How Is Thrombocytopenia Diagnosed?

Your doctor will diagnose thrombocytopenia based on your medical history, a physical exam, and test results. A hematologist also may be involved in your care. This is a doctor who treats blood diseases.

Once thrombocytopenia is diagnosed, your doctor will begin looking for its cause.

Medical History

Your doctor may ask you about factors that can affect your platelets, such as:

• The medicines you take, including over-the-counter medicines and herbal remedies, and whether you drink beverages that contain quinine
• Your general eating habits, including the amount of alcohol you normally drink
• Your risk for AIDS, including questions about blood transfusions, sexual partners, intravenous (IV) drugs, and exposure to infectious blood or bodily fluids at work
• Any family history of low platelet counts

Physical Exam

Your doctor will do a physical exam to look for signs and symptoms of bleeding, such as bruises or spots on the skin. He or she will check your abdomen for signs of an enlarged spleen or liver. You also will be checked for signs of infection, such as a fever.

Diagnostic Tests

Your doctor may order one or more of the following tests to help diagnose a low platelet count. For more information on blood tests, see the Diseases and Conditions Index Blood Tests article.

Complete Blood Count

A complete blood count (CBC) measures the levels of red blood cells, white blood cells, and platelets in your blood. For this test, a small amount of blood is drawn from a blood vessel, usually in your arm.

If you have thrombocytopenia, the results of this test will show that your platelet count is low.

Blood Smear

A blood smear is used to check the appearance of your platelets under a microscope. For this test, a small amount of blood is drawn from a blood vessel, usually in your arm.

Bone Marrow Tests

Bone marrow tests check whether your bone marrow is healthy. Blood cells, including platelets, are made in bone marrow. The two bone marrow tests are aspiration (as-pi-RA-shun) and biopsy.

Bone marrow aspiration may be done to find out why your bone marrow isn't making enough blood cells. For this test, your doctor removes a small amount of fluid bone marrow through a needle. He or she examines the sample under a microscope to check for abnormal cells.

A bone marrow biopsy often is done right after an aspiration. For this test, your doctor removes a small amount of bone marrow tissue through a needle. Your doctor examines the tissue to check the number and types of cells in the bone marrow.

Other Tests

If a bleeding problem is suspected, you may need other blood tests as well. For example, tests called PT and PTT may be done to see whether your blood is clotting properly.

Your doctor may order an ultrasound to check your spleen. An ultrasound uses sound waves to create pictures of your spleen. This will allow your doctor to see whether your spleen is enlarged.