Health Encyclopedia - Test
Factor X assay
How the Test is Performed
How to Prepare for the Test
How the Test will Feel
Why the Test is Performed
This test may be used to find the cause of excessive bleeding (decreased blood clotting).
A normal value is 50 - 200% of the laboratory control or reference value.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.
What Abnormal Results Mean
Decreased factor X activity may be related to:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
This test is most often performed on people who have bleeding problems. The risk of excessive bleeding is slightly greater than for people without bleeding problems.
When you bleed, the body starts a series of activities that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors (factor X is a coagulation factor).
Each factor's reaction triggers the next reaction. The final product of the coagulation cascade is the blood clot. Blood clots may not form normally if any one of the clotting factors is abnormally low.
Gailani D, Neff AT. Rare coagulation factor deficiencies. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 139.
Ragni MV. Coagulation factor deficiencies. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 177.
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.