This assay is included in Von Willebrand Panel.

1 to 3 days

Batched 1 to 2 times per week. Call 503-494-7383 if STAT.

Less than 19%

One full 2.7 mL LIGHT BLUE top tube, 3.2% sodium citrate, OR two 1 mL frozen sodium citrate plasma aliquots. Separate and freeze plasma. Hemostasis & Thrombosis Lab sodium citrate specimens must be processed and frozen within 2 hours of specimen collection. Stability is 14 days at -70 C.

Draw volume is critical due to the liquid anticoagulant. Allow tubes to fill by vacuum.
• Tubes with rubber stopper: fill to line on label.
• Tubes with plastic (Hemogard) cap: the fill level is above the top of the label.
• Syringe: do not remove the vacutainer stopper. Insert the needle through the stopper and allow the tube to fill by vacuum. Do not overfill the vacutainer.
• Pediatric tubes have no vacuum. Remove the cap and add blood to the 1.3 mL mark. Do not overfill.

OHSU clinics must cab specimen to the H&T Lab, Dillehunt Hall, Room 3050 if processing is delayed or not possible on site. A phone call is helpful to alert the lab at 503-494-8445.

Detailed specimen collection and processing instructions are located under Lab Sections and then the Hemostasis and Thrombosis (Opens in a new window) section.

One full pediatric 1.3 mL LIGHT BLUE top tube, 3.2% sodium citrate, OR two 0.5 mL frozen sodium citrate plasma aliquots. Separate and freeze plasma. Hemostasis & Thrombosis Lab sodium citrate specimens must be processed and frozen within 2 hours of specimen collection. Stability is 14 days at -70 C.

For pediatric patients requiring multiple coagulation tests, please call 503-494-7383 regarding draw volumes.

40% to 130%
For children less than 6 months, see link to published reference ranges (Opens in a new window).

This test aids in diagnosis of von Willebrand disease.

Von Willebrand disease is characterized by easy bruising or prolonged bleeding from mucosal surfaces due to quantitative (Type I) or qualitative (Type II) vWF deficiency. Both quantitative and qualitative (functional) assays are required for the diagnosis and appropriate therapeutic intervention. Because many patients with vWD have mild disease, repeated testing may be necessary to diagnose this disorder. Normal values do not exclude vWD. Female patients with vWD on oral contraceptives or who are pregnant may have normal values. Von Willebrand factor is also an acute-phase reactant and is elevated with stress or exercise.

Methodology: Turbidometric Enzymeimmunoassay.

This test was developed and its performance characteristics determined by OHSU.The U.S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

The clinical significance of vWF activity levels between 0.3 to 0.5 U/mL is unclear and clinical correlation is required. See NHLBI von Willebrand Disease Expert Panel Guidelines:
https://www.nhlbi.nih.gov/health-pro/guidelines/current/von-willebrand-guidelines/full-report/1-intro.htm  (Opens in a new window)