Platelet aggregation test
The platelet aggregation blood test checks how well platelets, a part of blood, clump together and cause blood to clot.
How the Test is Performed
A blood sample is needed.
Blood sample
Venipuncture is the collection of blood from a vein. It is most often done for laboratory testing.
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.
How to Prepare for the Test
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:
- Antibiotics
- Antihistamines
- Antidepressants
- Blood thinners, such as aspirin, that make it hard for the blood to clot
- Nonsteroidal anti-inflammatory medicines (NSAIDs)
- Statin drugs for cholesterol
Also, tell your provider about any vitamins or herbal remedies you take.
DO NOT stop taking any medicine without first talking to your provider.
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 bruising. This soon goes away.
Why the Test is Performed
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.
Bleeding disorder
Bleeding disorders are a group of conditions in which there is a problem with the body's blood clotting process. These disorders can lead to heavy a...
Platelet count
A platelet count is a lab test to measure how many platelets you have in your blood. Platelets are particles in the blood that help the blood clot. ...
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.
Normal Results
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.
What Abnormal Results Mean
Decreased platelet aggregation may be due to:
-
Autoimmune disorders that produce antibodies against platelets
Autoimmune disorders
An autoimmune disorder occurs when the body's immune system attacks and destroys healthy body tissue by mistake. There are more than 80 autoimmune d...
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Fibrin degradation products
Fibrin degradation products
Fibrin degradation products (FDPs) are the substances left behind when clots dissolve in the blood. A blood test can be done to measure these produc...
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Inherited platelet function defects
Inherited platelet function defects
Congenital platelet function defects are conditions that prevent clotting elements in the blood, called platelets, from working as they should. Plat...
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- Bone marrow disorders
-
Uremia (a result of kidney failure)
Uremia
Prerenal azotemia is an abnormally high level of nitrogen waste products in the blood.
Read Article Now Book Mark ArticleKidney failure
Acute kidney failure is the rapid (less than 2 days) loss of your kidneys' ability to remove waste and help balance fluids and electrolytes in your b...
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Von Willebrand disease (a bleeding disorder)
Von Willebrand disease
Von Willebrand disease is the most common hereditary bleeding disorder.
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Risks
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:
- Excessive bleeding
- 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)
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.
References
Pai M, Moffat KA. Laboratory evaluation of hemostatic and thrombotic disorders. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 127.
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.
Review Date: 2/2/2023
Reviewed By: Mark Levin, MD, Hematologist and Oncologist, Monsey, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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