The normal human peripheral blood count of red blood cells is 4-5.5 million/mL in adult males and 3.5-5 million/mL in adult females, if it exceeds the normal range it is considered high red blood cells. The causes of high erythrocytes include relative and absolute increases. Relative hyperplasia is common in cases of severe dehydration, such as profuse sweating, severe vomiting, diarrhea, and extensive burns, and is caused by a decrease in plasma volume. Absolute hyperplasia is common in cases of severe long-term hypoxia, such as residents of highland areas, severe chronic obstructive pulmonary disease, pulmonary heart disease and cyanotic congenital heart disease, as well as in myeloproliferative disorders such as primary thrombocythemia and true erythropoietic disorders, where there is a persistent increase in red blood cells and a significant increase in hemoglobin.