Overview

Thrombocytosis is a disorder in which your body produces too many platelets (thrombocytes), which play an important role in blood clotting. The disorder is called reactive thrombocytosis or secondary thrombocythemia when it's caused by an underlying condition, such as an infection.

Thrombocytosis (throm-boe-sie-TOE-sis) may also, less commonly, be caused by a blood and bone marrow disease. When caused by a bone marrow disorder, thrombocytosis is called autonomous, primary or essential thrombocytosis, or essential thrombocythemia.

Your doctor may detect thrombocytosis in routine blood test results that show a high platelet level. If your blood test indicates thrombocytosis, it's important to determine whether it's reactive thrombocytosis or if you have essential thrombocythemia, which is more likely to cause blood clots.

Source: http://www.mayoclinic.com

Symptoms

Reactive thrombocytosis rarely causes symptoms. More often, signs and symptoms relate to the underlying condition. If symptoms of reactive thrombocytosis do occur, they may include:

• Headache
• Dizziness or lightheadedness
• Chest pain
• Weakness
• Fainting
• Temporary vision changes
• 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 the condition unless a routine blood test reveals a higher than normal number of platelets. If your blood test results show a high platelet count, your doctor will try to determine the reason.

Source: http://www.mayoclinic.com

Causes

Bone marrow — spongy tissue inside your bones — contains stem cells that can become red blood cells, white blood cells or platelets (thrombocytes). Platelets stick together, helping blood to form a clot that stops bleeding when you damage a blood vessel, such as when you get a cut. A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood.

If you have thrombocytosis caused by a bone marrow disorder (essential thrombocythemia), your bone marrow overproduces the cells that form platelets (megakaryocytes), releasing too many platelets into your blood. In essential thrombocythemia, there is a much higher risk of clotting or bleeding complications. Therefore, if your blood test results reveal a high platelet count, it's important for your doctor to determine whether you have essential thrombocythemia or reactive thrombocytosis.

Reactive thrombocytosis causes include:

• Acute bleeding and blood loss
• Burns
• Cancer
• Coronary artery bypass
• Exercise
• Heart attack
• Hemolytic anemia — a type of anemia in which your body destroys red blood cells faster than it produces them, often due to certain blood diseases or autoimmune disorders
• Infections, including tuberculosis
• Inflammation, such as from rheumatoid arthritis, celiac disease, connective tissue disorders or inflammatory bowel disease
• Iron deficiency
• Major surgery
• Pancreatitis
• Removal of your spleen
• Trauma
• Vitamin deficiency

Medications that can cause reactive thrombocytosis include:

• Epinephrine (AUVI-Q, EpiPen, others)
• Tretinoin (Retin-A, Renova, others)
• Vincristine Sulfate (Marqibo Kit)
• Heparin sodium

Diagnosis

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

Source: http://www.mayoclinic.com