In children, anemia can affect growth and development, leading to a range of pathological consequences such as decreased immunity, loss of appetite and reduced mobility. The clinical manifestations depend on the degree of anemia, which is not easily detectable in mild cases but can lead to cardiac insufficiency and circulatory failure in severe cases, and can even be life-threatening. Anemia in children requires high clinical attention, active prevention, early detection and timely and effective diagnosis and treatment. Criteria for determining anemia in children Since the series of clinical manifestations caused by anemia mainly depend on the degree of Hb decrease, the clinical diagnosis of anemia is often based on the Hb decrease. Since children are in the stage of growth and development, there are obvious age differences in the tissues and functions of various systems, so the normal range of Hb also varies with age (month). Classification of anemia There are many possible causes of anemia in children, including malnutrition, various acute and chronic diseases or hematopoietic system lesions. Insufficient bone marrow RBC and Hb production can be caused by three types of factors: (1) deficiency of hematopoietic nutrients: iron deficiency, folic acid or vitamin B12 deficiency, especially iron deficiency anemia caused by iron deficiency; (2) diseases of the bone marrow hematopoietic system, mainly aplastic anemia; (3) various diseases that inhibit the hematopoietic function of the bone marrow, such as infectious diseases, chronic kidney diseases and malignant tumors (mainly leukemia). leukemia mainly), etc. The common hemolytic anemias (hemolysis) can be divided into two categories: congenital hereditary and acquired hemolytic anemia, of which congenital hemolysis, the common diseases are mainly hereditary spherocytosis, glucose-6-phosphate dehydrogenase (G-6PD) deficiency and thalassemia. Acquired hemolytic anemia, mainly autoimmune hemolytic anemia (AIHA). Excessive RBC loss (hemorrhage) Chronic blood loss disorders such as intestinal parasites, chronic gastrointestinal disorders or congenital GI malformations (e.g. Merkel’s diverticulum, etc.) and other long-term occult GI blood loss are clinically difficult to detect, but can manifest as persistent and difficult-to-correct iron deficiency anemia, which can be one of the important clues for clinical analysis.