Read LabGuide 32 and be able to:

1. Define prothrombin time and what the test demonstrates.
2. Describe thromboplastin, how it’s derived, and how different types affect the ability to monitor patients on anticoagulant therapy.
3. Explain why the introduction of international thromboplastin standards was necessary, and define the INR and how a patient INR value is determined.
4. Describe the prothrombin test procedure, quality control procedures needed to monitor the protime testing process, and limitations of the test.