Platelet Tests

Platelet Test

A platelet test is a blood test used to measure the number and function of platelets in a body. Platelets are a type of blood cell involved in the clotting process of blood. Abnormalities in the number, shape, and/or function of platelets can indicate an underlying medical condition.


A blood sample is typically required to perform a platelet test and is usually collected through a venipuncture. Patients should be properly rested prior to the test and follow any preparation instructions provided by the healthcare provider.


The number and function of platelets in a sample of blood is typically determined through a manual technique known as a platelet count or platelet estimate. This procedure involves placing a drop of the patient’s blood under a microscope in order to count the number and inspect the shape of individual platelets present.


The following platelet tests may be used to evaluate platelet function:

  • Complete Blood Count (CBC): A CBC measures platelet count as well as red and white blood cell levels and hemoglobin. It also provides information on hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration.
  • Bleeding Time Test: This test challenges the body with a small but harmless cut and then measures the amount of time it takes the injury to clot and stop bleeding.
  • Platelet Function Analysis: This test measures platelet activation as well as collagen and adenosine diphosphate (ADP).
  • Platelet Aggregation Test: This test challenges the body with an artificial substance or chemical that causes platelets to clump together.
  • Thrombopoietin Test: This test measures thrombopoietin, a hormone produced by the kidneys that regulates the production of platelets.


There are typically no risks associated with a platelet test, as the procedure is minimally invasive and requires only a small sample of blood.

Why Platelet Test is Done?

A platelet test may be done for a number of reasons, including to monitor existing medical conditions, to evaluate causes of bruising or abnormal bleeding, to detect and diagnose platelet disorders, to evaluate response to medical treatments, or to help diagnose anemia or other blood-related disorders.

When Platelet Test is Done?

A platelet test may be performed in certain laboratory settings (e.g., hospital laboratories), primarily as part of a comprehensive blood workup. However, in some scenarios it may also be performed at home or at a patient's bedside in intensive care settings.