Factor XI (FXI) is a protein synthesized by the liver. It participates in the contact phase which initiates the intrinsic pathway of coagulation.
It is activated by FXIIa to factor FXIa which will itself activate FIX in the presence of calcium ions.
The activity is determined from a calibration with the 1st international standard for human FXIa a NIBSC 13/100 used in the ROX Factor XIa kit.
The ROX FACTOR XIa is a quantitative enzymatic and chromogenic assay kit for the determination of FXI activity in concentrates of human FXI.
The amount of FXa generated is determined by hydrolysis of a chromogenic substrate for FXa.
The quantity of para-nitroaniline released during this hydrolysis and measured at 405 nm and is proportional to the concentration of FIXa in the reaction medium.
- 10 vials x 4 mL lyophilized plasma