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Definition
Factor V assay is a blood test to measure the activity of factor V -- one of the substances involved in coagulation (blood clotting).
How to prepare for the test
No special preparations are needed.
How the test will 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.
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.
Why the test is performed
This test is used to detect the specific cause of too much bleeding (decreased blood clotting).
Normal Values
The value is normally 50-200% of the laboratory control or reference value.
What abnormal results mean
Decreased factor V activity may be related to:
- Congenital (present at birth) deficiency of factor V
- Disseminated intravascular coagulation (DIC)
- Liver disease (such as cirrhosis)
- Primary fibrinolysis
What the risks are
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
- Multiple punctures to locate veins
Special 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.
References
McPherson RA and Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa.: WB Saunders; 2006.
Hoffman R, Benz Jr. EJ, Shattil SJ, et al. Hematology: Basic Principles and Pra ctice. 4th ed. Philladelphia, Pa: Churchill Livingston; 2005:1938.
| • | Factor V deficiency |
| • | Disseminated intravascular ... |
| • | Liver disease |
| • | Cirrhosis |
| • | Primary or secondary fibrin... |
Reviewed By: William Matsui, MD, Assistant Professor of Oncology, Division of Hematologic Malignancies, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, MD. Review provided by VeriMed Healthcare Network.
