Iron deficiency anemia is anemia that occurs when the body’s iron stores cannot meet the needs of normal red blood cell production. The clinical diagnosis can be made by the following tests: 1. Blood picture examination: small-cell hypochromic anemia, small red blood cells in the blood film, enlarged central light stained area, no change in red blood cell count and platelet count; 2. Bone marrow picture examination: active bone marrow hyperplasia, mainly red lineage hyperplasia; 3. Iron metabolism examination: decreased serum iron, increased total iron binding capacity, decreased transferrin saturation, decreased serum ferritin; 4. 4. free protoporphyrin of erythrocytes is elevated; 5. serum transferrin receptor is elevated.