Hepatitis B Serology Interpreter
Interpret hepatitis B serologic markers including HBsAg, anti-HBs, anti-HBc, HBeAg, and anti-HBe. This tool helps determine infection status, immunity, and guide clinical management decisions.
Serologic Markers
Additional Markers (Optional)
Understanding Hepatitis B Markers
Marker Definitions
Antigens (Virus Components)
- HBsAg: Surface antigen - indicates current infection (acute or chronic)
- HBeAg: e antigen - marker of active viral replication and high infectivity
- HBcAg: Core antigen - not measured in serum (found in liver tissue only)
Antibodies (Immune Response)
- Anti-HBs: Protective antibody - indicates immunity (vaccine or recovery)
- Anti-HBc: Core antibody - indicates past or present infection
- IgM Anti-HBc: Acute phase antibody - indicates recent infection
- Anti-HBe: Indicates lower viral replication
Natural History of HBV Infection
- 1.Incubation (1-4 months): All markers negative, virus present but not detectable
- 2.Acute Phase: HBsAg appears, followed by IgM anti-HBc and HBeAg
- 3.Window Period: HBsAg clears, anti-HBs not yet detectable (only anti-HBc positive)
- 4.Recovery: Anti-HBs appears, providing lifelong immunity
- 5.OR Chronic Infection: HBsAg persists >6 months (5-10% of adults, 90% of infants)
Treatment Indications
Antiviral therapy for chronic hepatitis B is indicated when:
- •HBV DNA >2000 IU/mL (or >20,000 for HBeAg-positive) AND elevated ALT
- •Evidence of significant fibrosis or cirrhosis regardless of ALT
- •Pregnancy to prevent vertical transmission (if high viral load)
- •Immunosuppressive therapy planned (reactivation prevention)
- •Extrahepatic manifestations (polyarteritis nodosa, glomerulonephritis)
Frequently Asked Questions
What is the difference between acute and chronic hepatitis B?
Acute hepatitis B is a recent infection (within 6 months) characterized by positive HBsAg and IgM anti-HBc. Most adults (95%) clear the virus and develop immunity. Chronic hepatitis B is persistence of HBsAg for more than 6 months, with negative IgM anti-HBc. Chronicity is more common in infants (90%) and young children (25-50%) than adults (5-10%).
What does isolated anti-HBc positive mean?
Isolated anti-HBc (positive anti-HBc with negative HBsAg and anti-HBs) can indicate: (1) remote infection with waning anti-HBs levels, (2) false positive test, (3) window period in acute infection, or (4) occult HBV infection. Check HBV DNA to distinguish between these. If DNA is negative and patient is at risk, consider vaccination.
How is the hepatitis B vaccine checked for effectiveness?
After completing the 3-dose vaccine series, check anti-HBs levels 1-2 months after the final dose. Levels >10 mIU/mL are considered protective. If levels are <10 mIU/mL, the person is a non-responder and may need a second vaccine series. About 90-95% of healthy adults develop protective immunity after vaccination.
What is HBeAg seroconversion?
HBeAg seroconversion is when HBeAg becomes negative and anti-HBe becomes positive. This typically indicates transition from active viral replication to an inactive state with lower HBV DNA levels. It's associated with improved long-term outcomes and reduced need for treatment. However, some patients develop HBeAg-negative chronic hepatitis with ongoing viral replication.
Can hepatitis B be cured?
Current antiviral therapies (tenofovir, entecavir) can suppress HBV replication but rarely achieve a "cure" (HBsAg loss). Treatment typically needs to be lifelong in most patients. However, a small percentage (5-10% over years of treatment) may achieve functional cure with HBsAg loss and development of anti-HBs. Newer therapies targeting cccDNA are in development.
Should everyone with chronic hepatitis B be treated?
No, not all chronic HBV carriers need treatment. The "inactive carrier state" (HBeAg-negative, low/undetectable HBV DNA, normal ALT, no fibrosis) requires monitoring but not immediate treatment. Treatment is indicated when there's evidence of active disease (elevated ALT, high HBV DNA) or significant fibrosis. All patients need periodic monitoring as reactivation can occur.
What is hepatitis B reactivation?
HBV reactivation occurs when the virus becomes active again in someone with prior infection or inactive chronic infection, usually triggered by immunosuppression (chemotherapy, biologics, steroids). It can occur even in anti-HBc positive/HBsAg negative patients (resolved infection). Prophylactic antiviral therapy is recommended before starting immunosuppressive therapy in at-risk patients.
How is hepatitis B transmitted?
HBV is transmitted through blood and body fluids. Routes include: vertical transmission (mother-to-child at birth - most common globally), sexual contact, needle sharing, needlestick injuries, and contaminated medical equipment. HBV is 50-100 times more infectious than HIV. It is NOT transmitted through casual contact, sharing food/drinks, or breastfeeding (unless cracked/bleeding nipples).