Platelet Function Tests
Platelet Function Tests
Why Get Tested?
To help determine the cause of or potential for excessive bleeding and/or to diagnose a platelet function disorder; to monitor and evaluate platelet function; to monitor the presence and effectiveness of anti-platelet medications
When To Get Tested?
When you bruise easily or experience excessive or prolonged bleeding from minor cuts, nose or gums, or excessive menstrual bleeding; when you are taking medications that can alter platelet function; prior to or during certain surgeries; if you have a family member with a history of excessive bleeding
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
You may be instructed to refrain from taking drugs that can affect the results of these tests, such as aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), or any over-the-counter medications that contain drugs such as these, anti-histamines, and certain antibiotics. The most common NSAIDs include ibuprofen, naproxen and COX-2 inhibitors. However, do not stop taking your medications unless instructed to do so by your health care practitioner.
What is being tested?
Platelets (also known as thrombocytes) are small, round cellular fragments that are vital for normal blood clotting. Platelet function tests indirectly evaluate how well a person’s platelets work in helping to stop bleeding within the body.
Platelets are produced in the bone marrow and circulate in the blood. When there is an injury to a blood vessel and bleeding begins, platelets are the first elements to help to stop bleeding. They do so in three ways. They:
- Adhere to the injury site
- Clump together (aggregate) with other platelets, forming a temporary plug
- Release compounds that stimulate further aggregation and the eventual formation of a blood clot
These reactions result in the formation of a loose platelet plug in a process called primary hemostasis. At the same time, activated platelets support the coagulation cascade, a series of steps that involves the sequential activation of proteins called clotting factors. This is called secondary hemostasis and the two processes result in the formation of a stable clot that remains in place until the injury has healed.
If there are insufficient platelets or if they are not functioning normally in any of the three main ways, a stable clot may not form and a person may be at an increased risk of excessive bleeding. The number of platelets in blood can be determined with a platelet count and can help diagnose disorders having to do with too many or too few platelets. However, the overall ability of platelets to function properly in the body is more difficult to measure.
Platelet function tests are a group of assays that use specialized equipment to measure the ability of platelets to aggregate and promote clotting in a sample of blood. There are a variety of tests available but no one test that identifies all problems with platelet function. Also, there is no widespread agreement on which test(s) is best for each circumstance.
Screening Tests
Platelet Count
https://www.labtestsguide.com/platelet-count-test-procedure
Bleeding time
https://medstudyworld.blogspot.com/2022/03/bleeding-time.html
How is the sample collected for testing?
A blood sample is drawn though a needle from a vein in the arm. Due to critical time constraints related to platelet activation/ function, you may be sent directly to the laboratory performing the tests. If you have a history of excessive bleeding, you should inform the healthcare practitioner drawing your blood.
Is any test preparation needed to ensure the quality of the sample?
In general, no test preparation is needed. However, you may be instructed to refrain from taking drugs that can affect the results of these tests, such as aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), or any over-the-counter medications that contain drugs such as these. The most common NSAIDs include ibuprofen, naproxen, and COX-2 inhibitors. (See MedlinePlus Drugs & Supplements for more information on drugs, drug ingredients, and brand names.) However, do not stop taking your medications unless instructed to do so by your health care practitioner.
https://www.testing.com/tests/platelet-function-tests/
https://medlineplus.gov/lab-tests/platelet-tests/
https://www.slideshare.net/AhmedMakboul/platelet-function-tests
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