Activated partial thromboplastin time:
Chapter: 20a
A coagulation test performed by adding a "partial thromboplastin" reagent (contact activating substance such as silica, phospholipid, and calcium) to citrated plasma, and measuring the time to clot (normal 25 - 35 seconds). Measures the integrity of the intrinsic and common coagulation pathways. Typically it is prolonged in hemophilia A, hemophilia B, some cases of von Willebrand disease, disseminated intravascular coagulation, and heparin therapy.
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