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Test Code LAB0213140 von Willebrand Factor Antigen, Plasma

Additional Codes

Mayo Test ID
VWAG

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Diagnosis of von Willebrand disease (VWD) and differentiation of VWD subtype (in conjunction with von Willebrand factor ristocetin cofactor activity and factor VIII coagulant activity)

 

Differentiation of VWD from hemophilia A (in conjunction with factor VIII coagulant assay)

 

Monitoring therapeutic efficacy of treatment with DDAVP (desmopressin) or von Willebrand factor concentrates in patients with VWD

Method Name

Latex Immunoassay (LIA)

Reporting Name

von Willebrand Factor Ag, P

Specimen Type

Plasma Na Cit


Ordering Guidance


For optimum clinical utility and diagnostic efficiency, this test's results generally must be used together with the results of the von Willebrand factor ristocetin cofactor activity and factor VIII coagulant activity tests. The diagnosis of von Willebrand disease requires a combination of clinical and laboratory information. For a streamlined approach to testing, a panel of tests with reflexive testing and interpretive reporting is recommended. See AVWPR / von Willebrand Disease Profile, Plasma.



Additional Testing Requirements


VWACT / von Willebrand Factor Activity, Plasma and F8A / Coagulation Factor VIII Activity Assay, Plasma are recommended in conjunction with this test (von Willebrand antigen).



Specimen Required


Specimen Type: Platelet-poor plasma

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

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing.

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

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

4. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, less than or equal to -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.


CentraCare Laboratory Services Note:

Freeze plasma within 2 hours of collection and submit frozen.

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

55-200%

Note: Individuals of blood group "O" may have lower plasma von Willebrand factor (VWF) antigen than those of other ABO blood groups, such that apparently normal individuals of blood group "O" may have plasma VWF antigen as low as 40% to 50%, whereas the lower limit of the reference range for individuals of other blood groups may be 60% to 70%.

Children: Neonates, infants, and children have normal or mildly increased plasma VWF antigen, with respect to the adult reference range.

Interpretation

Patients with congenital severe type III von Willebrand disease (VWD) have a markedly decreased or undetectable level of von Willebrand factor (VWF) antigen in the plasma (and in the platelets), in addition to a plasma ristocetin cofactor activity that is either very low or not detectable.

 

Patients with types IIA and IIB variants of VWF (with abnormal plasma VWF function and multimeric structure) may have normal or decreased plasma VWF antigen. However, they typically have decreased plasma ristocetin cofactor activity, along with decreased higher molecular-weight VWF multimers in the plasma.

 

Patients with types IIM or IIN VWD have normal levels of VWF antigen. In spite of this, they either have decreased vWF ristocetin cofactor activity, not caused by absence of higher molecular weight vWF multimers (type IIM VWD), or decreased factor VIII coagulant activity (type IIN VWD)

 

Patients with type I VWD (with decreased but normally functioning plasma VWF) have concordantly decreased plasma VWF antigen and ristocetin cofactor activity.

 

Patients with acquired VWD may have either normal or decreased plasma VWF antigen.

Day(s) Performed

Monday through Saturday

Report Available

1 to 3 days

Specimen Retention Time

7 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

85246

LOINC Code Information

Test ID Test Order Name Order LOINC Value
VWAG von Willebrand Factor Ag, P 27816-8

 

Result ID Test Result Name Result LOINC Value
VWAG von Willebrand Factor Ag, P 27816-8

Forms

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