IgM antibody to hepatitis B core antigen as a diagnostic parameter of acute infection with hepatitis B virus.

Because many patients with acute hepatitis B lack detectable hepatitis B surface antigen (HBsAg), a radioimmunoassay for IgM antibody to hepatitis B core antigen (anti-HBc) was developed and evaluated as a diagnostic test. IgM anti-HBc was detected in each of 47 patients with acute hepatitis and transient HBsAg (geometric mean titer, greater than or equal to 1:191,000), but also in five of 12 HBsAg carriers (geometric mean titer, 1:459) and one of 46 healthy individuals positive for anti-HBc. However, it was not present in one patient during the first six months of a persistent infection. Of 255 patients with acute hepatitis and HBsAg and/or anti-HBc, 210 were HBsAg-positive whereas 230 had IgM anti-HBc. The latter was the only specific marker in 12.3% of all cases of acute hepatitis B. Thus, IgM anti-HBc is a valuable marker for the diagnosis of acute infection with hepatitis B virus.