Elevated alpha fetoprotein should be highly cautioned for primary liver cancer, as well as the possibility of elevated alpha fetoprotein in pregnant women. The most notable cause of elevated alpha fetoprotein is primary hepatocellular carcinoma. A large amount of alpha-fetoprotein exists in the serum of patients with primary liver cancer, and when the serum alpha-fetoprotein level is greater than 400 μg/L can be used as the diagnostic threshold for primary liver cancer. When the concentration of methemoglobin increases but does not exceed 500 μg/L, it should be transient and can be considered as viral hepatitis, fulminant hepatitis. If the patient’s methemoglobin concentration is significantly elevated, the possibility of primary hepatocellular carcinoma should be highly noted in this case. Generally, if the methemoglobin is greater than 500μg/L for 4 weeks or greater than 200μg/L for 8 weeks, the diagnosis of hepatocellular carcinoma can be made based on the exclusion of pregnancy and germinal germ tumor. Of course, if you want to confirm the diagnosis of primary hepatocellular carcinoma, further examinations, such as ultrasound examination of the liver, CT examination and, if necessary, liver tumor puncture for pathological examination, are needed to be more accurate. If a patient has significantly elevated AFP, it is important to pay high attention to the possibility of hepatocellular carcinoma. If a pregnant woman has elevated AFP, it is also a physiological phenomenon, so it is important to pay high attention to the cause of elevated AFP and whether it is physiological or not.