Sign in →

Test ID: F8A Coagulation Factor VIII Activity Assay, Plasma

Reporting Name

Coag Factor VIII Activity Assay, P

Useful For

Diagnosing hemophilia A


Diagnosing von Willebrand disease when measured with the von Willebrand factor (VWF) antigen and VWF activity


Diagnosing acquired deficiency states


Investigation of prolonged activated partial thromboplastin time


Monitoring infusions of factor VIII replacement during interventional procedures and prophylactic infusions


This test is not useful for inferring carrier status in suspected female carriers of hemophilia A, unless it is 50% of normal (<28% activity in adults).

Specimen Type

Plasma Na Cit

Ordering Guidance

Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason we suggest ordering Coagulation Consultations.

Necessary Information

If priority specimen, mark request form, give reason, and request a call-back.

Specimen Required

Specimen Type: Platelet-poor plasma

Patient Preparation: Patient must not be receiving Coumadin (warfarin) or heparin therapy.

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Specimen must be collected prior to factor replacement therapy.

2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again.

4. Aliquot plasma into a plastic vial leaving 0.25 mL in the bottom of centrifuged vial.

5. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, ≤-40° C.

Additional Information:

1. Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.

2. Each coagulation assay requested should have its own vial.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reference Values

Adults: 55-200%

Normal, full-term newborn infants or healthy premature infants typically have levels greater than or equal to 40%.*

*See Pediatric Hemostasis References in Coagulation Guidelines for Specimen Handling and Processing  in Special Instructions.

Day(s) Performed

Monday through Saturday

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
F8A Coag Factor VIII Activity Assay, P 3209-4


Result ID Test Result Name Result LOINC Value
F8A Coag Factor VIII Activity Assay, P 3209-4

Clinical Information

Factor VIII is synthesized in the liver and, perhaps, in other tissues. It is a coagulation cofactor that circulates bound to von Willebrand factor and is part of the intrinsic coagulation pathway. The biological half-life is 9 to 18 hours (average is 12 hours).


Congenital factor VIII deficiency is the cause of hemophilia A, which has an incidence of 1 in 10,000 and is inherited in a recessive sex-linked manner on the X chromosome. Severe deficiency (<1%) characteristically demonstrates as hemarthrosis, deep-tissue bleeding, excessive bleeding with trauma, and ecchymoses.


Factor VIII may be decreased in von Willebrand disease. Acquired deficiency states also occur.


Antibodies specific for factor VIII are the most commonly occurring specific inhibitors of coagulation factors and can produce serious bleeding disorders (acquired hemophilia).


Spuriously decreased results may occur as factor VIII is highly susceptible to proteolytic inactivation.


Mild hemophilia A: 5% to 50% activity


Moderate hemophilia A: 1% to 5% activity


Severe hemophilia A: <1% activity


Congenital deficiency may also occur in combined association with factor V deficiency.


Liver disease usually causes an increase of factor VIII activity.


Acquired deficiencies of factor VIII have been associated with myeloproliferative or lymphoproliferative disorders (acquired von Willebrand disease: VWD), inhibitors of factor VIII (autoantibodies, postpartum conditions, etc), and intravascular coagulation and fibrinolysis.


Levels may be decreased with von Willebrand factor in VWD.

Clinical Reference

1. Spreafico M, Peyvandi F: Combined FV and FVIII deficiency. Haemophilia. 2008 Nov;14(6):1201-1208

2. Barrowcliffe TW, Raut S, Sands D, Hubbard AR: Coagulation and chromogenic assays of factor VIII activity: general aspects, standardization, and recommendations. Semin Thromb Hemost. 2002 Jun;28(3):247-256

3. Franchini M, Lippi G, Favaloro EJ: Acquired inhibitors of coagulation factors: part II. Semin Thromb Hemost. 2012 Jul;38(5):447-453

4. Carcao MD: The diagnosis and management of congenital hemophilia. Semin Thromb Hemost. 2012 Oct;38(7):727-734

Report Available

1 to 3 days

Testing Algorithm

See Hemophilia Testing Algorithm in Special Instructions.

Method Name

Optical Clot-Based

Mayo Clinic Laboratories | Hematology Catalog Additional Information: