Activated partial thromboplastin time
Activated Partial Thromboplastin Time
The Activated Partial Thromboplastin Time (APTT or aPTT) is a medical test that characterizes coagulation of the blood. It is pronounced as /æktɪˈveɪtɪd ˈpɑːrʃəl θrɒmbəˈplæstɪn taɪm/.
Etymology
The term originates from the process it measures. "Activated" refers to the initiation of the clotting process; "partial" indicates that only a part of the coagulation cascade is evaluated; "thromboplastin" is a substance in the blood that contributes to clotting; and "time" refers to the measurement of how long it takes for a clot to form.
Procedure
The APTT test is performed by adding a substance known as an activator to a sample of blood. This activator initiates the coagulation cascade, a series of reactions that ultimately leads to the formation of a blood clot. The time it takes for the clot to form is then measured and reported as the APTT.
Clinical Significance
The APTT test is primarily used to assess the function of the intrinsic and common pathways of the coagulation cascade. It is often used in conjunction with the Prothrombin Time (PT) test to diagnose and monitor bleeding disorders and to monitor the effectiveness of anticoagulant therapy.
Related Terms
- Coagulation: The process by which blood changes from a liquid to a gel, forming a clot.
- Coagulation Cascade: A series of reactions in which one clotting factor activates the next.
- Prothrombin Time (PT): A test that measures the time it takes for the plasma portion of blood to clot.
- Anticoagulant: A substance that prevents coagulation, thus prolonging the time it takes for a blood clot to form.
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