A study on false positive results of hepatitis B surface antigen (HBsAg) test: Frequency of samples considered false positives in relation to the HBsAg concentration

Abstract

The aim of this study was to clarify the percentage of samples considered false positive for hepatitis B surface antigen (HBsAg) in relation to the HBsAg concentration. The HBsAg concentrations were measured in 41,186 samples using chemiluminescent enzyme immunoassay. Samples with a concentration of ≥0.05 IU/mL were considered positive. The criteria for classifying a result as false positive were as follows: negative for anti-HBc, HBeAg, anti-HBe, and HBV-DNA as well as negative for HBsAg examined with the sample obtained on other day.

In total, 1147 samples were positive for HBsAg. Six subjects fulfilled the criteria of false positives. The HBsAg concentrations (IU/mL) were 0.05≤ <0.2 in 6 cases, and none of the samples with a value of ≥0.2 were false positive. The percentage of false positives among those with HBsAg 0.05≤ <0.2 was 25% (6/24). It should be remembered that samples with a low HBsAg concentration may contain false positives.