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Antithrombin

Published: July 27, 2026Updated: August 25, 2026

Antithrombin is a protein that inhibits blood clotting by inactivating thrombin and other clotting factors. It plays a crucial role in regulating the coagulation cascade.

Quick summary

Antithrombin measures the body's ability to regulate blood clotting.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
%
Clinical utility
diagnostic
Result kind
semi_quantitative
FDA-cleared
Roche Antithrombin, Siemens Antithrombin, Stago Antithrombin
interpretation: {"text":"Levels below 80% may indicate antithrombin deficiency, increasing the risk of thrombosis.","label":"Low"}; {"text":"Levels above 120% are less common but may occur in certain liver diseases or with anticoagulant therapy.","label":"High"}

Antithrombin is a natural anticoagulant protein that helps prevent excessive blood clotting by inhibiting the activity of thrombin and other clotting factors in the coagulation cascade.

A deficiency in antithrombin can lead to increased risk of thrombosis, as the balance of the coagulation system is disrupted.

Measuring antithrombin levels is important in diagnosing inherited or acquired antithrombin deficiency, which can inform treatment strategies for thrombotic disorders.

Frequently asked questions

What causes low antithrombin levels?
Low antithrombin levels can be caused by inherited deficiency, liver disease, nephrotic syndrome, or disseminated intravascular coagulation (DIC).
How is antithrombin deficiency treated?
Treatment typically involves anticoagulant therapy, such as heparin, and addressing any underlying conditions.
  1. 1
    Antithrombin Deficiency - Hematology.orgSource
  2. 2
    Antithrombin (AT) Test - MedlinePlusSource

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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

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 25, 2026. · Read our editorial policy