The platelet aggregation blood test checks how well platelets, a part of blood, clump together and cause blood to clot.
A blood sample is needed.
The laboratory specialist will look at how the platelets spread out in the liquid part of the blood (plasma) and whether they form clumps after a certain chemical or drug is added. When platelets clump together, the blood sample is clearer. A machine measures the changes in cloudiness and prints a record of the results.
Your health care provider may tell you to temporarily stop taking medicines that may affect the test results. Be sure to tell your provider about all the medicines you take. These include:
Also, tell your provider about any vitamins or herbal remedies you take.
DO NOT stop taking any medicine without first talking to your provider.
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 bruising. This soon goes away.
Your provider may order this test if you have signs of a bleeding disorder or a low platelet count. It may also be ordered if a member of your family is known to have a bleeding disorder due to platelet dysfunction.
The test can help diagnose problems with platelet function. It may determine whether the problem is due to your genes, another disorder, or a side effect of the medicine.
The normal time it takes for platelets to clump depends on temperature, and may vary from laboratory to laboratory.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your provider about the meaning of your specific test results.
Decreased platelet aggregation may be due to:
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. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
Note: This test is often performed because a person has a bleeding problem. Bleeding may be more of a risk for this person than for people without bleeding problems.
Chernecky CC, Berger BJ. Platelet aggregation - blood; platelet aggregation, hypercoagulable state - blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. Philadelphia, PA: Elsevier Saunders; 2013:883-885.
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.
Rao AK, Songdej N, Di Paola JA. Platelet disorders and von Willebrand disease. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 41.
Schafer AI. Approach to the patient with bleeding and thrombosis. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 162.BACK TO TOP
Review Date: 1/19/2021
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.
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