Aims The authors aimed to identify the correlation between quantitative hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA in Korean patients with a high level of HBsAg (>250 IU/ml) and characteristics of patients for whom quantitative HBsAg can be more suitably used to monitor HBV infection.

Methods Quantitative HBsAg and HBV DNA were measured in collected sera from 565 patients with a high level of HBsAg (>250 IU/ml). The correlation between HBsAg and HBV DNA was analysed by Spearman rank test. We also retrospectively analysed the correlation according to the HBV infection phase in which quantitative HBsAg is more appropriate to be used in clinical practice.

Results The overall correlation between quantitative HBsAg and HBV DNA was significant but very weak (Spearman ρ=0.121, p=0.004). Weak correlations were also noted in chronic hepatitis B patients (ρ=0.123, p=0.019) and in patients with hepatocellular carcinoma (ρ=0.328, p=0.002). No correlation was noted in liver cirrhosis patients (ρ=0.156, p=0.095). Relatively higher correlation was noted in hepatitis B e antigen positive patients without antiviral treatment and patients with a high HBV DNA to HBsAg ratio (>57.93).

Conclusions There was a weak correlation between quantitative HBsAg and HBV DNA. However, quantitative HBsAg appears to be more useful to reflect HBV DNA in the early replicative phase of chronic hepatitis B patients than those in the late non-replicative phase.