what is platelet
Platelets are tiny blood cells that help your body form clots to stop bleeding. If one of your blood vessels gets damaged, it sends out signals that are picked up by platelets. The platelets then rush to the site of damage and form a plug, or clot, to repair the damage.n this condition, your bone marrow makes too many platelets. People with thrombocythemia may have platelet counts that exceed 1 million. Symptoms can include blood clots that form and block blood supply to the brain or the heart. The cause of thrombocythemia is unknown.