Abstract：In order to evaluate the sensitivity of microparticle enzyme immunoassay ( MEIA) and enzyme-linked immunosorbent assay ( ELISA) , a standard concentration curve was established by measuring the HBsAg calibrator with a standard serum from the World Health Organization ( WHO) . Ninety-seven serum samples with low level HBsAg were analyzed via these two methods and compared with the individual patient’s clinical characteristics in order to investigate the significance of low level HBsAg detection. According to the HBsAg concentration standard curve, the sensitivities of MEIA and ELISA were 0. 095 and 0. 378 IU/ml, espectively. Only 44 out of 97 patients tested positive when samples were analyzed by ELISA. Among the 97 samples, the rate of HBV DNA≥ 1 ×103 opies /ml and abnormal liver function tests were 17. 5% ( 17/97) and 38. 1% ( 37/97) , respectively. Eleven cases of liver cirrhosis were found among 19 patients who were previously diagnosed as positive HBV. These results suggest that low level HBsAg infection should be detected using highly sensitive and specific methods in order to diagnose and treat patients in a timely manner. Patients with low serumconcentrations of HBsAg may also display increased levels of HBV DNA replication and chronic liver damage. It is implicated that patients with potential HBV infection should be monitored.
