vWF Activity

Single-analyte tests

• von Willebrand Factor (vWF) Activity 164509

  Plasma · Fasting not stated · Turnaround 1 - 3 days

  Method and collection

  Method

  This assay measures the ability of patient vWF to bind to platelet glycoprotein Ib (GPIb).6 The assay employs a recombinant GPIb genetically modified to include two gain-of-function mutations (GP1bM). These gain-of-function mutations allow for the measurement of vWF binding to GPIb without addition of ristocetin.11

  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

  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. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

  Reference notes

  50% to 150%. Average vWF levels tend to vary by blood type.6,8-12 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%

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Panels that include this biomarker

• von Willebrand Factor (vWF) Multimers 117245

  4 analytes · Plasma · Fasting not stated · Turnaround 5 - 7 days

  Method and collection

  Method

  The Sebia Hydragel™ assay employs an agarose gel for the separation of plasma proteins according to their molecular weight. The electrophoretic separation is carried out after sample treatment with an anionic detergent. This treatment disrupts the three-dimensional structure of the plasma VWF, allowing for the electrophoretic separation of the multimers based on their molecular weight. The system can reveal the loss or retention of HMWM and also intermediate MWM (IMWM) and thus serve as an aid in the characterization of the majority of VWD cases, for example, distinguishing samples with loss of HMWM (and potentially IMWM) (being type 2A, 2B or PT-VWD) from samples without loss of HMWM and/or IMWM (being type 1, 2M, 2N VWD or normal samples), from samples without VWF (i.e., type 3 VWD).1,2 von Willebrand Factor Antigen and Activity levels are measured in order to determine dilution needed for the multimer analysis and as an aid in interpretation of multimer pattern.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.24 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.25,26 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.27,28 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. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• DDAVP (Desmopressin) Challenge Profile 184080

  5 analytes · Plasma · Fasting not stated · Turnaround 5 - 7 days

  Method and collection

  Method

  See individual tests.

  Preparation

  Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  This challenge protocol is accomplished as follows: Citrate whole blood is collected (see Sample Collection). This sample should be labeled (Baseline-T0) with the time of collection. Immediately after collecting T0 sample, patient is dosed with DDAVP (Desmopressin) and described in drug labeling. This is not to be done by Labcorp staff. Desmopressin has several side effects, including headache, tachycardia, flushing, hypotension, hyponatraemia, and rarer seizures and coronary events.1,40 ,41 Therefore, the dosing and post-dose status of patients undergoing DDAVP stimulation needs to be carefully monitored by trained clinical personnel.42 One hour after drug dosing, a second citrate whole blood is collected. This sample should be labeled (One Hour-T1) with the time of collection. Three hours later (four hours after drug dosing), a third citrate whole blood is collected. This sample should be labeled (One Hour-T4) with the time of collection. Sample Collection Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.43 Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio.44,45 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.46,47 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 alternate 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. Centrifuge and carefully remove the plasma using a plastic transfer pipette, being careful not to disturb the cells. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested . Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• Menorrhagia Profile 336572

  5 analytes · Plasma · Fasting not stated · Turnaround 2 - 3 days

  Method and collection

  Method

  See individual tests.

  Preparation

  Do not draw from an arm with a heparin lock or heparinized catheter.

  Collection

  Citrated plasma samples should be collected by double centrifugation. 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, except when using a winged blood collection device (ie, "butterfly"), in which case a discard tube should be used.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 alternate 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. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a Labcorp PP transpak frozen purple tube with screw cap (Labcorp No. 49482). Freeze immediately and maintain frozen until tested. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• von Willebrand Factor Disease (vWD) Profile 086282

  5 analytes · Plasma · Fasting not stated · Turnaround 3 - 8 days

  Method and collection

  Method

  See individual tests.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.75 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.76,77 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.78,79 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. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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• von Willebrand Factor Disease (vWD) Reflex Profile 086284

  5 analytes · Plasma · Fasting not stated · Turnaround 3 - 8 days

  Method and collection

  Method

  See individual tests.

  Collection

  Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate.75 Evacuated collection tubes must be filled to completion to ensure a proper blood-to-anticoagulant ratio.76,77 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.78,79 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. Please print and use the Volume Guide for Coagulation Testing to ensure proper draw volume.

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Single-analyte tests

• von Willebrand Factor GPIbM Activity 13995

  Plasma · Fasting not stated · Turnaround Set up: Tues, Thurs, Sat

  Method and collection

  Method

  Latex-based Turbidimetric

  Collection

  Platelet-poor plasma: Centrifuge light blue-top tube for 15 minutes at approximately 1500 g within 60 minutes of collection. Using a plastic pipette, remove plasma, taking care to avoid the WBC/platelet buffy layer and place into a plastic vial. Centrifuge a second time and transfer platelet-poor plasma into a new plastic vial. Plasma must be free of platelets (<10,000/uL). Freeze immediately and ship on dry ice. Alternative methods for preparation of platelet-poor plasma may be used if validated by the laboratory. Note: Storage of whole blood at refrigerated temperatures prior to processing may lead to cryoprecipitate formation and falsely low Factor VIII and von Willebrand Factor studies.

  Reference notes

  43-207 %

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