Essential thrombocythemia is an uncommon disorder in which your body produces too many blood platelets (thrombocytes). It's also known as primary thrombocythemia (throm-boe-sigh-THEE-me-uh).
The most common symptoms of essential thrombocythemia include headache, lightheadedness, vision changes, and tingling, numbness or burning pain in the hands and feet. Essential thrombocythemia most often occurs in people over age 50 and is more common in women.
You may not need treatment for essential thrombocythemia if you don't have symptoms. If you have abnormal blood clotting or bleeding, however, medications can help you avoid potentially serious complications.