Platform
Company
Coagulation
Review status
Currently under review
Pending specialist review and validation.
This test measures the activity of factor X, a protein made in the liver that helps your blood clot properly. Factor X works in the middle of the clotting cascade, turning on a key step that allows a firm clot to form and stop bleeding.
The “1:40” refers to the dilution of your plasma used in the lab method. Diluting the sample in a standardized way helps the assay perform within its optimal range and reduces interference, so the reported value reflects your factor X activity more reliably.
Your clinician may order a factor X activity test if you have easy bruising, nosebleeds, heavy menstrual bleeding, bleeding after dental work or surgery, or if other clotting tests are prolonged. It helps distinguish an inherited factor X deficiency from acquired causes such as liver disease, vitamin K deficiency, or the effect of certain anticoagulant medicines.
Results can guide treatment decisions, such as vitamin K replacement, adjusting anticoagulant dosing, or considering specific factor replacement during procedures. This test may also be used to evaluate unexplained abnormal screening tests or to monitor recovery of clotting function after an illness or medication change.
If your factor X activity is lower than expected, it can point to a true deficiency or to an acquired problem that reduces factor X function, such as liver dysfunction, poor vitamin K status, or interference from anticoagulant drugs. Your clinician will interpret the result in the context of your symptoms, medications, and other lab tests, and may repeat the test to confirm stability.
If activity is higher than expected, it is usually not a cause for concern and can be seen with inflammation or physiologic changes. Follow‑up may include a review of your medicines, assessment of liver health and nutrition, or specialized studies such as mixing studies or inhibitor testing if an inhibitor is suspected. Always discuss results with your clinician before making any changes to treatment.
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.
Vitamin K antagonists and some direct oral anticoagulants can lower measured factor X activity or interfere with the assay, leading to a result that reflects drug effect rather than a true deficiency.
Factor X is made in the liver and requires vitamin K. Liver disease or poor vitamin K intake or absorption can reduce activity and should be considered when interpreting results.
Underfilled citrate tubes, clotted or hemolyzed specimens, or delays in processing can artifactually alter clotting results. Correct tube fill and prompt processing help ensure accuracy.
Specific factor X inhibitors or nonspecific inhibitors such as lupus anticoagulant can affect one‑stage factor assays. Additional tests like mixing studies may be needed to clarify the cause.
Unfractionated heparin, low molecular weight heparin, or fondaparinux may interact with certain reagent systems and influence measured activity; inform the lab about any recent doses.
Acute illness, inflammation, pregnancy, or recovery from bleeding may modestly shift factor levels. Your clinician will interpret the value alongside your clinical context.
References