High platelets, medically known as thrombocytosis, means having an abnormally elevated number of platelets in the blood, typically above 450,000 platelets per microliter (normal range is about 150,000 to 450,000)

. Platelets are small blood cells that help with clotting to stop bleeding when injuries occur. There are two main types of thrombocytosis:

• Primary (essential) thrombocytosis: This is a rare blood disorder where the bone marrow produces too many platelets due to genetic mutations (commonly in JAK2, CALR, or MPL genes). This type can cause platelets to malfunction, increasing the risk of dangerous blood clots, which may lead to stroke, heart attack, or other clotting complications

• Secondary (reactive) thrombocytosis: This is more common and occurs as a reaction to another condition such as infection, inflammation, iron deficiency, surgery, trauma, cancer, or certain medications. In this case, the elevated platelet count is usually temporary and resolves when the underlying issue is addressed

Symptoms of high platelet counts may be absent, but when present, they often relate to clotting problems such as headaches, chest pain, weakness, confusion, or shortness of breath. Less commonly, very high platelet levels can cause bleeding issues like nosebleeds or bruising

. High platelet counts require medical evaluation to determine the cause and appropriate treatment, especially to prevent serious complications like blood clots or bleeding