Can serum level of HBsAg differentiate HBeAg-negative chronic hepatitis B from inactive carrier state?

Hepatitis B envelope antigen (HBeAg)-negative hepatitis B virus (HBV) infection exerts both inactive carrier (IC) state and chronic hepatitis B (CHB), which are sometimes difficult to be differentiated. We aimed to assess the role of hepatitis B surface antigen (HBsAg) level in differentiation of CHB and IC among a group of chronic HBeAg-negative HBV-infected patients. A total of 251 HBeAg-negative HBV-infected patients were enrolled. Serum HBV DNA and HBsAg levels were determined for each patient. HBV DNA quantification with cutoff value 2000IU/mL for diagnosis of CHB had 99.0% sensitivity and 74.1% specificity. A cutoff value of HBsAg level at 1000IU/mL was more reliable for diagnosis of CHB with 82.7% sensitivity and 66.2% specificity than other HBsAg cutoff values. There was a positive correlation between HBV DNA and HBsAg levels in both CHB (r=0.42, P<0.001) and IC (r=0.43, P<0.001) groups. Single-point HBsAg quantification did not have enough sensitivity and specificity for differentiation of HBeAg-negative CHB and IC state.