How are specimens collected for von Willebrand factor antigen (vWF:Ag) assay?

Updated: Nov 05, 2019
  • Author: Vadim Kostousov, MD; Chief Editor: Eric B Staros, MD  more...
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Specimen: Citrated plasma

Collection: Tube with sodium citrate 3.2% citrate, blue top

Centrifugation: 2000-2500 g for 15 min or similar regime to produce platelet-poor plasma

Storage: Up to 6 hours at +18-25°C or plasma sample should be frozen; specimen is stable for 1 month at -20°C; whole blood after collection should not be stored at refrigerator temperatures (+2°C to +4°C) owing to cold-induced binding of vWF to platelets and selective loss of vWF:Ag in plasma. [3]

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