HEPATITIS B CORE IGM ANTIBODY, SERUM

Hepatitis B Core IgM Antibody, Serum

What it is

The Hepatitis B Core IgM Antibody (anti-HBc IgM) test detects IgM antibodies directed against the core antigen of the hepatitis B virus (HBV). These antibodies appear early in infection and are a reliable marker of acute or recent HBV infection. Unlike the surface antigen (HBsAg), which indicates viral presence, anti-HBc IgM confirms the body’s immune response during the acute phase.

Uses

This test is used to:

• Diagnose acute or recent hepatitis B infection.
• Differentiate between new infection and chronic HBV carriage.
• Identify the cause of recent symptoms of hepatitis when HBsAg may still be negative.
• Support clinical decision-making alongside other HBV markers (HBsAg, HBeAg, Anti-HBc IgG, HBV DNA).

Symptoms That May Lead to the Test

Your doctor may recommend this test if you have symptoms suggestive of acute hepatitis such as jaundice, dark urine, pale stools, abdominal pain, nausea, fatigue, loss of appetite, or unexplained elevations in liver enzymes. It may also be requested after recent exposure to HBV (e.g., blood contact, unprotected sex, needle stick injury).

Abnormal Results

Positive Anti-HBc IgM: Indicates acute or recent hepatitis B infection. This antibody usually appears within 1–2 weeks of symptoms and may persist for up to 6 months.

Negative Anti-HBc IgM: Suggests no recent HBV infection. If chronic infection is suspected, testing for anti-HBc IgG and HBsAg is required.

Note: Anti-HBc IgM is especially useful during the “window period,” when HBsAg has disappeared but protective anti-HBs antibodies have not yet developed.

Risks

The test requires a routine blood draw. Risks are minimal and may include mild bruising, slight pain, or temporary dizziness at the puncture site. These usually resolve quickly.