Objective: Hemodialysis patients with hepatitis B surface antigen (HBsAg) are considered to have the hepatitis B virus (HBV) and are segregated to limit transmission. However, transient de novo HBsAg has been identified in hemodialysis patients shortly after vaccination. Our hypothesis is that immunization rather than actual HBV infection is the most common cause of de novo HBsAg among hemodialysis patients.
Methods: We performed a prospective study between January, 1998 and June, 2000 of de novo HBV infection in over 2400 hemodialysis patients who were screened monthly for HBsAg using a standard enzyme immunoassay. Positive results were confirmed with a neutralization assay. If the confirmatory test was positive, anti-hepatitis B core antibody IgM testing was performed.
Results: We identified nine patients with de novo HBsAg confirmed with the neutralization assay. In eight of the nine patients with de novo HBsAg (89%), HBsAg was temporally related to HBV immunization. In none of these eight patients was there a detectable anti-hepatitis B core antibody IgM, an elevated ALT level, or clinical history suggestive of recent hepatitis. The mean age (+/- SD) of the four men and four women was 56.4 +/- 18.8 yr. HBsAg was detectable within 3 days of immunization in most patients.
Conclusion: Our results suggest that HBV immunization is the most common cause of detectable HBsAg in hemodialysis patients. Hemodialysis patients should not be screened for HBV within a week of immunization, and caution should be exercised when interpreting HBsAg seropositivity within 4 wk of HBV immunization.