This blood test shows if you have antibodies against platelets in your blood. Platelets are a part of the blood that help the blood clot.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
No special preparation is needed for this test.
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
An antibody is a protein produced by your body's immune system to attack harmful substances, called antigens. Examples of antigens include bacteria and viruses.
Antibodies may be produced when your immune system mistakenly considers healthy tissue to be a harmful substance. In the case of platelet antibodies, your body created antibodies to attack platelets. As a result, you will have a lower than normal number of platelets in your body. This condition is called thrombocytopenia, and it can cause too much bleeding.
This test is often ordered because you have a bleeding problem.
A negative test is normal. This means that you do not have anti-platelet antibodies in your blood.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results show that you have anti-platelet antibodies. Anti-platelet antibodies may appear in the blood due to any of the following:
- For unknown reasons (idiopathic thrombocytopenic purpura, or ITP)
- Side effect of certain drugs such as gold, heparin, quinidine, and quinine
Veins and arteries vary in size, so it may be harder to take a blood sample from one person than another.
Other slight risks from having blood drawn may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Miller JL, Rao AK. Blood platelets and von Willebrand disease. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 40.
Warlemtom TE. Thrombocytopenia due to platelet destruction and hypersplenism. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi J, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 134.
Update Date 1/27/2015
Updated by: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.