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Epic Test Code LAB306 Coagulation Factor VIII Activity Assay, Plasma

Additional Codes

MML Code: F8A

 

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Coag Factor VIII Activity Assay, P

Method Name

Optical Clot-Based

Specimen Stability Information

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


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.


Bassett Healthcare Network Clinical Laboratories Note:

Blood Tube Draw Volume
Min 90% draw volume  

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

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.

Report Available

1 to 3 days

Day(s) Performed

Monday through Saturday

CPT Code Information

85240

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

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).

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.

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.

Cautions

Factor VIII is a labile protein. Improper handling of a specimen may give a false result.

 

Factor VIII is highly susceptible to proteolytic inactivation, with the potential for spuriously decreased assay results. Normal results can be regarded as reliable, but decreased results need to be correlated with other clinical and laboratory information. Repeat testing may be necessary.

 

Factor VIII activity in frozen-thawed plasma specimens may be 10% to 20% lower than if assayed in fresh specimens, even under optimum conditions of processing and transportation, and may be even lower if these conditions are suboptimal.

 

Factor VIII activity rises in response to a number of factors, including pregnancy, estrogen therapy, stress, disease, etc.

 

Once artefactual reduction of factor VIII is excluded, it is important to measure von Willebrand factor levels to ensure that the patient does not have von Willebrand disease.

Specimen Retention Time

7 days

Testing Algorithm

For information see Hemophilia Testing Algorithm.

Forms

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

Disease States

  • Hemophilia A