What are platelet tests?
Platelets, also known as thrombocytes, are small blood cells that are essential for blood clotting. Clotting is the process that helps you stop bleeding after an injury. There are two types of platelet tests: a platelet count test and platelet function tests.
A platelet count test measures the number of platelets in your blood. A lower than normal platelet count is called thrombocytopenia. This condition can cause you to bleed too much after a cut or other injury that causes bleeding. A higher than normal platelet count is called thrombocytosis. This can make your blood clot more than you need it to. Blood clots can be dangerous because they can block blood flow.
Platelet function tests check your platelets' ability to form clots. Platelet function tests include:
Closure time. This test measures the time it takes for platelets in a blood sample to plug a small hole in a tiny tube. It helps screen for different platelet disorders.
Viscoelastometry. This test measures the strength of a blood clot as it forms. A blood clot has to be strong to stop bleeding.
Platelet aggregometry. This is a group of tests that are used to measure how well platelets clump together (aggregate).
Lumiaggregometry. This test measures the amount of light produced when certain substances are added to a blood sample. It can help show if there are defects in the platelets.
Flow cytometry. This is a test that uses lasers to look for proteins on the surface of platelets. It can help diagnose inherited platelet disorders. This is a specialized test. It is only available at certain hospitals and laboratories.
Bleeding time. This test measures the amount of time for bleeding to stop after small cuts are made in the forearm. It was once commonly used to screen for a variety of platelet disorders. Now, other platelet function tests are used more often. The newer tests provide more reliable results.
Other names: platelet count, thrombocyte count, platelet function tests, platelet function assay, platelet aggregation studies
