Symptoms

People with thrombocytosis often don't have signs or symptoms. Signs and symptoms of reactive thrombocytosis, if they do occur, relate to the underlying condition.

People with essential thrombocythemia might have signs and symptoms related to blood clots and bleeding, including:

• Headache
• Dizziness or lightheadedness
• Chest pain
• Weakness
• Numbness or tingling of the hands and feet

When to see a doctor

Because thrombocytosis isn't likely to cause symptoms, you probably won't know you have it unless a routine blood test reveals a higher than normal number of platelets. If that occurs, your doctor will try to determine the reason.