Total Antithrombin Concentration (Serum)
This test measures the amount of antithrombin III, a natural protein in your blood that helps prevent blood clots from forming. It’s important for people at risk of clotting or those taking blood thinners.
["Antithrombin III helps regulate blood clotting; low levels may increase clot risk."]
Key facts at a glance
- LOINC
- 42950-6
- Short code
- T canis Ab Titr Spec
- Synonyms
- T canis Ab Titr Spec
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if you have a history of blood clots, are taking anticoagulant medications, or have conditions like liver disease that can affect protein production. It may also be checked before surgery or during treatment for conditions like disseminated intravascular coagulation (DIC).
What to Expect Before the Test
No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, check with your doctor first to avoid unusual bleeding. Avoid smoking or caffeine before the draw if instructed by your provider.
How the Test Works
Blood is drawn and sent to a lab where it’s analyzed using an immunoassay method. This test detects the protein antithrombin III in your serum to determine its concentration.
What the Results Mean
Results are compared to a standard range. Low levels may suggest conditions like liver disease, clotting disorders, or exposure to certain medications. High levels could be due to inherited conditions or certain medications. Your doctor will discuss results in the context of your health history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Antithrombin III is a key protein in the blood’s natural anticoagulant system. Low levels can increase the risk of blood clots (thrombosis) and may require monitoring or treatment adjustments. High levels might indicate inherited deficiencies or certain medications, but further evaluation is needed to understand the cause.
Short name
Antithrombin III Level
Frequently asked questions
What causes low antithrombin III levels?
How long does it take to get results?
Can I eat or drink before 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