What lab tests should be ordered to diagnose and monitor hepatitis B?

Laboratory Testing for Hepatitis B

Order HBsAg, anti-HBc (total), anti-HBs, HBeAg, anti-HBe, HBV DNA quantification, and ALT/AST as the core panel for initial evaluation and monitoring of hepatitis B. 1

Initial Serologic Panel

The first-line serologic tests establish infection status and immunity:

• HBsAg is the primary marker for active HBV infection; positivity for >6 months defines chronic infection 1
• Anti-HBc (total) indicates current or previous HBV infection 1
• Anti-HBc IgM should be added when acute infection is suspected, as it indicates recent infection and may be the only positive marker during the "window period" when HBsAg has cleared but anti-HBs has not yet appeared 2, 1
• Anti-HBs indicates recovery from infection or successful vaccination 1
• HBeAg serves as a marker of high viral replication 1
• Anti-HBe usually indicates lower viral replication when HBeAg becomes negative 1

Virologic Testing

HBV DNA quantification is essential for all patients diagnosed with chronic hepatitis B to assess viral replication, guide treatment decisions, and predict disease progression 3, 1:

• HBeAg-positive chronic hepatitis B typically shows HBV DNA ≥20,000 IU/mL 1
• HBeAg-negative chronic hepatitis B typically shows HBV DNA ≥2,000 IU/mL 1
• Inactive carrier state is defined by HBV DNA <2,000 IU/mL 1
• Real-time PCR assays provide high sensitivity with a broad linear range (10–10⁸ IU/mL) 3

Biochemical Markers

Liver function tests assess hepatic inflammation and synthetic function:

• ALT/AST to evaluate liver inflammation 1
• Alkaline phosphatase and GGT as additional markers of liver injury 1
• Bilirubin to evaluate liver function 1
• Albumin to assess synthetic liver function 1
• Prothrombin time/INR to evaluate coagulation and liver synthetic function 1

Coinfection Screening

Test for other hepatotropic viruses and relevant coinfections:

• Anti-HAV IgG to determine immunity status; vaccinate if negative, particularly in patients younger than 50 years with chronic hepatitis B 3, 1
• Anti-HCV to rule out hepatitis C coinfection 1
• Anti-HDV in patients with injection drug use history or from endemic areas 1
• Anti-HIV in high-risk groups 1

Additional Baseline Testing

For comprehensive evaluation and risk stratification:

• Alpha-fetoprotein for baseline hepatocellular carcinoma screening 1
• Ultrasound for baseline evaluation in high-risk patients 1
• Complete blood count with platelets to assess for cytopenias suggesting advanced disease 4
• Liver biopsy or non-invasive fibrosis assessment (such as elastography) when indicated to evaluate inflammation and fibrosis 1

Interpretation of Common Serologic Patterns

Understanding these patterns prevents diagnostic errors:

• Acute HBV infection: HBsAg positive, IgM anti-HBc positive 1
• Chronic HBV infection: HBsAg positive for >6 months, total anti-HBc positive, IgM anti-HBc negative 1
• Past infection with immunity: HBsAg negative, anti-HBs positive, total anti-HBc positive 1
• Vaccine-induced immunity: HBsAg negative, anti-HBs positive, total anti-HBc negative 2, 1
• Isolated anti-HBc: Requires repeat testing in 3-6 months and may necessitate HBV DNA testing to rule out occult infection 2, 1

Monitoring Schedule for Chronic Hepatitis B

For untreated patients with chronic HBV:

• ALT every 3-6 months 1
• HBV DNA every 6-12 months 1
• HBeAg/anti-HBe status annually 1

For patients on treatment:

• Monitor ALT, HBV DNA, and other markers at regular intervals to assess response 1

For cirrhotic patients:

• More frequent monitoring with ultrasound for HCC surveillance every 6 months 1

Critical Pitfalls to Avoid

• Window period misinterpretation: Both HBsAg and anti-HBs may be negative during acute infection; IgM anti-HBc is the key marker during this period 2, 1
• Isolated anti-HBc positivity: This pattern requires careful follow-up testing and may indicate occult HBV infection, resolved infection with waning anti-HBs, or false-positive results 2, 1
• HBeAg-negative chronic hepatitis B: These patients can have lower HBV DNA levels (>2,000 IU/mL) but still develop progressive liver disease with severe necroinflammation 3, 1
• False negative anti-HBs: Can occur in immunocompromised patients despite true immunity 2
• Declining anti-HBs after vaccination: Levels may decrease over time, but most individuals retain immune memory 2