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Test ID: F_7 Coagulation Factor VII Activity Assay, Plasma

Reporting Name

Coag Factor VII Assay, P

Useful For

Diagnosing congenital deficiency of coagulation factor VII

 

Evaluating acquired deficiencies associated with liver disease, oral anticoagulant therapy, and vitamin K deficiency

 

Determining degree of anticoagulation with warfarin to correlate with level of protein C

 

Investigation of a prolonged prothrombin time

Specimen Type

Plasma Na Cit


Advisory Information


Coagulation testing is highly complex, often requiring the performance of multiple assays and correlation with clinical information. For that reason, we suggest ordering Coagulation Consultations.



Necessary Information


If priority specimen, mark request form, give reason, and request a call-back.



Specimen Required


Specimen Type: Platelet-poor plasma

Patient Preparation: Patient must not be receiving Coumadin or heparin therapy.

Collection Container/Tube: Light-blue top (3.2% sodium citrate)

Submission Container/Tube: Plastic vial

Specimen Volume: 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 in Special Instructions.

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° C or, ideally, ≤-40° C.

Additional Information:

1. 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.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Cit Frozen 14 days

Reference Values

Adults: 65-180%

Normal, full-term newborn infants or healthy premature infants may have decreased levels (≥20%) which increase within the first postnatal week but may not reach adult levels for ≥180 days postnatal.*

 

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

Day(s) and Time(s) Performed

Monday through Friday

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 U.S. Food and Drug Administration.

CPT Code Information

85230

LOINC Code Information

Test ID Test Order Name Order LOINC Value
F_7 Coag Factor VII Assay, P 3198-9

 

Result ID Test Result Name Result LOINC Value
F_7 Coag Factor VII Assay, P 3198-9

Clinical Information

Factor VII is a vitamin K-dependent serine protease synthesized in the liver. It is a component of the extrinsic coagulation scheme, measured by the prothrombin time. Plasma biological half-life is about 3 to 6 hours. Deficiency may result in a bleeding diathesis.

Interpretation

Liver disease, vitamin K deficiency, or warfarin anticoagulation can cause decreased factor VII activity.

 

Patients that are homozygous have levels usually less than 20% activity.

 

Patient that are heterozygous generally have levels of less than or =50% activity.

 

Newborn infants usually have levels greater than or =25%.

Clinical Reference

1. Girolami A, Scandellari R, Scapin M, Vettore S: Congenital bleeding disorders of the vitamin K-dependent clotting factors. Vitam Horm. 2008;78:281-374

2. Brenner B, Kuperman AA, Watzka M, Oldenburg J: Vitamin K-dependent coagulation factors deficiency. Semin Thromb Hemost. 2009 Jun;35(4):439-446

3. Mariani G, Bernardi F: Factor VII deficiency. Semin Thromb Hemost. 2009 Jun;35(4):400-406

Analytic Time

1 day

Method Name

Optical Clot-Based

Mayo Clinic Laboratories | Hematology Catalog Additional Information:

mml-coagulation-disorders