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Test Code Billings Clinic: 9561 Mayo: F8A Coagulation Factor VIII Activity Assay, Plasma

Reporting Name

Coag Factor VIII Activity Assay, P

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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).

Method Name

Optical Clot-Based


Ordering Guidance


Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, consider ordering a Coagulation Consultation.



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.

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, at or below -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 Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

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.

Interpretation

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.

Day(s) Performed

Monday through Saturday

Report Available

1 to 3 days

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

85240

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

Forms

If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.

Testing Algorithm

For information see Hemophilia Testing Algorithm.