RISTOCETIN COFACTOR ASSAY
- RISTOCETIN COFACTOR ASSAY
- Start Date
- Expiration Date
- vonWillebrand Factor
- CPT Codes
- Reference Test
Light blue top (3.2% buffered sodium citrate) tube, Platelet-poor plasma (PPP)
2.0 mL (Two aliquots, 1.0 mL each)
- Transport Info
Separate plasma from cells immediately
• Promptly centrifuge 15 minutes
• Carefully transfer plasma portion of sample to separate plastic tube using plastic pipette
• Centrifuge transferred plasma sample again to produce platelet-poor plasma (PPP)
• Use second plastic pipette to carefully transfer PPP sample into 2 plastic aliquot tubes
- Fasting Required?
- Patient Instructions
- Reference Range
Critical Low Value: 30%
Critical High Value: 500%
Aid in the diagnosis of vonWillebrand Disease and of diseases with changes in the Ristocetin Cofactor activity, such as vascular endothelial lesions, inflammations, and preoperative screening of bleeding tendency.
Ristocetin cofactor (vW factor; VIII:vW; vonWillebrand factor) is the property of the Factor VIII protein that is responsible for the agglutination of platelets in the presence of ristocetin. Decreased quantities or abnormalities of the vonWillebrand factor are associated with vonWillebrand syndrome, thus making quantitation of the factor most valuable in the diagnosis and evaluation of this coagulopathy.Levels of vonWillebrand factor are determined by the ability of a test plasma and ristocetin to induce agglutination of a standardized platelet suspension.