A prolonged aPTT result may indicate the following Congenital deficiencies of intrinsic system clotting factors such as factors VIII, IX, XI, and XII, including hemophilia A (Christmas disease) and hemophilia B (two inherited bleeding disorders resulting from a deficiency in factors VIII and IX, respectively) Congenital deficiency of Fitzgerald factor (prekallikrein) Von Willebrand disease, which is the most common inherited bleeding disorder, affecting platelet function owing to decreased von Willebrand factor activity Hypofibrinogenemia Liver cirrhosis (the liver makes most of the clotting factors, including those that are vitamin K-dependent ones); diseases of the liver may result in an inadequate quantity of clotting factors, prolonging the aPTT Vitamin K deficiency: The synthesis of some clotting factors requires vitamin K, so vitamin K deficiency results in an inadequate quantity of intrinsic system and common pathways clotting factors, as a result the aPTT is prolonged Disseminated intravascular coagulation (DIC): The clotting factors involved in the intrinsic pathway are consumed, prolonging the aPTT Heparin therapy, which inhibits the intrinsic pathway at several points (eg, prothrombin II), prolonging the aPTT Coumarin therapy, which inhibits the function of factors I, IX and X, prolonging the aPTT Nonspecific inhibitors, such as lupus anticoagulant and anticardiolipin antibodies, which bind to phospholipids on the surface of platelets Specific circulating anticoagulants, inhibitor antibodies that specifically target certain coagulation factor, such as in individuals with hemophilia after many plasma transfusions, systemic lupus erythematosus, rheumatoid arthritis, tuberculosis, and chronic glomerulonephritis...consult physician for proper evaluation and treatment