• Prothrombin consumption time (PCT). Detects deficiencies in blood platelets and other factors necessary for coagulation. This test measures the time it takes for a patient to generate thromboplastin.

  • Activated whole blood clotting time. This test measures how long it takes for a blood clot to form in a sample of freshly drawn, whole blood after an activating agent is used. It has largely replaced the activated partial thromboplastin time test (see below) in the monitoring of heparin therapy.

  • Activated partial thromboplastin time (APTT). Measures the time it takes for a sample of blood to clot. It is known as the “partial thromboplastin” test because of the absence of certain factors along the coagulation cascade. The test is commonly used to monitor the progress of patients who are taking certain anticoagulants, including heparin, which cannot be measured by the INR/PT test.

  • Thrombin time. This test measures the conversion of fibrinogen to fibrin, which is the final step in the clotting cascade. This test may be elevated if the patient has been given anticoagulant medications or if certain diseases (e.g., multiple myeloma) are present.

  • Coagulation factors screening tests. Used to identify both congenital (present since birth) and acquired deficiencies in clotting factors. Some of these factors may be altered in female patients taking oral contraceptives.

  • Fibrinogen test. Used to diagnose blood disorders in which there is either too much or too little fibrinogen – a key factor in blood clotting.

  • Bleeding time. A test in which three small scratches are made on the patient’s skin and then the time it takes for the bleeding to stop is recorded. It is used to assess the integrity of platelet function.