Factor
I assay - 1
Specimen requirements:
Fresh whole blood collected in
sodium citrate at a 9:1 ratio of blood to anticoagulant
Principle:
Ca++ is bound by sodium citrate keeping blood from
clotting
Specimen centrifuged and plasma used
in testing
Plasma is mixed with reagent
containing:
Thrombin
Tested within 2 hours or stored at
-20oC for 2 – 5 days
A standard curve is established
using known concentrations
of fibrinogen and used to convert patient clot time (sec.) to concentration of
fibrinogen (mg/dL).
Time starts with addition of
thrombin and ends with formation of clot.