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The partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT or APTT) is a medical test that characterizes blood coagulation. Apart from detecting abnormalities in blood clotting,〔(【引用サイトリンク】title=MedlinePlus Medical Encyclopedia: Partial thromboplastin time (PTT) )〕 it is also used to monitor the treatment effects with heparin, a major anticoagulant. PTT is a performance indicator of the efficacy of both the "intrinsic" (now referred to as the contact activation pathway) and the common coagulation pathways. It is used in conjunction with the prothrombin time (PT) which measures the ''extrinsic pathway''. Kaolin cephalin clotting time (KccT) is a historic name for the activated partial thromboplastin time. ==Methodology== Prothrombin time is typically analyzed by a medical technologist or a laboratory technician on an automated instrument at 37 °C (as a nominal approximation of normal human body temperature). The test is termed "partial" due to the absence of tissue factor from the reaction mixture. * Blood is drawn into a test tube containing oxalate or citrate, molecules which act as an anticoagulant by binding the calcium in a sample. The blood is mixed, then centrifuged to separate blood cells from plasma (as Partial thromboplastin time is most commonly measured using blood plasma). * A sample of the plasma is extracted from the test tube and placed into a measuring test tube. * Next, an excess of calcium (in a phospholipid suspension) is mixed into the plasma sample (to reverse the anticoagulant effect of the oxalate enabling the blood to clot again). * Finally, in order to activate the intrinsic pathway of coagulation, an activator (such as silica, celite, kaolin, ellagic acid) is added, and the time the sample takes to clot is measured optically. Some laboratories use a mechanical measurement, which eliminates interferences from lipemic and icteric samples. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Partial thromboplastin time」の詳細全文を読む スポンサード リンク
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