Elevated platelet levels or thrombocytosis is caused by a disorder of the bone marrow, known as primary thrombocythemia. It occurs in middle age, and affects women more than men, reveals Mayo Clinic.
The bone marrow has stem cells that form platelets, which help in blood clotting. Elevated platelet levels in primary thrombocythemia causes abnormal clotting. Primary thrombocythemia is not common; it affects 24 in every 100,000 people, according to Healthline Networks. Its exact cause is unknown, but it is linked to gene mutation. Usually, there are no symptoms for primary thrombocythemia but clots in the hands, feet or brain may be the first sign of this disorder. Depending on location, the symptoms of the blood clot include headache, weakness, fainting, dizziness, changes in vision, an enlarged spleen, chest pain and throbbing, pain, numbness or tingling in the hands or feet.
Bleeding may also occur but it is not common. In pregnant women, primary thrombocythemia may cause clots in the placenta, which can lead to problems in fetal development or cause miscarriage, notes Healthline Networks. A blood clot may also cause a stroke, which causes symptoms such as blurred vision, numbness, difficulty speaking, confusion, shortness of breath and seizures. People with primary thrombocythemia also risk having a heart attack. A person who experiences symptoms of a blood clot, stroke or heart attack should see a doctor immediately, advices Healthline Networks.