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HelpTest Code F7_IS Factor VII Inhibitor Screen, Plasma
Method Name
Only orderable as part of a profile. For more information see:
7INHE / Factor VII Inhibitor Evaluation, Plasma
ALBLD / Bleeding Diathesis Profile, Limited, Plasma
APROL / Prolonged Clot Time Profile, Plasma
Optical Clot-Based
Reporting Name
Factor VII Inhib ScrnSpecimen Type
Plasma Na CitSpecimen Minimum Volume
2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma Na Cit | Frozen | 14 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
Reference Values
Only orderable as part of a profile. For more information see:
7INHE / Factor VII Inhibitor Evaluation, Plasma
ALBLD / Bleeding Diathesis Profile, Limited, Plasma
APROL / Prolonged Clot Time Profile, Plasma
Negative
Day(s) Performed
Monday through Friday
Report Available
1 to 3 daysSpecimen Retention Time
7 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
85335
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| F7_IS | Factor VII Inhib Scrn | 81123-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 7810 | Factor VII Inhib Scrn | 81123-2 |
Specimen Required
Only orderable as part of a profile. For more information see:
7INHE / Factor VII Inhibitor Evaluation, Plasma
ALBLD / Bleeding Diathesis Profile, Limited, Plasma
APROL / Prolonged Clot Time Profile, Plasma
For more information see Coagulation Guidelines for Specimen Handling and Processing.
Useful For
Detecting the presence of a specific factor inhibitor directed against coagulation factor VII
Clinical Information
Patient plasma, normal pooled plasma (NPP), and a mixture of patient plasma and NPP are each tested for a specific factor, incubated at 37° C for 1 hour, and then retested for the same factor. In addition, a new mixture of patient plasma and NPP is prepared using the incubated plasmas and tested after the 1 hour incubation. The percentage of the recovered factor for each individual plasma and mixture being tested is calculated and compared. The procedure demonstrates the effect of a specific coagulation factor inhibitor on that factor present in normal pooled plasma, over a specific period of time.
An inhibitor directed against a coagulation factor may arise due to multiple exposures from transfusions in a patient deficient in that factor (as in the case of hemophiliacs), in response to certain disease states, or be drug-induced. Non-specific inhibitors may also be present in patients that will prolong screening tests (eg, prothrombin time and activated partial thromboplastin time). This test is used to qualitatively identify an inhibitor to a specific coagulation factor.
Interpretation
When testing is complete, if factor activity results fall within clinically normal ranges, an interpretive comment will be provided noting that inhibitor testing was not indicated and, therefore, not performed. If factor activity indicates the performance of inhibitor screen testing, an interpretive comment will be provided noting the presence or absence of a factor VII inhibitor.
Cautions
Occasionally, a potent lupus-like anticoagulant may cause false-positive testing for a specific factor inhibitor (eg, factor VIII or IX).
Clinical Reference
1. Bowie EJW, Thompson JH Jr, Didisheim P, Owen CA Jr. Mayo Clinic Laboratory Manual of Hemostasis. WB Saunders Company; 1971:111-115
2. Laboratory Hematology Practice. In: Kottke-Marchant K, ed. Wiley Blackwell Publishing;Â 2012
3. Hematology: Basic Principles and Practice. In: Hoffman R, Benz EJ Jr, Silberstein LE, eds. 7th ed. Elsevier; 2018
Method Description
The factor VII inhibitor screen is performed on the Instrumentation Laboratory ACL TOP. The assay consists of measuring the factor VII activity (prothrombin time based assay) before and after incubation of a mixture of normal plasma and patient's plasma for 1 hour at 37° C. Interpretation of the presence or absence of the indication of a factor VII inhibitor is determined by comparing the factor VII activity results and the calculated expected values.(Owen CA Jr, Bowie EJW, Thompson JH Jr. Diagnosis of Bleeding Disorders. 2nd ed. Little Brown and Company; 1975:14-144; Meijer P, Verbruggen HW, Spannagi M. Chapter 33: Clotting factors and inhibitors: Assays and Interpretation. In: Kottke-Marchant K, ed. Laboratory Hematology Practice. Wiley Blackwell Publishing; 2012:435-446)