When using methemoglobin to diagnose hepatocellular carcinoma, care should be taken to exclude elevations in methemoglobin caused by conditions other than liver cancer. These conditions include: 1. Hepatitis and cirrhosis Some of the active stages of hepatitis and cirrhosis are associated with hepatocyte damage and regeneration of hepatocytes. The regeneration process of hepatocytes produces a certain amount of alpha-fetoprotein, however, it usually does not exceed 400 micrograms per liter of blood. Therefore, we can dynamically observe the changes of alpha-fetoprotein and ghrelin, if the two increase simultaneously, it indicates that the increase of alpha-fetoprotein is caused by hepatitis, if the alpha-fetoprotein continues to increase and the ghrelin is normal, it indicates liver cancer. 2.Embryonic-derived tumors testis and ovarian embryonic-derived tumors contain yolk sac components, and yolk sac cells are also the source of methemoglobin production during the embryonic period, so embryonic-derived tumors will also produce certain amount of methemoglobin. Elevated methemoglobin caused by these organs can be excluded by careful examination of these organs. 3.Other cancers A few malignant tumors of the gastrointestinal tract will produce low levels of methemoglobin. In particular, 15% of gastric cancer cases are reported to have elevated AFP, but most do not exceed 400 micrograms per liter of blood. Examination of fecal occult blood, gastrointestinal x-ray or endoscopy can exclude elevated AFP caused by malignant tumors of the gastrointestinal tract. Other conditions such as pregnancy and neonatal fetoprotein are also positive.