Diagnosis of acute and inapparent hepatitis B virus infections by measurement of IgM antibody to hepatitis B core antigen.

IgM antibody to hepatitis B core antigen (anti-HBc) was determined by a reverse enzyme immunoassay. In all of 58 patients with transient hepatitis B surface antigen (HBsAg)-positive acute hepatitis, IgM anti-HBc was detected in high titer. In 79.3%, IgM anti-HBc disappeared within two years, but in the remaining 12, it was still detectable. In 20 of 21 patients who developed chronic hepatitis, IgM anti-HBc was present after two years. High titers of IgM anti-HBc were found in 13 patients with histologically confirmed hepatitis B in whom HBsAg could not be detected in the initial serum samples; 11 of them later developed antibody to HBsAg and/or e antigen. Furthermore, IgM anti-HGc was detected in eight (5.6%) of 142 HBsAg-negative blood donors with elevated levels of serum transaminases and in 11 (0.5%) of 2,400 HBsAg-negative blood donors with normal levels of serum transaminases. Thus, IgM anti-HBc might be a better indicator of hepatitis B than HBsAg and help differentiage acute from chronic infection in HBsAg-positive patients.