What can prolonged PT and aPTT indicate?

Prolonged PT (Prothrombin Time) and aPTT (Activated Partial Thromboplastin Time) are laboratory tests that measure different pathways of the coagulation cascade. When both of these tests are prolonged, it typically indicates the presence of coagulation factor deficiencies. These deficiencies can be due to a range of factors, including inherited clotting disorders, liver disease, or the use of anticoagulants.

PT primarily assesses the extrinsic pathway of clotting, which involves factors I, II, V, VII, and X, while aPTT assesses the intrinsic and common pathways, involving factors I, II, V, VIII, IX, X, XI, and XII. If these times are prolonged, it suggests that either one or more of the coagulation factors are deficient or dysfunctional, leading to an impaired ability to form clots effectively. Therefore, this prolonged testing outcome serves as an important indicator for clinicians to investigate further and diagnose potential underlying bleeding disorders or assess the impact of anticoagulation therapy.