Test Description: Prothrombin Time (PT) / International Normalized Ratio (INR)

The Prothrombin Time (PT) test measures the time it takes for blood to clot. It evaluates the function of several clotting factors produced by the liver. The International Normalized Ratio (INR) is a standardized value derived from the PT, used to monitor patients on anticoagulant therapy (such as warfarin) and ensure their blood is not clotting too quickly or too slowly. Abnormal PT/INR values can indicate bleeding disorders, liver disease, or vitamin K deficiency. This test is also used to assess the effectiveness of blood-thinning medications and guide dosage adjustments.