Dental OSCE (Objective Structured Clinical Examination) Practice Exam

Which test is used for monitoring Heparin therapy?

1. PTT (Partial Thromboplastin Time)

2. PT (Prothrombin Time)

3. INR (International Normalized Ratio)

4. All of the above

The correct answer is: PTT (Partial Thromboplastin Time)

The Partial Thromboplastin Time (PTT) is the most relevant test for monitoring Heparin therapy, particularly Unfractionated Heparin. This anticoagulant works by enhancing the activity of antithrombin III, which in turn inhibits thrombin and factor Xa, thereby affecting the intrinsic pathway of coagulation. PTT specifically assesses the integrity of this intrinsic pathway, which includes factors such as XII, XI, IX, VIII, X, V, prothrombin (factor II), and fibrinogen (factor I). In practice, when patients are on Heparin therapy, healthcare providers frequently monitor PTT levels to ensure that the coagulation parameters remain within the therapeutic range, thus minimizing the risk of clotting (if levels are too low) and bleeding (if levels are too high). Other coagulation tests like Prothrombin Time (PT) and International Normalized Ratio (INR) are more relevant for monitoring warfarin therapy, as they assess the extrinsic pathway and the common pathway of coagulation, which are not significantly affected by Heparin. Therefore, when specifically considering monitoring for Heparin therapy, PTT is the appropriate choice.