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von Willebrand Profile : 1002633
MessageThe aliquots must remain frozen. Freeze thaw cycle will adversely affect specimen integrity. CRITICAL FROZEN: Separate specimens must be submitted when multiple tests are ordered.
Test Code
VWP or 1002633
Alias/See Also
von Willebrand Panel; vWF Panel
CPT Codes
85246, 85245, 85240
Includes
Panel includes: von Willebrand Factor Ag, Ristocetin Cofactor Activity, and Factor VIII Activity.
Instructions
Blue top tube, 3.2% sodium citrate.
• Obtain venous blood by clean venipuncture. Avoid slow-flowing draws and/or traumatic venipunctures as either of these may result in an activated or clotted specimen. Do not use needles smaller than 23 gauge. Do not leave the tourniquet on for an extended length of time before drawing the sample.
• A pilot tube (non-additive or light blue tube) before drawing coagulation specimens in light blue vacuum tubes is only necessary when using a butterfly blood collection set as this will cause reduced draw volume in the first tube. Discard the pilot tube.
• Fill light blue tubes as far as vacuum will allow and mix by gentle inversion. Exact ratio of nine parts blood to one part anticoagulant must be maintained. Inadequate filling of the sample tube will alter this ratio and may lead to inaccurate results. Patients who have hematocrit values above 55 percent should have the anticoagulant adjusted to maintain the 9:1 ratio. Use the following formula to determine the amount of anticoagulant to use: [(100 – Hct) / (595 – Hct) ]* total volume = amount of anticoagulant required.
• After collecting the blood, examine the tube to ensure that it is filled to within 90% of the fill line.
• Note: Specimens containing heparin should not be used for coagulation studies. If possible, stop heparin therapy before the draw to avoid contamination. Heparin interferes with most clotting assays. If heparinized line must be used to obtain the sample, flush line with 5mL saline and discard the first 5 mL of blood drawn into a syringe, or 6 “dead space” volumes of the line.
• Obtain venous blood by clean venipuncture. Avoid slow-flowing draws and/or traumatic venipunctures as either of these may result in an activated or clotted specimen. Do not use needles smaller than 23 gauge. Do not leave the tourniquet on for an extended length of time before drawing the sample.
• A pilot tube (non-additive or light blue tube) before drawing coagulation specimens in light blue vacuum tubes is only necessary when using a butterfly blood collection set as this will cause reduced draw volume in the first tube. Discard the pilot tube.
• Fill light blue tubes as far as vacuum will allow and mix by gentle inversion. Exact ratio of nine parts blood to one part anticoagulant must be maintained. Inadequate filling of the sample tube will alter this ratio and may lead to inaccurate results. Patients who have hematocrit values above 55 percent should have the anticoagulant adjusted to maintain the 9:1 ratio. Use the following formula to determine the amount of anticoagulant to use: [(100 – Hct) / (595 – Hct) ]* total volume = amount of anticoagulant required.
• After collecting the blood, examine the tube to ensure that it is filled to within 90% of the fill line.
• Note: Specimens containing heparin should not be used for coagulation studies. If possible, stop heparin therapy before the draw to avoid contamination. Heparin interferes with most clotting assays. If heparinized line must be used to obtain the sample, flush line with 5mL saline and discard the first 5 mL of blood drawn into a syringe, or 6 “dead space” volumes of the line.
Transport Container
Centrifuge the blue top tube at a rate of speed to yield platelet poor plasma (<10,000 /uL), immediately remove only the top two-thirds of the platelet-poor plasma from the specimen using a plastic-transfer pipet (use of glass-transfer pipets may result in activation and/or clotting of the plasma) and split the citrated plasma (Min. 1.5 mL) into two standard transport tubes, and freeze the two aliquots.
Transport Temperature
Frozen.
Specimen Stability
Ambient: Whole blood 4 hours; After separation from cells: Refrigerated: Unacceptable; Frozen: 2 weeks
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Tubes not filled within 90% of the fill line will be rejected by the lab.
Methodology
Immunoturbidimetric, Agglutination, Clotting
Setup Schedule
Monday - Friday
Report Available
1-4 days
Reference Range
von Willebrand Factor Ag: 50-200%
Ristocetin Cofactor Activity: 58-172%
Factor VIII Activity: 50-200%
Ristocetin Cofactor Activity: 58-172%
Factor VIII Activity: 50-200%
Clinical Significance
von Willebrand disease is the most common congenital bleeding disorder. A decreased level of FVIII, vWF Ag, and ristocetin cofactor is observed in Type I von Willebrand disease. Presence of low FVIII and normal vWF Ag and Ristocetin Cofactor is noted in Hemophilia A disease.
Performing Laboratory
med fusion
