Partial Thromboplastin Time

**Definition:** The time required for the appearance of FIBRIN strands following the mixing of PLASMA with phospholipid platelet substitute (e.g., crude cephalins, soybean phosphatides). It is a test of the intrinsic pathway (factors VIII, IX, XI, and XII) and the common pathway (fibrinogen, prothrombin, factors V and X) of BLOOD COAGULATION. It is used as a screening test and to monitor HEPARIN therapy.

**Tree numbers:** - E01.370.225.625.115.600 - E05.200.625.115.600 - G09.188.660

**Synonyms:** - Activated Partial Thromboplastin Time - Thromboplastin Time, Partial