Activated partial thromboplastin time (APTT)

Last reviewed by: Aleksey Portnov , medical expert, on 31.05.2018

Reference values of activated partial thromboplastin time (APTT)

Activated partial thromboplastin time (APTT) is one of the most valuable common tests to obtain an idea of the blood coagulation system. APTTV is a test that detects exclusively plasma defects of the internal X-factor activation system in phase I (formation of prothrombinase) of blood coagulation.

Determination of activated partial thromboplastin time - modification of the test for determining the recalcification time of stabilized blood (plasma). It has a higher sensitivity to deficiency of plasma clotting factors (except VII and XIII), however, when using this test, it is not possible to reveal the insufficiency of coagulation activity of platelets.

The elongation of activated partial thromboplastin time (APTT) reflects a deficiency of plasma factors (except VII and XIII) and is observed with their significant (below 25-10%) decrease. Elongation of activated partial thromboplastin time (APTT) indicates a predominance of hypocoagulation.

Reference values: 38-55 s. However, it should be noted that reference values in different laboratories may vary depending on the sensitivity and composition of the diagnostic kits.

It is important to know!

Alpha2-antiplasmin is the main fast-acting plasmin inhibitor. It suppresses fibrinolytic and esterase activity almost instantaneously. The mechanism of its action is based on the fact that it interferes with the adsorption of plasminogen on fibrin, thus reducing the amount of plasmin formed on the surface of the clot and thereby dramatically slowing down fibrinolysis. Read more..

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