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The partial thromboplastin time (PTT), also known as the activated partial thromboplastin time (aPTT or APTT), is a blood test that characterizes coagulation of the blood. A historical name for this measure is the Kaolin-cephalin clotting time ( KCCT ), [ 1 ] reflecting kaolin and cephalin as materials historically used in the test.
Fresh normal plasma has all the blood coagulation factors with normal levels. If the problem is a simple factor deficiency, mixing the patient plasma 1:1 with plasma that contains 100% of the normal factor level results in a level ≥50% in the mixture (say the patient has an activity of 0%; the average of 100% + 0% = 50%). [3]
Clotting time is a general term for the time required for a sample of blood to form a clot, or, in medical terms, coagulate. The term "clotting time" is often used when referring to tests such as the prothrombin time (PT) , activated partial thromboplastin time (aPTT or PTT), activated clotting time (ACT), thrombin time (TT), or Reptilase time .
In case of a corrected mixing test, a lower dose of normal pooled plasma is often used, such as a 4:1 mix (4 times as much patient plasma than normal pooled plasma), as some studies suggest that this method is more sensitive for the detection of a weak lupus anticoagulant that is not enough prevalent or potent to affect a 1:1 mix. [11]
Batroxobin has a similar action to thrombin but unlike thrombin it is not inhibited by heparin, so reptilase time and thrombin time can be used concurrently to distinguish anticoagulant effect from hypofibrinogenemia or dysfibrinogenemia. [1] [5] Normal values for thrombin time may be 12 to 14 seconds, [6] but the test has significant reagent ...
A coagulation screen is a combination of screening laboratory tests, designed to provide rapid non-specific information, which allows an initial broad categorization of haemostatic problems. [ 1 ] Process
KCT is similar to the activated partial thromboplastin time test, except it does not use exogenous phospholipid. [2] Thus, a confirmatory test that uses excess phospholipid is needed to validate the presence of lupus anticoagulants. [2] Otherwise, diluting the test plasma in normal plasma before testing provides characteristic mixing patterns. [8]
The calibrated automated thrombogram (CAT or CT) is a thrombin generation assay (TGA) and global coagulation assay (GCA) which can be used as a coagulation test to assess thrombotic risk. [1] [2] It is the most widely used TGA. [3] The CAT is a semi-automated test performed in a 96-well plate and requires specialized technologists to be ...