Primary thrombocythemia, also known as essential thrombocythemia, is a rare blood clotting disorder that causes bone marrow to produce too many platelets. Bone marrow is the sponge-like tissue inside your bones. It contains cells that produce red blood cells, white blood cells, and platelets. Red blood cells carry oxygen and nutrients, white blood cells help fight infections, and platelets enable blood clotting.
A high platelet count can cause blood clots to develop spontaneously. Normally, your blood begins to clot to prevent a massive loss of blood after an injury. In people with primary thrombocythemia, however, blood clots can form suddenly and for no apparent reason. Abnormal blood clotting can be dangerous, as blood clots may block the flow of blood to the brain, liver, heart, and other vital organs.
People with primary thrombocythemia may experience dizziness, headaches, or numbness in the upper and lower body. They are also at risk for serious complications, such as a stroke or heart attack.
Primary thrombocythemia is most common among women and people over age 50. However, the condition can also affect younger people. The diagnosis is usually made after a physical examination and a series of blood tests.
Although there’s no cure for primary thrombocythemia, there are treatments than can help relieve symptoms. Treatment varies from person to person. Smokers and people with a history of blood clots may need medications to reduce their platelet count, while others may not need any treatment.
Primary thrombocythemia occurs when your body produces too many platelets, which can lead to abnormal clotting. However, the exact cause for this is unknown. According to the Mayo Clinic, approximately 80 percent of people with primary thrombocythemia have a gene mutation in the Janus kinase 2 (JAK2) gene. This gene is responsible for making a protein that promotes the growth and division of cells.
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 of thrombocythemia, inherited thrombocythemia, is very rare.
Primary thrombocythemia usually doesn’t cause symptoms. A blood clot may be the first sign that something is wrong. Blood clots can develop anywhere in your body, but they’re more likely to form in your feet, hands, or brain. The symptoms of a blood clot can vary depending on where the clot is located, but symptoms generally include:
- lightheadedness or dizziness
- numbness or tingling in your feet or hands
- redness, throbbing, and burning pain in your feet or hands
- changes in vision
- chest pain
- a slightly enlarged spleen
In rare cases, the condition can cause bleeding, which may occur in the form of:
- easy bruising
- bleeding from your gums or mouth
- bloody urine
- bloody stool
Women who have primary thrombocythemia and also take birth control pills have a higher risk of blood clots. The condition is also particularly dangerous for women who are pregnant. A blood clot located in the placenta can lead to problems with fetal development, or miscarriage.
A blood clot can cause a transient ischemic attack (TIA) or a stroke. Symptoms of stroke include:
- blurred vision
- weakness or numbness in the arm, leg, or face
- shortness of breath
- difficulty speaking
People with primary thrombocythemia 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
Call your doctor or go to the hospital immediately if you have symptoms of a blood clot, heart attack, or stroke. These conditions are considered medical emergencies and require immediate treatment.
Your doctor will first perform a physical examination and ask you about your medical history. Make sure to mention any blood transfusions, infections, and medical procedures you’ve had in the past. You should also tell your doctor about any prescription and over-the-counter medications and supplements you’re taking.
If primary thrombocythemia is suspected, your doctor will run certain blood tests to confirm the diagnosis. Blood tests may include:
- a complete blood count (CBC) to measure the number of platelets in your blood
- a blood smear to examine the condition of your platelets
- genetic testing to determine whether you have an inherited condition that causes a high platelet count
Other diagnostic testing may include bone marrow aspiration to examine your platelets under a microscope. This procedure involves taking a sample of bone marrow tissue in liquid form. It’s typically extracted from the breastbone or pelvis.
You will most likely be diagnosed with primary thrombocythemia if your doctor can’t find a cause for your high platelet count.
Your treatment plan will depend on a number of factors, including your risk of developing blood clots.
You may not need treatment if you don’t have any symptoms or additional risk factors. Instead, your doctor may choose to carefully monitor your condition. Treatment may be recommended if you:
- are over age 60
- 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 blood clotting
- prescription medications to lower the risk of clotting or to reduce platelet production in the bone marrow
- platelet pheresis, which is a procedure to remove platelets directly from the blood
Your outlook depends on a variety of factors. Most people don’t experience any complications for a long time. However, serious complications can occur, including:
- heavy bleeding
- heart attack
- pregnancy complications, such as high blood pressure (preeclampsia), premature delivery, and miscarriage
Bleeding issues are rare, but may lead to complications, such as:
- acute leukemia, which is a type of blood cancer
- myelofibrosis, which is a progressive bone marrow disorder
There’s no known way to prevent primary thrombocythemia. However, if you’ve recently been diagnosed with primary thrombocythemia, there are some things you can do to lower your risk of serious complications. The first step is managing any risk factors for blood clots. Controlling your blood pressure, cholesterol, and conditions such as diabetes can help reduce the risk of blood clots. You can do this by exercising regularly and eating a diet that largely consists of fruits, vegetables, whole grains, and lean protein. It’s also important to quit smoking, as smoking increases your risk of blood clots.
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
- avoiding contact sports or activities that increase the risk of bleeding
- promptly reporting abnormal bleeding or symptoms of blood clots to your doctor
Before any dental or surgical procedures, make sure to tell your dentist or doctor about any medications you may be taking to lower your platelet count.