Factor VIII Chromogenic Activity

Also known as: Antihemophilic Factor (AHF)

Clinical Use

Use

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.

Special Instructions

Not provided.

Limitations

Factor VIII is an acute phase reactant and can be elevated in various clinical conditions, affecting test accuracy in diagnosing hemophilia. Factor VIII levels should not be used to determine carrier status of females; genetic testing is advised. Inhibitors and lupus anticoagulant may affect results, and chromogenic factor VIII activity is recommended. Direct Xa inhibitor therapy may cause factitiously low results.

Test Details

Methodology

Other

Biomarkers

Factor VIII

Protein

Chromogenic Activity

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

49865-9 - Fact VIII Act/Nor PPP Chro

Result Codes

49865-9 - Fact VIII Act/Nor PPP Chro

Result Turnaround Time

3-5 days

Specimen

Plasma

Volume

1 mL

Minimum Volume

0.5 mL

Container

Blue-top (sodium citrate) tube

Collection Instructions

Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Fill evacuated collection tubes to completion. Mix immediately by gentle inversion at least six times.

Patient Preparation

Ideally the patient should not be on anticoagulant therapy. Avoid heparin and direct Xa inhibitor therapies for about three days prior to testing. Do not draw from an arm with a heparin lock or heparinized catheter.

Storage Instructions

Freeze

Causes for Rejection

Severe hemolysis; improper labeling; clotted specimen; specimen diluted with IV fluids; samples thawed in transit; improper sample type; sample out of stability.