Generality
Partial thromblopastin time (PTT) and activated partial thromboplastin time (aPTT) are laboratory tests conducted on a plasma sample; both evaluate the efficacy of the intrinsic pathway and the common pathway of coagulation.
In the presence of a plasma sample, made incoagulable with sodium citrate, the partial thromboplastin time (PTT - Partial Thromboplastin Time) is defined as the time between the addition of calcium and partial thromboplastin, and the formation of the fibrin clot at the "inside of the same.
The "partial" adjective refers to the fact that the sample is added with phospholipids isolated from the protein molecules normally present in tissue thromboplastin (glycoprotein also known as coagulation factor III or tissue factor), which allows to study the intrinsic pathway of coagulation .
The adjective "activated" refers to the addition in the plasma sample of activators - such as kaolin, celite, ellagic acid or inosine - which determine the maximum activation of factor XII. It follows that the times measured in the aPTT are shorter than those of the PTT.
What's this
The evaluation of the partial thromblopastin time (PTT) determines the activity of the factors belonging to the intrinsic coagulation pathway, compared to the normal one.
This test is used as an aid in assessing an individual's ability to form blood clots appropriately.
The PTT is indicative of the quantity and function of certain proteins called clotting factors, which play an important role in clot formation in the event of a blood vessel injury.
If this parameter is very high, the patient has an increased risk of spontaneous bleeding.
Because it is measured
Partial thromblopastin time (PTT) and activated partial thromboplastin time (aPTT) tests measure the number of seconds it takes for a clot to form in a person's blood after adding a certain substance (reagent) . These tests are mainly used to understand the unexplained causes of excessive bleeding or inappropriate clotting.
