Factor
XIII assay - 2
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:
Ca++
Tested within 2 hours or stored at
-20oC for 2 – 5 days
After plasma clots it is added to a
tube containing:
5M urea
A control using normal patient
plasma is also set up.
Time starts with addition of clot in
5M urea and ends with clot being dissolved or >24 hours.