Question: What is (are) Thrombocythemia and Thrombocytosis ?
Answer: Thrombocythemia (THROM-bo-si-THE-me-ah) and thrombocytosis (THROM-bo-si-TO-sis) are conditions in which your blood has a higher than normal number of platelets (PLATE-lets). Platelets are blood cell fragments. They're made in your bone marrow along with other kinds of blood cells. Platelets travel through your blood vessels and stick together (clot). Clotting helps stop any bleeding that may occur if a blood vessel is damaged. Platelets also are called thrombocytes (THROM-bo-sites) because a blood clot also is called a thrombus. A normal platelet count ranges from 150,000 to 450,000 platelets per microliter of blood. Overview The term "thrombocythemia" is preferred when the cause of a high platelet count isn't known. The condition sometimes is called primary or essential thrombocythemia. This condition occurs if faulty cells in the bone marrow make too many platelets. Bone marrow is the sponge-like tissue inside the bones. It contains stem cells that develop into red blood cells, white blood cells, and platelets. What causes the bone marrow to make too many platelets often isn't known. With primary thrombocythemia, a high platelet count may occur alone or with other blood cell disorders. This condition isn't common. When another disease or condition causes a high platelet count, the term "thrombocytosis" is preferred. This condition often is called secondary or reactive thrombocytosis. Secondary thrombocytosis is more common than primary thrombocythemia. Often, a high platelet count doesn't cause signs or symptoms. Rarely, serious or life-threatening symptoms can develop, such as blood clots and bleeding. These symptoms are more likely to occur in people who have primary thrombocythemia. Outlook People who have primary thrombocythemia with no signs or symptoms don't need treatment, as long as the condition remains stable. Other people who have this condition may need medicines or procedures to treat it. Most people who have primary thrombocythemia will live a normal lifespan. Treatment and outlook for secondary thrombocytosis depend on its underlying cause.
Source: NHLBI

Question: What causes Thrombocythemia and Thrombocytosis ?
Answer: Primary Thrombocythemia In this condition, faulty stem cells in the bone marrow make too many platelets. What causes this to happen usually isn't known. When this process occurs without other blood cell disorders, it's called essential thrombocythemia. A rare form of thrombocythemia is inherited. ("Inherited" means the condition is passed from parents to children through the genes.) In some cases, a genetic mutation may cause the condition. In addition to the bone marrow making too many platelets, the platelets also are abnormal in primary thrombocythemia. They may form blood clots or, surprisingly, cause bleeding when they don't work well. Bleeding also can occur because of a condition that develops called von Willebrand disease. This condition affects the blood clotting process. After many years, scarring of the bone marrow can occur. Secondary Thrombocytosis This condition occurs if another disease, condition, or outside factor causes the platelet count to rise. For example, 35 percent of people who have high platelet counts also have cancermostly lung, gastrointestinal, breast, ovarian, and lymphoma. Sometimes a high platelet count is the first sign of cancer. Other conditions or factors that can cause a high platelet count are: Iron-deficiency anemia (uh-NEE-me-uh) Hemolytic (HEE-moh-lit-ick) anemia Absence of a spleen (after surgery to remove the organ) Inflammatory or infectious diseases, such as connective tissue disorders, inflammatory bowel disease, and tuberculosis Reactions to medicine Some conditions can lead to a high platelet count that lasts for only a short time. Examples of such conditions include: Recovery from serious blood loss Recovery from a very low platelet count caused by excessive alcohol use and lack of vitamin B12 or folate Acute (short-term) infection or inflammation Response to physical activity Although the platelet count is high in secondary thrombocytosis, the platelets are normal (unlike in primary thrombocythemia). Thus, people who have secondary thrombocytosis have a lower risk of blood clots and bleeding.
Source: NHLBI

Question: What are the symptoms of Thrombocythemia and Thrombocytosis ?
Answer: People who have thrombocythemia or thrombocytosis may not have signs or symptoms. These conditions might be discovered only after routine blood tests. However, people who have primary thrombocythemia are more likely than those who have secondary thrombocytosis to have serious signs and symptoms. The signs and symptoms of a high platelet count are linked to blood clots and bleeding. They include weakness, bleeding, headache, dizziness, chest pain, and tingling in the hands and feet. Blood Clots In primary thrombocythemia, blood clots most often develop in the brain, hands, and feet. But they can develop anywhere in the body, including in the heart and intestines. Blood clots in the brain may cause symptoms such as chronic (ongoing) headache and dizziness. In extreme cases, stroke may occur. Blood clots in the tiny blood vessels of the hands and feet leave them numb and red. This may lead to an intense burning and throbbing pain felt mainly on the palms of the hands and the soles of the feet. Other signs and symptoms of blood clots may include: Changes in speech or awareness, ranging from confusion to passing out Seizures Upper body discomfort in one or both arms, the back, neck, jaw, or abdomen Shortness of breath and nausea (feeling sick to your stomach) In pregnant women, blood clots in the placenta can cause miscarriage or problems with fetal growth and development. Women who have primary thrombocythemia or secondary thrombocytosis and take birth control pills are at increased risk for blood clots. Blood clots are related to other conditions and factors as well. Older age, prior blood clots, diabetes, high blood pressure, and smoking also increase your risk for blood clots. Bleeding If bleeding occurs, it most often affects people who have platelet counts higher than 1million platelets per microliter of blood. Signs of bleeding include nosebleeds, bruising, bleeding from the mouth or gums, or blood in the stools. Although bleeding usually is associated with a low platelet count, it also can occur in people who have high platelet counts. Blood clots that develop in thrombocythemia or thrombocytosis may use up your body's platelets. This means that not enough platelets are left in your bloodstream to seal off cuts or breaks on the blood vessel walls. Another cause of bleeding in people who have very high platelets counts is a condition called von Willebrand Disease. This condition affects the blood clotting process. In rare cases of primary thrombocythemia, the faulty bone marrow cells will cause a form of leukemia (lu-KE-me-ah). Leukemia is a cancer of the blood cells.
Source: NHLBI

Question: How to prevent Thrombocythemia and Thrombocytosis ?
Answer: You can't prevent primary thrombocythemia. However, you can take steps to reduce your risk for complications. For example, you can control many of the risk factors for blood clots, such as high blood cholesterol, high blood pressure, diabetes, and smoking. To reduce your risk, quit smoking, adopt healthy lifestyle habits, and work with your doctor to manage your risk factors. It's not always possible to prevent conditions that lead to secondary thrombocytosis. But, if you have routine medical care, your doctor may detect these conditions before you develop a high platelet count.
Source: NHLBI