In China, a more extensive population ALT screening was conducted in the 1960s, and asymptomatic elevated serum ALT accounted for about 5-10% of the population. After the development of HBsAg testing, it was found that the detection rate of HBsAg was three times higher in those with abnormal ALT than in those with normal, and nearly half of those with elevated single ALT were hepatitis B without xanthogranuloma. So what are the reasons for the appearance of elevated single alt? Here is a brief introduction. 1, viral hepatitis B is caused by the hepatitis B virus (HBV), mainly liver inflammatory lesions, and can cause multi-organ damage. 2, viral hepatitis B does not have a certain epidemic period, the disease can occur throughout the year, but most of the distribution. 3, in the serum of HBV-infected patients there are small spherical particles, tubular particles and Dane particles of three different forms of viral particles. HBV can grow in human kidney and monkey kidney cells, human amniotic cells, and HBcAg can be detected in the above tissue cultures and cause cytopathic lesions. Hepatitis without jaundice with insidious onset in the acute phase is more likely to develop into chronic than acute jaundice, which is related to the fact that hepatitis without jaundice is easily misdiagnosed or missed and not promptly diagnosed and rested. Therefore, it is recommended that patients actively go to a professional and regular hospital for systematic diagnosis and treatment once they develop suspected symptoms to avoid delaying the disease.