What does a high platelet count in a CBC test indicate?

A high platelet count, known as thrombocytosis, may result from various conditions. It can be caused by infections, inflammation, or iron deficiency. In some cases, high platelet levels might indicate bone marrow disorders such as essential thrombocythemia or polycythemia vera, which cause the body to produce too many platelets. Elevated platelet counts increase the risk of blood clots, so your doctor may recommend additional testing or treatments to reduce the risk of complications like stroke or heart attack, depending on the underlying cause.