Patients with factor-specific coagulation inhibitors will have a prolonged prothrombin time (PT) and/or aPTT test results (depending on the coagulation factor that is targeted by the inhibitor). Clinically, this is associated with abnormal clotting and bleeding complications.
A prolonged aPTT, and sometimes PT, is seen with lupus anticoagulant. The antibody combines with the phospholipids on the surfaces of test reagents used in the aPTT test, and sometimes in the PT test, prolonging the test result(s). Because of this, the aPTT is not corrected in mixing studies of patients with lupus anticoagulant. Clinically, lupus anticoagulant is associated with thrombosis and not with bleeding symptoms.
