Total Antioxidant Capacity of Plasma (TAC)
This test measures the overall ability of your blood plasma to neutralize harmful free radicals, which can help protect cells from oxidative damage.
["Assesses your body’s natural antioxidant defenses."]
Key facts at a glance
- LOINC
- 20725-8
- Short code
- BRUCMRT
- Synonyms
- B abortus Ab Mlk Ql Ring aggl
- Category
- chemistry
- Sample
- serum
- Container
- Sterile milk collection vial or serum separator tube (SST) for serum testing
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- aggl-ring-test
- CPT
- 86622
- SNOMED
- 39535009
- Specimen volume
- 10 mL of milk or 5 mL of serum
- Stability
- Milk: 2-8°C for 24-48 hours; do not freeze. Serum: 2-8°C for 7 days, -20°C for long-term storage
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Does This Test Measure?
Total antioxidant capacity (TAC) reflects the combined activity of various antioxidants in your plasma, including vitamins (like vitamin C and E), enzymes, and other molecules that help prevent oxidative stress. This test does not identify specific antioxidants but provides an overall measure of your plasma’s antioxidant power.
Why Might You Need This Test?
Doctors may order this test to evaluate your risk of oxidative damage, monitor conditions linked to oxidative stress (e.g., chronic inflammation, certain cancers, or metabolic disorders), or assess how well your body is protecting itself from free radicals.
How Is the Test Performed?
A blood sample is drawn from a vein, typically in your arm. The plasma portion is then analyzed to determine its antioxidant capacity using a specialized laboratory method.
What Are Common Uses?
This test can help identify potential imbalances in antioxidant levels, guide dietary or supplement recommendations for oxidative stress management, or support research into conditions where oxidative damage plays a role.
Reference range
Negative: No antibody detected; Positive: Antibody detected (ring formation at cream layer)N/A
No special patient preparation required. Collect milk sample from individual animal or bulk tank. For serum testing, collect blood by standard venipuncture technique.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Plasma Antioxidant Level
Frequently asked questions
What does a low or high TAC result mean?
How often should I get this test?
Can antioxidants in supplements affect this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy