The red blood cell count is a measurement of the number of red blood cells per unit volume of peripheral blood and is one of the most common tests used to diagnose diseases such as anemia. Normally, the red blood cell count is greater than 5.5 x 10^12/L in adult females and 6.0 x 10^12/L in adult males, and if it is higher than this range, the red blood cell count is considered high. High erythrocyte count is divided into relative high and absolute high, which are analyzed as follows: 1. Relative high: mainly caused by a decrease in the patient’s blood volume, resulting in a relative increase in red blood cell volume, commonly seen in severe vomiting, diarrhea, profuse sweating, extensive burns, chronic hyperalgesia, uremia, hyperthyroidism, diabetic ketoacidosis, etc.; 2. Absolute high: mainly It is caused by long-term hypoxic environment or hypoxic diseases, commonly found in residents of highland areas, patients with severe chronic cardiopulmonary diseases, such as obstructive emphysema and pulmonary heart disease, etc. Due to low oxygen saturation, erythropoietin compensates for the increase, resulting in a high red blood cell count. In addition, high red blood cell counts can also be seen in true erythrocytosis, a myeloproliferative disorder that may initially be only high and may gradually manifest as a significant increase.