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
Your doctor may order this test if you have problems with blood clotting, such as excessive bleeding.
The normal range is 200 to 400 mg/dL (2.0 to 4.0 g/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
The test may also be performed during pregnancy if the placenta separates from its attachment to the uterus wall (placenta abruption).
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:
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 performed on people who have bleeding disorders. The risk for excessive bleeding is slightly greater in such people than it is for those who do not have bleeding problems.
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.
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.