From the Guidelines
A positive Hepatitis B (HBV) Immunoglobulin M (IgM) test result indicates an acute or recent HBV infection, as it is the most reliable marker for diagnosing acute hepatitis B infection, distinguishing it from chronic infection 1. This antibody appears early in the course of infection, typically within 4 weeks after exposure, and usually disappears within 6 months. The presence of IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) is a key indicator of acute infection. During acute infection, patients may experience symptoms like fatigue, jaundice, abdominal pain, nausea, and vomiting, though some individuals remain asymptomatic. Management typically involves supportive care, monitoring liver function, and avoiding hepatotoxic substances like alcohol. Most adults with acute hepatitis B recover completely without specific antiviral therapy, with approximately 95% clearing the virus naturally 1. However, close medical follow-up is essential to monitor for progression to chronic infection, which occurs in about 5% of adults but is more common in infants and immunocompromised individuals. Patients should also be educated about preventing transmission to others through blood and body fluids. It's worth noting that the interpretation of HBV test results should consider multiple markers, including HBsAg, total anti-HBc, IgM anti-HBc, anti-HBs, and HBV DNA, as outlined in the 2018 recommendations 1. In certain cases, isolated anti-HBc-positivity can be detected, which might indicate previous infection with loss of anti-HBs or chronic infection with undetectable HBsAg. In such cases, further evaluation and monitoring may be necessary to determine the individual's infection status and risk of transmission.
From the Research
Hepatitis B IgM Positive Test Result
A Hepatitis B (HBV) Immunoglobulin M (IgM) positive test result indicates an acute HBV infection. The presence of IgM antibody to hepatitis B core antigen (anti-HBc IgM) is generally considered a marker of acute infection [ 2, 3 ].
Key Points
- IgM anti-HBc is typically present in high titer during acute hepatitis B infection 2.
- A strong positive reaction for anti-HBc IgM during acute hepatitis is indicative of an acute HBV infection, even in hepatitis B surface antigens (HBsAg)-negative patients 2.
- The presence of anti-HBc IgM can help diagnose HBV infection in HBsAg-negative patients 2, 3.
- Acute hepatitis B virus (HBV) infection is typically distinguished from chronic disease by a positive IgM anti-hepatitis B core antigen (anti-HBc) test 4.
Diagnostic Value
The detection of IgM anti-HBc is a valuable marker for the diagnosis of acute infection with hepatitis B virus 3. It is especially useful in cases where HBsAg is not detectable 2, 3. However, the presence of anti-HBc IgM in HBsAg-positive patients without a recent history of acute hepatitis may not always be a definite marker of recent hepatitis B infection 2. Quantitation of the anti-HBc IgM results may improve the clinical value of the test 2.