Laboratory tests for anemia are best performed on an empty stomach. Anemia is a clinical syndrome that occurs when the volume of red blood cells in the peripheral blood is lower than normal, and the patient will experience a range of symptoms such as pallor, dizziness, weakness, panic, and chest tightness. Anemia is a lower than normal concentration of hemoglobin in the peripheral blood, but anemia can be seen for a variety of reasons, and special tests are often needed to confirm the cause of anemia. The most common clinical type of anemia is iron deficiency anemia. To confirm the diagnosis of iron deficiency anemia, serum iron and ferritin concentrations need to be tested, but the serum iron and ferritin concentrations require fasting tests. If the test is for megaloblastic anemia, folic acid and vitamin B12 concentrations are needed, both of which also need to be done on an empty stomach. Therefore, in order to find the cause of anemia more accurately and to provide better clinical guidance, it is best to perform anemia tests on an empty stomach.