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


Treatment for reactive thrombocytosis is directed at the underlying cause. If a recent surgery or an injury that caused significant blood loss is the cause, your elevated platelet count may not last long. If the cause is a chronic infection or an inflammatory disease, your platelet count may remain high until the condition is brought under control. In most cases, your platelet count will return to normal after the underlying cause is resolved.

If you have reactive thrombocytosis, it is unlikely that you will need drugs or a medical procedure to lower your platelet count. It is also unlikely that you will experience blood clotting or bleeding.

Removal of your spleen (splenectomy) may cause lifelong thrombocytosis, but you are unlikely to need treatment.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

Preparing for your appointment

It's likely that a routine blood test showing a high platelet count will be your first indication that you have thrombocytosis.

Besides taking your medical history, examining you physically and running tests, your doctor may ask you about factors that could affect your platelets, such as any recent surgical procedures, blood transfusions or infections. You may be referred to a doctor who specializes in blood diseases (hematologist).

Your doctor will look for what's causing your high platelet count, including determining whether it's reactive thrombocytosis due to an underlying condition or whether there's no apparent cause, which could indicate essential thrombocythemia or another bone marrow disorder.

Here's some information to help you get ready and to know what to expect from your doctor.

What you can do

  • Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason you are scheduling your appointment.
  • Write down your health history, including recent infections, surgical procedures, bleeding and anemia.
  • Write down key personal information, including any major stresses or recent life changes.
  • Make a list of all medications, vitamins and supplements that you're taking.
  • Take a family member or friend along. Sometimes it can be difficult to take in all the information you hear during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

For thrombocytosis, some basic questions to ask include:

  • What kinds of tests do I need?
  • Is my condition temporary or chronic?
  • What treatment do you recommend?
  • Will I need to take medication?
  • Will I have any side effects from the treatment?
  • What kind of follow-up will I need?
  • Do I need to restrict my activity?
  • What are possible complications of my condition?
  • I have other health conditions. How can I best manage them together?
  • Should I see a specialist?
  • Do you have any brochures or other printed material that I can take with me?
  • What websites do you recommend?

Don't hesitate to ask other questions that occur to you during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

  • What signs and symptoms have you noticed?
  • When did you first notice these signs and symptoms?
  • Have they gotten worse over time?
  • Have you had a recent medical procedure or blood transfusion?
  • Have you had a recent infection or vaccine?
  • Do you drink alcohol?
  • Do you have headaches, dizziness or weakness?
  • Do you have any chest pain?
  • Have you had any vision problems?
  • Have you had any bleeding or bruising?
  • Have you experienced any numbness or tingling in your hands or feet?
  • Do you have a family history of high platelet counts?

Thrombocytosis care at Mayo Clinic

April 07, 2018
  1. Tefferi A. Approach to the patient with thrombocytosis. http://www.uptodate.com/home. Accessed June 15, 2015.
  2. What are thrombocythemia and thrombocytosis? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/thrm/. Accessed June 15, 2015.
  3. Reactive thrombocytosis. Merck Manual Professional Edition. http://www.merckmanuals.com/professional/hematology-and-oncology/myeloproliferative-disorders/reactive-thrombocytosis-secondary-thrombocythemia. Accessed June 16, 2015.
  4. Sulai NH, et al. Why does my patient have thrombocytosis? Hematology/Oncology Clinics of North America. 2012;26:285.
  5. Kitchens CS, et al. Thrombocytosis. In: Consultative Hemostasis and Thrombosis. 3rd ed. Philadelphia, Pa.: Saunders Elsevier; 2013. http://www.clinicalkey.com. Accessed June 16, 2015.
  6. Mesa RA (expert opinion). Mayo Clinic, Phoenix/Scottsdale, Ariz. June 22, 2015.