Platelets are extremely small blood cells that have an important role in initiating the blood clotting process. When platelet levels become too high (thrombocythemia or thrombocytosis), there's a risk for thrombotic complications such as venous thromboembolism. More typically, individuals with high platelet counts do not usually require any treatment, as long as their condition remains stable. In some cases, however, high platelet counts can be the result of a serious underlying condition.
Primary Thrombocythemia
Primary thrombocythemia is a condition in which blood stem cells in the bone marrow produce too many platelets. The National Heart Lung and Blood Institute explains that the exact causes of this condition are not known. A rare form of thrombocythemia is genetically inherited and may be caused by a specific genetic mutation. Individuals with primary thrombocythemia often have abnormally functioning platelets that can cause either excessive clotting or excessive bleeding.
Iron-Deficient Anemia
The American Leukemia and Lymphoma Society explains that individuals with iron-deficient anemia may have high platelet counts. Iron is an important component of hemoglobin, a compound used by red blood cells to transport oxygen. Why low iron levels and low red blood cell levels have increased platelet numbers is unclear. One possibility is that low red blood cell levels may cause a feedback mechanism to cause more blood cell production in general by the bone marrow, which consequently increases platelet levels.
Cancer
According to the American Leukemia and Lymphoma Society, certain cancers can also cause high platelet counts. Although platelet counts should not be used to diagnose cancer, it is common knowledge among oncologists that cancer patients often have high levels of platelets. The manner is which cancer increases platelet levels is mysterious. In some cases, cancer can cause damage to normal tissues, initiating an immune response that signals the bone marrow to produce more blood cells, including platelets.
Spleen Removal
The spleen is a small, fist-shaped organ located in the lower abdomen, and plays an important role in blood cell homeostasis. The spleen helps to remove blood cells, including platelets, from the blood stream to regulate the number of blood in circulation. Certain medical conditions may require removing the spleen, a procedure known as a splenectomy. According to the Mayo Clinic, if the spleen is removed, it will no longer be able to collect platelets and the number of platelets in circulation may increase.
