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Order Code VWD8B von Willebrand Disease 2N (Subtype Normandy), Plasma

Test Down Notes

This test is temporarily unavailable. For additional details, see test update here.


Additional Testing Requirements


VWAG / von Willebrand Factor Antigen, Plasma; VWACT / von Willebrand Factor Activity, Plasma; and F8A / Coagulation Factor VIII Activity Assay, Plasma are recommended to supplement results of this test.



Necessary Information


If performed at another laboratory, forward the results of the following tests with the specimen:

-von Willebrand factor antigen

-VWF activity (ristocetin cofactor, latex immunoassay etc)

-Factor VIII activity

 

These results aid in the interpretation of this test.



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 vial, and centrifuge plasma again.

3. Aliquot plasma into a separate tube leaving 0.25 mL in the bottom of the 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.


Forms

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

Useful For

Diagnosing von Willebrand disease (VWD) type 2N

 

Evaluating patients diagnosed with mild-to-moderate hemophilia A with an autosomal inheritance pattern

 

Evaluating hemophilia A patients with a shortened survival of infused factor VIII (FVIII) (not caused by a specific FVIII inhibitor)

 

Evaluating female patients with low FVIII activity and no prior family history of hemophilia A

 

Evaluating patients with Type 1 or Types 2A, 2B, or 2M VWD with FVIII activity discordantly lower than the von Willebrand factor antigen level

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Reporting Name

VWD 2N (Normandy), P

Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Cit Frozen 56 days

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Reference Values

68-106%

Pediatric reference ranges have not been established for this assay but likely achieve adult reference range by 18 years of age.

Method Description

The von Willebrand factor (VWF):factor VIII (FVIII) B assay utilizes enzyme linked immunosorbent assay technology. A diluted plasma sample adjusted to 10 IU dL of VWF:antigen is incubated with a rabbit antihuman VWF F(ab')2, which is coated on the internal walls of the microplate wells. The factor VIII of the tested plasma dissociated during the incubation is washed away. Recombinant FVIII (FVIIIr) is then added, which binds to VWF. Next, mouse monoclonal antihuman FVIII antibody coupled with peroxidase binds to the remaining free antigenic determinants of the bound FVIIIr. Bound FVIIIr is quantified using a peroxidase-conjugated mouse antihuman FVIII monoclonal antibody. The intensity of the color is directly proportional with the concentration of VWF:FVIIIB initially present in the plasma sample.(Package insert: Asserachrom VWF:FVIIIB. Diagnostica Stago; 03/2014)

Day(s) Performed

Monthly on the third Thursday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

85246