Having too many platelets in the blood is a sign of either thrombocytosis or thrombocythemia. Thrombocytosis is a response to an infection or a disease in the bone marrow or blood, while thrombocythemia is more likely to lead to blood clotting problems, according to Mayo Clinic.
Normal platelet counts range between 150,000 and 450,000 in each microliter of blood. When a bone marrow or blood disorder has caused the high count, the bone marrow makes too many megakaryocytes, the cells that create platelets. Differentiating between thrombocytosis and thrombocythemia is crucial, as the treatment plans for the two differ. Causes for thrombocytosis include allergic reactions, infections, iron deficiency, heart or kidney failure, some forms of cancer, pancreatitis, and trauma. Epinephrine, vincristine and tretinoin are medications that can lead to thrombocytosis, states Mayo Clinic.
Thrombocythemia does not always present with other symptoms. Problems with vision, hearing, tingling or redness in the hands or feet, and headache are some symptoms, but given the common nature of these symptoms, improper diagnosis is common, according to the National Cancer Institute.
Thrombocythemia is a condition that appears without underlying causes, but thrombocytosis generally has a specific cause; when doctors treat that cause, the platelet count resolves, according to Mayo Clinic. Thrombocythemia requires its own treatment, including platelet removal and medications to keep the platelet count down to avoid clotting, according to the New York Times.