Abbreviation: APTT.
A laboratory test used to measure the intrinsic pathway of coagulation. In health, the APTT is about 16 to 40 sec, depending on the laboratory methods used. Prolonged PTT may indicate cirrhosis of the liver, disseminated intravascular coagulation, blood clotting factor deficiencies (VIII, IX, X), decreased levels of fibrinogen in the blood, von Willebrand's disease, or the presence of a lupus anticoagulant.