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
Optical Clot-Based
Coagulation Factor VII Assay, Plasma
FACTOR VII ACTIVITY
Factor VII Assay
Prothrombin
Factor VII
Plasma Na Cit
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.
If priority specimen, mark request form, give reason, and request a call-back.
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
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, less than or equal to -40 degrees 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.
If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.
0.5 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Gross icterus | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Plasma Na Cit | Frozen | 14 days |
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
Factor VII is a vitamin K-dependent serine protease synthesized
Adults: 65-180%
Normal, full-term newborn infants or healthy premature infants may have decreased levels (> or =20%) which increase within the first postnatal week but may not reach adult levels for > or =180 days postnatal.*
*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing
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 50% activity or less.
Newborn infants usually have levels 25% or more.
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.
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. doi: 10.1016/S0083-6729(07)00014-3
2. Brenner B, Kuperman AA, Watzka M, Oldenburg J: Vitamin K-dependent coagulation factors deficiency. Semin Thromb Hemost. 2009 Jun;35(4):439-446. doi: 10.1055/s-0029-1225766
3. Mariani G, Bernardi F: Factor VII deficiency. Semin Thromb Hemost. 2009 Jun;35(4):400-406. doi: 10.1055/s-0029-1225762
4. Franchini M, Marano G, Pupells S, et al: Rare congenital bleeding disorders. Ann Transl Med. 2018 Sep;6(17):331. doi: 10.21037/atm.2018.08.34
The factor VII assay is performed on the Instrumentation Laboratory ACL TOP using the prothrombin time (PT) method and a factor-deficient substrate. Patient plasma is combined and incubated with a factor VII-deficient substrate (normal plasma depleted of factor VII by immunoadsorption). After a specified incubation time, a PT reagent is added to trigger the coagulation process in the mixture. Then the time to clot formation is measured optically at a wavelength of 671 nm.(Owen CA Jr, Bowie EJW, Thompson JH Jr: Diagnosis of Bleeding Disorders. 2nd ed. Little, Brown and Company, 1975; Meijer P, Verbruggen HW, Spannagi M: Clotting factors and inhibitors: Assays and interpretation. In: Kottke-Marchant K, ed. Laboratory Hematology Practice. Wiley Blackwell Publishing; 2012:435-446)
Monday through Saturday
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.
85230
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
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
F_7 | Coag Factor VII Assay, P | 3198-9 |