Factor VIII assay

A blood sample is needed.

No special preparation is needed.

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.

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 A . The test may also be done to see how well treatment for hemophilia A is working.

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 health care provider about the meaning of your specific test results.

Decreased factor VIII activity may be due to: Hemophilia A (a bleeding disorder caused by a lack of blood clotting factor VIII) Disorder in which the proteins that control blood clotting become overactive disseminated intravascular coagulation (DIC) Presence of a Factor VIII inhibitor (antibody) Von Willebrand disease…

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…

Carcao M, Gomez K, Davide M, Pierce GF. Hemophilia A and B. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice . 8th ed. Philadelphia, PA: Elsevier; 2023:chap 134. Ragni MV. Hemorrhagic disorders: coagulation factor deficiencies. In: Goldman L, Schafer AI, eds. Goldman-Cecil…