Factor V assay
The factor V assay is a blood test to measure the activity of factor V -- one of the substances involved in blood clotting (coagulation).
Why is the Test Performed?
This test is used to find the cause of too much bleeding (decreased blood clotting).
How is the Test Performed?
A blood sample is needed. For information on how this is done, see: Venipuncture
Preparation for the Test
No special preparation is needed.
How will the Test Feel?
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.
Factor V assay Risks
Veins and arteries vary in size from one patient to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- 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.
Considerations
When you bleed, the body launches a series of activities that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors (factor V 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.
Normal Results for Factor V assay
The value is normally 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 V activity may be related to:
- Deficiency of factor V that is present at birth (congenital)
- Disseminated intravascular coagulation (DIC)
- Liver disease (such as cirrhosis)
- Primary fibrinolysis
Learn more about Factor V assay
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Copyright 2011 A.D.A.M., Inc.
