High blood erythrocytes means that the number of red blood cells in the peripheral blood exceeds the normal range. There are various reasons for high blood erythrocytes, and the common ones are: First, when blood is drawn in the morning on an empty stomach, the blood is concentrated due to the lack of food and water during the night, and there may be a relative increase in the number of red blood cells when doing routine blood tests. Second, if you smoke for a long time, it may cause an abnormally high number of red blood cells, and often after you quit smoking, the number of red blood cells may drop to normal. Chronic hypoxic diseases, such as chronic bronchial asthma, chronic obstructive pulmonary disease, congenital cyanotic heart disease, etc., due to long-term hypoxia, the body erythropoietin concentration increases, the red blood cells appear significantly high. Fourth, true erythrocytosis, which is a myeloproliferative disease, will appear abnormally high number of red blood cells.