Anemia can be detected by a routine blood test. The most basic blood test is called routine blood test, which contains most of the cellular components of the blood. These include red blood cells, hemoglobin, white blood cells and platelets, which are the more important items. Among them, hemoglobin is very important, regardless of the cause of anemia, hemoglobin will definitely be reduced. It is also possible to assess the cause of the anemia from the routine blood test. For example, if the anemia is iron deficiency, the hemoglobin value must be reduced, and the erythrocyte volume and the average volume of erythrocytes will be decreased. The white blood cells and platelets, on the other hand, are within the normal range. In the case of megaloblastic anemia, the blood test will show an increase in the average volume of red blood cells and the average hemoglobin level. Therefore, it is necessary to have a blood test when we have some symptoms, and the routine blood test can also determine the symptoms and causes of anemia initially.