Coagulation Factor VII Activity Assay, Plasma
Use
This test is useful for diagnosing congenital deficiency of coagulation factor VII, evaluating acquired deficiencies associated with liver disease, oral anticoagulant therapy, and vitamin K deficiency, and determining the degree of anticoagulation with warfarin to correlate with the level of protein C. It is also used in the investigation of a prolonged prothrombin time.
Special Instructions
Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. It is suggested to order Coagulation Consultations. If priority specimen, mark the request form, give reason, and request a call-back.
Limitations
Factor VII is the first vitamin K-dependent coagulation factor to decrease after starting warfarin therapy and one of the first to return to normal when anticoagulation is discontinued. Improper specimen collection and handling can affect results, as platelet contamination may cause spurious results.
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 3198-9
- 3198-9
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
1 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
1. Specimen must be collected prior to factor replacement therapy 2. For complete instructions, see Coagulation Guidelines for Specimen Handling and Processing. 3. Centrifuge, transfer all plasma into a plastic vial, and centrifuge plasma again. 4. Aliquot plasma into a plastic vial, leaving 0.25 mL in the bottom of centrifuged vial. 5. Freeze plasma immediately (no longer than 4 hours after collection) at -20 degrees C or, ideally, -40 degrees C or below.
Patient Preparation
Patient must not be receiving coumadin (warfarin) or heparin therapy. (If not possible for medical reasons, note on request.)
Causes for Rejection
Gross hemolysis, gross lipemia, gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |