The normal values for hemoglobin are 120-160 g/L for adult males and 110-150 g/L for adult females. Below or above the normal range are considered abnormal. Below the normal range is anemia, and the lower the hemoglobin concentration, the more serious the symptoms of anemia and the more severe the degree of anemia. In clinical practice, if hemoglobin is below 60g/L, it is considered severe anemia, and the patient will experience a series of symptoms such as pallor, dizziness, weakness, panic, chest tightness, tinnitus, blurred eyes, insomnia, and forgetfulness. In addition to these common symptoms, they are also closely related to the cause of the anemia. For example, in patients with megaloblastic anemia, in addition to the general symptoms of anemia, most patients will also have a significant decrease in appetite, as well as symptoms such as tongue inflammation and mirror tongue. In the case of iron deficiency anemia, patients will also have specific symptoms such as dry hair, difficulty in swallowing, and xerophagia. Therefore, anemia below the normal range of hemoglobin is very common in clinical practice and has multiple etiologies, so it is best to visit a hematologist if anemia occurs.