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Primary Thrombocythemia
Find information on primary thrombocythemia symptoms, causes, diagnosis, and treatment.

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Primary Thrombocythemia

Primary thrombocythemia is a rare blood clotting disorder that causes bone marrow (the sponge-like tissue inside your bones) to produce too many platelets (small blood components that help with clotting) with no known cause. According to the National Library of Medicine (NLM), this disorder typically affects people in middle age, and is more common among women (NLM, 2011).

Having a high platelet count can cause blood clots to develop in the body, typically in the hands, feet, and brain. This may produce symptoms such as dizziness, headache, or numbness in the extremities. Serious complications, like stroke and heart attack can occur.

Diagnosis is generally made after a physical examination and a series of blood tests. Treatment varies from person to person. Smokers and people with a history of blood clots may need medications to reduce platelet count, while others with may only need to monitor their condition.

The long-term outlook depends on your particular symptoms and risk factors.

This condition is sometimes called essential thrombocythemia. When your platelet count is too high due to a specific disease or condition, it is called secondary or reactive thrombocytosis. Primary thrombocythemia is less common than secondary thrombocytosis. Another form, inherited thrombocythemia, is rare.

Cause of Primary Thrombocythemia

Your bone marrow contains stem cells that are destined to become platelets. These platelets help to form clots, which help to stop the bleeding when you are injured. In primary thrombocythemia, your bone marrow produces too many platelets, which can lead to abnormal clotting.

The exact cause for this is not known. According to the Mayo Clinic, approximately half of people with this disorder also have a mutation in the Janus kinase 2 (JAK2) gene, which helps make a protein that promotes the growth and division of cells. However, the role of this gene mutation in causing primary thromocythemia is still being investigated (Mayo Clinic, 2010).

Risk Factors for Developing Primary Thrombocythemia

This condition is not common. According to the National Heart, Lung and Blood Institute (NHLBI), it is estimated that 24 out of every 100,000 people have primary thrombocythemia (NHLBI, 2012).

It can develop at any age, but usually affects people between 50 and 70 years of age. Women around age 30 have more risk than men of that age. The reason for this is unknown.

Signs and Symptoms of Primary Thrombocythemia

There are often no symptoms. A blood clot may be the first sign that something is wrong. Clots can occur anywhere in your body, but are more likely to develop in your feet, hands, or brain. Symptoms of a blood clot vary according to location and may include:

  • headache
  • lightheadedness, dizziness
  • weakness, fainting
  • numbness, tingling, throbbing, or pain in your feet or hands
  • changes in vision
  • chest pain
  • a slightly enlarged spleen

A less common symptom of this condition is bleeding, which can occur in the form of:

  • easy bruising
  • bleeding from your gums or mouth
  • nosebleeds
  • bloody urine
  • bloody stool


If you are pregnant, a blood clot located in the placenta can lead to problems with fetal development or miscarriage. Women who have this condition and also take birth control pills have a higher risk of blood clots.

A blood clot can cause a transient ischemic attack (TIA) or a stroke. Symptoms of stroke include:

  • blurred vision
  • weakness or numbness of your arm, leg, or face, generally on one side of your body
  • confusion, difficulty understanding speech
  • difficulty speaking
  • seizures
  • shortness of breath

People with this condition are also at risk for heart attack, as blood clots may block the flow of blood to the heart. Symptoms of a heart attack include:

  • clammy skin
  • squeezing pain in the chest that lasts for more than a few minutes
  • shortness of breath
  • pain that extends to your shoulder, arm, back, or jaw

If you have symptoms of a blood clot, heart attack or stroke, contact your healthcare provider immediately. Prompt medical attention is required.

Diagnosing Primary Thrombocythemia

Sometimes thrombocythemia is discovered upon routine blood testing. If you have symptoms of thrombocythemia, your doctor will perform a thorough medical examination. Be prepared to give a complete medical history, including blood transfusions, infections, and medical procedures. List all your prescription and over-the-counter medications and supplements.

Blood tests may include:

  • complete blood count (CBC) to measure the number of platelets in your blood
  • blood smear to examine the condition of your platelets
  • genetic testing to find out if you have an inherited condition that can cause a high platelet count

If your blood platelet level is too high, your doctor will try to determine if you have an underlying disease or condition. Other diagnostic testing may include bone marrow aspiration and biopsy to examine your platelets under a microscope. This procedure involves taking a sample of bone marrow tissue in liquid form, which is typically extracted from the breast bone or pelvis.

If no cause for your high platelet count is found, you will most likely be diagnosed with primary thrombocythemia.

Treatment for Primary Thromocythemia

Your individual treatment plan will depend on a variety of factors, including your risk of developing clots.

If you have no symptoms or additional risk factors, your doctor may decide no treatment other than careful monitoring is necessary. Treatment may be recommended if you:

  • are over 60 years old
  • are a smoker
  • have other medical conditions such as diabetes or cardiovascular disease
  • have a history of bleeding or blood clots

Treatment may include:

  • over-the-counter, low-dose aspirin to reduce the platelets ability to bind
  • prescription medications to reduce the risk of clotting or to suppress platelet production in the bone marrow
  • platelet pheresis (a procedure to remove platelets directly from the blood)

Long-Term Outlook for Primary Thrombocythemia

Your individual outlook depends on a variety of factors. Most people enjoy long periods with no complications. Serious complications include:

  • complications of pregnancy, such as high blood pressure (preeclampsia),separation of the placenta (placental abruption), problems with fetal development, premature delivery, and miscarriage
  • bleeding (hemorrhage)
  • stroke
  • heart attack

Bleeding issues are rare, but may lead to serious complications, such as:

  • acute leukemia (a type of blood cancer)
  • myelofibrosis (a progressive bone marrow disorder)

Living with Primary Thrombocythemia

Unfortunately, because the cause of this condition is unknown, there is no evidence suggesting that it can be prevented. However, if you have been diagnosed with primary thrombocythemia, there are some things you can do to lower your risk of serious complications. Managing risk factors for blood clots is typically the first line of defense. Controlling your blood pressure and cholesterol and managing conditions like diabetes can help reduce the risk of blood clots. Smoking also increases risk. If you smoke, talk to your doctor about smoking cessation programs.

Other behaviors that reduce risk for serious complications include:

  • taking all medications as prescribed
  • avoiding over-the-counter pain or cold medications that increase the risk of bleeding
  • maintaining a healthy diet and exercise routine
  • avoiding contact sports or activities that increase the risk of bleeding
  • promptly reporting bleeding or symptoms of blood clots to your doctor

If you are taking medication to lower your platelet count, always inform your dentist or doctor before dental or surgical procedures.

Written by: Ann Pietrangelo
Edited by:
Medically Reviewed by:
Published: Sep 11, 2012
Published By: Healthline Networks, Inc.
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