What is a high platelet level?

A high platelet level, also known as thrombocytosis, refers to an elevated platelet count in the blood. Thrombocytosis can be categorized as primary or secondary. Primary thrombocytosis, also called essential thrombocythemia, occurs when there is an abnormality in the bone marrow leading to an overproduction of platelets. Secondary thrombocytosis is typically a reactive response to an underlying condition, such as infection, inflammation, iron deficiency, or certain cancers. A high platelet level is diagnosed when the platelet count exceeds the upper limit of the laboratory reference range, usually above 450,000 platelets per microliter of blood. It is important to consult with a healthcare professional for proper evaluation and management of high platelet levels.