Cite this page: Parsons J. Factor VIII assay. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/coagulationfactorVIII.html. Accessed June 7th, 2020.
Definition / general
- Assay is usually a PTT - based clotting assay that measures factor VIII activity
- Use severely deficient factor VIII plasma as substrate for one stage clotting assay, although there is tremendous interlaboratory variability
- Can also use chromogenic assay, particularly when assessing B - chain deleted recombinant Factor VIII (i.e. “Refacto”)
- Low levels:
- Hemophilia, vWF disease with decreased vWF antigen levels, delay in transporting specimen to lab
- Note:
- Levels are not greatly decreased at birth or throughout childhood
- Levels may increase during pregnancy
