Depends on cause. Increase platelet count may be due to iron deficiency and easily treatable. However, there more serious caused of thrmbocytosis, e.g., leukemia. See your doctor to determine the cause.
Thrombocytosis. You really need to work with your hematologist--depending how high platelets, genetic factors, your bone marrow tretment low dose aspirin, hydroxyurea, anagrelide--also weght loss, stopping smoking, hydration--the fear is blood clots.