Geisinger Medical Laboratories Test Catalog
RISTOCETIN COFACTOR ASSAY |
||
ORDERING INFORMATION: |
Geisinger Epic Procedure Code: LAB3014 Geisinger Epic ID: 7126 | |
SPECIMEN COLLECTION |
||
Specimen type: |
Platelet-poor plasma | |
Preferred collection container: |
||
Alternate Collection Container: |
Other size blue-top (3.2% sodium citrate) tubes (e.g., 1.8 mL, 4.5 mL)
|
|
Specimen required: |
1 mL | |
Special notes: |
|
|
SPECIMEN PROCESSING |
||
Specimen processing instructions: |
Centrifuge specimen immediately at designated time and speed to obtain platelet-poor plasma (<10,000/µL). Using a plastic pipette, carefully remove plasma from cells, avoiding platelet/buffy layer by leaving a thin layer of plasma on top the cells. The centrifuged plasma should be aliquoted (1 mL per aliquot) into clearly labeled polypropylene tubes. The number of tests ordered will determine the aliquots needed. Check the residual specimen for clot and if present discard sample and redraw specimen. If plasma is icteric, lipemic or hemolyzed a lab comment should be generated to notify staff. Freeze upright in non-thaw freezer. | |
Transport temperature: |
Frozen on dry ice | |
Specimen stability: |
Room temperature (whole blood): 4 hours Frozen -20°C: 30 days Frozen -70°C: 6 months |
|
Rejection criteria: |
Clotted, hemolyzed, grossly icteric, grossly lipemic, improperly filled tubes, improper anticoagulant ratio (HCT >55% and citrate not adjusted), refrigerated specimens, or stability exceeded.
Note: Specimen suspected of thawing in transport, indicated by slant in aliquot or specimen in lid of tube, will have testing performed, and the comment “interpret results with caution as thawing suspected” added to results. |
|
TEST DETAILS |
||
Reference interval: |
> 40% | |
CPT code(s): |
85245 | |
Note: The billing party has sole responsibility for CPT coding. Any questions regarding coding should be directed to the payer being billed. The CPT codes provided by GML are based on AMA guidelines and are for informational purposes only. | ||
Test includes: |
von Willebrand Factor activity | |
Methodology: |
Platelet Aggregation/Agglutination |
|
Synonyms: |
Von Willebrand Factor Activity Assay, RICO, Clotting, VIII, VW, Vonwillebrand VWF activity
|
|
Clinical significance: |
Von Willebrand factor (VWF) is a glycoprotein synthesized in megakaryocytes and endothelial cells that is utilized in primary hemostasis (platelet aggregation) and as a carrier site for the clotting factor VIII. Decreased quantity and/or functionality of VWF leads to mucocutaneous bleeding and menorrhagia. Low VWF levels can be observed in acquired or congenital von Willebrand disease (VWD)
Ristocetin cofactor assay (VWF:RCo) is one type of test used to assess for VWD. It assesses the ability of the patients VWF to agglutinate reagent platelets. It is typically part of a panel of tests (including factor VIII activity and VWF antigen). Abnormalities could be suggestive of a VWD. |
|
Doctoral Director(s:) |
Michelle Grant DO | |
Review Date: | 03/31/2023 |