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Platelet associated antibodies
Definition
A test for platelet-associated antibodies shows whether you have antibodies that are directed against platelets in your blood.
How the Test is Performed
A blood sample is needed. For information on how this is done, see: Venipuncture
How to Prepare for the Test
No special preparation is necessary for adults.
How the Test Will Feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the Test is Performed
This test may be ordered when you have a low platelet count (thrombocytopenia). It is used to detect antibodies against platelets.
Normal Results
A negative test is normal.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results show that you have antiplatelet antibodies. These are proteins made by your body that attach to platelets and destroy them. This causes a low platelet count, which can lead to excessive bleeding.
Antiplatelet antibodies may appear in the blood for unknown reasons (idiopathic thrombocytopenic purpura), or as a side effect of certain drugs such as gold heparin, quinidine, and quinine. These drugs can sometimes cause the immune system to identify its own platelets as abnormal or foreign, and attack them.
The exact interpretation of the results of this test is controversial.
Risks
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.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Considerations
Current tests cannot tell for sure whether a low platelet count (thrombocytopenia) is caused by immune problems. Therefore, your doctor will make a diagnosis based on other tests and examinations.
This test is often performed because you have a bleeding problem. Bleeding may be more of a risk for you than for people who do not have bleeding problems.
References
Schmaier AH. Thrombocytopenia due to platelet destruction and hypersplenism. In: Hoffman R, Benz EJ Jr., Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier;2008:chap 140.
McMillan R. Hemorrhagic disorders: Abnormalities of platelet and vascular function. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 179.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
