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HelpTest ID 5INHE Factor V Inhibitor Evaluation, Plasma
Ordering Guidance
This test is for factor V inhibitors only. If the presence or type of inhibitor is unknown, first order APROL / Prolonged Clot Time Profile, Plasma, except for patients with known hemophilia A or B. When screening studies are needed for patients with known hemophilia A or B, order 8INHE / Factor VIII Inhibitor Evaluation, Plasma; or 9 INHE / Factor IX Inhibitor Evaluation, Plasma; respectively.
Shipping Instructions
Send all vials in the same shipping container.
Necessary Information
Specimen Required
Specimen Type: Platelet-poor plasma
Patient Preparation:
1. Fasting: 8 hours, preferred but not required
2. Patient must not be receiving Coumadin (warfarin) or heparin therapy.
Collection Container/Tube: Light-blue top (3.2% sodium citrate)
Submission Container/Tube: Polypropylene plastic vials
Specimen Volume: 3 mL in 3 plastic vials, each containing 1 mL
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 (1-2 mL per aliquot) into 3 separate plastic vials leaving 0.25 mL in the bottom of centrifuged vial.
5. Freeze plasma immediately (no longer than 4 hours after collection) at -20° C or, ideally, -40° C or below.
Additional Information:
1. A double-centrifuged specimen is critical for accurate results as platelet contamination may cause spurious results.
2. Each coagulation assay requested should have its own vial.
Secondary ID
607426Useful For
Detection and quantitation of inhibitors against coagulation factor V
This test is not useful for the detection of a lupus-like circulating anticoagulant inhibitor, a nonspecific circulating anticoagulant, or other inhibitors that are not specific for coagulation factors.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| 5AINH | FV Inhib Profile Prof Interp | No | No |
| 5BETH | FV Bethesda Units, P | No | No |
| F5_IS | Factor V Inhib Scrn | No | No |
Testing Algorithm
Testing begins with coagulation factor V activity assay with dilutions to evaluate assay inhibition; if the factor V activity assay is normal or increased, then a technical interpretation will be provided.
If the factor V activity assay is decreased, then an inhibitor screen will be performed at an additional charge to look for specific factor V inhibition and a professional interpretation will be provided. If specific inhibition is apparent, the titer of the inhibitor will be determined.
Special Instructions
Specimen Type
Plasma Na CitSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
FACTOR V ACTIVITY ASSAY
>1 month: 70-165%
<1 month: Normal, full-term and premature newborn infants may have mildly decreased levels (≥30% to 35%) that reach adult levels within 21 days postnatal.
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing
FACTOR V INHIBITOR SCREEN:
Negative
GENERAL FACTOR BETHESDA UNITS:
≤0.5 Bethesda Units
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
85390
85220
85335 (if appropriate)
85335 (if appropriate)
85390 (if appropriate)
Forms
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.