Activated partial thromboplastin time (APTT) is a commonly used screening test for haemostatic defects in the intrinsic and common pathway of the coagulation cascade, as well as the contact activation system. Thus, FV, FVIII, FIX, FX, FXI, FXII, prekallikrein and high-molecular weight kininogen deficiencies can result in a prolonged APTT. Moreover, APTT is also suitable for monitoring heparin treatment.

The MRX APTT reagent utilises the near colloidal contact activator silica to activate the contact activation system. This ensures sensitivity to mild deficiencies of FVIII, FIX, and FXI. MRX APTT is sensitive to heparin, FVIII, FIX and FXI, while being insensitive to the potential interferent LA. Thus, MRX APTT is suitable for monitoring heparin treatment and for haemophilia screening. MRX APTT reagent contains the contact activator silica and phospholipids to ensure a highly consistent and stable product.