Alpha-fetoprotein is mainly synthesized by fetal hepatocytes. It has a high concentration in fetal blood circulation and decreases after birth, and is basically replaced by albumin in the first 2-3 months of life, so it is difficult to be detected in blood. Methemoglobin is closely related to the development of hepatocellular carcinoma and many kinds of tumors, and it can show high concentration in many kinds of tumors, mainly as a tumor marker of primary hepatocellular carcinoma referred to as swelling marker. The reasons for high alpha fetoprotein can be divided into physiological, non-tumor, and tumor liver cancer. It is more important to detect alpha fetoprotein in patients with cirrhosis, and persistently elevated alpha fetoprotein in cirrhotic patients is considered to be possibly transformed into liver cancer and should be promptly consulted. In patients with primary liver cancer, fetoprotein level is increased, as well as testicular cancer, ovarian tumor, malignant teratoma, pancreatic cancer, gastric cancer, intestinal cancer, lung cancer and other patients. In patients with acute and chronic hepatitis, cirrhosis and other benign liver diseases, serum fetoprotein levels are increased to different degrees. The degree of elevation is related to the degree of hepatocyte necrosis and regeneration. As the disease improves it can decrease as a marker of non-neoplasticity, whereas benign liver disease has a transient increase in alpha-fetoprotein that usually lasts 2-3 weeks, whereas malignancy has a persistent increase. Therefore, dynamic observation of serum fetoprotein levels can identify both benign and malignant liver disease and allow early diagnosis of hepatocellular carcinoma. Under physiological condition, methemoglobin is secreted by embryonic stem cells. Fetal liver cells are not fully differentiated and secrete a greater amount of methemoglobin, which can enter the maternal blood through the umbilical cord blood, so methemoglobin will be elevated in pregnant women during pregnancy, which is a physiological elevation.