von Willebrand Factor (vWF) Antigen (Antigenic Factor VIII)

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Category:

Turnaround Time: 1 - 3 days
CPT Code:

85246

Test Type: 1 mL Plasma, frozen
Reference Range:

50% to 150%. Average vWF levels (both antigen and activity) tend to vary by blood type.6 One study found the mean vWF levels by blood type to be as follows:7

• Type O: 74.8%

• Type A: 105.6%

• Type B: 116.9%

• Type AB: 123.3%

Overview:

Diagnose von Willebrand factor (vWF) deficiency.6,8-10

A number of transient clinical conditions can raise the vWF levels of individuals with congenital deficiency into the normal range.8 vWF is an acute phase reactant and levels can increase due to stress, inflammation, acute infection, physical exercise, and following surgery.8 Levels can also increase with estrogen administration for contraception or hormone replacement.8 vWF levels are increased two- to threefold in the second and third trimesters of pregnancy.10 Individuals with type O blood tend to have approximately 30% lower vWF levels than those with other blood types.10

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

1. Adcock DM, Kressin DC, Marlar RA. Effect of 3.2% vs 3.8% sodium citrate concentration on routine coagulation testing. Am J Clin Pathol. 1997; 107(1):105-110. PubMed 8980376

2. Reneke J, Etzell J, Leslie S, et al. Prolonged prothrombin time and activated partial thromboplastin time due to underfilled specimen tubes with 109 mmol/L (3.2%) citrate anticoagulant. Am J Clin Pathol. 1998; 109(6):754-757. PubMed 9620035

3. National Committee for Clinical Laboratory Standardization. Collection, Transport, and Processing of Blood Specimens for Coagulation Testing and General Performance of Coagulation Assays; Approved Guideline. 5th ed. Villanova, Pa:NCCLS; 2008. Document H21-A5:28(5).

4. Gottfried EL, Adachi MM. Prothrombin time and activated partial thromboplastin time can be performed on the first tube. Am J Clin Pathol. 1997; 107(6):681-683. PubMed 9169665

5. McGlasson DL, More L, Best HA, et al. Drawing specimens for coagulation testing: Is a second tube necessary? Clin Lab Sci. 1999; 12(3):137-139. PubMed 10539100

6. Van Cott EM, Laposata M. Coagulation. In Jacobs DS, DeMott WR, Oxley DK eds. Laboratory Test Handbook With Key Word Index. Hudson, Ohio: Lexi-Comp; 2001: 327-358.

7. Gill JC, Endres-Brooks J, Bauer PJ, et al. The effect of ABO blood group on the diagnosis of von Willebrand disease. Blood. 1987; 69(6):1691-1695. PubMed 3495304

8. Adcock DM, Bethel MA, Macy PA. Coagulation Handbook. Aurora, Colo: Esoterix−Colorado Coagulation; 2006.

9. Brandt JT. Laboratory Evaluation of Platelet Disorders. In McClatchey KD, ed. Clinical Laboratory Medicine. 2nd ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2002:1010-1032.

10. Rick ME. von Willebrand Disease. In Kitchens CS, Alving BM, Kessler CM, eds. Consultative Hemostasis and Thrombosis. Philadelphia, Pa: WB Saunders Co; 2002: 91-102.

11. Liu MC, Kessler CM. A systemic approach to the bleeding patient. In Kitchens CS, Alving BM, Kessler CM eds. Consultative Hemostasis and Thrombosis. Philadelphia, Pa: WB Saunders Co; 2002:181-196.

Nichols WL, Hultin MB, James AH, et al. von Willebrand disease (VWD): Evidence-based diagnosis and management guideline, the National Heart, Lung, and Blood Institute (NHLB) Expert Panel report (USA). Haemophilia. 2008 Mar; 14(2):171-232. PubMed 18315614

Tefferi A, Nichols WL. Acquired von Willebrand disease: Concise review of occurrence, diagnosis, pathogenesis, and treatment. Am J Med. 1997 Dec; 103(6):536-540. PubMed 9428838

Collection Details:

Patient Preparation:

Avoid warfarin (Coumadin®) therapy for two weeks and heparin therapy for two days prior to the test. Do not draw from an arm with a heparin lock or heparinized catheter.

Collection Instructions:

If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.

Blue-top (sodium citrate) tube.

Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.1 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.2,3 The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system. With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.4,5 When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes. Any tube containing an alternative anticoagulant should be collected after the blue-top tube. Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.

Freeze.