PTT Activated

The aPTT is sensitive to deficiency or inhibition of factors in the intrinsic pathway. These include the contact factors; high molecular weight kininogen (HMWK), prekallikrein, and factor XII along with procoagulant factors XI, IX, VIII. The aPTT is less sensitive to deficiencies of X, V, prothrombin, and fibrinogen.¹ Nonspecific, lupus-type anticoagulants can also extend the aPTT, but the more sensitive aPTT-LA test should be used to screen for this condition.