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Blood Test Tracker

Hepatitis B e antigen (HBeAg)

A hepatitis B virus protein linked to active virus growth and higher infectiousness. It's usually checked only after a positive HBsAg.

AI-verified against cited sources. Awaiting expert reviewAlso called HBeAg, HBe AgLOINC 13954-3

What it is

HBeAg is a protein released by the hepatitis B virus while it is multiplying. Doctors check it when someone already has hepatitis B (a positive HBsAg) to understand how active the virus is and how easily it could spread. It's usually looked at along with the anti-HBe antibody, a viral load test (HBV DNA) and liver blood tests.

Why it matters

A positive HBeAg is linked to more virus in the blood and a higher chance of passing the infection on. A switch from HBeAg-positive to anti-HBe-positive, called seroconversion, is often linked to the infection moving into a quieter phase. The result doesn't tell the whole story alone, because some people have active hepatitis B with a negative HBeAg.

If it’s high

A positive result is linked to the virus multiplying, with more virus in the blood and higher infectiousness. It happens in the early phases of many long-term infections and in some new infections. It doesn't show how much liver damage there is. That depends on liver blood tests, viral load and sometimes imaging.

Common causes

  • An early (acute) hepatitis B infection
  • Long-term hepatitis B in an HBeAg-positive phase, including infection picked up at birth or in early childhood

What can help

  • Ask your hepatitis B specialist how often to repeat HBeAg, anti-HBe, viral load and liver tests
  • Ask about testing and vaccination for the people you live with and for sexual partners
  • If you are pregnant or planning a pregnancy, ask how your baby will be protected after birth

What can affect your result

  • It only matters when HBsAg is positive
  • Results can change over time as the infection moves between phases
  • Some people with active hepatitis B are HBeAg-negative because changes in the virus stop it from making the protein
  • Biotin supplements can interfere with some immunoassays
  • Mayo Clinic Laboratories asks patients to avoid biotin (vitamin B7) supplements for 24 hours before its chronic hepatitis B screen, which reflexes to this test.
  • The result mainly has meaning when HBsAg is positive. A positive HBeAg with a negative HBsAg is unusual, so your clinician may repeat it.

Changes as the infection moves between phases, which can take months to years.

When to talk to a clinician

Talk with your clinician about any positive HBeAg result. Get urgent care for yellow skin or eyes, dark urine, severe belly pain or confusion.

Questions you could ask

  • What phase of hepatitis B do my results fit?
  • What does my HBeAg result say about how active the virus is?
  • How often should my viral load, HBeAg and liver tests be repeated?
  • Should the people I live with or have sex with be tested or vaccinated?

Questions people ask

If my HBeAg is negative, does that mean the virus is inactive?

Not always. Some people have active hepatitis B even though HBeAg is negative, because changes in the virus stop it from making the protein. Viral load (HBV DNA) and liver tests are needed to tell.

What is seroconversion?

It's when HBeAg disappears and the antibody to it, anti-HBe, appears. It is often linked to the infection becoming less active. Your clinician will keep monitoring, because the picture can change over time.

Show the science and sources

For clinicians and researchers

HBeAg is a secreted product of the precore/core gene and a marker of active viral replication and high infectivity (CDC 2023). In the AASLD 2018 phase scheme, HBeAg-positive disease includes the immune-tolerant phase (HBV DNA typically above 1 million IU/mL with normal or minimally raised ALT/AST) and the HBeAg-positive immune-active phase (HBV DNA above 20,000 IU/mL with raised ALT/AST). HBeAg seroconversion is loss of HBeAg and detection of anti-HBe in someone previously HBeAg-positive and anti-HBe-negative. It often marks entry to the inactive phase (HBeAg-negative, anti-HBe-positive, HBV DNA below 2,000 IU/mL, persistently normal ALT/AST). It can be followed by HBeAg-negative immune-active disease (HBV DNA above 2,000 IU/mL with raised ALT/AST), often due to precore or core-promoter variants that stop or reduce HBeAg production (APASL 2015). Mayo Clinic Laboratories reflexes HBeAg and anti-HBe once a screening HBsAg is confirmed positive.

LOINC 13954-3 (primary), 31844-4, 5191-2. Specimen: serum-or-plasma.

Sources

  1. Screening and Testing for Hepatitis B Virus Infection: CDC Recommendations — United States, 2023, MMWR Recommendations and Reports (CDC) (2023)
  2. Update on Prevention, Diagnosis, and Treatment of Chronic Hepatitis B: AASLD 2018 Hepatitis B Guidance, Hepatology (AASLD) (2018)
  3. Chronic Hepatitis B Screen, Serum (test CHBVS), Mayo Clinic Laboratories (Extended Catalog)
  4. Understanding Your Hepatitis B Test Results, Hepatitis B Foundation
  5. Asian-Pacific clinical practice guidelines on the management of hepatitis B: a 2015 update, Hepatology International (APASL) (2016)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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