INTRODUCTION AND SCOPE

Blood coagulation is one of the steps of hemostasis necessary to stop bleeding. The coagulation cascade proceeds through the activation of several coagulation factors in the blood which include factor VIII (FVIII) and factor IX (FIX). There are two predominant methodologies used to assess the potency of FVIII and FIX concentrates intended for the treatment of hemophilia A and B: the one-stage (OS) clotting method and the chromogenic substrate (CS) method. Both methodologies require the use of a reference or potency standard to enable the calculation of relative potency. Guidance and recommendations on the selection of which method and reference standard to use depend on several factors, including local laboratory practices and regulatory considerations.