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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.
The aPTT-based APC resistance test involves a modified aPTT test performed in the presence and absence of activated protein C (APC). [1] [5] The ratio of these aPTT values is calculated and is called the APC sensitivity ratio (APCsr) or simply APC ratio (APCr). [1] [5] This ratio is inversely related to the degree of APC resistance. [7]
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.
Laboratories usually calculate their own ranges, based on the method used and the results obtained from healthy individuals from the local population. Variability arises from differences in thrombin concentration, dilution of plasma, presence and/or concentration of calcium ions, as well as the influence of analyser type. [ 5 ]
Thromboelastography (TEG) is a method of testing the efficiency of blood coagulation.It is a test mainly used in surgery and anesthesiology, although increasingly used in resuscitations in emergency departments, intensive care units, and labor and delivery suites.
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]
In alcoholic liver disease, the mean ratio is 1.45, and mean ratio is 1.33 in post necrotic liver cirrhosis. Ratio is greater than 1.17 in viral cirrhosis, greater than 2.0 in alcoholic hepatitis, and 0.9 in non-alcoholic hepatitis. Ratio is greater than 4.5 in Wilson disease or hyperthyroidism. [6]
The KCT test/control ratio of greater than or equal to 1.2 indicates that a defect is present. [4] If the test/control ratio is between 1.1 and 1.2, the test is equivocal. [4] A good way of expressing the result using mixes is to calculate the Rosner index. [10]