Factor II Assay

Definition

Factor II assay is a test to measure the activity of factor II -- one of the substances involved in coagulation (blood clotting).

Alternative Names

Prothrombin

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 should be 50-200% of the laboratory control or reference value.

What abnormal results mean

Decreased factor II activity may be the result of:

• Congenital (present at birth) deficiency of factor II
• Fat malabsorption
• Liver disease (such as cirrhosis)
• Vitamin K deficiency
• Taking warfarin

Additional conditions under which the test may be performed include disseminated intravascular coagulation (DIC)

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

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.

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 II 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 Practice. 4th ed. Philladelphia, Pa: Churchill Livingston; 2005:2081-83.

•	Factor II deficiency
•	Malabsorption
•	Liver disease
•	Cirrhosis
•	Vitamin K
•	Disseminated intravascular ...