What is the Fibrinogen Activity test?

The fibrinogen activity test is also known as a Factor I assay. It’s used to determine the level of fibrinogen in your blood.

Fibrinogen, or factor I, is a blood plasma protein that’s made in the liver. Fibrinogen is one of 13 coagulation factors responsible for normal blood clotting.

When you start to bleed, your body initiates a process called the coagulation cascade, or clotting cascade. This process causes coagulation factors to combine and produce a clot that will stop the bleeding. If you don’t have enough fibrinogen or if the cascade isn’t working normally, clots will have difficulty forming. This can cause excessive bleeding.


  • A fibrinogen value of less than 50 mg/dL may mean you’re in danger of bleeding after surgery.
  • A fibrinogen value of more than 700 mg/dl may mean you’re in danger of forming clots that could harm your heart or brain.

For more information on what your result means, please visit:

Leave a Reply


You are commenting using your account. Log Out /  Change )

Google photo


Twitter picture


Facebook photo


Connecting to %s


%d bloggers like this: