Platelets (PLT)

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 may include closure time, viscoelastometry, platelet aggregometry, lumiaggregometry, flow cytometry, and bleeding time.

If your results show a lower-than-normal platelet count (thrombocytopenia), it may be a sign of a cancer that affects the blood (such as leukemia or lymphoma), a viral infection (such as mononucleosis, hepatitis, or measles), an autoimmune disease, infection or damage to your bone marrow, cirrhosis, vitamin B12 deficiency, or gestational thrombocytopenia.

If your results show a higher-than-normal platelet count (thrombocytosis), it may be a sign of certain types of cancer (such as lung cancer or breast cancer), anemia, inflammatory bowel disease (such as Crohn's disease and ulcerative colitis), rheumatoid arthritis, a viral or bacterial infection, or severe blood loss.

If your platelet function test results were not normal, it may be a sign of an inherited or acquired platelet disorder.

Your provider may consider your symptoms, medical history, and the results of other blood tests to understand the results of your platelet tests.