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

Reporting Name

VWD 2N (Normandy), P

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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)


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.


Specimen Type

Plasma Na Cit

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
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.

Interpretation

A reduced capacity of a patient's von Willebrand factor (VWF) to bind to recombinant factor VIII (FVIII) is consistent with von Willebrand disease (VWD) type 2N (Normandy).

 

A mild to moderate decrease of the VWF to factor VIII (FVIII) binding ratio suggests the presence of a VWD Type 2N due to heterozygous variants in the FVIII binding domain of VWF. If clinically indicated, DNA sequence analysis of the FVIII binding domain of VWF may provide useful information.

 

Results do not exclude other variants of congenital VWD, eg, type 1, 2A, 2B, or 2M or congenital hemophilia A. Clinical correlation should be made between patient and family bleeding history and results of VWF antigen, factor VIII and VWF activity assays.

Day(s) Performed

Monthly on the third Thursday

Report Available

1 to 31 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It 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
VWD8B VWD 2N (Normandy), P 90919-2

 

Result ID Test Result Name Result LOINC Value
607336 VWF:FVIIIB 90919-2
607337 VWF:FVIIIB Interpretation 48595-3

Forms

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