Screening tests used in detection of clotting disorders.

Clinical Significance

A prothrombin time (PT) test measures how long it takes for a clot to form in blood sample. An INR international normalized ratio is a type of calculation based on the PT test result.

PT/INR: Screening test for abnormalities of coagulation factors that are involved in the extrinsic pathway. Also used to monitor effects of Warfarin therapy and to study patients with hereditary and acquired clotting disorders.

aPTT: the aPTT is a screening test that will detect deficiencies or inhibitors to the intrinsic (Factors VIII, IX, XI and XII) and common (Factor II, V, X and Fibrinogen) pathway coagulation factors.