Unit Code 9070:
Coagulation Factor VIII Activity Assay, Plasma
Useful For 
Suggests clinical disorders or settings where the test may be helpful
Diagnosing hemophilia A
Diagnosing vWD when measured with the vWF antigen and
ristocetin cofactor activity
Diagnosing acquired deficiency states
Investigation of prolonged activated partial thromboplastin time (APTT)
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Activated Partial Thromboplastin Clot-Based Assay
Not offered for detection of hemophilia carrier.
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."
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Coag Factor VIII Activity Assay, P
Ordering Mnemonic An alternate Mayo code (to the Unit Code) for a test
F8A
Aliases Lists additional common names for a test, as an aid in searching
Coagulation Factor VIII Activity Assay, Plasma
Factor VIII - Off hours order 399
Factor VIII Activity Assay
Hemophilia A
Soft-F8A
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
See "Coagulation Studies" in Special Instructions.
Container/Tube: Light blue-top (citrate) tube(s)-Glass vial is not acceptable.
Specimen Volume: 1 mL of platelet-poor plasma
Collection Instructions:
1. Spin down, remove plasma, spin plasma again, and place specimen in plastic vial.
Note: Double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Freeze specimen immediately at < or =-40 degrees C, if possible.
Note: Each coagulation assay requested should have its own vial.
3. If priority specimen, mark requisition, give reason, and request a call-back.
Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
0.5 mL
The amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Transport Temperature Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) and unacceptable transport temperature(s) are also included. The preferred transport temperature is listed first, followed by the alternate acceptable temperature (if appropriate) and lastly, the unacceptable transport temperature(s).
Frozen\Refrig NO\Ambient NO
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Specimens other than | Plasma |
| Anticoagulants other than | Sodium citrate |
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icteric | NA |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Factor VIII is synthesized in the liver, and perhaps in other tissues.
It is a coagulation cofactor which circulates bound to von Willebrand
factor (vWF) and is part of the intrinsic coagulation pathway. The
biological half-life is 9-18 hours (average is 12 hours).
Congenital Factor VIII decrease is 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's disease (vWD).
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).
Factor VIII is highly susceptible to proteolytic inactivation,
with the potential for spuriously decreased assay results.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Adults: 55-205%
Normal, full-term newborn infants or healthy premature infants usually have normal or elevated factor VIII.*
*See "Pediatric Hemostasis References" in "Coagulation Studies" in Special Instructions.
Interpretation Provides information to assist in interpretation of the test results
See "Cautionsâ€
Mild hemophilia A: 5-50%
Moderate hemophilia A: 1-5%
Severe hemophilia A: <1%
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 vWD),
inhibitors of Factor VIII (autoantibodies, post-partum conditions,
etc.), and intravascular coagulation and fibrinolysis.
May be decreased with vWF in vWD.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
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. A
normal plasma specimen (processed in same fashion as for patient)
must accompany patient specimen. Normal results can be regarded
as reliable, but decreased result needs to be correlated with
other clinical and laboratory information. Repeat testing may be
necessary.
Factor VIII activity in frozen-thawed plasma specimens may be
10-20% lower than if assayed in fresh specimens, even under
optimum conditions of processing and transportation, or maybe
even lower if these conditions are suboptimal.
Factor VIII rises in response to a number of factors- pregnancy,
estrogen therapy, stress, disease, etc.
Not useful for inferring carrier status in suspected female
carriers of hemophilia A, unless it is below 50% of normal.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
See "Specific Coagulation Factor Assay References" in Coagulation
Studies in Special Instructions.
Method Description Describes how the test is performed and provides a method-specific reference
Factor VIII is assayed using a factor-deficient substrate in the
APTT test. (Owen CA Jr, Bowie EJW, Thompson JH Jr: Diagnosis
of Bleeding Disorders. 2nd Edition. Boston, MA, Little, Brown
and Company, 1975)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; Varies a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
1 day
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
3 days
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
7 days
Performing Laboratory Location The location of the laboratory that performs the test
List Fee Provides the Mayo Medical Laboratories list fee for performing the test
$230.20
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared or approved by the U.S. Food and Drug Administration.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each unit code or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
85240
External
link
PDF
document
Excel
document
Word
document