Erythrocyte pressure volume is the volume of red blood cells in the peripheral blood as a percentage of the total blood volume, and mean red blood cell volume is the average volume of each red blood cell in the peripheral blood. Several of the most common diseases associated with low erythropoietic pressure volume and low mean erythrocyte volume are microcytic hypochromic anemia, including iron deficiency anemia, thalassemia, chronic disease anemia, and iron granulocytic anemia, the most common being iron deficiency anemia, especially in the northern part of China. Iron deficiency anemia is very common. Due to iron deficiency, red blood cells cannot synthesize hemoglobin normally, which leads to a lower hemoglobin content in red blood cells, resulting in a decrease in the average volume of red blood cells and also a decrease in the red blood cell pressure volume. If iron supplementation is given, the increase in hemoglobin content in red blood cells, the increase in average red blood cell volume, and the low red blood cell pressure volume will be significantly improved.