vWF Activity (vWF:AC-T4)

Panels that include this biomarker

• 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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