Marker of deficiency of factors of the internal pathway of hemostasis

The activated partial thromboplastin time (APTT) is one of the most valuable screening tests, sensitive to the deficiency of all coagulation factors (except factor VII), as well as to the presence of heparin, specific antibodies (to factors VIII and IX) and nonspecific coagulation inhibitors (for example, in systemic lupus erythematosus). The main function of the APTT is to screen for disorders of the intrinsic coagulation pathway. It is important to note that the prolongation of the APTT occurs with a 30-40% decrease in the level of any of the coagulation factors.