GI NOTES

Viral Hepatitis

1. Screening

Virus	Who	Test
Hepatitis B	All adults 18 and older at least once (CDC 2023); pregnancy; ongoing risk	Triple panel: HBsAg, anti-HBs, total anti-HBc
Hepatitis C	All adults 18 and older at least once (CDC 2020); every pregnancy; ongoing risk	Anti-HCV with reflex HCV RNA

2. Hepatitis B serology

HBsAg	Total anti-HBc	IgM anti-HBc	Anti-HBs	Interpretation
–	–	–	–	Susceptible: vaccinate
–	–	–	+	Immune from vaccination
–	+	–	+	Immune from past infection
+	+	+	–	Acute infection
+	+	–	–	Chronic infection (HBsAg for more than 6 months)
–	+	–	–	Isolated core antibody: resolved infection, occult infection, or false positive. Check HBV DNA if immunosuppression is planned.

3. Hepatitis B: who to treat

• Cirrhosis with detectable HBV DNA: treat, regardless of ALT.
• Immune-active disease: raised ALT with high HBV DNA: treat.
• HBeAg-positive with very high DNA and normal ALT (“immune tolerant”): treatment is now suggested if age above 40, or with moderate inflammation or fibrosis (F2 or more, for example liver stiffness of 8 kPa or higher). Shared decision-making for younger patients without these features.
• Indeterminate (grey-zone) phase: shared decision-making; male sex, age above 40 and platelets below 180,000 favor treatment.
• Others: HBV-related extrahepatic disease, family history of HCC, and prevention of transmission or reactivation.

Special situations

• Pregnancy: start TDF or TAF at about week 28 if HBV DNA is above 200,000 IU/mL; infant gets vaccine and HBIG at birth.
• Immunosuppression: check HBsAg and anti-HBc before chemotherapy, rituximab, high-dose steroids, or biologics. Give antiviral prophylaxis to HBsAg-positive patients and to core-antibody-positive patients on high-risk regimens such as anti-CD20 therapy.
• HCC surveillance: cirrhosis, and non-cirrhotic patients at high risk (for example people born in Africa, Asian men over 40 and women over 50, family history of HCC).

4. Hepatitis C

• Confirm active infection with HCV RNA; antibodies remain positive after cure.
• Before treatment: assess fibrosis (FIB-4 or elastography), check HBsAg, HIV, pregnancy, and drug interactions.
• Simplified treatment (treatment-naive, no decompensated cirrhosis): glecaprevir/pibrentasvir for 8 weeks, or sofosbuvir/velpatasvir for 12 weeks.
• Cure = undetectable RNA 12 weeks after therapy (SVR12). Reinfection is possible, so keep testing if risk continues.
• Patients with cirrhosis still need HCC surveillance after cure.
• Decompensated cirrhosis: refer to a specialist; protease inhibitors such as glecaprevir are contraindicated.

5. Hepatitis A and E

	Hepatitis A	Hepatitis E
Spread	Fecal-oral; travel, outbreaks, people experiencing homelessness	Fecal-oral (genotypes 1 and 2); undercooked pork or game (genotype 3)
Diagnosis	IgM anti-HAV	IgM anti-HEV, HEV RNA
Course	Self-limited; rarely acute liver failure	Usually self-limited; severe in pregnancy (genotype 1); can become chronic in immunosuppressed patients
Prevention	Vaccine	Food and water hygiene; no US-licensed vaccine

6. High-yield pearls

• HBsAg positive for more than 6 months defines chronic hepatitis B.
• Hepatitis D only occurs with hepatitis B; screen all HBsAg-positive patients for HDV antibodies.
• HBV can flare when HCV is cured with DAAs in co-infected patients; monitor or treat HBV.
• Acute hepatitis with very high ALT and a recent trip abroad: think hepatitis A or E.

References

• Ghany MG, Pan CQ, Lok AS, Feld JJ, et al. AASLD/IDSA Practice Guideline on Chronic Hepatitis B. Hepatology. 2025. doi:10.1097/HEP.0000000000001549.
• Conners EE, Panagiotakopoulos L, Hofmeister MG, et al. Screening and Testing for Hepatitis B Virus Infection: CDC Recommendations, United States, 2023. MMWR Recomm Rep. 2023;72(1):1-25.
• Schillie S, Wester C, Osborne M, Wesolowski L, Ryerson AB. CDC Recommendations for Hepatitis C Screening Among Adults, United States, 2020. MMWR Recomm Rep. 2020;69(2):1-17.
• AASLD-IDSA HCV Guidance Panel. Recommendations for Testing, Managing, and Treating Hepatitis C. hcvguidelines.org (continuously updated).

For educational purposes only. This note does not replace clinical judgment or local protocols. Check doses against current labeling and institutional guidance.