VON WILLEBRAND FACTOR ACTIVITY (RISTOCETIN COFACTOR)

Specimen Required
Draw blood in a light blue sodium citrate tube. See appendices for coagulation test collection instructions. Send 1.5 mL plasma (1.0 mL minimum) frozen in a screw-capped plastic vial. CRITICAL FROZEN.

Rejection Criteria
Serum, non-frozen or hemolyzed specimens

Methodology
Platelet Agglutination

Stability
Room Temerature: 4 hours; Refrigerated: Unacceptable; Frozen: 3 months

Reference Range
0-6 years:   51-215%  
7-9 years:   52-176%  
10-11 years:   60-195%  
12-13 years:   50-184%  
14-15 years:   50-203%  
16-17 years:   49-204%  
18 years and older:   51-215%  

Performed
Monday-Saturday

Turnaround Time4-6 days
Test CodeVWFAR
CPT-4 Code (s)
85245
LOINC Codes
6014-5

Warde
Medical
Laboratory