Abstract: Objective To distinguish acute hepatitis B (AHB) from chronic hepatitis B(CHB),and to diagnose AHB at the earliest time.Methods One hundred and thirty-two cases of AHB and 277 cases of CHB were collected and compared for identifying differential indexes between these two groups. Receiver operating characteristic (ROC) curve analysis was performed to obtain the maximum index in area under the curve (AUC) and calculate the sensitivity and specificity for diagnosing AHB.Results (1)The quantitative value of anti-HBc-IgM/DNA log within 48 hours after admission in AHB group was 5.18(0.03-13.65),which was significantly higher than those of 0.04(0.01-3.48) in CHB group (P=0.000). (2)The sensitivity and specificity of quantitative value of anti-HBc-IgM/DNA log in the diagnosis of AHB is 95.45% and 97.47%.The best Youden index is 0.929, the AUC is 0.991,and the cutoff value was 1.025. When simplified to 1, the sensitivity and specificity remained unchanged. (3)Compared with the traditional index anti-HBc-IgM, the AUC difference of anti-HBc-IgM/DNA log in the diagnosis ofAHB is statistically significant (P=0.001).Conclusion The quantitative log value of anti-HBc-IgM/DNA within 48 hours after admission can serve as a new index for early diagnosis of AHB. AHB can be considered when the log value is more than or equal to 1.

Key words: Quantitative log value for anti-HBc-IgM/DNA, Early diagnosis, Acute hepatitis B, Chronic hepatitis B