What to do if a patient is Hepatitis B surface antigen (HBsAg) positive?

Management of HBsAg Positive Patients

Patients who test positive for Hepatitis B surface antigen (HBsAg) require comprehensive evaluation, monitoring, and potentially antiviral treatment to prevent liver disease progression and reduce transmission risk.

Initial Evaluation

When a patient tests positive for HBsAg, the following assessments should be performed:

1. Complete serologic testing:

   • HBeAg and anti-HBe status
   • HBV DNA viral load quantification
   • Anti-HBc (total and IgM)
   • Anti-HBs

2. Liver disease assessment:

   • Liver function tests (ALT, AST, bilirubin, albumin, prothrombin time)
   • Complete blood count with platelets
   • Abdominal ultrasound to assess for cirrhosis and exclude focal lesions 1
   • Consider non-invasive fibrosis assessment or liver biopsy if indicated 2

3. Coinfection screening:

   • HIV antibody/antigen test
   • HCV antibody
   • HDV antibody (for all HBsAg-positive patients) 3
   • Hepatitis A immunity 2

Treatment Decision Algorithm

Treatment decisions should be based on HBeAg status, HBV DNA levels, ALT levels, and the presence of liver damage:

For HBeAg-positive patients:

• Treat if:
  • HBV DNA >20,000 IU/mL AND ALT >2× upper limit of normal (ULN) 4
  • OR age >40 with persistently high HBV DNA (even in immune tolerance phase) 4
  • OR moderate/severe inflammation or fibrosis on liver biopsy 4

For HBeAg-negative patients:

• Treat if:
  • HBV DNA >2,000 IU/mL AND ALT >2× ULN 4
  • OR moderate/severe inflammation or fibrosis on liver biopsy 4

For all patients:

• Treat regardless of ALT or HBV DNA if:
  • Cirrhosis is present 4
  • Receiving immunosuppressive therapy 4

Antiviral Treatment Options

First-line treatment should be with high genetic barrier drugs: entecavir, tenofovir disoproxil fumarate, or tenofovir alafenamide. 2

Recommended dosages:

• Entecavir: 0.5 mg daily (1 mg if lamivudine-resistant) 5
• Tenofovir disoproxil fumarate: 300 mg daily 6
• Tenofovir alafenamide: 25 mg daily 2

Monitoring During Treatment

• HBV DNA levels every 3-6 months 2
• ALT and AST every 3-6 months 2
• HBeAg/anti-HBe every 6-12 months (if initially HBeAg-positive) 2
• Renal function tests every 6-12 months (especially with tenofovir) 2
• Annual assessment for hepatocellular carcinoma in high-risk patients (Asian men >40 years, Asian women >50 years, Africans >20 years, cirrhotic patients, family history of HCC) 4

Patient Education and Transmission Prevention

All HBsAg-positive patients should be counseled to:

1. Prevent transmission to others:

   • Notify household, sexual, and needle-sharing contacts for testing and vaccination 4
   • Use condoms with non-immune sexual partners 4
   • Cover cuts and skin lesions 4
   • Clean blood spills with bleach solution 4
   • Avoid sharing household items that could be contaminated with blood (toothbrushes, razors) 4
   • Refrain from donating blood, plasma, tissue, or semen 4

2. Protect their liver:

   • Avoid or limit alcohol consumption 4
   • Get vaccinated against hepatitis A if not immune 4
   • Avoid hepatotoxic medications when possible 4

3. For pregnant women:

   • Ensure newborns receive hepatitis B vaccine and hepatitis B immune globulin at birth 4

Special Considerations

1. Immunosuppressive therapy:

   • All HBsAg-positive patients should receive prophylactic antiviral therapy before starting immunosuppressive or chemotherapy 4
   • Continue antiviral therapy for at least 6-12 months after discontinuation of immunosuppression 4

2. HBV reactivation risk:

   • Patients who are HBsAg-positive OR HBcAb-positive with negative HBsAg should receive prophylactic antiviral therapy when receiving rituximab or other anti-CD20 monoclonal antibodies 4

3. Inactive carriers:

   • Patients with normal ALT, HBV DNA <2,000 IU/mL, and no evidence of liver disease can be monitored without treatment 4
   • Regular monitoring is still required (every 6-12 months) 2

Common Pitfalls to Avoid

1. Do not rely solely on ALT levels for treatment decisions, as 20% of HBsAg-positive patients may have normal ALT despite liver disease 7

2. Do not discontinue treatment abruptly as it may lead to severe hepatitis flares 2

3. Do not use sequential monotherapy with low-barrier drugs (lamivudine, adefovir) as it increases the risk of multidrug resistance 2

4. Do not delay rescue therapy after detecting viral breakthrough, as early intervention is more effective 2

5. Do not miss screening for HDV coinfection, which significantly worsens prognosis and requires different management 3

By following this comprehensive approach to managing HBsAg-positive patients, clinicians can significantly reduce the risk of disease progression, liver-related complications, and transmission to others.