Find

Learn More

Definition

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.

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 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.

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 inflammatory drugs (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.

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.

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient 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
  • 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.

What Abnormal Results Mean

Decreased platelet aggregation may be due to:

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.

The test can help diagnose problems with platelet function and determine whether the problem is due to your genes, another disorder, or a side effect of medicine.

Review Date: 2/7/2017
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.

ADAM QualityA.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 9-1-1 for all medical emergencies. Links to other sites are provided for information only—they do not constitute endorsements of those other sites. © 1997-2010 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.