Factor VII Activity
Also known as: Proconvertin
Use
Evaluate an isolated prolonged PT and document factor VII deficiency6-8
Special Instructions
If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted. Refer to Coagulation Collection Procedures for directions. Ideally, the patient should not be on anticoagulant therapy. Avoid warfarin therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing. Do not draw from an arm with a heparin lock or heparinized catheter.
Limitations
Direct Xa or thrombin inhibitor therapy may cause factitiously low results. Artifactual elevations in factor VII can occur as the result of cold activation of factor VII in the collection tube prior to analysis. Refrigerating or placing the sample on ice for an extended period prior to freezing the plasma can result in the conversion of factor VII to activated factor VIIa.
Methodology
Other
Biomarkers
LOINC Codes
- 3198-9
- 3198-9
Result Turnaround Time
2-3 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
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. A discard tube is required if using a winged collection set.
Patient Preparation
Avoid warfarin (Coumadin®) therapy for two weeks prior, and heparin, direct Xa, and thrombin inhibitors for about three days prior to testing. Do not draw from an arm with a heparin lock or heparinized catheter.
Storage Instructions
Freeze.
Causes for Rejection
Gross hemolysis; clotted specimen; frozen specimen thawed in transit; improper labeling
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 28 days |