Ristocetin Cofactor

Last Modified: 8/13/2020 2:23:07 PM


Medical Necessity Documentation:  
Client Notes:  
Patient Preparation:  
Specimen Requirements:

1.0 mL platelet poor plasma from a Blue Top Tube - 3.2% Na Citrate in a Plastic Vial
Collection Instructions: Please submit a separate, frozen vial for each special coagulation assay ordered. 

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 WBS/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/mcL). 
Freeze immediately and ship on dry ice. 
Minimum Volume: 0.5 mL PP Plasma
Transport & Storage: Temperature/Stability: 6 hours Ambient
30 days Frozen -20°
1 year Frozen -70°
Rejection Criteria: Refrigerated • Thawed plasma • Hemolysis • Lipemia
Reference Range: 50% - 150%
Critical Ranges:  
Test Comments:  
Methodology: Platelet Agglutination
Clinical Significance: von Willebrand disease is the most common hereditary bleeding disorder. von Willebrand Factor is necessary for platelet adhesion to injured endothelium. Ristocetin cofactor is useful in assessing binding of von Willebrand Factor to platelet factor GP1b. When combined with other tests, results are useful in categorizing the type of von Willebrand disease.
Documentation:  
Custom Panel: No

PRODUCTION SCHEDULE

Turn Around Time: 3 to 5 days
Days Performed: Monday, Thursday, Saturday
Sites Performed: Quest - Chantilly
PHL Test Code: RIST1
EPIC Test Code: LAB335
Send Out Test Code: 4459
Alternate Test Names: RcoF; Von Willbrand Ristocetin COF; von Willebrand Factor Activity
Included Tests:  
CPT Coding: 85245

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