A high hemoglobin may be a physiological factor and may also be associated with diarrhea, blood system disorders, and cardiopulmonary diseases. Hemoglobin plays an important role in maintaining the transportation of various elements in the blood. 1. Physiological factors: for example, residents of plateau area, due to long time at high altitude, low oxygen content, the body in order to adapt to the plateau environment, produce more hemoglobin to carry oxygen. 2. Diarrhea: Prolonged diarrhea, vomiting and other causes of plasma water loss, there may be blood concentration, hemoglobin content is relatively high. 3. Hematologic diseases: such as true erythrocytosis, in addition to the obvious increase in hemoglobin, it is also accompanied by enlargement of the spleen, hypertension and other manifestations. 4. Cardiopulmonary diseases: such as tetralogy of Fallot, chronic obstructive pulmonary emphysema, etc., can also cause hemoglobin increase. There are other causes of hemoglobin increase, and patients are advised to seek medical treatment as soon as possible to avoid delaying their condition.