Q: Is ACT (Activated Coagulation Time) and PTT (Partial Thromboplastin Time) are interchangeable during Heparin infusion? - Yes or No


Answer: No 

 During Heparin infusion, ACT and PTT monitoring are not interchangeable. They have very poor correlation. ACT and PTT results should be followed independently. It is better to determine patient's heparin anticoagulant requirement, stabilize him/her, and follow one monitoring tool.

The ACT is measured in seconds - the longer the time blood takes to clot, the higher the degree of clotting inhibition.

PTT has more complex way to perform - The blood is spun in a centrifuge, which separates plasma from the cells. Calcium and activating substances are added to the plasma to start the intrinsic pathway of the coagulation cascade. PTT is the time it takes for a clot to form, measured in seconds.