Coagulation laboratory tests

Factor VIII assay

Topic Completed: 1 June 2012

Minor changes: 17 September 2020

Copyright: 2002-2022,, Inc.

PubMed Search: Factor VIII assay [title]

Jeremy C. Parsons, M.D.
Page views in 2021: 97
Page views in 2022 to date: 3
Cite this page: Parsons JC. Factor VIII assay. website. Accessed January 17th, 2022.
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

Back to top
Image 01 Image 02