Platform
Company
Coagulation
Review status
Currently under review
Pending specialist review and validation.
This test measures the activity of factor V, a protein in your blood that helps form stable clots. Factor V works with other clotting factors to stop bleeding after an injury. The result reflects how well factor V is functioning, not how much of the protein is present.
The “1:10” indicates a dilution used in the laboratory method to ensure accurate measurement within the test system. The assay is performed on a plasma sample collected in a light blue citrate tube and compared against standardized materials to estimate factor V activity.
Doctors order this test when there is unexplained easy bruising, nosebleeds, heavy bleeding with injury or surgery, or abnormal screening clotting tests. It helps identify inherited factor V deficiency, acquired problems such as antibodies against factor V, and reductions from conditions that consume or reduce clotting proteins.
Because factor V is made in the liver and used during widespread clotting activation, this test can support evaluation of liver disease and disseminated intravascular coagulation. It does not diagnose the Factor V Leiden genetic variant, which is assessed with a different test for resistance to activated protein C or with genetic testing.
If your factor V activity is lower than expected, your clinician may consider inherited deficiency, a temporary decrease from severe liver disease, consumption during a serious illness, or an antibody that interferes with factor V. Further testing such as a mixing study, factor V antigen, and inhibitor evaluation can help clarify the cause. Treatment and follow up depend on your symptoms, medical history, and the underlying condition.
Higher than expected factor V activity is uncommon and usually not clinically significant on its own. Results can also be influenced by medications and sample handling. Your clinician may repeat testing when you are stable, off interfering medicines, or after an acute illness has resolved. If there is concern about the Factor V Leiden variant, a separate test will be recommended.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Underfilled citrate tubes, clotted or hemolyzed samples, prolonged tourniquet time, or delayed processing can artifactually alter clot-based factor results. Proper fill line and prompt centrifugation are important.
Direct oral anticoagulants, unfractionated heparin, and direct thrombin inhibitors can interfere with clot-based assays and yield falsely low activity. Tell your care team about all blood thinners before testing.
status primarily affect other factors, not factor V. However, some methods may still be influenced by these drugs, so interpretation should consider your medication history.
Factor V is synthesized in the liver and can be reduced in advanced liver disease or during disseminated intravascular coagulation, where clotting proteins are consumed.
Autoantibodies to factor V can develop, occasionally after exposure to bovine thrombin in surgical hemostatic agents, leading to a low activity result with bleeding symptoms.
Newborns and young infants can have different physiologic levels. Mild changes can occur with pregnancy or inflammation. Your clinician will interpret results in the context of your situation.
Transfusion of plasma can temporarily raise factor V activity and may mask an underlying deficiency. Timing of testing relative to transfusion is important.
Strong lupus anticoagulants can interfere with some clot-based factor assays, producing misleading activity results. Alternative methods or additional studies may be needed.
References