Patients with factor-specific coagulation inhibitors will have prolonged prothrombin time (PT) and/or aPTT test results, depending on the coagulation factor targeted by the inhibitor. Clinically, this is associated with abnormal clotting and bleeding complications.
With lupus anticoagulants, a prolonged aPTT, and sometimes PT, is seen. 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. Because of this, the aPTT is not corrected in mixing studies of patients with lupus anticoagulants. Clinically, lupus anticoagulants are associated with thrombosis and not with bleeding symptoms.
