Harr – Hemostasis questions with correct answers

Which characteristic describes antithrombin (AT)? A. It is synthesized in megakaryocytes B. It is activated by protein C C. It is a cofactor of heparin D. It is a pathological inhibitor of coagulation Answer C. It is a cofactor of heparin C Antithrombin is heparin cofactor and it is the most important naturally occurring physiological inhibitor of blood coagulation. It represents about 75% of antithrombotic activity and is an α2-globulin made by the liver. Which laboratory test is affected by heparin therapy? A. Thrombin time B. Fibrinogen assay C. Protein C assay D. Protein S assay Answer A. Thrombin time A Heparin is an antithrombin drug, and therefore increases the thrombin time test along with the APTT and PT. Heparin therapy has no effect on fibrinogen, protein C, or protein S assays. APTT is the test of choice for monitoring heparin therapy An abnormal APTT caused by a pathological circulating anticoagulant is: