Thrombocytosis

Thrombocytosis is a condition that causes a high platelet count, meaning your body has more platelets than normal. Platelets are blood cells that help stop bleeding by forming clots. While platelets play an important role in healing, elevated platelets can sometimes increase the risk of blood clots and related complications.

Because thrombocytosis can have different causes, getting the right diagnosis is an important first step. At Penn Medicine, hematologists use advanced testing to determine what’s causing your high platelet count and whether treatment is needed. From routine monitoring to care for more complex blood clotting disorders, you’ll receive expert guidance focused on lowering your risk of complications and supporting your long-term health.

Many people with thrombocytosis don’t have symptoms. When symptoms do occur, they’re often related to blood clots or bleeding.

Symptoms may include:

• Headaches
• Dizziness or lightheadedness
• Changes in vision
• Chest pain
• Weakness or numbness in part of the body
• Tingling or burning pain in the hands or feet
• Easy bruising
• Frequent nosebleeds or bleeding gums

There are two main types of thrombocytosis: primary and secondary.

Primary thrombocytosis, also known as essential thrombocythemia, is a rare type of thrombocytosis that occurs when a bone marrow disorder causes the body to produce too many platelets. It can increase the risk of blood clots, which may lead to complications like heart attack, stroke, or deep vein thrombosis. People with this condition may also have a higher risk of pregnancy complications and, in rare cases, it can progress to myelofibrosis or leukemia.

Secondary thrombocytosis, also called reactive thrombocytosis, is more common and happens when another condition causes platelet levels to rise. In many cases, platelet counts return to normal after the underlying condition is treated.

The causes of thrombocytosis depend on the type.

Primary thrombocytosis develops when changes in certain genes cause the bone marrow to produce too many platelets. These gene changes usually happen during a person’s lifetime, although the exact cause is often unknown. They aren’t typically inherited.

Secondary thrombocytosis can develop as the body’s response to another health condition or event. Common causes include infections, inflammatory diseases, iron deficiency, certain cancers, surgery, major injuries, and recovery after significant blood loss.

Treatment for thrombocytosis depends on your platelet count, the cause of the condition, and your risk of developing blood clots or experiencing abnormal bleeding. Some people may only need periodic monitoring, while others may benefit from medications to lower platelet counts. In rare situations, when platelet counts are very high or causing serious complications, a procedure called plateletpheresis may be used to quickly remove excess platelets from the blood.

Managing thrombocytosis requires specialists with expertise in blood disorders. At Penn Medicine, hematologists evaluate both common and complex causes of thrombocytosis and develop care plans to fit your needs.

When you choose to partner with us, you have access to:

• Hematologists with experience diagnosing and treating thrombocytosis and other blood disorders
• Advanced testing to help determine the cause of elevated platelet counts
• Care for both primary and secondary thrombocytosis
• The latest treatments and clinical trials, when appropriate
• Ongoing monitoring to help lower the risk of blood clots and other complications

Wherever you are in your care journey, our team is here to provide guidance, answer your questions, and support you every step of the way.