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Ristocetin Co-Factor
Test CodeRCF
Alias/See Also
RCF
CPT Codes
85245
Preferred Specimen
4.5 ml of whole blood preferred. 2.7 ml tube minimum
Instructions
Collect one full sodium citrate tube (blue top). Send to lab immediately. If the specimen needs to be transported, centrifuge the specimen, aliquot the specimen into a separate container, spin again, aliquot the specimen into a new container and freeze.
Transport Container
Sodium citrate (blue top)
Transport Temperature
Frozen
Specimen Stability
Specimen must be centrifuged within one hour of collection.
Room Temperature: 4 hours (centrifuged)
Refrigerated: Not acceptable
Frozen: 30 days
Room Temperature: 4 hours (centrifuged)
Refrigerated: Not acceptable
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Specimens which are not properly filled do not contain the proper anti-coagulant to blood ratio and are therefore rejected. Hemolyzed and clotted specimens are also unacceptable for testing.
Methodology
Clotting
Setup Schedule
Monday and Thursday
Report Available
Report available in 1 to 4 days
Reference Range
REFERENCE INTERVAL: 50-150%
The results vary with blood type through an unknown mechanism. It has been shown that individuals with type O blood have approximately 30% less activity than type A, B or AB individuals
The results vary with blood type through an unknown mechanism. It has been shown that individuals with type O blood have approximately 30% less activity than type A, B or AB individuals
Clinical Significance
The vonWillebrand Factor (ristocetin co-factor) activity assay reflects the effectiveness of patient vWF in supporting platelet adhesion to damaged endothelial cells. Von Willebrand disease is an autosomal dominant inherited system of three types of bleeding disorders caused by either defective synthesis (quantitative) or functionality (structural abnormality) of vWF multimers. It is the most common inherited bleeding disorder. Clinically, it is often characterized by mucocutaneous hemorrhages. The differential diagnosis should include laboratory tests for PFA, RCF, aPTT, Factor VIII, vWF antigen and activity, and platelet count.
