Protein C Antigen/Factor VII Antigen
Use
This assay is used to obtain a presumptive diagnosis of protein C deficiency while a patient is receiving antivitamin K therapy. Use of this assay is discouraged.
Special Instructions
Use of this assay is discouraged. It involves measuring vitamin K-dependent factors and requires specific specimen handling including double centrifugation and freezing.
Limitations
Presence of anti-rabbit antibodies in certain subjects can lead to aberrant results. This procedure may be considered by Medicare and other carriers as investigational and therefore may not be payable as a covered benefit. Final diagnosis should not be made until after removal from warfarin therapy for at least two weeks and subsequent testing.
Methodology
Immunoassay (ELISA)
Biomarkers
LOINC Codes
- 27438-1
- 27820-0
- 49870-9
Result Turnaround Time
3-6 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
Not provided
Container
Blue-top (sodium citrate) tube
Collection Instructions
Citrated plasma samples should be collected by double centrifugation. Blood should be collected in a blue-top tube containing 3.2% buffered sodium citrate. Evacuated collection tubes must be filled to completion to ensure a proper blood to anticoagulant ratio. The sample should be mixed immediately by gentle inversion at least six times to ensure adequate mixing of the anticoagulant with the blood. A discard tube is not required prior to collection of coagulation samples. Centrifuge for 10 minutes and carefully remove 2/3 of the plasma using a plastic transfer pipette, being careful not to disturb the cells. Deliver to a plastic transport tube, cap, and recentrifuge for 10 minutes. Use a second plastic pipette to remove the plasma, staying clear of the platelets at the bottom of the tube. Transfer the plasma into a LabCorp PP transpak frozen purple tube with screw cap (LabCorp N° 49482). Freeze immediately and maintain frozen until tested.
Storage Instructions
Freeze.
Causes for Rejection
Hemolysis; clotted specimen; specimen contaminated with heparin (ie, drawn with blood gases); samples containing fibrin clots; specimens received thawed for more than 24 hours