Alpha fetoprotein is found at extremely low levels in normal adults and cannot be detected. However, if fetoprotein levels are only high, it is not necessarily due to a disease, such as a normal physiological phenomenon in women during pregnancy. Of course, elevated fetoprotein levels can also be caused by diseases such as germline embryonic tumors, active hepatitis, and primary liver cancer. Testicular cancer, ovarian tumors, pancreatic cancer, stomach cancer, intestinal cancer, lung cancer, and malignant teratoma may also cause mild elevation of alpha fetoprotein. However, elevated methemoglobin alone cannot diagnose a specific disease and needs to be combined with clinical symptoms and signs as well as relevant ancillary tests for clarification. In addition, for patients who are not found to have abnormal examination, but have underlying liver diseases such as cirrhosis and hepatitis B, they should also pay attention to regular follow-up observation of AFP and liver imaging for early detection of possible primary hepatocellular carcinoma, which is very important to improve the survival of patients.