Inaccurate therapeutic decisions in patient with lupus anticoagulant as a result of falsely elevated prothrombin time

Abstract

71 year old patient was admitted to the hospital with a suspicion of infective endocarditis. Laboratory investigations using human recombined tromboplastin Innovin showed a considerably prolonged prothrombin time (INR above 4) and APTT. Due this vitamin K was administered (iv). During further investigations using Innovin significantly prolonged prothrombin time persisted, but using thromboplastin Technoplastin HIS was in reference range. Deficiency of vitamin K dependent coagulation factors (VII, X, II), factor V and fibrinogen were not found. Therefore a comparative test using Innovin and three other thromboplastins (Technoplastin HIS Tromborel S, RecombiPlasTin 2G) were performed. These gave prothrombin time in reference range. Prolonged aPTT resulted from presence of lupus anticoagulant. Thrombotic prophylaxis with low molecular weight heparin was applied (2 weeks after admission to the hospital). However, two days later, edema of upper limb has appeared due to cephalic vein thrombosis. There was no central catheter placed in any of central veins. The falsely elevated prothrombin time caused inaccurate therapeutic decisions such as iv supply of vitamin K, and delate antithrombotic treatment of patient with the increased risk of thrombosis (immobilization, inflammations and presence of the lupus anticoagulant). These decision surely contributed to the cephalic vein thrombosis. Our results demonstrated that protothrombin time/INR determined with thromboplastin Innovin can be prolonged also in patients with lupus anticoagulant not submitted to anticoagulation treatment. Therefore, in patients with LA before therapeutic decision, the verification of elevated prothrombin time using other than Innovin thromboplastins is necessary.