Antithrombin Activity

External bleeding can occur when you get cut or injured. The healing process causes the platelets in your blood to stick together, forming blood clots to prevent excessive blood loss. This is known as coagulation. Normal coagulation is a standard response of your body to begin the healing process. However, clotting inside the body must not occur. Thrombophilia or Hypercoagulability is a problem where excessive blood clotting takes place.

Hypercoagulability is usually a genetic or inherited disorder or can occur due to some acquired conditions. A person with a genetic disorder suffers from blood clots from the time they are born while acquired conditions could be a trauma or the result of surgery. It can also be due to medications.

Genetic or inherited hypercoagulable conditions can happen because of the following factors:

• Natural protein deficiency such as protein C and protein S 
• Antithrombin deficiency or antithrombin III deficiency
• Factor V Leiden, a blood clotting factor mutation 
• Prothrombin gene mutation
• Increased level of the amino acid homocysteine 
• Dysfunctional fibrinogen
• Hypoplasminogenemia and dysplasminogenemia
• High levels of factor VIII or Antihemophilic Factor

Hypercoagulability or Thrombophilia can increase the risk of blood clots even in the arteries and veins. If left untreated, this can be fatal. The blood clots within the blood vessel can travel across the bloodstream and cause thrombosis in your legs, arms, liver, kidneys, intestines, and pelvis. It can even cause a pulmonary embolus or blood clot in the lungs.

In the case of genetic Hypercoagulability, the problem is transferred to the child from the parents. So, the parents may also be screened in case of the following:

• Thrombosis in unusual sites, like the liver, veins of the arms, etc. 
• Abnormal blood clotting at a young age (less than 50 years) 
• Recurring blood clots 
• Past miscarriages 
• Stroke at a young age

The antithrombin activity test is used to detect the inherited hypercoagulable states. It is also known as an antithrombin antigen test, functional AT, AT activity, or antithrombin III test. Since a blood clot can be fatal, the antithrombin activity and antigen test help doctors identify such presence.

The healthcare specialist may recommend one or both tests if the irregular blood clots persist. The test is done through a standard blood test. Apollo 24|7 offers both.

In some cases, due to certain conditions, the antithrombin level may be poor. For instance:

• Excessive blood clots 
• Trauma 
• Severe burns 
• Undergoing chemotherapy, especially with the drug asparaginase
• A blood disorder called disseminated intravascular coagulation or DIC

If such is the case, your doctor may ask you to stop taking anti-clotting or blood-thinning medicines, like heparin or warfarin. If the results of the antithrombin activity test are unsatisfactory, you may need to retake the test in two weeks. 
 

Medically reviewed by Dr. Soumya Bhattacharya, Haematologist ,Apollo Multispeciality Hospitals , Kolkata,Kolkata.