Pale nose color is one of the symptoms of anemia. Anemia is a pathological condition in which the amount of hemoglobin, red blood cell count and red blood cell pressure volume per unit volume of circulating blood is lower than normal. To confirm the diagnosis of anemia, patients need to undergo the following three tests: 1. Routine blood tests for anemia The presence or absence of anemia and the severity of anemia, whether it is accompanied by changes in the number of white blood cells or platelets. Erythrocyte parameters (MCV, MCH and MCHC) can be used to classify the morphology of anemia and provide relevant clues for diagnosis. Reticulocyte count indirectly reflects the proliferation and compensation of bone marrow red lineage; peripheral blood smear can observe the number or morphological changes of erythrocytes, leukocytes, platelets, whether there are malaria parasites and abnormal cells, etc. Bone marrow examination for anemia Bone marrow smear reflects the degree of proliferation, cell composition, ratio and morphological changes of bone marrow cells. Bone marrow biopsy reflects the structure, degree of proliferation, cellular composition and morphological changes of bone marrow hematopoietic tissue. Bone marrow examination has diagnostic value for certain anemias, leukemia, bone marrow necrosis, bone marrow fibrosis or marbling, and infiltration of extramedullary tumor cells. It must be noted that the limitations of bone marrow sampling, when there is a contradiction between bone marrow examination and blood routine, multi-site bone marrow examination should be done. 3. Examination of the pathogenesis of anemia Such as iron metabolism in iron deficiency anemia and examination of the primary cause of iron deficiency; determination of serum folate and vitamin B12 level in megaloblastic anemia and examination of the primary cause of the lack of such hematopoietic material; examination of the primary cause of hemorrhagic anemia; increase in free hemoglobin, decrease in binding pearl protein, increase in potassium, increase in indirect bilirubin, etc. may occur in hemolytic anemia. Sometimes, examination of red blood cell membrane, enzymes, bead protein, hemoglobin, autoantibodies, alloantibodies or PNH clone is also required; examination of chromosomes, antigen expression, cell cycle and genes of bone marrow hematopoietic cells; and examination of T cell subpopulation and its secreted factors or bone marrow cell autoantibodies.