Factor VIII chromogenic activity

Alphabetical Test listing

Factor VIII chromogenic activity-994

Factor VIII chromogenic activity
Antihemophilic Factor
Factor 8 chromogenic activity
  • Used in the diagnosis of nonsevere hemophilia A.6, 7, 13
  • Useful in the accurate determination of factor VIII (FVIII) activity in the presence of a lupus anticoagulant or when certain modified recombinant FVIII replacement products are present.
  • This assay can also be used in place of the one-stage (standard) FVIII activity assay for any indication.
  • Ideally the patient should not be on anticoagulant therapy
  • Avoid heparin and direct Xa inhibitor therapies for about three days prior to testing
Sodium citrate (Na cit) plasma
1.0 mL
0.5 mL
  • Do not draw from an arm with a heparin lock or heparinized catheter.
  • If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.
  • Immediatley following collection, mix sample thoroughly by gentle inverting 8 - 10 times, to prevent clotting
  1. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells.
  2. Deliver to a plastic transport tube, cap, and recentifuge for 10 minutes.
  3. Use a second plastic pipette to remove plasma, staying clear of the platelets at the bottom of the tube.
  4. Transfer the plasma into a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
  5. Freeze immediately

Frozen (preferred) - 2 weeks

Freeze/thaw cycles: Stable x2

Ambient - 4 hours

Refrigerated - 4 hours

  • Severe hemolysis
  • Improper labeling
  • Clotted specimen
  • Specimen diluted with IV fluids
  • Samples thawed in transit
  • Improper sample type
  • Sample out of stability
LabCorp Burlington (500192): R-NX
3 - 5 days

Factor VIII activity is determined by a two-stage chromogenic substrate assay where the amount of activated factor X generated is proportional to the amount of functional FVIII present in the test plasma in the presence of excess activated FIX. The amount of activated factor X generated is read with a chromogenic substrate and the activity is determined from a standard curve.


50 - 170%