Reasons, Preparation & Procedure For Conducting a Activated Clotting Time Test

Submitted on March 27, 2012

What is a Activated Clotting Time Test?

The activated clotting time test is a test that is usually conducted during a coronary bypass to check whether the levels of a substance called heparin has been administered in the correct quantity. Heparin is an anticoagulant that is created within our bodies naturally in mast cells but can also be acquired from animal sources and used during surgeries as mentioned above. Heparin, in a normally functioning body, prevents the formation of clots in the blood but does not destroy existing clots that have formed. This is one of the drugs that is used in the treatment of venous thrombosis and deep vein thrombosis. The reason why the drug needs to be controlled is because of the adverse reactions that can occur.

Reasons Why It is Conducted

The activated clotting time test is performed usually in the operating room as it gives immediate results for the levels of heparin that have been administered to prevent clotting. Heparin has an extremely short life of just about an hour in the body. Administering heparin can be dangerous because it can cause a condition called thrombocytopenia to develop. This is condition in which the blood platelets end up being the target of an immune response. This damage is not permanent and is usually reversed as soon as administration of the drug is completed.


There is no special preparation that needs to be done for the test; however, as with all tests in immunology, it is advised that you stay off Non Steroidal Anti-Inflammatory Drugs or NSAIDS like acetylsalicylic acid, ibuprofen, and acetaminophen. Corticosteroids must also not be used though some may be allowed as per doctor's orders.


The test is conducted with a blood culture measured for the time that it takes to clot. The test usually doesn't take more than fifteen minutes. Heparin levels can then be adjusted if inaccurately judged the first time around. Heparin is a drug that has been indicted in a lot of mistaken injections given to patients. The drug was also used in a case of euthanasia. Hyperkalemia is one of the major side effects of heparin use and is a condition characterized by too much potassium in the body. Alopecia or hair loss and osteoporosis are also some of the reported side effects of using the drug. Protamine sulfate is the drug that is administered immediately once a heparin overdose is suspected to have taken place. The drug is administered slowly over four hours.