Ristocetin Cofactor, Plasma

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Primary Name Ristocetin Cofactor
Synonym Von Willebrand factor activity
Synonym --
Contraction VWF Activity
Contraction VWF:RCo
Contraction --
UAB Procedure Number 2500350
CPT Code 85245
Specimen Collect one (1) blue-stopper tube (3.2% sodium citrate), filled to specified volume. Do not underfill or overfill.

Specimen Management Centrifuge blue-stopper tube within one (1) hour of collection, separate plasma and test or quick-freeze at -70°C.
Specimen Accepted Daily including weekends
Times Available 0730-1600
Test Performed Monday-Friday
Available Stat? Pathologist approval required.
Description The ristocetin cofactor test is the primary assay used to diagnose von Willebrand disease as it measures plasma von Willebrand factor activity.
Reference Interval 50-166%
Critical Value --
Therapeutic Range --
Follow-up Test *The ristocetin cofactor test is usually performed together with the von Willebrand factor antigen and the factor VIII activity assay, forming the von Willebrand disease profile. * When type 2B von Willebrand disease is suspected, the ristocetin response curve is suggested. *When type 2A or 2B von Willebrand disease is suspected, the von Willebrand factor multimer assay is suggested.
Associated With Bleeding disorders
Associated With Von Willebrand disease
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