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 single alt elevation tests? Here is a look together. 1, blood tests: total white blood cell count is normal or slightly low, sorted count neutrophils can be reduced, lymphocytes are relatively increased. 2, liver ultrasonography and electrocardiogram with abnormal changes. 3, laboratory tests: elevated serum alanine aminotransferase, mild or moderate abnormal liver function turbidity or flocculence test, and always normal serum bilirubin. 4, the detection of HBV viral markers: (1) HBsAg and anti-HBs: HBsAg can be detected in the serum of HBV-infected patients 2 to 8 weeks before the elevation of serum aminotransferase. HBsAg is an antigen that appears earlier in acute HBV infection and generally lasts 2 to 6 months to turn negative …… (2) HBeAg and anti- HBe: Positive serum HBeAg can be seen in acute and chronic hepatitis and asymptomatic carriers. HBeAg is closely related to HBVDNA, DNA polymerase activity and Dane particles, and is a marker of viraemia, indicating that the patient is infectious. (3) HBcAg and anti-HBc: HBcAg is the core component of HBV and contains viral nucleic acid. HBcAg positive indicates viral replication and infectiousness. HBsAg is mostly positive in those with high titers of HBsAg, HBeAg and DNA polymerase positivity. (4) HBVDNA and DNA polymerase: HBVDNA can be detected directly by applying nucleic acid hybridization technology. Some patients are positive for HBVDNA even if they are negative for HBsAg and HBeAg, which still indicates that HBV is replicating and is infectious. (5) HBv current infection judgment based on: ① positive serum HBsAg; ② positive serum HBVDNA or DNA polymerase; ③ positive serum IgM anti-HBc; ④ positive intrahepatic HBcAG and (or) HBsAg, or HBVDNA positive.