High hemoglobin levels are a rare occurrence but is usually treated as a symptom for an underling disease. Consulting a doctor is the best treatment, so he/she can diagnose your illness and give a recommended treatment plan to lower hemoglobin levels back to normal.
Hemoglobinemia
Thalassemia
Sideroblastic anemia
Myelophthisic anemia
Alpha-thalassemia
Megaloblastic anemia
Beta thalassemia
Paroxysmal nocturnal hemoglobinuria