Postgraduate medicine
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Five studies are important to the diagnosis of bleeding disorders: bleeding time (BT) (Simplate), platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). If the platelet count alone is low, the cause is usually peripheral destruction of platelets, immunothrombocytopenia, or an abnormality of bone marrow production. ⋯ An abnormal PT, with or without an abnormal aPTT but with normal results in the other three tests, indicates an abnormal reduction in the vitamin K-dependent clotting factors (II, VII, IX, X) or factor V. When the TT is abnormal, disseminated intravascular coagulation, the presence of plasma heparin, or a hepatopathy should be suspected.