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St. John Health System
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Index:

Von Willebrand Factor Activity (Ristocetin Cofactor)

Order Name RISTOC COF
Test Number: 1502200
Revision Date 11/03/2023
Test Name Methodology LOINC Code
Von Willebrand Factor Activity (Ristocetin Cofactor)
Clot Detection 6014-5 
SPECIMEN REQUIREMENTS
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 2 mL (1) Plasma Sodium Citrate 3.2% (Blue Top) Frozen
Instructions Frozen Citrated plasma, plasma must be double spun and frozen in 1.5 ml aliquots. Do not pool plasma from multiple tubes! Do not thaw. Hemolyzed specimens are not acceptable. See Specimen Collection Section, Coagulation Testing. Fasting for at least 8 hours is preferred.

Specimen Stability: Room temperature: unacceptable, Refrigerated: unacceptable, Frozen: 3 months
GENERAL INFORMATION
Testing Schedule Friday 
Expected TAT 5-8 Days 
Clinical Use Also known as von Willebrand Factor Activity 
CPT Code(s) 85245
Internal Comments 11/30/16 - Updated ref lab information - JLS 1/30/17 - this test was brought in house in CPCL Special Coag. removed the ARUP information from test notes.
Reference Lab: ARUP
ARUP Test Code: 30250
Click Here to view information on the ARUP website.
2/28/18 updated schedule from Mon, Wed, Fri / TAT 2-5 Days  to Friday and TAT 5-8 days. - JK
11/3/23 per Joseph Lucas hlp tkt, change methodology from Plt Agg to clot det -hdm
Service Provided By Labcorp Oklahoma, Inc.
Lab Section Coagulation