Composition of HBsAg is predictive of HBsAg loss during treatment in patients with HBeAg-positive chronic hepatitis B

•Ratios of large (L), medium (M) and small (S) HBsAg varied before and during antiviral treatment in patients achieving or not achieving HBsAg loss.•The proportion of MHBs is a suitable marker for early prediction of HBsAg loss.•Quantification of HBsAg proteins might be a novel tool to predict HBsAg loss early on treatment.•With this tool, treatment approaches may be individualized and HBsAg loss rates increased.