Ferritin is a protein with a large molecular weight and is the main storage form of iron. Ferritin is measured at 400ng/ml as the upper limit of normal, and is often elevated and greater than this value in certain tumors, commonly in: acute leukemia, Hodgkin’s disease, lung cancer, colon cancer, liver cancer, and prostate cancer. Detection of ferritin has diagnostic value for metastatic tumors in the liver. 76% of patients with liver metastases have ferritin levels higher than 400 ng/ml. Combined testing with AFP, especially in patients with liver cancer with normal AFP, can improve the diagnostic rate. The elevated ferritin may be due to cell necrosis, blocked erythropoiesis or increased synthesis in tumor tissue. Ferritin measurement is suitable for understanding the iron metabolism in the body. The detection of ferritin at the early stage of treatment can reflect the iron stores in the body at that time and can detect the deficiency of iron stores in the reticuloendothelial system early. In clinical practice, a threshold of 20 ng/ml can effectively determine latent iron deficiency and indicate depletion of iron stores. Under normal conditions stored iron can be used for hemoglobin synthesis and below 12ng/ml, latent iron deficiency is judged. Both of these measurements, without further laboratory references, remain true even in the presence of normal blood cell morphology. The presence of iron deficiency is indicated if there is also microcytic hypochromic anemia. If the ferritin level is high and the possibility of an abnormal iron supply is excluded, this reflects a condition of excess iron in the body. Ferritin is one of the main forms of iron stored in the body. It is currently detected by radioimmunoassay and enzyme-linked immunosorbent assay. Clinical significance: This test is an important indicator for the diagnosis of iron deficiency anemia and one of the markers of malignancy. Increased serum ferritin, aplastic anemia (decreased iron utilization), hemolytic anemia (excessive iron release); hemochromatosis and repeated blood transfusions (increased iron absorption or storage), anemia due to lead poisoning and vitamin B6 deficiency (decreased iron utilization), malignant tumors, liver lesions, acute infections.