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Test Code Billings Clinic: 2015 Von Willebrand Factor Activity

Performing Laboratory

Billings Clinic Laboratory: Coagulation

Useful For

In-vitro diagnostic determination of ristocetin cofactor activity in human plasma. Used as an aid in the diagnosis of von Willebrand Syndrome and disorders involving changes in ristocetin cofactor activity, such as lesions and inflammation of the vascular endothelium, as well as for pre-operative screening of bleeding disorders.

Methodology

Platelet agglutination

Specimen Requirements

3.2% sodium citrate blood, centrifuged immediately and supernatant plasma removed.

Reference Values

Results are reported as a percent of Normal Activity.

NOTE: Individuals of blood group Type "O" have been shown to have lower plasma von Willebrand factor activity than that of other ABO blood groups.

 

Type O:          49%- >150%

Non-Type O:   65%- >150%

Day(s) Test Set Up

Daily, 24/7

Test Classification and CPT Coding

CPT Code:     85245

LOINC Code:  6014-5