Spanish Version
 
E-mail Form
Email Results

 
 
Print-Friendly
Bookmarks
bookmarks-menu

Factor IX assay

Christmas factor assay; Serum factor IX; Hemophilic factor B; Plasma thromboplastin component; PTC

The factor IX assay is a blood test that measures the activity of factor IX. This is one of the proteins in the body that helps the blood clot.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

You may need to stop taking some medicines before this test. Your health care provider will tell you which ones.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

This test is used to find the cause of too much bleeding (decreased blood clotting). Or, it may be ordered if a family member is known to have hemophilia B. The test may also be done to see how well treatment for hemophilia B is working.

Normal Results

A normal value is 50% to 200% of the laboratory control or reference value.

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your provider about the meaning of your specific test results.

The examples above show the common measurements for results for these tests.

What Abnormal Results Mean

Decreased factor IX activity may be related to:

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person 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 lightheaded
  • Multiple punctures to locate veins
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

This test is most often done on people who have bleeding problems. The risk of excessive bleeding is slightly more than for people without bleeding problems.

References

Carcao M, Moorehead P, Lillicrap D. Hemophilia A and B. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 135.

Chernecky CC, Berger BJ. Factor IX (Christmas factor, hemophilic factor B, plasma thromboplastin component, PTC) - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:505-506.

Pai M. Laboratory evaluation of hemostatic and thrombotic disorders. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 129.

        Tests for Factor IX assay

         
         

        Review Date: 1/29/2019

        Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

        The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
        adam.com

         
         
         

         

         

        A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.
        Content is best viewed in IE9 or above, Firefox and Google Chrome browser.