Coagulation laboratory tests
Factor VIII assay

Author: Jeremy Parsons, M.D. (see Authors page)

Revised: 12 May 2016, last major update June 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Factor VIII assay [title]

Cite this page: Factor VIII assay. website. Accessed December 13th, 2018.
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