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Platelet Function Test

Last updated April 28, 2018

A Platelet Function Blood Test measures platelets’ abilities to clot blood. A sample is treated with some of the same chemical signals, to which platelets would be exposed in the body. Adherence, above or below normal is a sign that platelets may not be functioning properly.


What are the other Names for this Test? (Equivalent Terms)

  • Aggregometer Blood Test
  • Platelet Aggregation (PA) Blood Test
  • Platelet Function Assay (PFA) Test

What is Platelet Function Test? (Background Information)

  • Platelets, or thrombocytes, are not actually cells but cell fragments. They travel through the blood and form a clot upon breakage of a blood vessel. This prevents excessive loss of blood
  • Many of the body’s platelets, up to one-third, are in storage at any one time. The spleen and liver serve as storage facilities. Platelets are then steadily released, when needed by the body
  • The process of clotting requires not just one, but many platelets communicating through chemical signals. Thus, the platelets’ ability to respond and release signals is essential to their proper function, of minimizing the damage to our bodies
  • A Platelet Function Blood Test measures platelets’ abilities to clot blood. A sample is treated with some of the same chemical signals, to which platelets would be exposed in the body. Adherence, above or below normal is a sign that platelets may not be functioning properly

What are the Clinical Indications for performing the Platelet Function Test?

The following are clinical indicators for performing a Platelet Function Blood Test:

  • In order to monitor the effects of drug therapy and chemotherapy
  • Screen blood donations
  • Excessive bleeding
  • Easy bruising
  • Skin discoloration (petechiae or purpura, depending on discoloration)
  • Living at extreme altitudes
  • Blue coloration (cyanosis) of a tissue due to oxygen deprivation (hypoxia)

How is the Specimen Collected for Platelet Function Test?

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: None

What is the Significance of the Platelet Function Test Result?

Low platelet aggregation may indicate:

  • Medications are decreasing the abilities of platelets to clot blood
  • Defective platelets or defective signaling due to a genetic disorder
  • Kidney malfunction or uremia
  • Liver malfunction or cirrhosis

High platelet aggregation may indicate:

  • Excessive fat levels in the blood (hyperlipidemia)
  • Type I or type II diabetes mellitus

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • The Platelet Function Test should not be confused with the platelet count test
  • Certain factors may interfere with the test and these include: Medications, such as aspirin and certain NSAIDs

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

References and Information Sources used for the Article:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: March 10, 2014
Last updated: April 28, 2018