Antithrombin Activity with Reflex to Antithrombin Antigen Test

The antithrombin activity and antigen tests are used to help find out what may be causing abnormal blood clots in your body. A blood can be good or bad, depending on the case. Antithrombin is a protein produced by the liver that helps regulate blood clot formation. Normally you have a healthy balance between chemicals in your body that help clotting and chemicals that stop clotting. One important protein that helps clotting is thrombin. The protein that blocks thombin is called antithrombin. Antithrombin works to thin the blood slightly so that it doesn't clot too much. A lack of antithrombin can make it more likely for you to form blood clots.

You don't need to do anything special to prepare for this test. Make sure your doctor is aware if you are taking warfarin or heparin or getting chemotherapy with asparaginase. And be sure your doctor also knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use. Testing for antithrombin deficiency is not recommended if a person's condition may affect the antithrombin level or the person has been treated with heparin for a blood clot.

The results vary depending upon age, health History and method used for test. Here is result for both Activity and Antigen Tests as given in percentage: 80% to 120% is considered normal for adults People with genetically inherited antithrombin deficiency typically have test results between 40% and 60%. Newborns usually have about half as much antithrombin as adults. In both type 1 and type 2 AT deficiency, the antithrombin activity test shows a low result because you don't have as much working antithrombin as you should have.

The Procedure of Antithrombin test is as follows: Activity Test: -This test is done to evaluate whether the total amount of functional antithrombin is normal. Antigen Test: - If the antithrombin activity is low, then the antithrombin antigen test is performed to determine the quantity of antithrombin present. These two tests can be used to differentiate between type 1 and type 2 antithrombin deficiencies. The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand.