Iron deficiency anemia appears as weak pulse manifested as weakness, easy tiredness, dizziness, headache, tinnitus, palpitation, shortness of breath, poor nausea; with pallor, increased heart rate. Tissue iron deficiency manifestations: abnormal mental behavior, such as irritability, irritability, inattention, heterophagia; decreased physical strength and endurance; easy infection; children’s growth retardation, mental retardation; stomatitis, tongue inflammation, tongue papillae atrophy, stomatitis, iron deficiency swallowing difficulties; dry hair, shedding; dry, wrinkled skin; finger (toe) nail lack of luster, brittle and easy to crack, and in severe cases, finger (toe) nail flattening, or even concave in the shape of spoon (spatulate nail). Iron deficiency primary manifestations: such as peptic ulcer, tumor or hemorrhoids caused by black stool, bloody stool or abdominal discomfort, intestinal parasitic infections caused by abdominal pain or stool trait changes, women with excessive menstruation, tumor disease wasting, intravascular hemolysis of hemoglobinuria, etc.. The following tests are required: 1. Blood picture: small cell hypochromic anemia is present. Mean red blood cell volume (MCV) is less than 80fl, mean red blood cell hemoglobin volume (MCH) is less than 27pg, and mean red blood cell hemoglobin concentration (MCHC) is less than 32%. Small erythrocyte volume and enlarged central faintly stained area are seen in the blood film. Reticulocyte count was normal or mildly increased. The white blood cell and platelet counts are normal or reduced. Bone marrow picture: active or apparently active proliferation; red lineage proliferation is predominant, granulocyte and megakaryocyte lineages have no obvious abnormalities; red lineage is dominated by middle and late juvenile erythrocytes, with small size, dense nuclear chromatin, little blue cytoplasm and uneven margins, and poor hemoglobin formation, showing the phenomenon of “old nuclear plasma and young”. Iron metabolism: serum iron is lower than 8.95μmol/L, total iron binding capacity is higher than 64.44μmol/L; transferrin saturation is lower than 15%, sTfR concentration is more than 8mg/L. Serum ferritin is lower than 12μg/L. After bone marrow smear is stained with potassium ferricyanide (Prussian blue reaction), there are no dark blue iron-containing heme particles in the bone marrow granules; young The iron granules in erythrocytes were reduced or disappeared, and the iron granules in young erythrocytes were less than 15%. 4. Intra-erythrocytic porphyrin metabolism: FEP > 0.9 μmol/L (whole blood), ZPP > 0.96 μmol/L (whole blood), FEP/Hb > 4.5 μg/gHb.