Tests and diagnosis

By Mayo Clinic Staff

You may find out you have thrombocytosis through one of the following tests:

  • A routine blood test. This test may show a higher than normal platelet count.
  • During a physical exam. If your doctor finds that your spleen is enlarged or you have signs or symptoms of an infection or another condition, he or she may order a complete blood count (CBC) to determine your platelet count.
  • A blood smear. Your doctor may examine a small amount of your blood under a microscope to view the size and activity of your platelets.

Because a number of conditions can cause a temporary rise in your platelet count, your doctor likely will repeat the blood tests to see if your platelet count remains high over time.

A normal range for platelets is 150,000 to 450,000 platelets per microliter of blood. If your blood count is above 450,000, your doctor will likely look for an underlying condition. In most cases, signs and symptoms of the underlying condition help guide the diagnosis. Your doctor may also:

  • Check the level of iron in your blood
  • Test for markers of inflammation
  • Order genetic testing to help determine if you have a blood and bone marrow disorder such as essential thrombocythemia
  • Conduct a bone marrow aspiration and biopsy to collect and examine bone marrow tissue
July 10, 2015