Ristocetin Cofactor Activity


Sunquest Code:RI  
Epic Code:LAB3715Epic Name:Ristocetin Cofactor
Synonyms:von Willebrand Factor Ristocetin Cofactor Activity; VWF:Rco; VWF Ristocetin Cofactor Activity; Ristocetin Cofactor Activity; RCF
Methodology:Platelet Agglutination
CPT Code:----------CPTCODES HERE----------
Turnaround Time:Specimens are sent to the reference laboratory Mon-Sat; results are reported in 1-3 days.
Special Instructions:RCF is the outreach code (Atlas and paper requisition) for Ristocetin Cofactor Activity send out test. DO NOT SEND OUT DIRECTLY TO REFERENCE LAB, SEND TO SPECIAL COAGULATION LAB. Special Coagulation will determine if a ristocetin cofactor activity is required based on the von Willebrand Factor Panel Algorithm or von Willebrand Factor Screen Algorithm prior to sending specimen to ARUP Laboratories for testing. Usually performed as part of a von Willebrand screen or von Willebrand panel. If Special Coagulation Lab determines testing is required, the sample will be returned to Specimen Management for sending to the reference laboratory. See associated links for additional information.
Associated Links:

Specimen Collection and Processing for Coagulation Specimens, von Willebrand Factor (VWF) Panel Algorithm, von Willebrand Factor (VWF) Screen Algorithm



Collection Instructions

Specimen:Blood
Optimal Volume:2.7 mL in 3 mL tube; filled to fill line on the tube.
Minimum\Peds Volume:2.7 mL in 3 mL tube; filled to fill line on tube. If part of a von Willebrand panel, collect TWO tubes.
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Incorrect anticoagulant or over or under filled tubes. Clotted specimens.


Processing and Shipping

Specimen Processing:See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab Special Coagulation  (UMMC-East Bank)


Interpretive

Reference Range:
   
Use:To measure the "activity" of von Willebrand factor. Ristocetin was found to cause thrombocytopenia in most patients by inducing platelet aggregation. This platelet aggregation is reduced in patients with von Willebrand's disease. Therefore, the "activity" of von Willebrand antigen can be measured by the rate at which the patient's platelet-poor plasma causes aggregation of stabilized human platelets in the presence of Ristocetin.


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