Alpha-fetoprotein is usually found in the liver and yolk sac during early fetal development, and gradually disappears after birth, and is present at extremely low levels in normal humans, usually less than 25 μg/L. Alpha-fetoprotein is often used clinically for the screening and early diagnosis of hepatocellular carcinoma, and also for the evaluation of the efficacy of hepatocellular carcinoma after resection. When the test value is high, it helps to help diagnose hepatocellular carcinoma. At the same time, the clinical significance of a high result is different for different groups of people. I. General population: 1. Liver disease: If the value of methemoglobin is elevated but still below 400 μg/L, it is usually considered as acute and chronic hepatitis, cirrhosis and other diseases. Benign liver disease may show a transient increase in the value of alpha-fetoprotein, which usually can gradually decrease to normal value after active treatment. If the value of methemoglobin continues to rise, the possibility of hepatocellular carcinoma should be considered, which needs to be differentially diagnosed by ultrasound, CT and other auxiliary examinations; 2. Other diseases: elevated methemoglobin is mainly seen in liver metastasis of gastric cancer, teratoma, ovarian embryonal tumor, and may also be gastric cancer, colon cancer, pancreatic cancer, ovarian cancer, testicular tumor, bile duct cell carcinoma, etc. Further examination of gynecological ultrasound or abdominal ultrasound, CT or even puncture biopsy for clear diagnosis. Pregnant women: 1. Physiological factors: The serum alpha-fetoprotein value of pregnant women will also increase in the 3rd month of pregnancy and reach the highest value in 7-8 months, and return to normal in 3 weeks after delivery. Therefore, if the serum fetoprotein is high during pregnancy, generally <400μg/L, there is no need to worry too much; 2. Pathological factors: if the serum fetoprotein of pregnant women is abnormally high, it is considered that it may be fetal hydrocephalus, pre-eclampsia, intrauterine asphyxia and other conditions. If the amniotic fluid alpha-fetoprotein is high, it is usually seen in anencephalic or spina bifida fetuses, or fetal anomalies such as congenital nephropathy, esophageal atresia, congenital gonadal insufficiency, etc.