Factor 7 activity

Alphabetical Test listing

Factor 7 activity-994

Factor 7 activity
Factor VII activity

Evaluate an isolated prolonged PT and document factor VII deficiency


Direct Xa or thrombin inhibitor therapy may cause factitiously low results.

  • Ideally, the patient should not be on anticoagulant therapy
  • Avoid warfarin (Coumadin®) therapy for two weeks prior to the test and heparin, direct Xa, and thrombin inhibitor therapies for about three days prior to testing
Sodium citrate (Na cit) plasma
1.0 mL
  • If the patient's hematocrit exceeds 55%, the volume of citrate in the collection tube must be adjusted.
  • Do not draw from an arm with a heparin lock or heparinized catheter
  • 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 to ensure adequate mixing of the anticoagulant with the blood.
  • A discard tube is not required prior to collection of coagulation samples unless the sample is collected using a winged (butterfly) collection system.
    • With a winged blood collection set a discard tube should be drawn first to account for the dead space of the tubing and prevent under-filling of the evacuated tube.
  • When noncitrate tubes are collected for other tests, collect sterile and nonadditive (red-top) tubes prior to citrate (blue-top) tubes.
  • Any tube containing an alternative anticoagulant should be collected after the blue-top tube.
  • Gel-barrier tubes and serum tubes with clot initiators should also be collected after the citrate tubes.


  1. Spin
  2. Transfer 1.0 mL plasma to a Screw-cap polypropylene frozen transport vial/tube - 4mL (LabCorp), labelled as Na cit plasma
  3. Freeze


  • Gross hemolysis
  • Clotted specimens
  • Specimens that have thawed in transit
  • Improperly labeled specimens
LabCorp Burlington (800599): R-NX
4 days

Prothrombin Time (PT)-based one-stage clotting time assay. Factor VII- depleted plasma is used as the substrate and the substrate and the clotting time with the patient plasma is compared to the clotting time of normal pooled plasma.


51 - 186%

Direct Xa or thrombin inhibitor therapy may cause factitiously low results.

Result 3198-9