Prothrombin time ( PT ) prolongation

The Prothrombin Time (PT), measured as part of the International Normalized Ratio (INR), is a crucial test used in medical diagnostics to evaluate the functionality of the blood's clotting ability, specifically through the extrinsic and common pathways of the coagulation cascade.

Here’s a breakdown of how the PT works and its significance:

1. Functionality of PT: The primary role of the PT test is to assess the clotting efficiency of the blood's extrinsic pathway (which is triggered by external trauma leading to blood escaping the vascular system) and the final common pathway. These pathways involve several clotting factors that play critical roles in blood coagulation.
   
   

2. Test Procedure: During a PT test, patient plasma is mixed with calcium and a substance called thromboplastin, an activator of the extrinsic pathway. Thromboplastin contains tissue factor, which is a protein necessary for the initiation of the clotting process.
   
   

3. Measurement and Results: The PT measures the time it takes for the blood to clot after these substances are added. This duration is recorded in seconds. A normal PT time indicates that the extrinsic and common pathways are functioning correctly, enabling blood to clot within an expected time frame.
   
   

4. Indications of Prolonged PT:...