Antithrombin Activity (ATIII)

Other names: Anti-Thrombin Act, Antithrombin, Enzymatic (Activity)

Optimal Result: 76 - 128 %.

Blood Clotting / Coagulation Tests: What They Measure, Normal Ranges & What Results Mean

From Healthmatters.io Team

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Antithrombin Activity (ATIII), also known as AT III or AT 3, is a key biomarker that measures how effectively antithrombin, a natural anticoagulant protein, functions in the blood. Antithrombin is crucial for regulating clot formation by inhibiting thrombin and clotting factors like factor Xa, helping maintain a balance between clotting and bleeding. Normal ATIII activity ranges from 80% to 120%.

A decrease in ATIII activity may indicate inherited or acquired deficiencies and is often linked to conditions like deep vein thrombosis (DVT), pulmonary embolism, liver disease, nephrotic syndrome, disseminated intravascular coagulation (DIC), or vitamin K deficiency. While elevated ATIII activity is less common, it may occur during inflammation, certain stages of pregnancy, or after antithrombin supplementation or anticoagulant therapy.

Testing for antithrombin activity is vital for diagnosing clotting disorders, monitoring anticoagulant therapies (e.g., heparin), and evaluating overall hemostatic function. It is often performed alongside other tests, such as Protein C and S Activity, aPTT, PT/INR, and Factor V Leiden, to assess thrombophilia risk comprehensively. The test involves a blood draw, with plasma used as the specimen.

Emerging research highlights that certain demographic factors, such as Hispanic ethnicity, may influence ATIII activity in clinical contexts. This underscores the importance of considering patient-specific characteristics when interpreting test results.

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Antithrombin Activity (ATIII)

All Your Lab Results. One Simple Dashboard.

All Your Lab Results. One Simple Dashboard.

Import, Track, and Share Your Lab Results Easily

Import, Track, and Share Your Lab Results

Article Review & Sources

Bring All Your Lab Results Together — In One Place

Gather Your Lab History — and Finally Make Sense of It

Finally, Your Lab Results Organized and Clear

Advanced Plan

Unlimited Account

Pro Monthly

What's included in a Healthmatters membership

Import Lab Results from Any Source

See Your Health Timeline

Understand What Your Results Mean

Enter Your Lab Reports Yourself — Always Free Enter Your Lab Reports — Always Free

Visualize Your Results

Export Your Complete Lab History in a Single File Export Your Complete Lab History

Comprehensive Data Entry Service for Your Reports Data Entry Service for Your Reports

Securely Share With Anyone You Trust

Let Your Lab Results Tell the Full Story

Once your results are in one place, see the bigger picture — track trends over time, compare data side by side, export your full history, and share securely with anyone you trust.

Bring all your results together to compare, track progress, export your history, and share securely.

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All Your Lab Results.
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