molecules that can cause cellular damage if left unchecked. The test typically uses a standardized method to quantify this protective capacity, often expressed in arbitrary units or relative terms.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms or conditions linked to oxidative stress, such as chronic inflammation, certain autoimmune diseases, or if you’re undergoing treatments that increase free radical production (e.g., chemotherapy). It may also be used in research or clinical trials to monitor antioxidant levels in specific populations.

How Is the Test Performed?

A blood sample is drawn from a vein in your arm. The plasma portion is separated and analyzed using a method that measures its ability to scavenge free radicals over time. Results are compared to a reference range that varies by lab, but are not typically expressed in absolute numeric values.

What Do the Results Mean?

Results indicate your plasma’s overall antioxidant capacity. Lower levels may suggest insufficient protection against oxidative damage, while higher levels may indicate stronger defenses. However, individual reference ranges are not standardized, so interpretation depends on clinical context and your doctor’s guidance.