Antithrombin Deficiency and INR

Cristina Granada asks, does antithrombin III deficiency (type 1) affect the INR? My antithrombin levels came back low but my INR came back at 1.17.

Thank you for your question, Cristina. Antithrombin (also called AT, antithrombin III or ATIII) deficiency does not affect the INR result, and in fact, an INR of 1.17 falls within the normal range of 0.8 to 1.2 for most laboratories. Most likely your physician has or will repeat and confirm your AT assay after a few weeks, because the level drops during and shortly after a thrombotic event or during kidney or liver disease. Your physician may also inform you about the use of antithrombotic (anti-clotting) therapy, particularly in high-risk situations. You may also wish to consult Dr. Stephan Moll’s column in the factor V Leiden web site.

Thank you for contacting The Fritsma Factor. Our information is not specific to your medical condition and does not substitute for consultation with your physician.