Platelet Tests

Why this test may be ordered

• To monitor or diagnose conditions that cause too much bleeding or clotting.
• As part of a complete blood count during a routine checkup.
• To help diagnose platelet diseases.
• To check platelet function during complex surgical procedures (e.g., coronary artery bypass surgery, trauma surgery).
• To evaluate patients before surgery if they have a personal or family history of bleeding disorders.

Preparation and collection

For a platelet count test, no special preparation is needed. For platelet function tests, you may need to stop taking certain medicines (such as aspirin or ibuprofen) before the test. Do not stop any medicine unless your provider tells you to.

Blood draw from a vein in the arm. The procedure usually takes less than five minutes.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

Platelet test results are reported as a number (platelet count) or as a qualitative assessment (platelet function). The meaning of your results depends on your overall health and other test results. The following patterns are based on the information provided by MedlinePlus.

• Lower-than-normal platelet count: Lower-than-normal platelet count (thrombocytopenia) may be associated with conditions such as leukemia, lymphoma, viral infections (mononucleosis, hepatitis, measles), autoimmune disease, bone marrow damage, cirrhosis, vitamin B12 deficiency, or gestational thrombocytopenia (a mild, common low-platelet condition during pregnancy that usually resolves on its own). Limitation: The source describes lower-than-normal platelet count as a possible sign of several conditions, but it is not a definitive diagnosis. Next step: Follow up with your healthcare provider to discuss potential causes and further evaluation.
• Higher-than-normal platelet count: Higher-than-normal platelet count (thrombocytosis) may be a sign of certain types of cancer (lung, breast), anemia, inflammatory bowel disease, rheumatoid arthritis, viral or bacterial infection, or severe blood loss. Limitation: The source describes higher-than-normal platelet count as a possible sign of several conditions, but it is not a definitive diagnosis. Next step: Follow up with your healthcare provider to discuss potential causes and further evaluation.
• Normal platelet count: The number of platelets in your blood is within the expected range. No specific conditions are indicated by this result. Limitation: A normal platelet count does not rule out all platelet disorders; platelet function tests may be needed if symptoms persist. Next step: No further action is typically needed based on this result alone. Continue routine health care as recommended by your provider.
• Abnormal platelet function test: Abnormal platelet function may indicate an inherited disorder (e.g., von Willebrand disease, Glanzmann thrombasthenia, Bernard-Soulier syndrome, storage pool disease) or an acquired disorder (e.g., due to kidney failure, certain leukemias, myelodysplastic syndrome). Limitation: Abnormal platelet function tests suggest a possible disorder, but further testing and clinical correlation are necessary for a diagnosis. Next step: Discuss with your healthcare provider, who may recommend additional tests or a specialist consultation based on your symptoms and history.

• The source does not provide specific reference ranges or units; results are interpreted by the healthcare provider.
• Platelet function tests may not be available at all locations; some specialized tests are only available at certain hospitals and laboratories.
• False positives or false negatives are possible; results must be interpreted in the context of symptoms, medical history, and other tests.

What to do next

Your healthcare provider will interpret your results based on your personal history, symptoms, and other laboratory findings. No action is required for normal results; abnormal results will guide follow-up discussions with your provider.

• What are the symptoms that led to this test?
• Are you taking any medicines that affect blood clotting?
• Do you have a personal or family history of bleeding or clotting disorders?

Evidence source

U.S. National Library of Medicine: Platelet Tests