High hemoglobin may be due to physiological factors, or it may be caused by diseases such as tetralogy of Fallot and obstructive emphysema. And high hemoglobin may lead to thrombosis, insufficient blood perfusion and so on. 1. Causes (1) Generally newborns and highland residents will have physiologically high hemoglobin. (2) Patients with tetralogy of Fallot, obstructive emphysema, pulmonary heart disease, congenital or acquired cardiopulmonary disease, cyanotic congenital heart disease, pulmonary arterio-venous fistula, true erythrocytosis, dehydration, etc. may cause pathologically high hemoglobin. 2. Harm High hemoglobin is often accompanied by thrombocytosis, which may lead to thrombosis. If the thrombus blocks the arteries of the lower limbs, it may cause intermittent claudication. If the thrombus blocks the cerebral artery, it may cause cerebral infarction or limb paralysis. In addition, high hemoglobin will also increase the blood viscosity, at this time the blood flow will be slowed down, the patient will have dizziness, fatigue, tinnitus, excessive sweating, numbness of the extremities and other symptoms. Physiological high hemoglobin does not need to be treated, but if the patient has a pathologically high hemoglobin, he needs to consult a doctor in time, and the doctor will choose the appropriate treatment for the cause of the disease.