Platelet Count Test

Why am I having this test?

Platelets are blood cells that help the blood clot. When you get a tissue injury like a cut, platelets gather at the site of the injury to stop the bleeding. You may have a platelet count test if you have symptoms that may be related to bleeding too much or having blood that does not clot like it should. These symptoms may include:

• A rash of very small red and purple dots on your skin (petechiae). These are small collections of blood in your skin.
• Heavy bleeding during menstrual periods.

You may also get a platelet count test to help monitor treatment. This may be done if you have:

• Thrombocytopenia. This is a condition in which you have a low platelet count.
• Bone marrow failure. Bone marrow is the soft tissue inside your bones.

What is being tested?

This test measures how many platelets you have within a certain amount (volume) of blood.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel or by sticking a finger with a small needle.

Tell a health care provider about:

• Any allergies you have.
• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any bleeding problems you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.

How are the results reported?

Your test results will be reported as a value. This value shows how many platelets are in the blood volume. It will be given as platelets per cubic millimeter (mm³) of blood.

Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Adult or elderly: 150,000–400,000/mm³.
• Child: 150,000–400,000/mm³.
• Infant: 200,000–475,000/mm³.
• Premature infant: 100,000–300,000/mm³.
• Newborn: 150,000–300,000/mm³.

What do the results mean?

A result that is within your reference range is considered normal. This means that you have a normal number of platelets in your blood.

A result that is higher than your reference range means that you have too many platelets in your blood. This may mean that you have:

• A type of cancer, such as leukemia or lymphoma.
• Polycythemia vera. This is when your bone marrow makes extra cells, such as platelets.
• Post-splenectomy syndrome. This can happen after you have surgery to remove your spleen.
• Rheumatoid arthritis.
• Iron deficiency anemia. This is when your body does not make enough red blood cells because of a lack of iron.

A result that is lower than your reference range means that you have too few platelets in your blood. This may mean that you have:

• Hypersplenism. This is when the spleen breaks down platelets faster than it should.
• A lot of blood loss (hemorrhage) or not enough red blood cells (anemia).
• Immune thrombocytopenia. This is when your body's disease-fighting system (immune system) attacks your platelets.
• A type of cancer. Treatments to kill cancer cells, such as chemotherapy, can also cause a low platelet count.
• Thrombotic thrombocytopenia. This is a rare, serious condition that causes blood clots.
• Certain conditions like alcohol use disorder and hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. HELLP syndrome can occur when you are pregnant.
• Certain disorders that are passed from parent to child (inherited).
• Disseminated intravascular coagulation (DIC). This can cause blood clots to form and block blood vessels.
• Systemic lupus erythematosus (SLE). This can cause long-term inflammation and pain in many parts of the body.
• Infection.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?