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. Diagnosis of pale nose due to anemia: I. Medical history Ask in detail whether there is fatigue, muscle weakness, headache, dizziness, syncope, palpitations, dyspnea; whether there is a history of bleeding, vomiting blood, black stool, dark coffee-colored urine; whether there is excessive menstruation, pregnancy, childbirth (or abortion) and breastfeeding in women; whether there is nutritional deficiency or partiality; whether there is contact with chemical toxins or radioactive substances in the workplace and living environment. Are there any drugs that can cause anemia before the onset of the disease; are there any symptoms suggesting chronic inflammation, infection, kidney disease, liver disease, malignant tumor, collagen disease, endocrine dysfunction and other diseases; are there any patients with hereditary diseases such as thalassemia and congenital spherocytosis in the family? Physical examination In addition to the comprehensive examination, attention should be paid to the presence of pale skin, pale conjunctiva, jaundice, enlarged lymph nodes, liver, spleen, skeletal pressure, abnormalities of the heart, etc. The rebound nail and tongue inflammation appear in severe iron deficiency anemia; tongue papillary atrophy and posterior spinal cord and lateral cord signs appear in vitamin B12 deficiency; skeletal malformation appears in hemolytic anemia. Laboratory tests In addition to erythrocytes, hemoglobin and erythrocyte ratio, the most basic hematologic tests should include: (i) Reticulocyte count, corrected reticulocyte count = patient’s erythrocyte pressure volume/0.45/L × reticulocytes (%). (ii) Measurement of MCV and MCHC. (iii) Peripheral blood smear to observe the presence of anomalous erythrocytes, such as spherical erythrocytes, target-shaped erythrocytes, lytic cells, uneven erythrocyte size, hypochromic and multi-stained erythrocytes, alkalophilic dotted color, Cabot’s sphere, Howe’s week vesicles, etc. The number and morphological changes of white blood cells and platelets, and the presence of abnormal cells. (d) Bone marrow aspiration for bone marrow smear examination is indispensable for diagnosis, and bone marrow biopsy should be performed if necessary. Bone marrow examination must include staining to confirm or exclude iron deficiency anemia and iron granulocytic anemia. On the basis of morphological classification, certain special tests, such as tests for various hemolytic diseases, are purposefully selected to determine the diagnosis. Other tests: urine routine, fecal occult blood and parasitic eggs, blood urea nitrogen, blood creatinine and lung X-ray should not be neglected. V. Identification The indicators to identify the nature of anemia are the mean red blood cell volume (MCV), mean red blood cell hemoglobin (MCH) and mean red blood cell hemoglobin concentration (MCHC) calculated from the red blood cell count, red blood cell pressure and hemoglobin volume. An increased MCV is seen in aplastic anemia and a decreased MCV is seen in iron deficiency anemia. An increased MCV is indicative of hemolysis, a decreased MCV with microcytosis is iron deficiency anemia, and a decreased MCV with macrocytosis is aplastic anemia. The changes in MCV, MCH and MCHC can be combined to differentiate anemia into three types of anemia: hypohemoglobinemic microcytic anemia and hyperchromic macrocytic anemia (increased MCV and higher than normal MCHC).