Activated protein C resistance test

A method of determining functional activity of protein C in a human plasma sample, said method comprising the steps of:

• a) incubating the human plasma sample with an exogenous reagent, activated exogenous protein C and components necessary for clotting of the human plasma sample, wherein said exogenous reagent either activates factor V and the common pathway of the blood coagulation mechanism through factor X by directly activating said factor X and said exogenous reagent is derived from Vipera russelli snake venom;
• or said exogenous reagent induces the presence of thrombin in a factor-V-dependent manner and is derived from Vipera russelli snake venom;
• b) monitoring a reaction indicative of the rate of coagulation of the human plasma sample;
• c) comparing the rate of coagulation determined in step b) with an equivalent rate of coagulation for a normal subject, or comparing the rate of coagulation determined in step b) with an equivalent rate of coagulation determined for the human plasma sample in the absence of the activated exogenous protein C;
• and
• d) determining the functional activity of the free protein C from the comparing of step c).