APTT-ACTIVATED PARTIAL THROMBOPLASTIN TIME

Overview

The activated partial thromboplastin time (APTT) measures the integrity of the intrinsic (factors VIII, IX, XI and XII) and common (factors II, V, X, and I fibrinogen pathway. A prolonged APTT may be caused by congenital or acquired coagulation factor deficiencies, anticoagulant effect such as heparin anticoagulation therapy, and inhibition due to lupus anticoagulants as well as other nonspecific coagulation inhibitors. Shortening of the APTT usually reflects either elevation of factor VIII activity secondary to acute or chronic illness or inflammation, or spurious results from suboptimal venipuncture, specimen collection or processing.