What Is The Difference Between A PT And APTT Blood Test?

What Is The Difference Between A PT And APTT Blood Test? Partial thromboplastin time (PTT) and activated partial thromboplastin time (aPTT) are used to test for the same functions; however, in aPTT, an activator is added that speeds up the clotting time and results in a narrower reference range. What is the difference between PT